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Thermophysics and Aeromechanics

2016 year, number 6

Experimental study of aerodynamic characteristics of a reentry vehicle on a setup with free oscillations at supersonic velocities

N.P. Adamov1, A.M. Kharitonov1, E.A. Chasovnikov1, A.A. Dyadkin2, A.N. Krylov2, and E.N. Aleksandrov2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Korolev Rocket and Space Corporation Energia, Korolev, Moscow region, Russia
Keywords: reentry vehicle, free oscillations, pitch damping coefficient, aerodynamic characteristics
Pages: 791800

Abstract >>
A setup with free oscillations containing a transverse sting for holding the test model and possible test regimes are described. The method of testing and data processing is presented. Aerodynamic characteristics of the pitching moment of the model in a wide range of Mach numbers are obtained. Comparisons of quasi-steady data with numerical predictions and of damping derivatives with those obtained previously in tests of the model mounted on the base sting and with calculated results are performed. The model is found to be statically and dynamically stable except for regimes with = 1.75 and 2.25, where nondecaying oscillations are excited.

DOI: 10.1134/S0869864316060019

Response of axisymmetric separated flow to its spatially localized perturbation

A.V. Dovgal, B.Yu. Zanin, and A.M. Sorokin
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: axisymmetric body, flow separation, control of separation, hydrodynamic stability
Pages: 801807

Abstract >>
The flow past an axisymmetric body with laminar boundary-layer separation in a low-velocity air stream has been studied. The hot-wire technique was employed to identify the variation of velocity field induced by a local stationary perturbation of separation region at the stern of the experimental model. A large-scale influence upon the near-wall flow due to a cylinder roughness element provided on the model surface was observed. The obtained data substantiate the possibility of controlling the laminar boundary-layer separation on an axisymmetric body using a local external forcing.

DOI: 10.1134/S0869864316060020

Numerical simulation of the evolution of unstable disturbances of various modes and initial stages of the laminar-turbulent transition in the boundary layer at the freestream Mach number = 6

D.V. Khotyanovsky and A.N. Kudryavtsev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia
Keywords: direct numerical simulation, laminar-turbulent transition, supersonic boundary layer
Pages: 809818

Abstract >>
Direct numerical simulations of linear and nonlinear stages of the evolution of unstable disturbances of various modes and initial stages of the laminar-turbulent transition in the boundary layer on a flat plate at the freestream Mach number M = 6 are performed on the basis of full unsteady NavierStokes equations for a compressible gas. A considerable effect of three-dimensional unstable disturbances on initiation of the laminar-turbulent transition is demonstrated.

DOI: 10.1134/S0869864316060032

Methods of measuring velocity fields in the problem with a channel with periodic hills

L.A. Kozinkin and M.N. Karchevskiy
Kutateladze Institute of Thermophysics, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia
Keywords: Particle Image Velocimetry (PIV), Particle Tracking Velocimetry (PTV), Pyramid Correlation, velocity field, pulsations
Pages: 819829

Abstract >>
The work studies the flow characteristics in a channel with periodic hills on the basis of three algorithms for calculating the flow velocity fields through the images: Particle Image Velocimetry, Particle Tracking Velocimetry, and Pyramid Correlation. Descriptions of algorithms, detailed information about the experiment and parameters of the received data processing, as well as the results of calculations of instantaneous velocity fields at selected time points obtained by corresponding methods are provided. In addition, the presented techniques are compared on the basis of experimental data.

DOI: 10.1134/S0869864316060044

Panoramic diagnostics of shear stresses on the channel wall with a step using the liquid crystals

G.M. Zharkova1, V.N. Kovrizhina1, A.P. Petrov1, and S.P. Podyachev2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia
Keywords: shear stress, liquid crystals, visualization, measurements, subsonic flow
Pages: 831838

Abstract >>
Measurements results on the shear stresses of surface friction by means of thin-film coatings based on holesteric liquid crystals and specialized software for digital processing of experimental video are presented in the paper. The calibration dependencies of shear stress relative to the hue and azimuth angle as well as shear stress spatial distribution at subsonic turbulent flow (V∞ = 84 m/s) around a step, trapezoidal in plane (Reynolds number calculated for step height h, Reh = 2.57×104), with a base angle of 46 were derived for two geometries of experiment. The experiments demonstrated high sensitivity of liquid crystals to rearrangement of the near-wall flow structure and possibility to obtain quantitative data about mean shear stress levels.

