On the recombination mechanism of atomic nitrogen near a catalytic surface in a stream of dissociated air

It is shown that the heterogeneous recombination of nitrogen atoms on a catalytically active surface in a stream of dissociated air is accompanied by intense gas-phase recombination of the nitrogen in exchange reactions whose rate is determined by the rate of heterogeneous recombination of atomic oxygen.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 156–158, May–June, 1980.     

Effect of surface catalytic activity on nonequilibrium heat transfer in a subsonic jet of dissociated nitrogen

The present paper investigates experimentally and numerically the effect of the heterogeneous recombination of atoms on the heat transfer of models in a subsonic jet of dissociated nitrogen for the conditions of an experiment in the VGU-2 plasma generator and determines the effective probabilities of the heterogeneous recombination of nitrogen atoms for a number of materials at high temperatures.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 166–172, May–June, 1985.     

Experimental investigation of the flow of a vibrationally nonequilibrium gas in a profiled nozzle

The results are given of measurements of the gain in a planar profiled nozzle for a mixture containing carbon dioxide gas and nitrogen with admixtures of oxygen and water vapor.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 203–206, January–February, 1980.We thank V. A. Poltoratskii for assistance in the experiments and G. D. Smekhov and S. A. Losev for helpful discussions.     

Study of three-dimensional wave structure of nonstationary gas outflow from a planar sonic nozzle

Results are reported of an experimental study of the three-dimensional structure of nonstationary gas outflow from a planar nozzle. Outflow of a heated shock wave in a nitrogen tube at different moments of time from the start of outflow (0–1 msec) in two mutually perpendicular directions is considered. A scheme for reconstructing the flow at different outflow stages is proposed. The dimensions of the Riemann wave are found to oscillate.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 41–45, January–February, 1976.     

Model of the physico-chemical kinetics behind the front of a very intense shock wave in air

A model of the physico-chemical kinetics of the reactions taking place behind the front of an intense shock wave propagating in air with a speed of 9–14 km/s is proposed. The problem of describing the chemical reactions, namely, molecular dissociation and exchange reactions involving vibrationally excited molecules in the absence of vibrational equilibrium, is solved. The vital role of the vibrational excitation delay in the dissociation of oxygen and nitrogen is established. The rate of the exchange reaction between nitrogen molecules and oxygen atoms in the shock wave depends only slightly on the vibrational excitation level. It is demonstrated that the rate constants for thermally nonequilibrium dissociation reactions can be represented within the framework of the one-temperature approximation at constant vibrational temperatures of the dissociating species satisfying quasi-stationary conditions.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 169–182, March–April, 1995.     

Energy characteristics of a carbon monoxide gasdynamic laser

The characteristics of gasdynamic lasers based on mixtures of carbon monoxide with nitrogen and inert gases were investigated and the populations of vibrational levels of CO molecules, the gain of the mixture, and the generation power were determined in [1–8]. But the parameters of a gasdynamic laser (GDL) in the optimum emission mode have not been determined up to now. The difficulties in calculating the optimum energy characteristics are connected with the complexity of the calculating model and the large number of parameters of the system. The energy characteristics of a CO gasdynamic laser are calculated and optimized in the present report on the basis of a simple model.Translated from Zhurnal Prikladnoi Mekhaniki Tekhnicheskoi Fiziki, No. 5, pp. 16–23, September–October, 1978.     

Influence of the parameters of a cross-flow on the gain in a jet

A system of equations is proposed for calculating a turbulent axisymmetric jet in a cross-flow for gases with different physical properties. The mixing of carbon dioxide gas with excited nitrogen and helium in a gas-discharge laser has been investigated numerically. Vibrational relaxation of the mixed gases was taken into account. The calculated gain agrees satisfactorily with the experimental data.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 34–37, July–August, 1930.We thank A. P. Napartovich for helpful discussions and V. F. Gerasiaov for providing the experimental data.     

