On the spectrum of magnetic field and scalar impurity fluctuations in acoustic turbulence

The fluctuations of a magnetic field in acoustic turbulence are examined. An equation is derived for the spectral tensor of homogeneous magnetic field fluctuations. In a certain limit case the spectrum of steady-state pulsations is obtained in the presence of an external source. It is shown that three kinds of spectra exist in an inertial subdomain, each of which corresponds to a definite domain in wave space. Analogous results have been obtained for the fluctuations of a homogeneous scalar impurity.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 26–31, March–April 1971.In conclusion, the author grateful to R. Z. Sagdeev for discussing the results obtains at a seminar.     

Convective heating of a blunt-nosed body in a nonuniform hypersonic gas stream

An investigation is made into the convective heating of a blunt-nosed body in an expanding stream of heated gas. The gas parameters at the outer edge of the boundary layer are determined on the basis of a solution obtained earlier by the authors [3]. Expressions are obtained which make it possible to convert the convective heat flux to a body in a uniform gas stream to one in a nonuniform stream. Dimensionless numbers are found and their influence on the convective heat flux to the body is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 127–133, July–August, 1981.     

Mixing in Hypervelocity Flows

This study considers analysis of data obtained from tests witha generic combustor model at the pulse facility T5 located in theGraduate Aeronautical Laboratories at California Institute of Technology(GALCIT). Comparisons were made between the flow predictions usingBaldwin–Lomas and k–epsilon turbulence models. Computedpredictions of mixing efficiency, wall pressure signatures, eddyviscosity distributions, etc., obtained from both the turbulence modelswere similar. Computed wall pressure distributions agreed with thosefrom experiments. Spatial uniformity of the injectant-test gas mixturewas considered. Based on the results obtained, use of the Baldwin–Lomaxturbulence model can be considered to be sufficient for the conditionsconsidered, as it yields adequate predictions with significant savingsin computational costs.     

Probability distribution of velocity difference in the inertial interval of a turbulence spectrum

The statistical turbulence characteristics are analyzed in the inertial interval of a spectrum. An equation is obtained for the probability distribution of the velocity difference at two points. Parameters characterizing the turbulence spectrum in the inertial interval enter into the equation in the role of unknown constants. These constants are calculated from the condition that a solution exists which has a physical meaning.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 32–41, May–June, 1976.The author wishes to thank E. A. Novikov for his discussion of the paper and for his critical observations.     

Nonsteady burning of a solid propellant in a gaseous oxidizer flow

The burning of a solid propellant is investigated for nonsteady heat propagation in the induction zone. The equation of heat conduction in the propellant is solved in finite form for the case of a sharp change in burning rate; the time dependence of the temperature gradient at the propellant surface is obtained and used to investigate the mechanism of collapse of the diffusion flame above the surface. The combustion stability of a propellant burning in a channel with a large free volume is analyzed. The perturbations of the gas-dynamic quantities are related with the perturbations of the burning rate and hence with the properties of the induction zone in the solid phase. An analysis of the dispersion relation for the limiting case of propagation of acoustic waves in a stationary gas shows that the longitudinal acoustic perturbations that develop in the channel may grow with time, interacting with the heated subsurface layer of propellant.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fizikt, No. 4, pp. 44–52, July–August, 1971.In conclusion the author thanks B. V. Librovich for formulating and discussing the problem and A. G. Istratov and V. G. Markov for their valuable comments.     

Escape of a turbulent jet under the effect of acoustic perturbations

Results are presented of experimental investigations of the local effect of acoustic oscillations of different frequency and constant intensity on the root part of a nonisothermal axisymmetric subsonic turbulent jet escaping from a gas jet atomizer at a different velocity in the S = 0.053–3.84 range of Strouhaille numbers. Data have been obtained indicating the presence of unstable escape modes of a subsonic turbulent jet in an acoustic field; experimental dependences are presented of the relative aperture of the turbulent jet flowing in an acoustic field as a function of various parameters.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 58–62, January–February, 1972.The author is grateful to A. S. Ginevskii and B. S. Burikov for discussing the results of this paper, and also to A. S. Modnov and R. A. Arkhipova for assistance in conducting and processing the experiments.     

