Basic research. Fundamental research Calculation of crank presses studies. allowance

The supersonic jet has a periodic structure consisting of repeating barrel-shaped cells. If the jet off-design, which is defined as the ratio of the pressure at the supersonic nozzle section to the pressure in the environment, differs significantly from unity, then direct shock waves, which are called Mach disks, become clearly visible in the shock-wave structure of the jet. The Mach disk has significant dimensions only in the first barrel of the jet and sometimes in the second. However, its presence strongly influences the downstream jet geometry. Failures in the construction of methods for calculating jets, as a rule, are largely associated with the inability to find the position of the Mach disk. On the other hand, the flow in the vicinity of the Mach disk is characterized by large pressure gradients and a strong viscous-inviscid interaction. In the jets of rocket engines in the regions behind the Mach disks, combustion and dissociation reactions occur, which leads to a significant increase in temperature, pressure, and radiant flux. Despite the practical importance of the problem, there is still no complete theory of the formation of a Mach disk in a supersonic jet. Below we present the necessary information about triple configurations of shock waves, describe the "stationary Mach configuration" model, and justify its application to the problem of calculating a Mach disk in a supersonic jet of an ideal gas.

triple point.

triple configuration of shock waves

stationary Mach configuration

irregular reflection of the jump

regular jump reflection

mach stem

Mach disk

1. Gas dynamics of supersonic non-isobaric jets / V.S. Avduevsky, E.A. Ashratov, A.V. Ivanov, U.G. Pirumov. - M.: Mashinostroenie, 1989. - 320 p.

2. Belyaev N.M., Karteshkin V.A. Investigation of the parameters of a sonic underexpanded cold gas jet. - Dnepropetrovsk: DSU, 1982. - 14 p.

3. Bulat P.V., Zasukhin O.N., Uskov V.N. Formation of a jet during the smooth start of the Laval nozzle // Gas dynamics and heat transfer. Issue. 10. Flows of gases in channels and jets. - St. Petersburg: Publishing House of SPU, 1993. - S. 1-22.

4. Melnikov D.A. Reflection of shock waves from the axis of symmetry // Mechanics and Engineering. - 1962. - No. 3. Ed. Academy of Sciences of the USSR.

5. Interference of stationary gas-dynamic discontinuities / V.N. Uskov and others - Novosibirsk: VO "Nauka", 1995. - 180 p.

6. Uskov V.N. Interference of stationary gas-dynamic discontinuities. Supersonic gas jets. - Novosibirsk: Nauka, 1983. - S. 82-96.

7. Abbett M.J., Mach Disk in Underexpanded Exhaust Plumes // AIAA Journal. - 1971. - Vol.9, March. - R. 512-514.

8. Dash S.M. Seiner J.M., Wolf D.E. Analysis of Turbulent underexpanded Jets. Part. 1: Parabolized Navier Stokes Model, SCIPVIS // AIAA J. - 1985. - vol. April 23, 23 - R. 505-514.

9. Dash S.M. Seiner J.M., Wolf D.E. Analysis of Turbulent underexpanded Jets. Part. 2: Parabolized Navier Stokes Model, SCIPVIS // AIAA J. - 1985. - vol. May 23, 23

10. Dash S.M. Thorpe R.D. Shock - Capturing Model of One- and Two-Phase Supersonic Exhaust Flow // AIAA J. - July 1981. - vol. 19. - R. 842-851.

11. Dash S.M., Sinha N. Noninteractive Cross - Flow integration Procedure for the Pressure - Split Analysis of two Dimensional, Subsonic Mixin Problems // AIAA J. - 1985. - vol. 23 Jan. - R. 183-185.

12. Dash S.M., Sinha N., York B.J. Implicit/Explicit Analysis of Interactive Phenomena in Supersonic Chemically - Reaching Mixing and Boundary Layer Problems // AIAA paper 8517, 17 July 1985.

13. Dash S.M., Wolf D.E. Interactiv Phenomen in Supersonic Jet Mixing Problems, Part. 1. - AIAA J. - May 1984. - P. 905-913.

14. Dash S.M., Wolf D.E., Pergament H.S. A Chock-Capturing Model for Two - Phase, Chemically reaching Flow in Rocket Nozzles and Diffusers, - AIAA P. 85-0.

15. Jungowski W.M. On flow in suddelargement of a duct. fluid dynamic. - 1969. - vol. 4. - R. 231-241.

Supersonic jet (Fig. 1) In the general case, the outflow from the nozzle of an aircraft moving at a certain speed is a combination of shocks, surfaces of tangential velocity discontinuities, and regions of smooth flow. The presence of bottom rarefaction in region 1, compression waves 3, 7 resulting from the interaction of the jet with a supersonic cocurrent flow 2, mixing layers 4, 9, 10 formed on tangential discontinuities lead to the formation of a complex shock-wave structure (SWS) of the jet. It consists of rarefaction waves 4, 6 and shock waves. The falling shock 5 is always reflected from the axis with the formation of a triple configuration of shock waves or, as they say, a triple point. A direct shock at a triple point is called a Mach disk or a Mach disk, and shock 8 is called reflected.

It should be noted that as the incident shock approaches the axis of symmetry, its curvature TOσ tends to infinity, because TO σ ~y-1 , therefore, the conditions for the formation of a Mach disk in an off-design jet are always created. This fact corresponds to the well-known from the works of Melnikov D.A. (1962) to the statement about the impossibility of regular reflection of the shock wave from the axis of symmetry, which is indicated by and dynamic compatibility conditions(UDS) on shock waves. On the axis of symmetry, the conditions of equality to zero of the slope of the velocity vector and the curvature of the streamline behind the reflected shock must be satisfied, but at y= 0 is impossible.

Rice. Fig. 1. Supersonic flow around the bottom of the aircraft: 1 - bottom area; 2 - cocurrent; 3 - tail jump; 4 - dividing current line; 5 - hanging jump; 6 - subsonic region of the mixing layer; 7 - compression waves and closing shock; 8 - reflected jump; 9 - region of mixing behind the Mach disk; 10 - mixing layer at the jet boundary

Models for the formation of a Mach disk - a history of study

Let us dwell in more detail on the question of the position of the Mach disk in the jet. The Mach disk has noticeable dimensions only in the first barrel and sometimes in the second. However, its presence strongly influences the downstream jet geometry.

Failures in the construction of methods for calculating jets, as a rule, are largely associated with the inability to find the position of the Mach disk. A detailed analysis of this issue is carried out in , where various hypotheses available in the literature for the transition from regular reflection of the shock wave from the axis to irregular (Mach) reflection are discussed. The most famous of them is the so-called Abbet procedure, often mentioned in the famous works of Dash, devoted to the construction of a method for calculating the torch of an engine of a solid-propellant tactical missile, as well as various assumptions about the pressure value behind the reflected shock at the triple point. We will not consider the latter, because today it is already known that they are not applicable in the general case.

