Thermophysics and Aeromechanics

Adamov, N. P.;Vasenev, L. G.;Zvegintsev, V. I.;Mazhul, I. I.;Nalivaichenko, D. G.;Novikov, A. V.;Kharitonov, A. M.;Shpak, S. I.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020016

Abstract Aerodynamic coefficients of the HB-2 AGARD reference model measured in a new AT-303 hypersonic wind tunnel with adiabatic compression are presented. The experiments are performed in the ranges of Mach numbers M = 9.7 − 15.6 (Red = 0.14·106 − 1.32·106) and angles of attack α = −4°−12° with the use of an internal six-component strain-gauge balance. The technique used for processing and correcting measured results, which takes into account the dynamic properties of the model and the specific features of the nozzle structure, is described in detail. The aerodynamic coefficients obtained for this model are compared with similar data obtained in wind tunnels of Germany, France, and the USA.

Aulchenko, S. M.;Zamuraev, V. P.;Kalinina, A. P.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020028

Abstract The work deals with an investigation of possibilities of controlling the aerodynamic characteristics of airfoils with the aid of external local pulsed-periodic energy supply at transonic flight regimes. The alteration of flow structure near a symmetric airfoil and its wave drag has been studied on the basis of a numerical solution of two-dimensional nonstationary gas dynamics equations versus the energy supply period, the localization and shape of the energy supply zone. The energy supply upstream of the closing shock in the immediate proximity of the contour in the zones extended along it is found to result in a considerable reduction of the profile wave drag. The nature of such a drag reduction is elucidated. The existence of a limiting frequency of energy supply is established.

Borodulin, V. I.;Ivanov, A. V.;Kachanov, Y. S.;Komarova, V. Yu.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S086986430602003X

Abstract The distributed (over the longitudinal coordinate) excitation of two-dimensional (2D) Tollmien — Schlichting (TS) waves by weak non-stationary free-stream vortices propagating along the edge of the laminar boundary layer developing over a surface with small-amplitude 2D roughness is examined. The vorticity vector of the free-stream vortices was oriented over the span of the model, i. e., did not depend on the transverse coordinate. The theoretical analysis of the excitation mechanism reported in [1] was refined to develop, around it, a procedure making it possible to experimentally determine the coefficients of distributed vortical receptivity of the flow and the coefficients of “vortex-roughness” receptivity by fitting the experimental distributions with analytical solutions. Under conditions with controllable excitation of disturbances, a detailed hot-wire study of free-stream disturbances and boundary-layer disturbances at several vortex frequencies and at several surface-roughness periods was performed, and the shape of the controllable surface roughness was measured. The point-source method was employed to experimentally examine the characteristics of linear three-dimensional (3D) stability of the flow to TS waves, necessary for determination of the coefficients of distributed receptivity. It was found that the free-stream vortices with transverse orientation of the vorticity vector excited boundary-layer TS waves via two receptivity mechanisms: (a) on the smooth surface (due to natural non-uniformity of the flow) and (b) during interaction of the vortices with the surface roughness. The developed approach was used to experimentally estimate the amplitudes and phases of the coefficients of both types of distributed vortical receptivity as dependent on problem parameters. The absolute values of both types of receptivity coefficients were found to rapidly grow in value with increasing vortex frequency. It is shown that the most efficient excitation of TS waves is observed in the situation with satisfied resonance conditions for streamwise vortex, surface-roughness, and TS-wave streamwise wavenumbers, resulting in strong deviation of the increments of the TS waves from the linear-stability increments. Under no-resonance conditions, only amplitude beats of boundary-layer disturbances were observed.

Petrov, G. V.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020041

Abstract The computations of nonlinear development of pairs of oblique Tollmien — Schlichting waves in a boundary layer on a plate are carried out for M = 2 using the non-local (parabolized) stability equations. Besides such waves, a harmonic engendered by them is involved in the interaction.

Chernoray, V. G.;Kozlov, V. V.;Loefdahl, L.;Pratt, P. R.

