Thermophysics and Aeromechanics

Katasonov, M. M.; Kozlov, V. V.; Sboev, D. S.; Sorokin, A. M.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010013

In a model experiment, the process of interaction of an external artificial disturbance with the leading edge of a straight wing model was investigated. The characteristics and features of the development of boundary layer disturbances, generated as a result of the interaction of external disturbances, and the blunted leading edge of the wing model have been obtained. The research was carried out in a subsonic low-turbulence wind tunnel using a hot-wire anemometry method for detecting disturbances. Localized disturbances generated in the incoming flow were shown to induce longitudinal streaky structures in the boundary layer of the straight wing. High-frequency wave packets (precursors) appeared at the boundaries (fronts) of longitudinal structures. The dynamics of the development of wave packets and localized longitudinal structures in the boundary layer above the wing profile in a gradient flow was studied.

Afanasev, L. V.; Yatskikh, A. A.; Kosinov, A. D.; Semionov, N. V.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010025

The results of experimental measurements are presented to assess the correlation characteristics of disturbances in the boundary layer of a flat plate with a sharp leading edge and pulsations of the incoming flow in cases of natural pulsations and influence of an N-wave for Mach 2 on the leading edge. The parameters of the cross-correlation of signals from two constant-temperature anemometry (CTA) are obtained digitally. The frequency ranges with apparent correlation between the mass flow rate pulsations measured by the probes are determined.

Gordienko, M. R.; Kabardin, I. K.; Pravdina, M. Kh.; Kakaulin, S. V.; Polyakova, V. I.; Meledin, V. G.; Bakakin, G. V.; Yavorsky, N. I.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010037

The gas temperature measurements at the level of the inner wall of Ranque vortex tubes of the square and circular cross sections with variations in the cold mass fractions for both tubes showed the presence of three characteristic zones of temperature growth, which do not change over a wide range of the cold mass fraction. These zones are typical when analyzing the flow in a vortex tube within the framework of the flow crisis concept.

Gimon, T. A.; Elistratov, D. A.; Zhelonkin, A. D.; Lukashevich, S. V.; Morozov, S. O.; Shiplyuk, A. N.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010049

The flow in the vicinity of the source of controlled harmonic non-stationary perturbations of a gas medium, applicable for generating Görtler vortices in a compressible boundary layer, is studied. The source has a flat surface with linearly arranged cylindrical channels, leading alternately to two cavities of variable volume. Various configurations of the source are considered: with separate channel outlet openings and with a slit opening above them. Numerical simulation is performed in the Solid Works Flow Simulation package, and experimental measurement of gas velocity is realized by the PIV method. The developed source is shown to create periodic velocity fluctuations with an amplitude of up to 2 m/s at a frequency of 1 kHz near the surface. The shapes of the profiles of velocity normal to the surface along the source are close to sinusoidal in both time and space.

Tsyryulnikov, I. S.; Korotaeva, T. A.; Gromyko, Yu. V.; Maslov, N. A.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010050

A method of panoramic temperature measurement based on registering the fluorescence of thin-walled coatings on the inner surface of a flying vehicle model is considered. The method allows investigations in optically polluted flows of high-enthalpy short-duration wind tunnels. The temperature and heat fluxes on the aerodynamic model surface are retrieved by means of combining the results of temperature measurements with the numerical solution of an adjoint problem of the flow around the flying vehicle. Implementation of this method in practice is performed in the flow of a hotshot wind tunnel based at ITAM SB RAS.

Sakhnov, A. Yu.; Bryzgalov, K. V.; Naumkin, V. S.; Lebeda, K. S.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010062

Investigation results on the airflow in a convergent channel with a hot bottom wall at a set constant heat flux or at a set constant wall temperature are presented. The numerical simulation was carried out in the OpenFOAM software using the k-ω-SST turbulence model. The verification of simulation results demonstrated a good agreement between the calculated data and the experimental velocity profiles and the thermal Stanton number. The study showed that an increase in the temperature of the convergent channel wall leads to the phenomenon of the streamwise velocity overshoot, suppression of turbulence and a decrease in the skin-friction coefficient and thermal Stanton number. In contrast to a zero pressure gradient flow, the type of thermal boundary conditions has a noticeable effect on the skin-friction and heat transfer in the convergent channel.

Kashkovsky, A. V.; Kudryavtsev, A. N.; Shershnev, A. A.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010074

Numerical simulations of an underexpanded supersonic jet exhausting from a circular nozzle are reported. The study is performed in a three-dimensional formulation using two different approaches: Navier–Stokes equations and Direct Simulation Monte Carlo method. In both cases, a reverse flow zone is formed behind the Mach disk in the first shock cell. Thus, this phenomenon, which was previously observed in axisymmetric simulations, cannot be attributed to inaccuracies of approximation of these equations near the axis of symmetry.

Lysenko, V. I.; Smorodsky, B. V.; Kosinov, A. D.; Yatskikh, A. A.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010086

Influence of streamwise slots with the orientation angle φ = 0 and various depths h (corresponding Reynolds number Reh = 0–2000) on the stability of the supersonic (M = 2) flat-plate boundary layer with relation to natural disturbances of the first (vorticity) instability mode driving laminar-turbulent transition was investigated experimentally. Experiments shown that such kind of disturbances can be stabilized by small-depth streamwise slots, wherein the maximum stabilization occurs at the Reynolds number (based on the slot depth) of about Reh ≈ 1000.

Abramov, M. A.; Arefyev, K. Yu.; Voronetskii, A. V.; Grishin, I. M.; Kruchkov, S. V.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010098

The work is devoted to the study of random statistical processes in two-phase flows. The objective is to obtain new computational and experimental data on the influence of previously undetermined factors on the trajectories of particle motion, their segregation, and the formation of a locally continuous flow field of the dispersed phase in supersonic turbulent two-phase flows. The results of computational and experimental study of the flow features of a two-phase supersonic flow are presented. A new experimental method was applied for analysis of influence of random statistical factors on the particle distribution in a high-speed carrier flow. The physical basis of the proposed method is to indicate the flow rate of the dispersed phase by means of particle adhesion to an obstacle installed in the flow. In order to analyze the segregation of the dispersed phase in the flow, the approach of quasi-continuumization of individual particle trajectories is applied. The method obtains a locally continuous flow stress field for dispersed phase flow. Empirical coefficients resulting from the influence of random statistical factors on the motion of dispersed particles in a two-phase flow are determined. The obtained computational and experimental data clarify the prediction of the distribution and segregation of dispersed phase particles with a size of 15–40 microns in a supersonic free flow.

Mazhul, I. I.; Gounko, Yu. P.

2024 Thermophysics and Aeromechanics

doi: 10.1134/s0869864324010104

Results of a numerical study of supersonic flows formed in channels with a square cross section are reported. Configurations consisting of a constricting entrance section formed by four compression wedges aligned at a right angle to each other and a subsequent channel with a constant cross section are considered. The initial shock waves formed on the nose compression wedges pairwise intersect each other in dihedral corners of the configuration along the swept lines, and a complex system of reflected and subsequent interacting shock waves of the general three-dimensional position is formed further downstream. The data are obtained in a supersonic range of freestream Mach numbers M = 2–4 for compression wedge angles of 3° and 8° in flows with both regular and irregular interaction of the initial shock waves in dihedral corners of the configuration.