Abbet's procedure establishes some analogy between a Mach disk in a jet and a starting shock wave (SW) that occurs when a Laval nozzle is launched. Initially, it was assumed that in the minimum cross section of the flow behind the Mach disk, the pressure is equal to atmospheric pressure. Later it turned out that this assumption is approximately fulfilled only in strongly underexpanded jets, in which a turbulent section begins immediately after the first barrel. In undersized jets, Abbet's hypothesis leads to too large errors.

Abbet's hypothesis was modernized by Dash, assuming that in the critical section behind the Mach disk the "throat of the flow" condition is satisfied, i.e. the flow velocity becomes equal to the local speed of sound. If we specify the position of the triple point on the falling shock, then we thereby determine the initial conditions for calculating the flow limited by the Mach disk and the tangential discontinuity. Considering this flow to be one-dimensional, one can perform the calculation in the same way as in the Laval nozzle. If, as a result of the calculation, in the minimum section of the flow behind the Mach disk, the velocity is equal to the local speed of sound, then in the Abbet-Dash procedure it is considered that the position of the Mach disk in the jet is chosen correctly.

Among other models, the experimentally described criterion is well confirmed, according to which the formation of a Mach disk occurs when the intensity of the incident shock reaches the value J=J 0 corresponding stationary Mach configuration(QMS) . Such configurations of shock waves have been studied in detail in connection with the problem of shock reflection from a solid wall.
An indirect substantiation of the criterion J 0 is the solution of the first-order problem of triple configurations of shock waves (jumps). If at each point of the hanging (falling on the axis of symmetry) shock to perform a formal calculation of the triple configuration of shock waves, then at intensities J< J 0, the outgoing tangential discontinuity τ has a positive curvature. At the jump point where J=J 0 , the curvature τ becomes negative, which corresponds to the established empirical ideas about the shape of the tangential discontinuity.

Brief information from the theory of triple configurations of jumps

A triple configuration (TC) of shock waves (shocks) is a shock-wave structure consisting of three shock waves σ intersecting on a certain line and the surface of a tangential discontinuity τ emanating from this line (Fig. 2), σ 1 is called an incoming shock, σ 2 - outgoing, σ With - main shock wave.

Rice. 2. Triple configuration of shock waves

Triple configurations occur during irregular reflection of a shock from a solid surface and from the axis of symmetry in axisymmetric flows, in some problems on the interaction of oncoming shocks, and also in the interaction of overtaking shocks. The concept of TC was first introduced in the problem of shock wave running into a wedge. As it propagates along the wedge, the intensity of the incident wave increases, and its surface curves, remaining perpendicular to the surface of the wedge. Starting from some moment, the shock wave branches with the formation mach legs.

Later, the stationary case of shock reflection from a solid wall was studied. At a low intensity of the shock incident on the wall, it is reflected from the wall in a regular manner (Fig. 3). Starting from a certain intensity, the reflected shock can no longer rotate the flow in such a way that the velocity vector behind it is parallel to the wall, because the limiting angle of the flow turn at the shock, calculated from the Mach number behind the first shock, is less than the angle of inclination of the velocity vector to the wall surface behind the first shock. Then the reflection occurs irregularly with the formation of an SMC. In contrast to the nonstationary case, the intensity of the Mach stem is equal to the maximum J m (M).

It is convenient to study triple configurations on the plane of shock polars. lnJ-β , nicknamed for their characteristic appearance heart-shaped curves. A detailed analysis of heart-shaped curves, singular points, areas of existence of the TC is given in. According to the classification, triple configurations TK-1, TK-2 and TK-3 are distinguished.

Rice. 3. Regular (left) and irregular (right) shock reflection from the wall: σ With - mach stem

Triple configurations TK-1 arise during the interaction of opposite shock waves of different directions, for example, in supersonic air intakes of internal compression. TK-1 corresponds to the point of intersection of the left branches of the polars (Fig. 4). As the intensity of the incoming shock 1 increases, the intersection point moves towards the top of the main polar until it reaches it, this moment corresponds to the SMC.

TK-1 can only exist at Mach numbers M > M T

At lower Mach numbers, the polars do not intersect. With a Mach number equal to M T, behind the shock, the maximum static pressure is reached, at a given adiabatic index γ (for air γ = 1.4). Triple configurations TK-2 occur at irregular reflection of the shock wave from the wall. The difference from TK-1 is that in TK-2 the direction of flow deflection on the main shock (Mach stem) is reversed (Fig. 5). As the intensity of the jump increases J 1 major jump 4 warps. When shock 1 is reflected from the wall, the Mach stem is bent, approaching the wall orthogonally.

Rice. 4. Triple configuration TK-1

Rice. 5. Triple configuration TK-2

Triple configurations TK-3 arise during the interaction of overtaking shock waves of the same direction. Their study is of great practical importance for the design of external compression supersonic air intakes. Triple jump configurations and jet Mach disks

Let us dwell in more detail on the triple configurations of TK-2, since they are directly related to the problem of calculating the Mach disk in a supersonic jet. The triple configurations TK-1 and TK-2 are separated by a stationary Mach configuration, which corresponds to the case when the secondary shock polar crosses the main polar at its apex. In the SMC (Fig. 6), the main shock wave (4) is direct. characteristic intensity J 0 is obtained from the solution of the cubic equation corresponding to the intersection of the polars at the top of the main polar (Fig. 6).

z 0 = J 0 ,

Rice. 6. Stationary Mach Configuration (SMC)

For some characteristic Mach number M OR. in the SMC, the polar corresponding to the incoming shock 1 crosses the top of the main polar at the point of the limiting rotation angle 4 (Fig. 7).

This implies a transcendental equation for a special number M 0R:

Odds Ai have the same meaning as in the previous equation.

For Mach numbers less than M OR , the polar intersects with the y-axis inside the main polar, and often the intensity is taken as a criterion for the transition to irregular reflection J R, which corresponds to the touch of the polar of the y-axis (Fig. 8), which makes it possible to find the value of this intensity from the solution of the following equation:

Rice. 7. Special configuration corresponding to MOR

This criterion has not received experimental confirmation in the stationary case.

Verification of the SMC Hypothesis for the Case of Formation of a Mach Disk in a Jet

In order to correctly check the compliance of the calculation technique with the experimental data, it is necessary to reduce the influence of viscous effects, which distort the flow pattern in the vicinity of the nozzle edge, to a minimum in the experiment. This can be achieved in an installation in which the jet flows out of a sonic nozzle with a bottom screen. Inside such a nozzle, the boundary layer is small, and there is no ejection flow at its edge.

Rice. 8. TC corresponding to J = JR, M< МOR

A similar experiment was carried out at Dnepropetrovsk University. On fig. Figures 9 and 10 show the deletion dependencies L from the nozzle exit of the characteristic sections of the jet, as well as the value of the diameter D of the corresponding element of the first barrel of the jet from the self-similar parameter, obtained by calculation by the method of characteristics.