2006 Thermophysics and Aeromechanics

doi: 10.1134/10.1134/S0869864306020053

Abstract The nonlinear stage of breakdown to turbulence is a strongly three-dimensional process and represents a difficult task for experimental studies. Investigation of laminar-turbulent transition in aerospace applications additionally involves a complex base-flow with pressure gradients and secondary velocity components resulting in successive increase of necessary measurements. The developed hot-wire visualization technique offers a possibility for an advanced analysis whilst retaining the advantages of traditional visualization methods and is especially suitable for resolving such complex flows.

Goonko, Yu. P.;Kudryavtsev, A. N.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020065

Abstract The inviscid supersonic flows in corners between intersecting compression wedges were studied numerically. Under usual conditions, the flows in such corner configurations are conically self-similar. Besides, shock waves formed by wedges are plane and they interact with one another in these flows and the downstream development of the shock interaction structure at that occurs in a region which is bounded in cross-sectional directions by the walls and contracts towards the corner rib, and in this sense the above interaction of shocks may be subjected to influence of the rib. The corner flows of another type with an interaction of shocks not subjected to the “rib effect”, in other words free, were considered. This was ensured by that the corner configurations were designed with a gradually expanding gap along the rib in a way that the reflected shocks arising as a result of interaction passed through the gap without falling onto the walls. This eliminated the influence of a local flow near the corner rib on the interaction of plane shock waves formed by the wedges. The inviscid flows symmetric with respect to the bisector plane of the corner dihedral angle were considered. The computations showed that, in the gapped corner configurations with the free interaction of shocks, if these interactions were irregular, the cross-flow patterns were practically the same as in the original corner configurations without a gap. The conditions for the flows over corner configurations were also considered under which the interaction of shocks corresponded to the Neumann criterion of mechanical equilibrium. These conditions are equivalent to those, which take place in two-dimensional steady flows, when a hysteresis phenomenon is possible, which manifests itself in changing the moment of transition from a regime of regular reflection of shocks to an irregular one and conversely at a direct and inverse courses of varying the flow parameters—the Mach number and the inclination angle of the wedges. The conducted computations showed that a hysteresis is possible for considered corner flows in gapped configurations, but it must be followed by a detachment of shocks from the corner apex and a breakdown of the conical flow structure.

Bondar, Ye. A.;Gimelshein, S. F.;Markelov, G. N.;Ivanov, M. S.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020077

Abstract The applicability of a new model in terms of the description of real gas effects in the Direct Simulation Monte Carlo method is analysed. The model is used in a numerical study of the internal structure of the front of a strong shock wave and relaxation zone behind the front for conditions corresponding to spacecraft entry into the Martian atmosphere. The influence of the free-stream parameters on relaxation of various energy modes of molecules in the wave front and in the relaxation region is considered. The effect of chemical reactions on the flow structure is studied. A detailed analysis of flow nonequilibrium is performed at the level of the velocity distribution function and population of rotational and vibrational levels of molecules.

Berdnikov, V. S.;Filippova, M. V.;Krasin, B. A.;Nepomnyashchikh, A. I.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020089

Abstract Conjugate heat transfer was studied numerically at multisilicon production from flat-bottom crucible using a vertical version of the Bridgman — Stockbarger method. The equations of convective heat transfer in the area occupied by melt, and heat-conductivity equations for the solid silicon body and crucible walls were solved, considering the heat of phase transition.

Musakaev, N. G.;Urazov, R. R.;Shagapov, V. Sh.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020090

Abstract In this work, equations and methods of multiphase media mechanics were used to simulate the hydrodynamic, thermophysical, and heat-and mass-transfer processes in natural-gas flow through a horizontal pipe with allowance for gas-hydrate deposition onto the inner pipe wall. The influence of several factors on the hydrate formation process was numerically examined.

Kler, A. M.;Marinchenko, A. Yu.;Sushko, S. N.

2006 Thermophysics and Aeromechanics

doi: 10.1134/S0869864306020107

Abstract The technique for optimization of parameters of a power unit of a gas-turbine small-size heat and power plant was developed with regard for seasonable nature of heat and electric energy loads; the approach uses linear versions of dependency of outlet parameters on the inlet parameters. A mathematical model of the energy unit of a mini-HPP was developed. Optimization calculations for a coal gas-turbine mini-HPP were carried out for several optimization criteria: minimal revenue from the produced heat and electric energy (at different levels of fuel price), minimum of fuel consumption during year, and minimal investment at a given internal return rate.