DOI: 10.1134/S0869864316060056

Flow structure due to hexagonal cavities and bumps on a plate surface

U. Butt1 and C. Egbers2
1 The University of Lahore, Pakistan
2 BTU Cottbus, Cottbus, Germany
Keywords: flow visualization, oil film interferometry, flow control
Pages: 839847

Abstract >>
We present the results of flow visualization and velocity measurements on a hexagonal structured surface. Several configurations with concave and convex hexagonal structures are investigated. Each hexagonal structure is 2.7 mm deep and 33 mm wide (width between flats) and has a height to diameter ratio of 0.05 based on equivalent diameter. Considered are flow velocities 19 m/s, 24 m/s, and 27 m/s. The flow bifurcates on the leading edge of the concave configuration into two counter rotating vortices and propagates further in streamwise direction. The circulating regions are identified by the peaks in r.m.s. velocity curves. In case of concave configuration, the flow splits up into counter rotating vortical structures in a vertical plane parallel to the flow. The lower vortex rotating in the opposite direction of the flow cause the oil film fringes to drift upstream. Complex circulating regions similar to the arrangement of slices in an orange can be observed on the trailing edge of the concave hexagonal structure.

DOI: 10.1134/S0869864316060068

Expansion of capabilities of the short-duration wind tunnel with an opposing pressure multiplier

V.V. Shumskii1 and M.I. Yaroslavtsev1,2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Novosibirsk State University, Novosibirsk, Russia
Keywords: short-duration wind tunnel, settling chamber, test gas, stabilization of parameters, pressure multiplier, driver air
Pages: 848856

Abstract >>
A method for raising the maximum settling-chamber pressure in a short-duration wind tunnel equipped with pressure multipliers arranged in opposition to each other for stabilization of test gas parameters is proposed. For this purpose, a wind-tunnel design with an additional third pressure multiplier attached to the body of the second pressure multiplier was developed. The rod of the additional multiplier contacts the large-area piston stage of the second multiplier, and the pre-piston space being connected to the receiver. The inclusion of an additional pressure multiplier in the wind-tunnel design at the maximum attainable driver-gas pressure of 150-170 bar, defined by the standard industrial pressure of air used for filling wind-tunnel receivers with the driver gas, allows a two-fold increase in the maximum settling-chamber pressure, from 1100 to 2000-2200 bar. For raising the maximum settling-chamber pressure above 20002200 bar, the use of one additional pressure multiplier proved to be insufficient because, in the latter case, its becomes necessary to simultaneously raise the driver-gas pressure over 150-170 bar.

DOI: 10.1134/S086986431606007X

Heat exchange at laminar flow in rectangular channels

E.P. Valueva and M.S. Purdin
National Research University Moscow Power Engineering Institute, Moscow, Russia
Keywords: heat exchange, pulsatile laminar flow, rectangular channel, numerical modeling
Pages: 857867

Abstract >>
Numerical modeling of heat exchange at a laminar stationary and pulsatile flow in rectangular channels with different aspect ratios of side lengths γ has been carried out by a finite difference method for two boundary conditions: a constant wall temperature and a constant heat flux density on the wall. For the boundary condition of the first kind, the similarity of distributions of the heat flux density and shear stress on the walls over the channel perimeter has been established. The reasons for a nonmonotonous dependence of the initial thermal interval length on γ are discussed. For the boundary condition of the second kind, the difference of the Nusselt number averaged over the peri-meter at γ → 0 from its value for a flow in a flat channel has been explained. An increase in the Nusselt number averaged over the perimeter and the period of oscillations has been revealed for a pulsatile flow in the quasi-stationary regime at large amplitudes of the oscillations of the velocity averaged over the cross section.

DOI: 10.1134/S0869864316060081

Peculiarities of evolution of shock waves generated by boiling coolant

M.V. Alekseev1, I.S. Vozhakov1,2, S.I. Lezhnin1,2, and N.A. Pribaturin1
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Novosibirsk State University, Novosibirsk, Russia
Keywords: explosive boiling, shock wave, impingement, slip flow
Pages: 869878

Abstract >>
Simulation of compression wave generation and evolution at the disk target was performed for the case of explosive-type boiling of coolant; the boiling is initiated by endwall rupture of a high-pressure pipeline. The calculations were performed for shock wave amplitude at different times and modes of pipe rupture. The simulated pressure of a target-reflected shock wave is different from the theoretical value for ideal gas; this discrepancy between simulation and theory becomes lower at higher distances of flow from the nozzle exit. Comparative simulation study was performed for flow of two-phase coolant with account for slip flow effect and for different sizes of droplets. Simulation gave the limiting droplet size when the single-velocity homogeneous flow model is valid, i.e., the slip flow effect is insignificant.