Rice. 9. Comparison of the removal of the main sections of the first barrel of the underexpanded jet, obtained by calculation, with the experimental data:
L b - distance from the nozzle exit to the point of intersection of the reflected shock with the jet boundary; L BC is the distance from the nozzle exit to the section with the maximum diameter of the hanging shock; L M - distance from the nozzle exit to the section with the maximum diameter of the jet boundary; L DM - distance from the nozzle exit to the flywheel

Rice. 10. Comparison of the results of calculating the diameter of the main elements of the first barrel of the jet with the experiment: D BC - the maximum diameter of the hanging shock; D M - maximum diameter of the jet boundary; D DM - flywheel diameter

The triple point on the hanging shock was chosen in the section in which the intensity of the hanging shock was equal to J0. There is not only a qualitative, but also a satisfactory quantitative agreement with the experiment.

Conclusion

It is shown that the stationary Mach configuration model makes it possible to predict well the position of Mach disks in a supersonic jet. When calculating the Mach disk at the point of the hanging shock, at which its intensity J = J0, it is possible to determine the diameter of the Mach disk and its distance from the nozzle exit. The calculation results showed good agreement with experiment. The above arguments can only serve as an indirect proof of the model; its theoretical substantiation and the results of a complete computational and experimental study are beyond the scope of this work and will be considered separately.

Reviewers:

Baranov I.V., Doctor of Technical Sciences, Professor, Deputy Director of the Institute of Refrigeration and Biotechnology, St. Petersburg National Research University information technologies, mechanics and optics”, St. Petersburg;

Pelenko V.V., Doctor of Technical Sciences, Professor, Deputy Director for Academic Affairs of the Institute of Refrigeration and Biotechnology, St. Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg.

The work was received by the editors on July 20, 2012.

Bibliographic link

Uskov V.N., Bulat P.V., Prodan N.V. HISTORY OF STUDYING THE IRREGULAR REFLECTION OF A COMPACTION SHOCK FROM THE AXIS OF SYMMETRY OF A SUPERSONIC JET WITH THE FORMATION OF A Mach DISK // Fundamental Research. - 2012. - No. 9-2. - S. 414-420;
URL: http://fundamental-research.ru/ru/article/view?id=30239 (date of access: 07/29/2019). We bring to your attention the journals published by the publishing house "Academy of Natural History"

searching results

Found results: 47824 (1.49 sec)

Free access

Limited access

License renewal is being specified

Health-improving and professional-applied effectiveness of physical culture and mass work in the dormitory of SPTU (on the example of a building)

M.: PROMEDIA

Therefore, the mandatory set of simulators for a bricklayer, for example, included a "Health Disc", for a plumber-gas welder

Preview: Health-improving and professional-applied effectiveness of physical culture and mass work in the dormitory of the vocational school (on the example of a construction one).pdf (0.3 Mb)

media magnetic disks.<...>Users and even programmers often say: "Drive A:", "Drive B:", etc.<...>from a disk, for example, to a screen, to another disk, or to a printer.<...>The teacher prepared for this Purpose: disks for each workplace (on each Micron disk with text<...>The list of filenames stored on a disk is called a disk directory.

Preview: Informatics Grade 3.pdf (0.6 Mb)

No. 5 [Thermophysics and Aeromechanics, 2015]

The flow behind the reflected shock is supersonic, and behind the Mach disk is subsonic.<...> <...>Mach disk at rA = 0.35 and rA = 0.26.<...>subsonic flow zone behind the Mach disk.<...>Mach disk at rA = 0.35 and rA = 0.26.

Preview: Thermophysics and Aeromechanics №5 2015.pdf (0.6 Mb)

The results of numerical simulation of the impingement of an underexpanded pulsed gas-dispersed jet with a high concentration of particles onto a rigid barrier unlimited in the transverse direction are presented. The characteristic features of such an interaction are studied, in particular, the “anomalous” formation of a shock-wave structure of a two-phase flow at subsonic velocity along the carrier gas and the development of self-oscillations

Some differences, such as the calculated size of the Mach disk, are larger than those observed in the experiment (Fig.<...>In this case, the Mach 1 disk for the case of the initial bulk concentration of particles (Fig. 4) consists of two parts<...>This is due to the vortex motion of mixture 2, which is adjacent to the Mach disk near the symmetry axis.<...>In the second variant - behind the Mach disk x ′′ = 6.<...>Then the two-phase medium runs over the barrier with the formation of a Mach 4 disk.

A method for correcting PIV data for reconstructing the gas velocity from the velocity of particles in supersonic underexpanded jets is considered. The method is based on estimating the velocity delay of tracers from their velocity relaxation parameter as a correction to the PIV data in the Newtonian approximation of interfacial interaction. It is shown that the rate relaxation parameter of tracers in flows with velocity jumps can be determined from the initial PIV data. Correction with the found parameter of the rate relaxation of the phases showed good accuracy.

<...> <...> <...> <...>

The problem of initiating and stabilizing the detonation combustion of a hydrogen-air mixture entering an axisymmetric channel with a central body of finite length in a flow with Mach number M0 = 5 ÷ 9 is solved. stabilization of detonation combustion of a stoichiometric hydrogen-air mixture at freestream Mach numbers M0 > 7. Different channel configurations are compared depending on the amount of thrust resulting from the detonation combustion of a stoichiometric hydrogen-air mixture.

When a high-speed supersonic flow enters the central body, a disk is formed near the axis of symmetry<...>hydrogen-air mixture was obtained for a nozzle with an internal cylinder, the presence of which prevents the formation of a disk<...>Thus, in an axisymmetric convergent-divergent nozzle without a central body, a disk is formed in the flow<...>the flow of the flammable mixture begins to interact with the central body as beyond the point of formation of the disk<...>Mach, and in front of it (Fig. 4).

The paper presents the results of a study of the impingement of a supersonic underexpanded air jet onto a porous metal barrier of finite thickness, the front plane of which is perpendicular to the jet axis, and the side surface is impermeable to the gas flow. To determine the effect of porosity on the gas-dynamic characteristics of the interaction of a jet with an obstacle, the case of a non-porous obstacle of the same diameter was also considered.

The Mach number in the outlet section is Ma = 1.72, the degree of non-design of the jet outflow is n = 2.1.<...>A porous barrier in the form of a disk with a diameter dp = 100 mm and a thickness ∆lp = 20 mm was inserted into a metal<...>Supersonic underexpanded jet interacting with a porous barrier: a - minimum distance between the disk<...>The amplitude of the Mach disk oscillations along the jet axis is 0.15da.<...>T. 56, N-◦ 3 corresponded to the rotation of the flow through an angle equal to 90◦, while the Mach disk was at a relative

No. 1 [Thermophysics and Aeromechanics, 2018]

Journal Founders: Siberian Branch of the Russian Academy of Sciences S.S. Kutateladze SB RAS Institute of Theoretical and Applied Mechanics. S.A. Khristianovich SB RAS The main scientific topics of the journal are: - hydrogasdynamics - heat and mass transfer - turbulence - means and methods of aero- and thermophysical experiment - physics of low-temperature plasma - physical and technical problems of energy

However, with an increase in flight speeds above M = 4, the size of the Mach disk decreases significantly and the frontal<...>At moderate supersonic Mach numbers of the oncoming flow, the Mach disk has some finite transverse<...>The dimensions of the Mach disk decrease significantly with an increase in the Mach number of the oncoming flow.<...>Mach , and further systems of funnel-shaped shock waves with Mach disks are formed.<...>must match the presence of Mach disks (with subsonic flow immediately behind them).

