Thermophysics and Aeromechanics

Chasovnikov, E. A.;Chasovnikov, S. A.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010013

Abstract Two methods are developed for determining the equivalent aerodynamic damping of reentry vehicle models. In the first method, the equivalent aerodynamic damping is determined on the basis of the experimental envelopes of the transitional process for the angle of attack changing with time; in the second method, all experimental points of the transitional process are involved. Both methods are found to produce similar results. The adequacy of the methods is verified by an example of a reentry vehicle model, which demonstrates that the predicted transitional processes for the angle of attack changing with time are in good agreement with the experimental data.

Voevodin, A. V.;Kornyakov, A. A.;Petrov, A. S.;Petrov, D. A.;Sudakov, G. G.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010025

Abstract The effectiveness of use of an ejector pump for controlling the flow around a wing under take-off and landing conditions of flight is investigated. The proposed device permits organization of simultaneous suction of boundary layer through a slot on the upper surface of the wing and gas blowing in the vicinity of the trailing edge of wing through a flat slot-type diffuser; the latter makes it possible to effectively implement the principle of wing-flow control using gas suction and jet blowing. The design of the ejector pump makes it possible to obtain values of suction and blowing velocities of order 50–100 m/s. The paper proposes a mathematical model of the flow around the wing airfoil taking into account the operation of the ejector pump, and presents results of a computational study of aerodynamic characteristics of one- and three-element wing airfoil under landing conditions. It is shown that the simultaneous use of suction and blowing improves the flight characteristics of the mechanized airfoil more effectively in comparison with the separate use of these means.

Kislovskiy, V. A.;Zvegintsev, V. I.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010037

Abstract The results of numerical investigation of the interaction of a supersonic free stream with the Mach number of 3.85 with a transverse gas jet blown from the surface of an axisymmetric model located at zero angle of attack with respect to the flow are presented. The numerical modeling was conducted using the averaged Navier-Stokes equations employing the k-ω SST turbulence model. The investigation of the influence of the gas jet blowing on pressure redistribution over the axisymmetric model surface and on the formation of an additional transverse force and moment has also been conducted. The shift of the blowing orifice along the model length leads to a significant variation of arising forces and moments. A fundamental difference in the distribution of pressures over the surface at the jet blowing from the axisymmetric body and from a flat plate is shown.

Kossov, V. N.;Fedorenko, O. V.;Zhakebaev, D. B.;Kizbaev, A. P.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010049

Abstract The peculiarities of the change of the regimes “diffusion-gravitational concentration convection” have been studied numerically. It is shown that at a certain mixture composition and pressure, substantially nonlinear distributions of the concentrations of components arise at the expense of the difference in the diffusion coefficients of components, which lead to the corresponding distribution of the gaseous mixture density. This is a reason for the formation of structured formations and the rise of convective instability in the mixtures under study. The time of the rise of convective flows and of the mean velocity of the components transfer has been estimated. Obtained results are compared with experimental data.

Moshkin, N. P.;Fomina, A. V.;Chernykh, G. G.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010050

Abstract A numerical model has been constructed and the investigation of the dynamics of a cylindrical localized region of turbulent disturbances in a longitudinal horizontally homogeneous shear flow of a linearly stratified fluid has been carried out. Computational results have shown a considerable generation of turbulence energy at the expense of shear flow gradients. It was also found that the shear flow affects weakly the internal waves generated at the evolution of the turbulent mixing zone.

Kulik, B. M.;Boiko, A. V.;Lee, I.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010056

Abstract Experiments on the effect of two-layer compliant coatings on the surface friction of a flat plate at flow velocities of up to 16 m/s carried out in a water tunnel are described. To document the properties of the coatings, the dynamic viscoelastic properties of used rubbers were measured in the frequency range approximately corresponding to the frequency range of wall pressure oscillations at current flow velocities. The data on characteristics of the viscoelastic properties of coatings and experimental data on interaction of coatings with the flow form a database required to test various theories and semi-empirical models for predicting the effectiveness of such interaction.

Bedarev, I. A.;Temerbekov, V. M.;Fedorov, A. V.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010062

Abstract Initiating detonation in a reactive hydrogen-oxygen mixture by a spherical projectile of small diameter, flying with velocity exceeding the Chapman-Jouguet one, has been studied numerically. The mathematical model is based on the given kinetic scheme for the description of chemical reactions. At verification of the computational algorithm, the flow regimes and the detonation cell size were compared for numerical and experimental data. The agreement between the calculated and the experimental flow patterns and the quantitative correspondence of the modes of existence of inclined detonation waves have been obtained.

Kuzmin, V. A.;Zagrai, I. A.;Maratkanova, E. I.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010074

Abstract The paper presents a method for study of thermal emission characteristics from heterogeneous combustion products in a plume of a model solid-fuel rocket engine. Simulation experiments found the influence of speed and temperature types of non-equilibrium on spectral and integral densities of radiation energy flux and emissivity factors. The values of non-equilibrium were determined at different critical nozzle cross sections and at different average sizes of particle. It was found that the speed non-equilibrium has a minor influence within the gas emission bands; meanwhile it is stronger for transparency bands of gas phase. The non-equilibrium in temperature is the main factor in calculating the emission characteristics of the flow, while the speed delay of particles relative the gas flow is manifested stronger at this background.

Boyarshinov, B. F.;Fedorov, S. Yu.;Abdrakhmanov, R. Kh.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010086

Abstract We studied a lean propane-butane-air mixture ascending through a round hole of 10-mm diameter, covered by a brass mesh as a single element of the multicellular flame. Gas temperature was measured by the CARS method (Coherent anti-Stokes Raman Scattering) with original software for spectra processing. The vertical and horizontal velocity components were measured by the PIV method (Particle Image Velocimetry). Distributions of heat release intensity and heat fluxes, which cannot be obtained in direct measurements, were estimated using balance relationships in the energy equation. The results were compared with the data obtained for the rich mixture flame in experiments with the same burner. Convective and molecular heat fluxes were considered separately. It was shown that when the rich air mixture with propane-butane burns, the heat flux caused by thermal conductivity reach a maximum at the center of the heat-release zone. Their intensity is substantially lower in comparison with the convective fluxes behind the flame front, which in turn are almost twice as weak as the convective flux in the flame of a lean mixture. The maximal intensities of heat release in the flame of a rich mixture are lower than in the lean one.

Toktaliev, P. D.;Galitskiy, I. O.;Martynenko, S. I.;Volokhov, A. V.;Amosova, E. S.;Volokhov, V. M.;Yanovskiy, L. S.

2019 Thermophysics and Aeromechanics

doi: 10.1134/S0869864319010098

Abstract A mathematical model of physical and chemical processes in a turbulent flow of mixtures of alkanes with the number of carbon atoms 0 < C < 9 in heated channels has been developed. The Navier-Stokes equations were used to describe the turbulent transfer, and a detailed kinetic mechanism served to describe the thermal decomposition of hydrocarbons. A detailed description of the developed model and the results of its verification based on experimental data is given. In the present paper, the model is used to numerically study the conjugate heat transfer in a plane heated channel of the cooling system of advanced ramjet aircraft engines on endothermic hydrocarbon fuels. A two-criterion optimization of the initial composition of endothermic hydrocarbon fuel was performed to obtain the maximum endothermic effect and energy content of the resulting hydrocarbon fuel mixture, further fed into the combustion chamber of the engine. The limitations in the optimization are the maximum permissible temperature of the heated channel walls (the condition of thermal resistance of the structure) and the maximum acceptable degree of decomposition of the hydrocarbon mixture, in excess of which the intensive formation of solid deposits begins on the washed channel walls.