Home – Home – Jornals – Thermophysics and Aeromechanics 2014 number 2

Vladimir V. Struminskii devoted the period from 1966 to 1971 to the development of aerodynamics in Siberia. It was a period of construction of aerodynamic facilities of the institute, which later formed the basis for the high level of ITAM researches and recognition of ITAM results by both domestic and foreign aerodynamic centers and universities. The undoubted credit should be given to V.V. Struminskii for creating a team of researchers-aerodynamicists within several years when he was the ITAM Director. It was in those years that the unique experimental basis in the Academy of Sciences of the USSR was developed and constructed; these facilities provided a possibility of development of basic research in aerogasdynamics. Many pioneering and fundamental results on stability and transition to turbulence, separated flows, aerodynamic interference, and rarefied gas dynamics were obtained in these wind tunnels.

The development of disturbances in the boundary layer of compressible gas on a flexible surface has been investigated in the linear and nonlinear approximations (the weakly nonlinear stability theory). The regimes of mode-rate (the Mach number М = 2) and high (М = 5.35) supersonic velocities as well as a model of a porous wall, on which a flexible film is spanned, have been considered. The boundary conditions for disturbances with regard for their trans-formation by a flexible porous coating have been derived. The character of the variation of the coefficients of the stream-wise growth of linear oscillations of different nature (the vortex waves of the first mode and the acoustic waves of the second mode) is shown. The direction and the degree of their deformations are determined by the flexible coating parameters. It is found that at moderate Mach numbers, the stabilization of disturbances and the diminution of increments occur, whereas at high М on a surface with a film, the acoustic components are destabilized, which may lead to an earlier onset of nonlinear processes. The nonlinear interactions in three-wave symmetric triplets between the vortex waves at М = 2 and between the waves of different nature at М = 5.35 are considered. In the latter case, the plane acoustic wave is the pumping wave, which excites the three-dimensional subharmonic components of vortex nature.

The work presents the results of investigating the process of supersonic flow deceleration in a duct of the two-dimensional inlet throttled by variation of the outlet cross-sectional area. An inlet with three external compression shock waves designed for the freestream Mach number М_d = 7 was considered as an example for the investigation. A one-dimensional analysis of the conditions for realization of the supersonic flow deceleration regimes in the inlet duct with two throats — in the inlet entrance and at the inlet duct outlet, has been carried out. The parametric numerical computations of two-dimensional inviscid or turbulent flows in the inlet were performed with the use of the Euler and Navier—Stokes codes of the program package FLUENT. The critical conditions for the nonuniform flow in the outlet throat bringing to choking the inlet duct were determined.

Results of an experimental study of a cylindrical air inlet designed for high flight speeds on the basis of plane flows are reported. For an air inlet intended for Mach number М = 4, the flow-rate characteristics at М = 2.85, 3.83, and 4.95 for angles of attack ranging from 0 to 9 degrees have been measured. The results of tests have shown that at free-stream Mach number М = 3.83, close to the design Mach number, the mass rate of the air flow captured by the air inlet was 96 % of its design value, and this rate increased to 99 % as the Mach number was increased to 4.95. At a lower, in comparison with the design value, free-stream Mach number, М = 2.85, the mass rate of the air flow captured by the inlet installed under zero angle of attack has decreased to 68 %. For all the examined Mach numbers, an increase in the angle of attack from 0 to 9 degrees resulted in an 8-14 % decrease of the mass rate of inlet-captured air flow. For comparison, numerical calculation of the air-inlet flow at Mach number М = 3.83 was performed. The obtained data were found to be in a qualitative agreement with experimental data.