Preview: Thermophysics and Aeromechanics №1 2018.pdf (0.5 Mb)

Numerical modeling of the flow, which is formed during the transverse injection of a jet into a supersonic flow through a slotted nozzle, is carried out at different pressures in the injected jet and the main flow. For calculations on grids with different resolutions, the Spalart-Almaras turbulence model, the realized k–ε model, the k–ω model, and the SST model are used. Based on a comparison of the calculated and experimental data on the pressure distribution on the wall, the length of the recirculation region, and the depth of jet penetration into the supersonic flow, conclusions are drawn about the accuracy of the results of calculations using various turbulence models and the applicability of these models to solving similar problems.

Mach and shock wave due to re-compression of the flow.<...> <...>injection, and the depth of penetration of the jet into the main flow H, which is determined by the position of the upper edge of the disk<...>Mach.<...>Mach 5.

A computational-theoretical study of the features of the flow of supersonic high-enthalpy flows in narrow cylindrical channels has been carried out. Mathematical model is based on solving the complete non-stationary system of Navier-Stokes equations in an axisymmetric formulation. The calculations were performed for laminar and turbulent flow regimes using various turbulence models. The influence of the geometrical parameters of the channel on the characteristics of the flow is analyzed. The features of the distribution of the Mach number along the radius of the flow in various sections of the channel are considered. It is shown that, depending on the conditions, deceleration of varying intensity takes place up to the formation of a subsonic flow zone of considerable length in the channel.

has several maxima, which, in our opinion, corresponds to the formation of additional jumps behind the disk<...>Mach during deceleration of a supersonic flow).<...>supersonic flows in narrow cylindrical channels 15 such as the mentioned additional jumps behind the disc<...>Mach, can be identified more distinctly.<...>of supersonic flows in narrow cylindrical channels 17 In the k−ε model, the first disk

The work numerically simulates a supersonic air flow in a flat channel with a transverse injection of a turbulent hydrogen jet through a slot on the bottom wall. An algorithm for solving the Favre-averaged Navier–Stokes equations for the flow of a perfect multicomponent gas based on the WENO scheme is proposed. The main attention is paid to the interaction of the shock wave structure with the boundary layers on the lower and upper walls of the channel under conditions of internal turbulent flow, namely, a detailed study of the flow structures was carried out, separation and mixing were studied depending on the width of the jet slot. It has been established that, in addition to the known shock-wave structures arising from the interaction of the oncoming flow with the transverse jet and from the interaction of the head shock wave with the boundary layers near the walls, an additional system of shock waves and flow separation on the lower wall at a certain distance from the jet downstream are formed. A comparison with experimental data is made.

On the graphs of isobars 4, the Mach disk is clearly visible.<...>the size of the slot leads to the expansion of the barrel-shaped structure in the jet and, as a consequence, to an increase in the disk<...>Mach (Fig. 4a and 4b).<...>However, in the case of the maximum slot size (h3) (Fig. 4c), the Mach disk decreases, since the separation zone<...>Mach , which demonstrates the distribution of the local Mach number (2 2M ,u w c= + here с  local speed

<...> <...> <...>

A three-dimensional supersonic turbulent flow with a symmetrical perpendicular injection of round jets from the channel walls is numerically modeled. Using the algorithm built on the basis of the ENO-scheme, the original Favre-averaged Navier-Stokes equations are solved, closed using the (k–ω)-turbulence model. For the values of the off-design parameter 3 6 n 6 50, the mechanism of the formation of vortex structures during the interaction of a jet with an oncoming flow has been studied. It has been experimentally established that at n > 10, as a result of mixing of the jet and the incoming high-speed flow, a pair of vortices appears and an additional separation occurs near the wall behind the jet. It is shown that the results of calculating the pressure distribution on the wall in front of the jet in the plane of symmetry agree satisfactorily with the experimental data.

flow behind the jet due to the formation of a low pressure zone; the appearance of a barrel-shaped structure and a disc<...>Mach in the jet.<...>are formed in the mixing zone, a pair of vortices 9 is formed due to the interaction of the jet passing through the disk<...>Mach D, with a high-speed oncoming flow.<...>way: - in the jet u = 0, v = 0, T = 0.6, w = √ T M0 / M∞, P0 = nP∞, z = 0, x 2 + y2 6 R (M0 is the Mach number

The results of spectroscopy of the initial section of a supersonic plasma jet formed by a pulsed discharge in a capillary with an ablating wall made of a carbon-containing polymer are presented. The features of the spatial distribution of the electron density and the intensity of the spectral components are revealed, which, in particular, are caused by the high value of the electron temperature in the "hot" central zone, which exceeds the "normal" temperature, as well as by the significant non-isobaricity of the initial section of the supersonic jet. The radiative properties of the high-temperature jet core recorded with high temporal (1-50 µs) and spatial (30-50 µm) resolution (intensity and contour of the Balmer Hα and Hβ lines, relative intensities of the C II ion lines) made it possible to establish the main regularities in the distributions of pressure and temperature in the vicinity of the central shock wave. Due to the presence of molecular components in the flow, which exhibit their radiative properties at the periphery of the jet, it was possible to obtain an idea of the plasma parameters in the zone of formation of "hanging" shock waves.

based on the results of optical visualization of the flow and by analyzing shock wave structures: Mach number<...>The temperatures thus determined are Te ~ 2 eV in the vicinity of the Mach disk (z = 2.5<...>The pressure profile p(r) reconstructed using the above procedure in the vicinity of the Mach disk is qualitatively<...>The reconstructed pressure profile in the vicinity of the Mach disk agrees qualitatively and quantitatively with the results

No. 3 [Thermophysics and Aeromechanics, 2018]

At moderate supersonic Mach numbers of the oncoming flow, the Mach disk has a finite transverse dimension<...>The dimensions of the Mach disk decrease significantly with an increase in the Mach number of the oncoming flow, and in the resulting<...>should correspond to the presence of subsonic Mach disks directly behind them.<...>Mach pseudojump.<...>behind the second Mach disk (x = 3.93 m, x = 10.15), curve 5 ⎯ end of the separation zone of the boundary layer (x =

Preview: Thermophysics and Aeromechanics №3 2018.pdf (0.5 Mb)

The results of experimental studies and numerical simulation of self-oscillations in a supersonic radial jet flowing from a flat radial nozzle into a flooded space are presented. It is shown that bending vibrations develop in the jet, leading to its destruction. It has been established that a large role in the formation of self-oscillations is played by feedback, which is carried out by sound waves in the gas surrounding the supersonic jet.