Large-scale turbulence in a thin layer of nonisothermal rotating fluid

The dynamics of large-scale nonisothermal turbulence in a thin rotating layer of fluid are investigated. An hierarchical model, obtained by averaging the initial Boussinesq equations with respect to the vertical coordinates and subsequently projecting the two-dimensional equations onto a basis consisting of a system of axisymmetric spiral vortices of progressively decreasing scale, is proposed. It is shown that the presence of horizontal temperature inhomogeneities leads to a considerable increase in the turbulence decay time.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 48–55, July–August, 1988.     

Determination of correlation functions of turbulent velocity and sound speed fluctuations by means of ultrasonic technique

An experimental study of the propagation of high-frequency acoustic waves through grid-generated turbulence by means of an ultrasound technique is discussed. Experimental data were obtained for ultrasonic wave propagation downstream of heated and non-heated grids in a wind tunnel. A semi-analytical acoustic propagation model that allows the determination of the spatial correlation functions of the flow field is developed based on the classical flowmeter equation and the statistics of the travel time of acoustic waves traveling through the kinematic and thermal turbulence. The basic flowmeter equation is reconsidered in order to take into account sound speed fluctuations and turbulent velocity fluctuations. It allows deriving an integral equation that relates the correlation functions of travel time, sound speed fluctuations and turbulent velocity fluctuations. Experimentally measured travel time statistics of data with and without grid heating are approximated by an exponential function and used to analytically solve the integral equation. The reconstructed correlation functions of the turbulent velocity and sound speed fluctuations are presented. The power spectral density of the turbulent velocity and sound speed fluctuations are calculated.     

Stability of combustion of powder in a phenomenological model with nonadiabatic flame

A stability criterion for combustion of powder is obtained, taking into account the effect of the processes in the gas phase. It is shown that consideration of the effects of a nonadiabatic flame leads to the stability reserve of combustion being reduced and the natural frequency of vibrations being lowered. The effects thus found are physically explained by the radiation of a part of energy from the combustion zone with thermal and acoustic waves.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 82–87, November–December, 1973.Deceased.     

Effect of precursor radiation on the flow structure and ionization behind the shock front in inert gases

The problem of the propagation of strong, intensely radiating shock waves in inert gases is considered. It is shown that the heating of the shock tube walls by the precursor radiation, accompanied by an increase in the temperature of the adjacent gas, leads to the transverse stratification of the medium and to the disturbance of the one-dimensionality of the flow of shock-heated gas behind the wave front. Ionization kinetics calculations which take this into account indicate an acceleration of ionization near the tube walls, which is consistent with experiment. On the basis of the gas heating values obtained it is possible to establish critical values of the gas pressures ahead of the front and the shock wave Mach numbers, transition through which is accompanied by a radical restructuring of the flow with the formation of a configuration.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 124–131, May–June, 1991.     

Wave processes in semi-open tubes

A numerical method based on the solution of the complete problem of integration of a system of nonstationary nonlinear Euler equations for an ideal and perfect gas is developed. A special form of the dimensionless equations is obtained and the concept of the asymmetry of the pressure peak at the closed end of the tube is introduced, making it possible, using Godunov's scheme, to obtain a physically explicable solution even on grids with a small number of points. The frequency characteristics of the semi-open tube are obtained on the Strouhal number interval from 0.05 to 1.25. It is shown that at the linear resonance frequencies the conditions are favorable for the formation and amplification of shock waves leading to heating of the gas.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 169–171, September–October, 1990.     

Nonlinear waves in a liquid containing gas bubbles with allowance for phase transition

An equation describing the kinetics of the mass transfer accompanying the process of gas bubble growth in an incompressible liquid is proposed. The equation of state of the two-phase system, whose derivation is based on the mechanism of interphase mass transfer due to the solubility of the gas atoms in the liquid, is obtained. An evolution equation generalizing the usual Burgers-Korteweg-de Vries (BKdV) equation is derived for describing the nonlinear waves in a gas-containing liquid. The solution of this equation is obtained in the form of a solitary wave.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 114–119, May–June, 1989.     