Investigation of unsteady flow structure during discharge of a shock-heated gas

This paper examines the structure of the near-gasdynamic section of a jet discharging into a rarefied volume. The experimental part of the article deals with unsteady discharge of a high-temperature gas. Discharge from a slot and from a circular aperture is investigated for air, nitrogen, CO₂, and argon with nonuniformities from 20–200. Approximate relations are obtained to describe the motion of the front of a discharging substance in dimensionless coordinates and the associated perturbation along the flow axis. It is established that the time for a steady geometric structure to form in the gasdynamic section of the jet is greater than the values obtained from data available in the literature.Translated from Zhurnal Prikladnoi Mekhaniki i Teoreticheskoi Fiziki, No. 5, pp. 34–40, September–October, 1973.     

Direct initiation of detonation in a hydrogen-oxygen mixture diluted with nitrogen

The direct initiation of plane and cylindrical detonation waves in a hydrogen-oxygen mixture diluted with nitrogen using an exploding copper wire and a moving piston is investigated.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.6, pp. 151–156, November–December, 1992.The authors are grateful to G. D. Smekhov for calculating the Chapman-Jouguet detonation parameters and to V. V. Mitrofanov, who reviewed the article, for his useful comments.     

Numerical investigation of the flow of nitrogen past a sphere with allowance for rotational relaxation

The supersonic flow of nitrogen past a sphere is studied in the framework of the complete Navier-Stokes equations and the relaxation equation with allowance for rotational-translational relaxation.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 170–174, March–April, 1980.I thank V. N. Gusev for interest in the work and valuable discussions and V. K. Molodtsov for assisting in the development of the numerical algorithm for solving the problem.     

Diffusion separation of chemical elements on a catalytic surface

An asymptotic expansion of the solution, for large Schmidt numbers, of the system of equations of a chemically nonequilibrium multicomponent boundary layer on the catalytic surface of a blunt body [1] is used to obtain expressions for the diffusion fluxes of the reaction products and chemical elements and the heat flux as functions of the gradients of the reaction product concentrations, chemical element concentrations and enthalpy across the boundary layer. It is shown that when the body is exposed to a supersonic air flow, the diffusion separation of the chemical element oxygen depends importantly on the atom concentration at the outer edge of the boundary layer and the nature of the homogeneous and heterogeneous catalytic reactions. If the surface promotes the rapid recombination of oxygen atoms and is chemically neutral with respect to nitrogen atoms, then an excess of the chemical element oxygen is formed on the body. Otherwise we get an enhanced concentration of the element nitrogen. As distinct from the case of an ideally catalytic wall [2–4], on a surface possessing the property of catalytic selectivity the diffusion separation of chemical elements takes place even when only atoms are present at the outer edge of the boundary layer. On a chemically neutral surface diffusion separation may be caused by homogeneous recombination reactions between oxygen and nitrogen atoms if their rate constants are essentially different.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 115–121, July–August, 1988.     

Procedure for constructing an equation of state for a liquid from experimental p,v, T data with the aid of a computer

We propose a procedure for the construction of an equation of state of a liquid on a computer, based on the simultaneous determination of all the coefficients of the equation by the method of least squares. This enables one to describe experimental p, v, T data analytically, as represented for individual values of temperature and pressure for every experimental point. The procedure is tested on the basis of experimental data on liquid nitrogen, argon, and carbon dioxide.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 119–124, March–April, 1972.     

Flow dynamics of an intensively evaporating wave film of a liquid

Experimental results on the behavior of a laminar–wave film of liquid nitrogen evaporating intensively under conditions of a gravitational flow on a locally heated vertical surface are described. It was found that certain heat fluxes change significantly the shape of the residual layer and increase the relative amplitude of large waves. For the first time, data are obtained on the change in the probability density of the local film thickness as a function of the heat–flux density within the range of Reynolds numbers from 32 to 103. The effect of the heat–flux density on the phase velocity and shape of large waves is shown. Heat–flux densities at which dry spots arise were determined as functions of the streamwise coordinate of the wave film of the saturated liquid.     