bounded by cylindrical surfaces with radii r1, r2, and a radial channel bounded by two disks<...>The tilt angle of the Mach waves with respect to the jet axis is α ≈ 40°.<...>On fig. 6 shows the distribution of the Mach number on the jet axis at different times.<...>Using these values, we find the convective Mach number of the jet Mc = 2M/(1+ c0/cj) ≈ 2.3.<...>given the outflow regime on the jet axis, there is a regular interaction of shock waves without the formation of a disk

Experimental study of the influence of acoustic-vortex self-oscillations on the process of destruction of an underexpanded supersonic jet in a flooded space [Electronic resource] / Alexandrov, Arefiev, Ilchenko // Thermophysics and Aeromechanics.- 2016 .- No. 4 .- P. 45-55 .- Access mode: https://site/efd/434738

The intensification of the mixing of the gaseous working fluid supplied through the jet nozzles with the environment is an important scientific and technical problem, the solution of which will improve the efficiency of the working process in power and power plants. A topical, but little studied direction is the generation of acoustic-vortex self-oscillations in jet nozzles, which can accelerate the disintegration of a supersonic jet and thereby improve mixing performance. The article presents the features of the excitation of acoustic-vortex self-oscillations in jet nozzles; the main results of an experimental study of a model jet nozzle are presented, in the channel of which plates are installed that provide the excitation of acoustic-vortex self-oscillations; regularities were found for the decay of an underexpanded supersonic jet in a flooded space for various flow regimes. The presented data show the possibility of effective application of jet nozzles with generated acoustic-vortex self-oscillations in relation to gaseous fuel supply systems. The results of the study can be used in the design of power plants for promising samples of aerospace equipment and technological devices.

Reflection from the axis of the shock wave results in the formation of a Mach 7 disk.<...>The frequency of the acting force is determined by the formula: St M ,f c t= ⋅ ⋅ here M  the Mach number of the flow in the cavity<...>centered rarefaction wave, 4  jet boundary, 5  compression wave, 6  hanging shock wave, 7  disk<...>Mach , 8  reflected shock wave, 9  outer mixing region.<...>In experiments, the change in the Mach number in the cavity was controlled by changing the diameter d of the MSF nozzle.

No. 3 [Applied mechanics and technical physics, 2004]

shock waves 3, 4, 5; 7 - fan of rarefaction waves; b: 1 - nozzle; 2 - compression jump; 3 - Mach disk<...>Mach near the axis (r/Ra = 0÷0.15).<...>Free flow Mach number M = 5.<...>Mach.<...>time may result in the loss of information recorded on the disc.

Preview: Applied Mechanics and Technical Physics No. 3 2004.pdf (0.3 Mb)

No. 5 [Physics of combustion and explosion, 2015]

The journal publishes articles with the results of original experimental and theoretical research in the following sections: combustion in gases and condensed media detonation of condensed explosives, gases and heterogeneous systems production of new materials by self-propagating high-temperature synthesis, shock and detonation waves high-speed impact, dynamic loading of materials and structures welding explosion and detonation spraying

Mach 3, and the flow velocity directly behind the Mach disk becomes subsonic.<...>The flow velocity in front of the Mach disk reaches V = 545 m/s according to PIV. 5.<...>Further behind the Mach disk, the velocity abruptly drops to V = 190 m/s and U = 95 m/s (PIV and calculation, respectively<...>Even on a direct jump (Mach disk), due to averaging over a large number of instantaneous realizations, one can see<...>On fig. 6 it is also seen that behind the Mach disk, after a sharp deceleration of the flow, the velocity lag of particles

Preview: Physics of combustion and explosion No. 5 2015.pdf (0.1 Mb)

M.: Publishing house of MSTU im. N.E. Bauman

The principles of magnetic-inertial thermonuclear fusion and laser-plasma methods for generating fields during the implosion of a magnetized target are considered. The results of the work open up the possibility of creating new high-density plasma sources for their use in materials science experiments and for promising areas of energy. Such plasma systems can be used to diagnose and test various materials. The Richtmyer-Meshkov instability in impulsive systems with inertial particle confinement has been studied.

field, i.e. at 0)B = , consisting of a group of lateral hanging shock waves (SW) and a central disk<...>Mach crossing the axis of symmetry.<...>Here, behind the central Mach disk (at subsequent moments of time), a vortex wake (toroidal<...>in this case, it is limited along the radial coordinate with a size of 1 cm. R ≤ In this spatial zone, the Mach number<...>structure, and the maximum temperature in the jet is at the level 3max 18 10 K,T ≈ ⋅ Mach number

No. 3 [Thermophysics and Aeromechanics, 2017]

The diameter of this disk depends on the Mach number of the oncoming flow and the intensity of the incident shock.<...>In the case under consideration, the Mach disk practically does not manifest itself as when falling on the axis of the initial shock<...>This is due to the high flow velocity when an initial Mach disk of small transverse size is formed.<...>Mach of a larger size, then subsequent Mach disks are formed (Fig. 4b).<...>The region with detachments and Mach disks gradually moves forward, and as a result, in front of the entry section

Preview: Thermophysics and Aeromechanics №3 2017.pdf (0.5 Mb)

№5 [Applied mechanics and technical physics, 2015]

The journal publishes original articles and commissioned reviews on the mechanics of liquid, gas, plasma, dynamics of multiphase media, physics and mechanics of explosive processes, electric discharge, shock waves, state and motion of matter at ultrahigh parameters, thermal physics, mechanics of deformable solids, composite materials, methods diagnostics of gas-dynamic physical and chemical processes.

Mach in the jet.<...>The region of jet penetration into the main flow is limited by hanging shocks and the Mach disk.<...>Mach.<...>Mach 5.<...>Experimental study of the rise of a glass round disk from the surface of the water, the purpose of which was

Preview: Applied Mechanics and Technical Physics No. 5 2015.pdf (0.2 Mb)

Parallel computing in solving problems of aerohydrodynamics by the method of large particles studies. manual on the course "Parallel programming"

M.: Publishing house of MSTU im. N.E. Bauman

The problems of flow past bodies of various geometric shapes at various velocities of the oncoming flow (subsonic and supersonic) in the plane and axisymmetric cases are considered in the entire range of permeability: from impermeability to free flow. Descriptions of programs for calculating three-dimensional non-stationary problems taking into account the gravitational field (Rayleigh-Taylor instability problems) using the difference scheme of the large-particle method on triangular, hexagonal and orthogonal computational grids are given. The textbook is accompanied by a CD-ROM containing the texts of 20 working programs in the FORTRAN algorithmic language, designed to solve problems of aerohydrodynamics using the KRUCHA-2 PPP.

Flow schemes: a - thin permeable body; b - disk with a visor-shell 2.<...>and P(30, 2) = 0.63 behind the disk near the axis of symmetry at time TK = 20.00.<...>and P(30, 2) = 0.78 behind the disk near the axis of symmetry at time TK = 20.00.<...>and P(30, 2) = 0.80 behind the disk near the axis of symmetry at time TK = 20.00.<...>and RO(30, 2) = 0.47 behind the disk near the axis of symmetry at time TK = 20.00.