DOI: 10.1134/S0869864316060093

Regularities of interaction between drops of UHV coolants and surfaces of traps of frameless heat removal systems in space

A.A. Koroteev1, N.V. Bondareva1, Yu.A. Nagel2, N.I. Filatov2, and I.V. Baidenko2
1 Moscow Aviation Institute, Moscow, Russia
2 Keldysh Research Center, Moscow, Russia
Keywords: drop refrigerator-emitter, droplet stream generator, trapping device, ultra-high vacuum, coolant, drop sheath
Pages: 879885

Abstract >>
The regularities of interaction of drops of ultra-high vacuum liquid working media of space drop emitters with surfaces of trapping devices were considered. Their comparison with the characteristics of the interaction of drops of distilled water was performed. The achievability of trapping regimes without secondary drop formation in space was justified.

DOI: 10.1134/S086986431606010X

Evolution of temperature of a droplet of liquid composite fuel interacting with heated airflow

D.O. Glushkov, A.V. Zakharevich, P.A. Strizhak, and S.V. Syrodoy
National Research Tomsk Polytechnic University, Tomsk, Russia
Keywords: composite liquid fuel, coal-water fuel, droplet, airflow, heat transfer, ignition
Pages: 887898

Abstract >>
The macroscopic patterns of a temperature change at the center of a droplet of three-component (coal, water, petroleum) composite liquid fuel (CLF) were studied using a low-inertia thermoelectric converter and system of high-speed (up to 105 frames per second) video recording during the induction period at different heating intensity by the air flow with variable parameters: temperature of 670-870 K and motion velocity of 1-4 m/s. The studies were carried out for two groups of CLF compositions: fuel based on brown coal and coal cleaning rejects (filter cake). To assess the effect of liquid combustible component of CLF on characteristics of the ignition process, the corresponding composition of two-component coal-water fuel (CWF) was studied. The stages of inert heating of CLF and CWF droplets with characteristic size corresponding to radius of 0.75-1.5 mm, evaporation of moisture and liquid oil (for CLF), thermal decomposition of the organic part of coal, gas mixture ignition, and carbon burnout were identified. Regularities of changes in the temperature of CLF and CWF droplets at each of identified stages were identified for the co-occurrence of phase transitions and chemical reactions. Comparative analysis of the times of ignition delay and complete combustion of the droplets of examined fuel compositions was performed with varying droplet dimensions, temperatures, and oxidant flow velocity.

DOI: 10.1134/S0869864316060111

Temporal structure of gas temperature fluctuations and ignition of fine particles

I.V. Derevich and D.D. Galdina
Bauman Moscow State Technical University, Moscow, Russia
Keywords: turbulence, thermal explosion, ignition, probability density function, thermal inertia of particles, temperature fluctuation, Semenovs diagram
Pages: 899912

Abstract >>
The paper studies ignition of fine particles, i.e., irreversible growth of particle temperature from an exothermal heterogeneous reaction, with the rate approximated with the Arrhenius law. The particles are suspended in gas with fluctuating temperature, and heat transfer from the particle surface occurs according to the Newtonian law. The equations take into account the temporal structure of gas temperature fluctuations. Modern methods of functional analysis were applied for deriving a closed equation for the probability density function for the particle temperature distribution. The gas temperature fluctuations lessen the threshold for the particle ignition in the hot gas as compared with the deterministic variant. The equations for probability density function produce a closed system of conjugate equations for the average temperature and dispersion of particle temperature fluctuations. The results of simulation illustrate the phenomenon of self-speeding drift of particle temperature towards the temperature of ignition startup.

DOI: 10.1134/S0869864316060123

Density changes of bismuth and alkaline metals at the transition to the liquid state

S.V. Stankus, R.N. Abdullaev, and R.A. Khairulin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: density, bismuth, sodium, potassium, rubidium, melting, gamma-ray attenuation technique
Pages: 913918

Abstract >>
Relative density changes drf of sodium, potassium, rubidium, and bismuth on melting-crystallization were studied using monochromatic gamma-ray attenuation technique. The measurement error of density changes was 0.10.12 %. A comparison of the obtained results with the known literature data was carried out, and the values of drf recommended as reference data were determined.