Effect of thermodiffusion on intensity of surface burn-out in a heterogeneous turbulent boundary layer

On the basis of an analysis of the binary diffusion equation in the viscous sublayer of the turbulent boundary layer an estimate is given of the effect of thermodiffusion on the concentration of components at an impervious wall, on the permeability of the wall, and on the intensity of heating of the reactive surface. Experimental results are presented on the burnout of a graphite wall in mixtures of air with nitrogen, argon, and helium.Translated from Zhurnal Prikaldnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 119–125, September–October, 1972.     

Transonic flow of a gas jet from a vessel with plane walls

The problem of transonic flow of a gas jet with equilibrium excitation of the vibrational degrees of freedom of the molecules from an infinite symmetrical vessel with plane walls is reduced to a generalized Tricomi boundary-value problem for an equation of Chaplygin type. It is solved using a difference scheme [13] based on the decomposition of the difference operator in accordance with the type of differential operator. Calculation results are presented for a mixture of oxygen and nitrogen simulating air. The effect of the angle between the walls, the stagnation temperature and the back-pressure coefficient on the flow coefficient is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 128–135, November–December, 1987.The authors are grateful to F. Yu. Stepanov for his useful comments.     

The effect of nonequilibrium dissociation on boundary layer flow

The effect of nonequilibrium non-Arrhenius dissociation kinetics, which cannot be reduced to two-temperature kinetics, on the microparameter distribution in a boundary layer and, in particular, on the heat transfer to the surface of the body is considered with reference to the flow of a binary mixture of nitrogen molecules and nitrogen atoms in the neighborhood of the stagnation point on a blunt body.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 168–178, July–August, 1995.     

Turbulent mixing of relaxing gases in a supersonic nozzle

Processes of turbulent mixing of hot nitrogen and carbon dioxide gas (CO₂) in a supersonic nozzle are investigated in connection with gasdynamic lasers with selective thermal excitation. The actual flow pattern in the nozzle and cavity is simulated by the system of equations of a turbulent boundary layer. The results of calculations of the gain profile, the CO₂ concentration, and the laser power agree satisfactorily with experimental data.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 156–160, March–April, 1981.We are very grateful to B. S. Aleksandrov and V. K. Pozdyshev for numerous helpful discussions.     

Increased heat transfer to a titanium surface with oxygen injection into the nonequilibrium boundary layer

The results of an experimental and numerical investigation of the heat transfer between a subsonic jet of dissociated nitrogen and a titanium surface, through which molecular oxygen is blown into the jet, are presented. It is established that in the nonequilibrium boundary layer regime the dependence of the heat flux on the injected oxygen flow rate is nonmonotonic. At a certain flow rate the heat transfer to the titanium surface reaches a maximum that considerably exceeds (by 20%) the heat transfer to an impermeable wall. The observed increase in heat transfer in the presence of injection is attributed to the interaction of the gas-phase exchange reactions and the recombination of atoms on the titanium surface, which has sharply different catalytic properties with respect to the recombination of nitrogen and oxygen atoms.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 148–155, July–August, 1991.     

Nonequilibrium ionization accompanying hypersonic flow of carbon dioxide gas over blunt bodies

A study is made of the nonequilibrium ionization in the shock layer when carbon dioxide gas flows over cones with spherical noses at velocity 4–7 km/sec, the density of the oncoming flow being 10^–8-10^–5 g/cm³. The influence of admixtures of nitrogen and sodium on the electron concentration is investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 183–186, January–February, 1981.     

Overequilibrium heating of the surface of a heat-shield tile in a subsonic jet of dissociated air

The results of measuring and numerically calculating the surface temperature distributions of heat-shield tiles with uniform and nonuniform catalytic coatings exposed to subsonic dissociated-air flows in an induction plasmotron are presented. The measurements are consistent with the calculated surface temperature profiles obtained from a numerical solution of the Navier-Stokes equations for a chemical-nonequilibrium flow of dissociated nitrogen. The results are compared with the data of a space shuttle flight experiment on the effect of a discontinuity of heat shield catalyticity on the overequilibrium surface temperature jump.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 144–150, May–June, 1991.