The present paper aims at evaluating the mean wall skin friction data in laminar and turbulent boundary layer flows obtained from two optical and one thermal measuring techniques, namely, laser-Doppler anemometry (LDA), oil-film interferometry (OFI), and surface hot-film anemometry (SHFA), respectively. A comparison among the three techniques is presented, indicating close agreement in the mean wall skin friction data obtained, directly, from both the OFI and the LDA near-wall mean velocity profiles. On the other hand, the SHFA, markedly, over estimates the mean wall skin friction by 3.5–11.7% when compared with both the LDA and the OFI data, depending on the thermal conductivity of the substrate and glue material, probe calibration, probe contamination, temperature drift and Reynolds number. Satisfactory agreement, however, is observed among all three measuring techniques at higher Reynolds numbers, Re_x > 106, and within ±5% with empirical relations extracted from the literature. In addition, accurate velocity data within the inertial sublayer obtained using the LDA supports the applicability of the Clauser method to evaluate the wall skin friction when appropriate values for the constants of the logarithmic line are utilized.

The present work is devoted to a description and substantiation of an original module for computing the location of laminar-turbulent transition in subsonic boundary layer flows, which is based on the eN -method and enables more accurate computations of the flow around bodies in the presence of the so-called natural transition to turbulence in the boundary layer. A combined work of the module and the RANS solver from the aerodynamic part of the LOGOS package is demonstrated by the example of the flow past a flat plate. The obtained computed locations of the beginning and the end of the laminar-turbulent transition coincide with known reference values.

A non-steady, non-isothermal flow while filling a channel is studied with account for dissipation of mechanical energy, dependency of viscosity on temperature, and existence of free surface. Simulation results are presented for fields of temperature, viscosity, dynamic and kinematic parameters of flow as a function of key dimensionless parameters.

The present paper studies high-velocity heterogeneous flows produced with nozzle designs unconventional for cold spray; the process of coating deposition was studied under these conditions. The possibility of using uncon-ventional gas dynamic tools (swirling of main flow, nozzles with permeable profiles and with slots in the supersonic part of nozzle) for control of particle distribution in the supersonic jet is investigated: this might be useful for obtaining a proper shape of the spray spot. These experiments offered a method of gas-dynamic design for the spray spot shape, which extends the possibilities of cold spray technique.

Numerical computations of the electric arc in the external magnetic field have been done for testing the unsteady three-dimensional mathematical model. The arc of a conical and helical shape has been implemented numerically. A satisfactory agreement of the computational results with experimental data points overall to the correctness of the mathematical model and of the computational algorithm.

The work considers heat and mass transfer in the homophasic polymerization reactor. The reactor is a coaxial channel with internal tube in the form of a channel of confusor-diffuser type. The authors compared the degree of polymer transformation in the intensified coaxial reactor with internal tube of confusor-diffuser type and the reactor with constant rectilinear longitudinal section. It was found that in coaxial channels with internal tube of confusor-diffuser type, it is possible to reach high values of the transformation degree and to improve the quality of the obtained polymer.

Thermodynamic studies of the converter characteristics were performed to produce hydrogen-containing syngas from hydrocarbon fuel (kerosene) with its separated supply for thermo-oxidative and steam reforming. It is demonstrated that the optimal conditions of the converter performance correlate with the oxidant ratio of α > 0.5 at the heat-transfer wall temperature of 1200 K. Hydrogen content in the final syngas reaches 60 % by volume, free carbon (soot) deposition in reforming products is excluded, and there is no need to apply walls water cooling in the converter.

We have performed an experimental study of the evaporation intensity for droplets in atomized-liquid flow moving through a flame of fixed height. Integral characteristics of the atomized-liquid evaporation process were evaluated. Evaporation of two water droplets moving sequentially one after the other through high-temperature combustion products is analyzed. A comparison of obtained data with available theoretical predictions is given.

Results of a study of the flow rate — pressure head characteristics of a perforated membrane immersed in an oscillating liquid flow are reported; such characteristics need to be known when hydropneumodiodes are used as a pump. We show that the perforation pattern (or, more specifically, the number of perforated holes) affects just the rate of the liquid flow through membrane.

On February 20, 2014 Anatoliy M. Grishin, researcher in the field of mechanics, aerothermochemistry and thermophysics, Honored Scientist of RF and Honored Professor of Tomsk State University became 75 years of age.