Preview: Parallel computations of the problem of aerohydrodynamics by the method of large particles.pdf (0.1 Mb)

Teaching balances and turns in sports aerobics studies. allowance

Publishing house SibGUFK

The manual provides information about the technique of performing balances and turns, as well as a methodology for teaching these elements, taking into account the physical qualities and functional abilities necessary for successful training at the stage of initial training in sports gymnastics. The manual provides new information that reflects the methodology for teaching balances and turns in sports aerobics, based on the general biomechanical patterns of their implementation, taking into account the requirements of the competition rules of this sport popular among young people.

Balance with tilt (vertical max). 2. Study of the 180° turn on the "health disk". 3.<...>on the “health disc”, arms to the sides: 1–2 – left push and swing of the hands turn on the disc by 360; 3-4 -<...>health", left on the floor, arms to the sides: 1-2 - with a push of the left and a swing of the hands, turn on the disk by 360,<...>, left on the floor, arms to the sides: 1–2 - with a push of the left and a swing of the hands, turn on the disk by 360, bending the left<...>floor, arms to the sides: 1-2 - with a push of the left and a swing of the hands, turn on the disk by 360 with eyes closed;

Preview: Teaching balance and turns in sports aerobics. 2013 ed.pdf (0.3 Mb)

№5 [Applied mechanics and technical physics, 2001]

In this case, the inner diameter of the jet, determined from the diameter of the Mach disk, is almost 10 times greater than<...>Mach , the flow around the element occurs without the departure of the Mach disk .<...>Under these conditions, there is no significant change in the size of the jet behind the Mach disk, and as the area<...>of the jet around the side holes, one can take the area of the jet at the level of the Mach disk.<...>For practical use with a Mach disk diameter 10 times the diameter of the outlet hole

Preview: Applied Mechanics and Technical Physics No. 5 2001.pdf (0.3 Mb)

№2 [Applied mechanics and technical physics, 2010]

As well as a set of wheels and a fairing.<...>Top Profiled Disc , Disc Set , Rotor Fairing Top and Guide Top Edge<...>; N is the number of revolutions per minute of the classifier discs.<...>Mach, jet boundary.<...>Estimated distribution of Mach numbers at the exit of a multi-mode nozzle with different exit Mach numbers

Preview: Applied Mechanics and Technical Physics №2 2010.pdf (0.2 Mb)

Thermogasdynamic calculation of centrifugal compressors. allowance

The calculation procedure is described and the algorithm for calculating the flow path of a centrifugal stationary compressor is presented. Examples of calculations for impellers, diffusers, reverse guide vanes, and outlet devices are given. The issues of optimization and selection of the flow part of the compressor are considered.

in section i; 111 awM w = is the Mach number in section 1 with respect to velocity 1w ; 222 acM c = is the Mach number in the cross section<...>Mach number for circumferential speed (conditional Mach number) .612.0 28558.49695.030.1 83.25522 = ⋅⋅⋅ === nn<...>Wheel closed type consists of the main disk 1, the covering disk 2 and the blades 3 (Fig. 7.1).<...>The blades can be integrally milled together with the main disk, and the covering disk is soldered to them.<...>The blades are first welded to the main disk, and then the cover disk is soldered to the blades.

Preview: Thermogasdynamic calculation of centrifugal compressors. Tutorial.pdf (0.2 Mb)

Run! Jump! Throw! Official IAAF Athletics Training Guide: [training method. allowance]

M.: Man

The Official IAAF Training Guide for Athletics Run! Jump! Throw!" divided into three main sections, each of which covers one group of species, which is the name of the section. The main sections begin with a very brief overview and basics of each species group. This includes the most important sections of the basic theory - general goals, basic biomechanical principles and an overview of the structural phases - basic exercises, teaching recommendations and examples of games that will help introduce the skills that are required to engage in the species included in this group. The running section also provides a brief overview of middle and long distance running training.

the leg swings in front of the body and straightens for contact (front swing), while the jerk<...>Copyright JSC "Central Design Bureau "BIBKOM" & OOO "Agency Kniga-Service" 182 DISC THROWING DISC THROWING<...>backswing and ▲ active - forward.<...>NOTES: Don't grab the drive. ▲ Bend your legs as you roll the ▲ disc on the ground.<...>NOTES: Hold the disc at ▲ head level. Feel the disc release through your index finger.

Preview: Run! Jump! Throw! Official IAAF Training Guide for Athletics.pdf (0.3 Mb)

Methodology for the development of strength in the process of physical education of students at the university method. recommendations

This work introduces students to the methods of developing strength abilities in physical education classes. The paper discusses the main and additional means that can be used in physical education classes to develop students' strength abilities. This paper proposes control exercises to determine the level of development of strength abilities.

Tilt forward to perform with a half squat and swing your arms back, straighten with a wave of your arms forward and up<...>Breathing: swing legs back inhale, exhale forward. 7.<...>Breathing: swing your legs up, inhale, legs down, exhale. eight.<...>Breathing: in and. p. inhale, max exhale. 37.<...>one leg, simultaneously swing the thigh of one leg.

Preview: Methods of strength development in the process of physical education of students at the university.pdf (0.5 Mb)

No. 3 [Thermophysics and Aeromechanics, 2019]

Data estimates showed that for a water drop with d = 2.7 mm, the Mach numbers of the shock wave Ms = 1.3, 1.5<...>Mach 5 at NPR = 4 (Fig. 4a) and NPR = 6 (Fig. 4c).<...>Mach »  in a pure gas, and in a two-phase jet core it is an indirect sign of the existence of a «third<...>Mach in a supersonic underexpanded jet consisting only of gas.<...>Here M∞  Mach number , Re1  unit Reynolds number, T∞  free flow temperature, p∞  pressure

Preview: Thermophysics and Aeromechanics №3 2019.pdf (0.5 Mb)

Athletics. Question-answer methodological recommendations for students of the Faculty of Physical Education of higher educational institutions

FGBOU VPO "SHGPU"

The methodological recommendations were compiled on the basis of the educational and methodological complex for the discipline "Athletics", developed at the Department of Sports Disciplines of the State Educational Institution of Higher Professional Education "SPU". The recommendations are intended for students of the faculty of physical culture of pedagogical universities, teachers and teachers of physical culture.

Disc holding.<...>Turns without a disc and with a disc at different speeds. 2.<...>Leg swings, standing against the wall on the push leg. 2.<...>Coaches consider the straightening leg swing to be more effective.<...>Disk.

