Thermophysics and Aeromechanics

Terekhov, V. I.; Yarygina, N. I.; Smul’sky, Ya. I.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030036

Results of an experimental hydrodynamic and heat-transfer study of the turbulent separated flow developing over a system of several cross-flow ribs are reported. Conditions with low and high free-stream turbulence are considered. Visualization and heat-transfer data are presented, and a comparison for two turbulence levels is given. In the system of three or more ribs, a very unstable flow in the second inter-rib cell was observed under low-turbulence conditions. Under a high level of free-stream turbulence, the flow in the first inter-rib cell is unstable; this observation is supported by measured pressure distributions. Addition of each next rib makes the separation flow region behind the last rib and the pressure recovery region less extended, and decreases the coordinate at which the rate of heat transfer attains its maximum. In the high-turbulent flow, the heat-transfer intensification in the second inter-rib cell amounts to 30 %.

Adamov, N. P.; Brodetsky, M. D.; Vasenev, L. G.; Zvegintsev, V. I.; Mazhul, I. I.; Kharitonov, A. M.; Paulat, J. -C.; Muylaert, J.; Kordulla, W.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030012

Results of an experimental study of aerodynamic characteristics of models of two hypersonic re-entry vehicles (ARES-H aerospace demonstrator proposed by EADS-ST and EXPERT re-entry capsule proposed by ESA ESTEC) are presented. The experiments were performed in a new wind tunnel AT-303 at ITAM SB RAS in the range of free-stream Mach numbers M = 10–18 at real values of Reynolds numbers. The test results and specific features of wind-tunnel tests in conical nozzles are discussed.

Mironov, S. G.; Tsyryul’nikov, I. S.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030024

Characteristics of the fields of mean density and density fluctuations measured with introduction of periodic disturbances into a hypersonic viscous boundary layer on a flat plate are presented. The experiments are performed for a flow Mach number M∞ = 21, Reynolds number per meter Re1∞ = 6·105 m−1, and temperature factor of the surface Tw/T0 = 0.26. The disturbances are introduced into the shock layer by an oblique gasdynamic whistle.

Kornilov, V. I.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030048

The effect of periodic blowing/suction on characteristics of a turbulent boundary layer formed on an axisymmetric body of revolution in a nominally gradientless incompressible flow is studied experimentally. The Reynolds number based on the momentum thickness at the location of an annular slot for blowing/suction is 1176. The dimensionless slot width in the wall units is 68. It is demonstrated that blowing/suction aimed at controlling the boundary-layer flow is a fairly effective method for controlling the near-wall turbulence structure and ensures a certain gain in friction drag over the initial configuration (the maximum gain reaches 25–30 %).

Klinkov, S. V.; Kosarev, V. F.; Sova, A. A.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s086986430603005x

An ejector scheme intended for forming supersonic heterogeneous flows is experimentally examined as applied to conditions typical of cold gas-dynamic spraying. Pressure and temperature distributions in the supersonic part of the nozzle are reported, and critical operating regimes of the nozzle are identified. Specific features and advantages demonstrated by this scheme in practical applications are considered. Results of preliminary tests on the application of coatings with the use of the nozzle unit under study are presented.

Vasil’iev, E. N.; Derevyanko, V. A.; Nesterov, D. A.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030061

A computational model for processes in the duct of an experimental setup consisting of a shock tube and an MHD duct is presented. The one-dimensional model is used for determining the flow characteristics in the entire setup duct, and the three-dimensional model is used for studying the current layer dynamics in the MHD channel. Computations have enabled the elucidation of flow structure and of the peculiarities of current layer formation.

Kashinsky, O. N.; Kurdyumov, A. S.; Randin, V. V.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030073

This paper deals with wall shear stress in an upward gas-liquid slug flow inside a vertical tube. Local characteristics were measured by the electrodiffusion method. The method of conditional averaging over realization ensemble was used, and this allows distinguishing large-scale structures on the background of turbulent pulsation of liquid. While averaging, each slug velocity measured by a double probe of electric conductivity was taken into account. Averaged distributions of shear stress over the wall under a gas slug were obtained for different mode parameters.

Maltsev, L. I.; Malyuga, A. G.; Novikov, B. G.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030085

Two different mechanisms responsible for the were revealed impact of gas bubbl injected into a boundary layer on the shear stress on the wetted surfaces. Both mechanisms exist due to extremely high sensitivity of bubbles even to very low pressure gradients and due to a high value of the virtual mass and coefficient of viscous drag for bubbles. The first mechanism manifests itself at the interaction of vortex structures with bubbles in the near-wall layer y+ < 250. The second mechanism is due to pressure gradient along the wetted surface. Ascertainment of these mechanisms explains the known discrepancies in the experimental results on gas saturation obtained on different experimental setups.

Kostolomov, I. V.; Kutushev, A. G.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030097

Mathematical modelling of three-dimensional steady free convective incompressible viscous gas flows in the rooms with a heat source is carried out within the framework of the Navier — Stokes equations with the effective viscosity determined on the basis of the κ-ɛ turbulence model. The investigation is carried out for the case of model rooms and heat sources having the form of rectangular parallelepipeds with square bases. The influence of the heat source power and the sizes of the room base on local and averaged values of the air velocity and temperature in the rooms is analysed. The flow pattern in the room is shown to have a torus-like shape. It is found that the variation of sizes of the room base rather than the capacity variation of the heat source is of determining importance for the gas motion character in a closed volume.

Mezentsev, I. V.; Vernikovskaya, N. V.; Aristov, Yu. I.; Mukhin, V. A.

2006 Thermophysics and Aeromechanics

doi: 10.1134/s0869864306030103

Experimental results on reversing non-stationary heat transfer are presented for filtration of an air flow through an immobile heat accumulating medium consisting of lead (D = 2.0, 3.5, and 4.5 mm) and glass (D = 3.2 mm) balls. The studied device imitated the cyclic modes of heat regeneration in the ventilation system for domestic and office rooms. Dependency between the time of flow switching and Re number was measured. The mathematical model describing heat transfer between a gas flow and an immobile layer of balls was developed. Good correspondence between the experimental data and calculation results is observed for high Reynolds numbers. For low Re numbers the effect of heat losses is considerable, and experimental time of flow switching is shorter than the calculation one.