Thermophysics and Aeromechanics

Ivanov, A. V.;Kachanov, Y. S.;Mischenko, D. A.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060018

Abstract The present study is devoted to the investigation of several, presumably most efficient, mechanisms of the production of non-stationary Görtler vortices in a laminar boundary layer on a concave wall due to scattering of 2D and 3D free-stream vortices by streamwise localized 3D and 2D surface and flow non-uniformities. The experiments were carried out by means of the method of controllable non-stationary disturbances. The interaction of downstream-propagating 3D free-stream vortices with the growing boundary layer, presenting natural 2D bas-flow non-uniformity, was found to lead to a rather efficient excitation of unsteady Görtler modes. This mechanism of distributed receptivity is able to modify considerably the growth rates of the excited Görtler vortices in comparison with the linear stability laws. In the present paper, definitions of the coefficients of distributed vortical receptivity are given and some estimates of values of these coefficients are reported. In spite of a high measurement accuracy and a rather broad range of examined parameters, no excitation of Görtler vortices due to other examined mechanisms was identified.

Adamov, N. P.;Kharitonov, A. M.;Chasovnikov, E. A.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S086986431406002X

Abstract The paper deals with an experimental study of stationary and nonstationary aerodynamic characteristics of a circular cone in the range of Mach numbers 1.75–7. The experimental equipment and the method of determining the aerodynamic characteristics are briefly described. The integral aerodynamic characteristics of the model in tests with force measurements and the aerodynamic derivatives of the pitching moment in dynamic tests on a setup with free oscillations are obtained. The experimental data are compared with numerical predictions.

Mikhaelis, M. V.;Zanin, B. Yu.;Katasonov, M. M.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060031

Abstract Results of an experimental study of the air flow past a straight-wing model in a low-turbulence wind tunnel are reported. The influence of a turbulent wake due to a thin filament on the structure of boundary layer on the model surface was examined. Flow visualization in boundary layer, hot-wire measurements of flow velocity, and also measurements of the amplitude and frequency spectra of flow pulsations, were performed. The wake substantially modified the boundary layer flow pattern: the separation bubble disappeared from the flow, and the formation of longitudinal structures was observed.

Terekhov, V. I.;Smulsky, Ya. I.;Sharov, K. A.;Zolotukhin, A. V.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060043

Abstract The results of experimental study of the turbulent flow structure at longitudinal flow around the cellular surface with hexagonal cells of 5-mm size, 21-mm depth and wall thickness of 0.2 mm are presented. The measurements were performed using the PIV system for the developed flow in the channel with cross section of 21×150 mm and length of 1000 mm. Stroboscopic visualization of the flow was performed, and velocity and turbulence components were measured in the channel with and without the cells. It is shown that in a vicinity of cells, the boundary layer is less filled, but it has the higher level of turbulent fluctuations. It is noted that in contrast to the profile on a smooth wall there is no logarithmic region on the cellular surface. In this case, there are no effects of velocity slip on the cellular surface under the experimental conditions.

Sentyabov, A. V.;Gavrilov, A. A.;Dekterev, A. A.;Minakov, A. V.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060055

Abstract Numerical modeling of the unsteady flow in the draft tube of the test bench hydro turbine is conducted. The hybrid RANS-LES methods for modeling turbulent flows are compared. The intensity and frequency of pressure fluctuations, which are induced by the vortex core precession under the runner, and the integral characteristics are considered. An analysis of the synchronous and asynchronous parts of pressure fluctuations is done; the generating and influence of the synchronous component of fluctuations are considered. The vortex core interaction with the draft tube elbow is considered.

Kashkovsky, A. V.;Vashchenkov, P. V.;Banyai, T.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060067

Abstract Changes in aerodynamic characteristics of a space vehicle model due to interaction of the control thruster plume with the incoming flow are numerically studied. Parameters of the plume escaping from the thruster nozzle and flight data (velocity and altitude) are taken to be the parameters of the Intermediate eXperimental Vehicle. Simulations are performed by the Direct Simulation Monte Carlo Method. A multizone approach is used for combined modeling of the dense plume and the rarefied incoming flow. If the control thruster plume is fairly close to the space vehicle surface, flow interference is possible, which may alter the force and moment characteristics. In the problem considered in this paper, the pitching moment changes approximately by 10 % at altitudes below 120 km due to this interference.

Shishkin, A. V.;Sokol, M. Ya.;Shatrova, A. V.;Fedyaeva, O. N.;Vostrikov, A. A.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060079

Abstract The work has detected an influence of a constant electric field (up to E = 300 kV/m) on the structure of a nanocrystalline layer of zinc oxide, formed on the surface of a planar zinc anode in water under supercritical (673 K and 23 MPa) and near-critical (673 K and 17. 5 MPa) conditions. The effect of an increase of zinc oxidation rate with an increase in E is observed under supercritical conditions and is absent at near-critical ones. Increase in the field strength leads to the formation of a looser structure in the inner part of the zinc oxide layer.

Solonenko, O. P.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060080

Abstract A theoretical analysis of the processes proceeding during treatment of agglomerated particles in plasma flows is performed within the context of obtaining hollow microspherical powders from such particles. For the first time, approximate theoretical solutions were used to formulate the criteria to the plasma flow, and also the criteria to the particle material characteristics, whose realization is required for forming hollow microspheres with maximum possible diameter and minimum wall thickness of the particle shell. The study can prove useful for workers engaged in the development of processes for obtaining and application of powder materials.

Askarova, A. S.;Messerle, V. E.;Ustimenko, A. B.;Bolegenova, S. A.;Maksimov, V. Yu.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060092

Abstract Numerical experiments on the torch combustion of the coal dust prepared by a plasma-thermochemical treatment for combustion have been done using the method of three-dimensional simulation. It is shown that the plasma preparation of coal for combustion enables one to optimize the process, improve the conditions for inflammation and combustion and minimize the emissions of harmful substances.

Leontiev, A. I.;Milman, O. O.

2014 Thermophysics and Aeromechanics

doi: 10.1134/S0869864314060109

Abstract The dependency of condensing steam flow parameters in tubes and channels was studied as a function of different flow modes for the coolant: counter-flow, co-flow, cross-flow. The drop for the total pressure of steam is higher for the counter-flow than for the co-flow or cross-flow modes. The pressure drop was estimated with different computation models as a function flow mode. Calculation results were compared with experimental data.