Preview: Athletics. Q&A.pdf (0.5 Mb)

№6 [Applied mechanics and technical physics, 2009]

In the papers, overexpanded jets are considered, the Mach disk and the subsonic zone are obtained by calculation<...>In the case of an underexpanded jet, a flow field with a vortex formed behind the Mach disk is obtained.<...>Since the flow in the nozzle was off-design, oblique shocks and a Mach disk were formed inside it, and<...>In front of the Mach disk, the gas accelerates to Mach numbers on the M axis = 6.8; 4.4 corresponding to the values<...>On the calculation of a supersonic overexpanded jet of an ideal gas in the presence of a Mach disk in the flow // Uchenye

Preview: Applied Mechanics and Technical Physics №6 2009.pdf (0.2 Mb)

Athletics: the basics of knowledge (in questions and answers) studies. allowance

The textbook contains brief information on the history of the development of athletics, analysis of techniques and methods of teaching track and field exercises, organization and basic rules for refereeing competitions in sports, which are presented in a form convenient for study and assimilation. Are given typical mistakes when performing athletics exercises and recommendations for their correction.

copper or bronze disc.<...>In long jump, the swing is performed with one hand up and forward, in the triple jump, the swing is performed as two<...>, the disk is around the vertical.<...>Perform a swing with a bent leg. Circle radius 8–10 m. 2.<...>the swing was made with the heel forward) 2.

Preview: Athletics knowledge base (in questions and answers).pdf (0.6 Mb)

Initial motor training in sports aerobics studies. allowance

Publishing house SibGUFK

The textbook is written on the basis of the requirements of the federal state educational standard of higher professional education, direction 034300.62 "Physical culture", and the work program of the discipline "Theory and methodology of the chosen type of physical culture and sports activities." The manual substantiates the structure of types of initial training in sports aerobics, presents complexes of special exercises in combination with simulators for initial motor training in sports aerobics, outlines the main organizational forms of educational and extracurricular work.

right back within 40°; 2 max right forward up; 3 - swing right back; 4 swing right forward up<...>health, 1_2 _ push (, m left and with a swing of the HAND turn on the disk to ZM ’°’ left back to the BOTTOM; 3 -4 the same C<...>“’m left and with a swing of the hands turn on the disk to ZbO ° С0 ГНУВ left forward; 3-4 the same; 5-8 the same 1, but the left AND<...>RUSHVST ° R ° H 1: 1 -2 with a push of the left ° y and a swing of the hands, turn on the disk by 36 “with closed eyes; 3-4 the same<...>* in the th stand on the right, on the health disk; 6 push - "eve and swing of the HAND turn to the right by 360 7

Preview: Basic motor training in sports aerobics.-2nd ed., Revised. and additional 2013 ed.pdf (1.2 Mb)

Special exercises for teaching the types of athletics studies. allowance

Sib. feder. university

It contains a systematic presentation of methodological and practical material on athletics, which is necessary for students of higher educational institutions to master the profession of a coach-teacher, teacher of physical culture. Film records and technique diagrams are presented in the main types of athletics - running and walking, jumping and throwing - with methodological recommendations for their development, as well as examples of basic lead-in, imitation and special training exercises for training sections.

Mahi leg, standing sideways at the gymnastic wall.<...>Performing a swing without moving the body forward and up; simultaneously with the swing, the body deviates back<...>Jumps on one leg backwards: a) without a swing of the left foot, b) with a swing of the left foot, c) with staging<...>Imitation exercises for teaching the technique of throwing the discus Discus and hammer throw is given to students<...>The mass of the male disk is 2 kg, the female disk is 1 kg.

Preview: Special exercises for teaching the types of athletics.pdf (0.4 Mb)

Calculation of crank presses studies. allowance

This manual describes the procedure for performing calculations related to the design of the drive, parts and assemblies of crank presses. The schemes necessary for this and the calculated dependencies are presented. Complete reference material provided. Designed for university students in the study of disciplines: "Forging and stamping equipment", "Calculation and design of forging and stamping equipment".

Data for determination of friction parameters and disc thicknesses 60 5.2.3.<...>Calculate the estimated length of the belts by the formula:     2 0.25 2 1.57 max.<...>   2 2 0.25 1.57 0.125max wq max wqL D D D D      .<...>, cm hd Drive plate thickness , cm h1 Number of inserts, pcs mv 5.2.3.<...>Drive disc thickness 1 (0.11 0.0002) mh B n    . (5.17) 5.3.4.

Preview: Calculation of crank presses.pdf (0.7 Mb)

Rhythmic gymnastics at the university

Publishing and Printing Center of Voronezh State University

The teaching aid was prepared at the Department of Physical Education and Sports of the Voronezh State University.

I. p. - emphasis on your knees: 1 - swing with the right leg back; 2 - sitting on the heels; 3 - swing left leg back<...>I. p. - emphasis on your knees: 1 - swing with the right leg back; 2 - swing with the right foot to the right; 3 - account 1; 4<...>.; 3 - swing leg forward; 4 - i. P.; 5 - leg back; 6 - i. P.; 7 - max up; 8 - i. 36.<...>I. p. - the same: 1 - swing right forward; 2 - max right to left hand; 3 - swing right forward; 4 - i. P.<...>Disco walking. Slow walking. 26.

Preview: Rhythmic gymnastics at the university.pdf (0.5 Mb)

No. 5 [Thermophysics and Aeromechanics, 2016]

Mach number 10, height 90 km.<...>Mach.<...>Mach a strong jet, limited by the contact surface.<...>With an increase in the disk rotation speed on the cylinder axis, the axial component first decelerates<...>With a further increase in disk rotation, this region with a reduced value of the axial velocity component

Preview: Thermophysics and Aeromechanics №6 2014.pdf (1.1 Mb)

№6 [Applied mechanics and technical physics, 2017]

Calculation and design of centrifugal compressor machines studies. allowance

Publishing house of OmSTU

In the 2nd edition of the textbook, the issues of thermogasdynamic calculation, design and strength analysis of the elements of the flow part of centrifugal compressors are considered; the thermogasdynamic design of the flow path is described using the method of calculation through dimensionless parameters; examples of thermogasdynamic and strength calculations are given.

The Mach number MW1 should have the values MW1  0.55…0.65 (for axial-radial CVs MW1  0.87) .<...>To determine the Mach number in the "throat" section of the MW1G RK, you can use the technique developed by<...>The Mach number for the velocity at the outlet of the diffuser is 444 TRkCMC  . (1.119) Gas pressure, Pa:   .)1()1(<...>To the calculation of the Mach numbers in the "throat" section of the bladed diffuser lattice Equation (1.130) is non-linear,<...>In this case, the conditional Mach numbers for the RC of section I turn out to be quite large MU = 0.88, and the Mach numbers according to

Preview: Calculation and design of centrifugal compressor machines A. D. Vanyashov, G. G. Kustikov, 2017. - 255 p..pdf (0.9 Mb)

№3 [Applied mechanics and technical physics, 2011]

An important gas-dynamic characteristic of a supersonic jet is the position of the Mach disk - a direct shock<...>The position of the Mach disk was determined by the formula lM = 0.67d∗ √ p0/pk, where lM is the distance to the Mach disk<...>These data made it possible to estimate the flow regimes in the jets and to determine the position of the Mach disk at various<...>For measurements in the supersonic region of the jet (in front of the Mach disk), a point was chosen at a distance from the shear<...>nozzle equal to 8 mm, in the area behind the Mach disk - a point at a distance from the nozzle exit equal to 50 mm.