DOI: 10.1134/S0869864316060135

Effect of plasma spraying regimes on structure and properties of Ni3Al coatings

E.E. Kornienko1, D.O. Mul1, O.A. Rubtsova1, S.P. Vaschenko2, V.I. Kuzmin2, I.P. Gulyaev2, and D.V. Sergachev2
1 Novosibirsk State Technical University, Novosibirsk, Russia
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: plasmatorch, plasma deposition, Ni3Al, wear resistance
Pages: 919927

Abstract >>
The structure and tribological properties of coatings made of PN85YU15 powder were studied. The coatings were deposited on the mild steel blanks by the technology of air-plasma spraying using a unit of annular input and gas-dynamic powder focusing. Efficiency of heating and acceleration of powder particles was studied preliminarily. Measurement results on temperature and velocity distributions of particles at a certain spraying distance by the method of spectral pyrometry and time-of-flight method are presented. The effect of plasmatorch arc current and amount of propane-butane in the plasma flow on the structure and properties of coatings is analyzed in this paper. It is determined that the phase composition of coatings and initial powder is the same: the main phase is Ni3Al compound; moreover, the structure contains Ni5Al3 phase. It is shown that an increase in the amount of propane-butane increases coatings porosity. The densest coatings (5.77%) were obtained at the plasmatorch arc current of 200 A with the reduced amount of propane-butane. The coatings obtained at the minimal arc current of 100 A with an increased amount of propane-butane are characterized by maximal porosity (20.38%). The results of tribological testing of the coatings under the conditions of sliding friction with a lubricant by the disc-plane scheme are presented. From the standpoint of obtaining the densest coatings with high performance, the optimal regimes of plasma spraying of PN85YU15 powder are the current from 140 A to 200 and using the air and propane-butane mixture only as the shielding gas (anode curtain).

DOI: 10.1134/S0869864316060147

Numerical models of a far turbulent wake of an elongated body of revolution

A.G. Demenkov1,2, O.A. Druzhinin3, and G.G. Chernykh4,5,6
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Novosibirsk State Technical University, Novosibirsk, Russia
3 Institute of Applied Physics RAS, Nizhny Novgorod, Russia
4 Institute of Computational Technologies SB RAS, Novosibirsk, Russia
5 Novosibirsk State University, Novosibirsk, Russia
6 Siberian State University of Telecommunications and Information Sciences, Novosibirsk, Russia
Keywords: turbulent wake of an elongated body of revolution, mathematical modeling, DNS, semi-empirical models of turbulence, self-similar decay
Pages: 929632

Abstract >>
The work presents a comparison of numerical models of a far turbulent wake of a towed elongated body of revolution in a homogeneous fluid: model based on the direct numerical simulation, and two semi-empirical models involving the equation of the turbulence energy balance. Computational results demonstrate the self-similarity of the decay and agree with known experimental data.

DOI: 10.1134/S0869864316060159

On the influence of a single roughness element on the flow in supersonic boundary layer on a blunted cone

S.V. Kirilovskiy1,2 and T.V. Poplavskaya1,2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Novosibirsk State University, Novosibirsk, Russia
Keywords: numerical modeling, supersonic flows, hydrodynamic stability
Pages: 933936

Abstract >>
The work presents the results of numerical modeling of a supersonic flow around a blunted cone with an isolated cylindrical roughness on the forebody surface in the three-dimensional formulation. The roughness element is shown to distort the mean flow and to give rise to small-amplitude disturbances with distinguished spectral peaks in the boundary layer.

DOI: 10.1134/S0869864316060160

Gas flow from a supersonic nozzle with screen into vacuum

V.N. Yarygin, V.G. Prikhodko, P.. Skovorodko , and I.V. Yarygin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: supersonic nozzle, flow into vacuum, backflow, gas-dynamic protective devices
Pages: 937940

Abstract >>
The backflow formation under gas outflow from the supersonic nozzle into vacuum was studied in detail both experimentally and numerically. Possibilities of backflow control (minimization) by using the gas-dynamic protective devices (screens) mounted at the nozzle outlet were discussed. It was shown that certain screen configurations can increase the backflow instead of decreasing it.

DOI: 10.1134/S0869864316060172

On hydrodynamic interpretation of folding of an α-helical protein

V.A. Andryushchenko1,2 and S.F. Chekmarev1,2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Novosibirsk State University, Novosibirsk, Russia
Keywords: α-helical protein, folding, folding flux, turbulence
Pages: 941944

Abstract >>
Using the method of molecular dynamics, the simulation of folding of an α-helical protein from the unfolded to compact and functional (native) state is performed. The protein folding is interpreted as a stationary motion of a compressible folding fluid. It is shown that the densities of folding fluxes obey the same similarity relations as the velocities of an incompressible fluid in the Kolmogorovs turbulence theory, except that instead of the rate of change of kinetic energy per mass unit, the rate of change of flux variance per volume unit plays the role of the key parameter.

DOI: 10.1134/S0869864316060184