Thermophysics and Aeromechanics

Pakhomov, M. A.;Terekhov, V. I.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030015

Abstract Dynamics of a disperse phase in a swirling two-phase flow behind a sudden tube expansion is simulated with the aid of Eulerian and full Lagrangian descriptions. The carrier phase is described by three-dimensional Reynolds averaged Navier–Stokes equations with consideration of inverse influence of particles on the transport processes in gas. The velocity profiles calculated using these two approaches are practically the same. It is shown that the main difference between the Eulerian and Lagrangian approaches is presented by the concentration profile of the dispersed phase. The Eulerian approach underpredicts the value of particle concentration as compared with the Lagrangian approach (the difference reaches 15−20 %). The dispersed phase concentration predicted by the Lagrangian approach agrees with the measurement data somewhat better than the data obtained through the Eulerian approach.

Abdrakhmanov, R. Kh.;Dvornikov, N. A.;Lukashov, V. V.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030027

Abstract The Particle Image Velocimetry (PIV) technique and laser Doppler anemometer (LDA) were used to measure the components of tangential and axial velocities of gas and particles in a vortex chamber with a fluidized bed, particle layer dynamics was estimated qualitatively, and the flow in the vortex chamber with a centrifugal fluidized bed of solid particles was simulated numerically. It is shown that with the growth of gas velocity in the swirler slots, the rotation velocity of bed grows almost linearly, and with an increasing bed mass, the rotation velocity decreases. Data on distributions of the volume fraction of particles and gas flow velocity inside the bed were obtained by numerical calculation.

Chikishev, L. M.;Dulin, V. M.;Gobyzov, O. A.;Lobasov, A. S.;Markovich, D. M.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030039

Abstract Using planar optical methods based on laser-induced fluorescence and particle image velocimetry instantaneous velocity fields and passive tracer concentration are measured simultaneously in a model of GT-combustor at realistic flow rates. Spatial distributions of velocity pulsations and passive tracer concentration pulsations are measured at air flow rate about 0.4 kg/s. Correlations of velocity and concentration pulsations are measured. The most intense turbulent mass flux in the region of swirling flow mixing layer was observed. The contribution of advective and turbulent components in the transfer of a passive tracer in the axial direction was estimated.

Morenko, I. V.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030040

Abstract The numerical simulation of the laminar viscous flow past a cylinder performing rotary oscillations around its axis is carried out. The Navier–Stokes equations are solved by finite volume method using the program package OpenFOAM. The values of the amplitude and frequency of forced oscillations are found, at which the maximum reduction of the drag coefficient of the cylinder is achieved.

Gorelov, D. N.;Govorova, A. I.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030052

Abstract The plane nonlinear initial boundary value problem about the separated flow past a plate set in motion at a constant velocity from the state of rest has been considered. Results of a numerical experiment which have allowed us to trace in detail the vortex-wake formation process behind a vertical plate are reported. It is shown that, after the beginning of the plate motion, several stable vortical structures, including a Karman street, form in succession behind the plate. It is found that, on the emergence of the Karman street, there occurs a sharp and substantial growth of vortex-wake intensity and hydrodynamic drag force with a pulsating time behavior. A conclusion about the origination, in this regime, of self-sustained oscillations of the liquid in the vicinity of the plate is drawn.

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

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030064

Abstract The work presents the results of an analysis of starting conditions for some frontal axisymmetric inlets of internal compression tested at freestream Mach numbers М = 3−8.4 in the hot-shot wind tunnels based at Khristianovich Institute of Theoretical and Applied Mechanics (ITAM). The results of these inlets test are compared with the data of numerical computations of inviscid, laminar, and turbulent flows carried out by the pseudo-unsteady method. There were determined the inlet throat areas limiting either with regard to the inlet starting or with regard to providing the maximally possible degree of geometric compression of the inlet-captured supersonic airstream at its deceleration in the already started inlet. Reshaping of computed flow patterns in the inlets depending on the variation of the minimal cross section of the inlet internal duct is analyzed.

Maltsev, L. I.;Podzharov, Yu. S.;Kabov, O. A.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030076

Abstract A criterion was elaborated for the phenomenon of dry spot evolution in isothermal liquid films on a horizontal substrate. The formulas are presented for gravity force and surface tension acting upon an element of the rim around the dry spot. The forces balance gives the evolution of initial dry spot: to expand or to contract.

Sharypov, O. V.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030088

Abstract Within the framework of approximate physical and mathematical model, we considered the stationary problem of propagation of evaporation front in superheated liquid along the flat heater. The analytical dependence of the vapor layer thickness on the coordinate and physical parameters has been obtained. The solution is presented in invariant dimensionless form. Satisfactory agreement between theoretical results and new experimental data is shown.

Molchanov, A. M.;Bykov, L. V.;Yanyshev, D. S.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S086986431703009X

Abstract The method has been developed to calculate infrared radiation of vibrational nonequilibrium gas based on k-distribution. A comparison of the data on the calculated nonequilibrium radiation with results of other authors and with experimental data has shown satisfactory agreement. It is shown that the results of calculation of radiation intensity using nonequilibrium and equilibrium methods significantly differ from each other. The discrepancy increases with increasing height (decreasing pressure) and can exceed an order of magnitude.

Kirilovskiy, S. V.;Poplavskaya, T. V.;Tsyryulnikov, I. S.;Maslov, A. A.

2017 Thermophysics and Aeromechanics

doi: 10.1134/S0869864317030106

Abstract The results of the numerical and experimental investigations of the evolution of the disturbances in a hypersonic shock layer on a flat plate streamlined by a flow of the mixture of vibrationally excited gases are presented. The experimental study was conducted in the hot-shot high-enthalpy wind tunnel IT-302 of the ITAM SB RAS. The numerical simulation was carried out with the aid of the ANSYS Fluent package using the solution of the unsteady two-dimensional Navier−Stokes equations with the incorporation of the user-created modules and enabling the consideration of the vibrational non-equilibrium of the carbon dioxide molecules within the framework of the model of the two-temperature aerodynamics. It was obtained that an increase in the carbon dioxide concentration in the mixture with air leads to a reduction of the intensity of pressure disturbances on the surface. The efficiency (up to 20 %) of the method of sound absorbing coatings in the vibrationally excited flows of the mixture of the carbon dioxide and air has been shown.