Preview: Applied Mechanics and Technical Physics №3 2011.pdf (0.2 Mb)

No. 1 [Bulletin of the Moscow State Technical University named after N.E. Bauman. Series "Engineering", 2010]

M.: Publishing house of MSTU im. N.E. Bauman

Questions are covered in the following areas: mechanics of load-bearing structures for various purposes; energy problems; modern problems of technologies; fundamental problems of mathematics, physics, continuum mechanics, etc.

At Mach numbers M > 3, it is necessary to switch to a direct-flow circuit.<...>Mach number fields in the central axial section during flight with zero angle of attack for Mach numbers М=6,8,10<...>The dependences of these characteristics on the Mach number and angle of attack were studied.<...>; μ is the coefficient of friction between the block and disk 45

No. 3 [News of the Russian Academy of Sciences. Fluid and Gas Mechanics, 2017]

Theoretical, computational and applied research in the field of aeromechanics, hydrodynamics, plasma dynamics, soil hydrodynamics, biomechanics of continuous media is published. Particular attention is paid to new areas of research, such as the theory of multiphase flows and their application, chemically reactive flows, flows of liquids and gases in electromagnetic fields, new hydrodynamic methods for increasing oil production, new approaches to describing turbulent flows, etc. The journal is peer-reviewed and included in the VAK list.

front view, angle between the line of sight and the disk axis Θ = 0°; b – from the side Θ = 90°; c - the disk is turned at an angle<...>Plane and axisymmetric configurations streamlined with the maximum critical Mach number // PMM. 1987<...>Optimization of the shape of symmetric flat bodies in order to increase the critical Mach number // Uch. app.<...>The Mach number M1 of the total velocity of a uniform flow behind a plane shock wave attached to the front<...>edge of the leeward console, or behind a centered rarefaction wave (symbols I); Mns - Mach number

Preview: Proceedings of the Russian Academy of Sciences. Fluid and Gas Mechanics No. 3 2017.pdf (0.1 Mb)

The National Training Methodological Center for Testing Abrasive Materials, at the request of the editorial board of the KUZOV magazine, has begun a new series of tests. The center's research includes testing abrasives in P120 grit wheels, one of the most common grit grades used in bodywork, on two types of surfaces - putty and putty metal. The test involves abrasive wheels of fourteen series of various manufacturers - almost everyone who is present on the Russian market today, from leaders to little-known brands. All samples are tested under exactly the same conditions, on an identical surface, at the same humidity and temperature. According to the results of two tests, the tested abrasive wheels were scored according to the system 1 point for the minimum result and then in ascending order.

During the test, the disc wear was uneven.<...>The NORTON A275 disk also worked stably.<...>JSC Central Design Bureau BIBCOM & LLC Agency Book-Service BODY 201363<...>RADEX Gold 9 4 12 Skilled Red 10 3 12 NORTON A275 10 3 11 Siarun 11 2 8 Mirka Abranet 12 1 1 max accrual<...>Skilled Red 13 5 81 siarun 14 4 75 NORTON A275 15 3 53 Mirka Abranet 16 2 46 RADEX Gold 17 1 2 max accrual

No. 4 [Thermophysics and Aeromechanics, 2014]

I installed VirtualBox on my Linux PC I really wanted to use one of the LXFDVDs to install virtual system linux. But I am getting an error that states that VirtualBox does not recognize the disk format. I think the reason is that the drive is a hybrid ISO file. Is it possible to create a standard ISO disk image for Linux installations in virtualbox? If yes, how to do it?

I think the reason is that the disc is a hybrid ISO file.<...>This will allow you to select which physical disk to use.<...>A better safe distribution like Tails if you download it on non-newer systems<...>This is not a requirement of Windows 10, which also boots on older BIOS/MBR systems, but<...>and writing tags, the quality of the copied files will be the same in all programs

(Mach rings) [ ] - stationary repetitive wave formations in a supersonic jet of gases emanating from the nozzles of turbojet, ramjet and rocket engines. Mach disks become visible when fuel is burned outside the engine. In a turbojet engine, this is possible when the afterburner is turned on.

Mechanism of education

Mach disks are formed in a supersonic jet of outgoing gases, the pressure of which at the nozzle exit is slightly greater or less than atmospheric pressure. At the exit from the nozzle, atmospheric pressure expands/compresses the underexpanded/overexpanded gas jet, which leads to a change in the direction of movement of the outer layers of gas from axial to radial. The change in the direction of the supersonic gas flow occurs on oblique shock waves. Where the direction of the gas flow again becomes parallel to the center line of flow, the first direct shock wave is located. The jet of gases, passing through a direct compression shock, heats up and ignites the unburned fuel, making the first Mach disk visible. The luminous area may be in the form of a disk or a rhombus. The distance from the nozzle exit to the first Mach disk can be approximated by the following formula:

x = 0.67 D 0 P 0 P 1 (\displaystyle x=0.67D_(0)(\sqrt (\frac (P_(0))(P_(1))))),

where D 0 is the nozzle exit diameter,

P 0 - flow pressure at the nozzle exit,

When passing through a direct compression shock in the Mach disk, the gas pressure can become higher than atmospheric pressure. Then the expansion process is repeated with the final formation of the next Mach disk. This intermittent compression/expansion process would be infinite were it not for the effect of gas viscosity on the damping of pressure fluctuations.

Education in supersonic jet gases coming from nozzles turbojet , once-through and missile engines. Mach disks become visible when fuel is burned outside the engine. In a turbojet engine, this is possible when you turn on afterburner.

Mechanism of education

Mach disks are formed in a supersonic jet of outgoing gases, the pressure of which at the nozzle exit is slightly greater or less than atmospheric pressure. At the exit from the nozzle, atmospheric pressure expands/compresses the underexpanded/overexpanded gas jet, which leads to a change in the direction of movement of the outer layers of gas from axial to radial. The change in the direction of the supersonic gas flow occurs at oblique shock waves. Where the direction of gas flow again becomes parallel to the center line of flow, the first direct shock wave is located. The jet of gases, passing through a direct compression shock, heats up and ignites the unburned fuel, making the first Mach disk visible. The luminous area may be in the form of a disk or a rhombus. The distance from the nozzle exit to the first Mach disk can be approximated by the following formula:

x = 0.67 D 0 P 0 P 1 (\displaystyle x=0.67D_(0)(\sqrt (\frac (P_(0))(P_(1))))),

where D 0 is the nozzle exit diameter,

P 0 - flow pressure at the nozzle exit,

When passing through a direct compression shock in the Mach disk, the gas pressure can become higher than atmospheric pressure. Then the expansion process is repeated with the final formation of the next Mach disk. This periodic contraction/expansion process would be infinite if it were not for the influence viscosity gas to dampen pressure fluctuations.