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Panina, A. V.;Kosinov, A. D.;Yermolaev, Yu. G.;Gorev, V. N.;Semionov, N. V.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010028
Abstract For the first time, detailed experiments aimed at evaluation of the influence of flat microroughness elements (adhesive tape stickers attached to the streamlined surface) on the mean and pulsation flow characteristics in flat-plate and swept-wing boundary layers were carried out under comparable dimensional conditions. At Mach number M = 2, the sticker shape was found to have almost no influence on the amplitude of mass-flow pulsations in the wake of sticker. The relative receptivity of 3D boundary layer to stationary disturbances was obtained to be approximately 1.5 times higher than the receptivity of 2D boundary layer. It was found that the presence of a sticker at the line of the source of controlled disturbance changes the pulsation spectra in 2D and 3D boundary layers in comparison with unperturbed flow. In the wake behind the center of a sticker, the flow can be most unstable.
Uskov, V. N.;Chernyshov, M. V.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S086986431401003X
Abstract The stationary shockwave systems (the sequences of shocks, isentropic expansion and compression waves), which arise at a planar supersonic flow of perfect inviscid gas around the bodies are investigated theoretically. The domains of the existence of shockwave systems under consideration are found analytically and numerically for the model problems of supersonic aerodynamics (the flow around a single plate, the plate with the frontal shield, polygonal profiles), the parameters of systems are determined, which provide the extrema of the force and thermal loadings as well as of the aerodynamic coefficients of streamlined bodies.
Panov, L. V.;Chirkov, D. V.;Cherny, S. G.;Pylev, I. M.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010041
Abstract A new approach was proposed for simulation of unsteady cavitating flow in the flow passage of a hydraulic power plant. 1D hydro-acoustics equations are solved in the penstock domain. 3D equations of turbulent flow of isothermal compressible liquid-vapor mixture are solved in the turbine domain. Cavitation is described by a transfer equation for liquid phase with a source term which is responsible for evaporation and condensation. The developed method was applied for simulation of pulsations in pressure, discharge, and total energy propagating along the flow conduit of the hydraulic power plant. Simulation results are in qualitative and quantitative agreement with experiment. The influence of key physical and numerical parameters like discharge, cavitation number, penstock length, time step, and vapor density on simulation results was studied.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010053
Abstract It is suggested to use the method of experimental investigation of temperature conditions at the spacecraft with application of their reduced thermal models based on the similarity criteria formulated under the assumption of the mathematical nodal model of the studied object. Usually thermal-vacuum experiments with full-size object have tight time constraints due to a significant cost. However, on the basis of result of this limited experiment we can specify the parameters of the scale model developed using the nodal mathematical model. This correction ensures the compliance between the results of full-size and scale experiments. After that the scale thermal experiment can supplement the full-scale experiment due to investigation of thermal conditions, which cannot be reproduced experimentally in the full-scale experiment because of the limited resources. The suggested method will significantly expand the possibility to get reliable experimental data about the temperature modes of space objects without a considerable increase in costs.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010065
Abstract The mathematical model for determination of boiling expectation time and total local evaporation in the falling wavy liquid films at unsteady heat release has been developed. Numerical simulation of the process of wave formation in the falling films of liquid nitrogen has been carried out. Dependence of boiling expectation time on heat flux density under the conditions of graduated heat load increase has been calculated. Satisfactory agreement between the results of numerical simulations and experimental data is shown.
Palani, G.;Kirubavathi, J. D.;Kim, Kwang Yong
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010077
Abstract The present numerical analysis addresses free convection flow of a viscous incompressible fluid along an inclined semi-infinite flat plate considering the variation of viscosity and thermal diffusivity with temperature. The governing equations are developed with the corresponding boundary conditions are transformed to non-dimensional form using the appropriate dimensionless quantities. Due to complexity in the transformed governing equations, analytical solution will fail to produce a solution. Hence, most efficient and unconditionally stable implicit finite difference method of Crank-Nicolson scheme has been used to solve the governing equations. Numerical results are obtained for different values of the viscosity, thermal conductivity, inclination angle, Grashof number, and Prandtl number. The overall investigation of the variation of velocity, temperature, shearing stress and Nusselt number are presented graphically. To examine the accuracy of the present approximate results, the present results are compared with the available results.
Bouakkaz, R.;Talbi, K.;Khelil, Y.;Salhi, F.;Belghar, N.;Ouazizi, M.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010089
Abstract The heat transfer and air flow around an unconfined heated rotating circular cylinder is investigated numerically for varying rotation rates (α = 0–6) in the Reynolds number range of 20–200. The numerical calculations are carried out by using a finite volume method based commercial computational fluid dynamics solver FLUENT. The successive changes in the flow pattern are studied as a function of the rotation rate. Suppression of vortex shedding occurs as the rotation rate increases (α > 2). A second kind of instability appears for higher rotation speed where a series of counter-clockwise vortices is shed in the upper shear layer. The rotation attenuates the secondary instability and increases the critical Reynolds number for the appearance of this instability. Besides, time-averaged (lift and drag coefficients and Nusselt number) results are obtained and compared with the literature data. A good agreement has been obtained for both the local and averaged values.
Kozlovskii, Yu. M.;Stankus, S. V.;Yatsuk, O. S.;Agazhanov, A. Sh.;Komarov, S. G.;Anufriyev, I. S.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010090
Abstract The article presents the results of investigation of thermal expansion of 16Kh12V2FTaR steel in the temperature range 20–1000 °C. Measurements were carried out by dilatometric method with the error (1.5–2)×10−7 K−1. The temperature dependences of thermal coefficient of linear expansion of steel have been obtained in ferrite-martensite and ferrite-perlite states, and reference tables have been calculated. Influence of samples cooling rate on martensite phase formation is shown.
Zaikovskii, V. N.;Klinkov, S. V.;Kosarev, V. F.;Melamed, B. M.;Trubacheev, G. V.
2014 Thermophysics and Aeromechanics
doi: 10.1134/S0869864314010107
Abstract This paper presents a study of supersonic jets formed by approaches that are new for cold spray technique: the main flow is swirled, the nozzles with permeable profiles and with exit slots on the supersonic section are engineered. The flow swirling achieved in the nozzle prechamber retains downstream to substrate surface. The system of vortices created within the permeable nozzles changes the shock wave features of the overexpanded jet and the geometry of the bow shock wave ahead of the substrate surface. These new features of flow may affect particle motion and particlesubstrate interaction under the conditions of cold spray process; this offers tools for obtaining the necessary shape of a spray spot.
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