Acoustic effect on the root part of a turbulent jet

Results are presented of experimental investigations of the effect of low-frequency acoustic perturbations of different frequency and constant intensity on the root part of a nonisothermal subsonic turbulent jet escaping from a direct-jet injector with a conical diffusor in the 0.031–0.054 range of Strouhal numbers. Experimental dependences of the mean velocity and the longitudinal intensity of the turbulence are presented as a function of different parameters for both the unperturbed flow and for the flow in the acoustic field.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 182–186, July–August, 1970.The authors are grateful to A. S. Ginevskii, I. M. Koshelev, and A. S. Modnov for discussing the results of this research.     

Excitation of unstable modes in a supersonic boundary layer by acoustic waves

The acoustic excitation of the first and second boundary layer modes in the neighborhood of the sharp leading edge of a plate in a supersonic gas flow is analyzed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 67–74, July–August, 1991.     

Heating of Dry Samples under an Acoustic-Convective Action

The action of an acoustic field on samples with a regular mesh structure, which do not contain any moisture, is examined. It is experimentally demonstrated that the degree of heating of samples exposed to an external flow with an acoustic action depends substantially on the material of the clamping plates. A mathematical model of coupled heat transfer in the sample and in the plate is constructed, which can describe the phenomenon qualitatively and (approximately) quantitatively.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 116–122, September–October, 2005.     

Calculation of isotropic turbulence spectrum

The spectral function of isotropic turbulence is obtained on the basis of semi-empirical turbulence theory.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 161–164, November–December, 1974.     

Gas-dynamic processes in a strongly radiation-heated layer of gas which accelerates a barrier

Numerical methods involving two variables have been used to study gasdynamic processes in a gas layer next to a barrier. A flow of gas arises because of absorption by the gas of intense radiation. It is shown that cumulative effects can occur leading to the establishment of a quasisteady flow and heating regime if the radiation is applied for a prolonged period.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 131–137, November–December, 1982.     

Turbulence generation by electric body forces

The effect of an electric body force on vorticity production and turbulence generation in a gas is investigated by examination of the governing electrohydrodynamic equations. The theoretical concepts are illustrated by hot-film anemometer measurements of the electrically induced turbulence in a large scale electrostatic precipitator. The results indicate dramatic increases in turbulence and diffusivity due to the corona discharge and suggest that turbulence control in this application requires a modification in electrode geometry.This paper was presented at the Ninth symposium on turbulence, University of Missouri-Rolla, October 1–3, 1984     

Propagation of disturbances in supersonic vibrationally nonequilibrium gas flows

The propagation of finite disturbances in nonequilibrium supersonic gas flows is investigated, and the effect of entropy and acoustic disturbances on the inversion characteristics of the medium is analyzed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 128–134, March–April, 1990.     

Certain Aspects of an “Incompressible Fluid“ Model in Gas Dynamics

An “incompressible fluid” model in gas dynamics is developed in the linear approximation. Using the dissipative relaxation time as a characteristic scale, we arrive at another form of the dimensionless Boltzmann equation. In the limiting case of small Knudsen numbers an approximate solution is obtained in the form of a Hilbert multiple-scale asymptotic expansion. It is revealed that for slow, weakly nonisothermal processes the asymptotic expansion for the linearized Boltzmann equation leads in a first stage to equations for the velocity, pressure and temperature that do not contain the density (quasi-incompressible approximation). The density depends on the temperature and can, if necessary, be found from the equation of state. The next-approximation equations contain the Burnett effects, the velocity calculation being reduced to the general problem of finding a vector field from a given divergence and rotation. With reference to a simple case of the heating of a stationary gas in a half-space it is shown that the temperature establishment process is accompanied by gas flow from the wall.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, 2005, pp. 170–178.Original Russian Text Copyright © 2005 by Chekmarev.