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Thermophysics and Aeromechanics

2008 year, number 3

1.
Thermal equation of state for real gas in a wide range of state parameters, including the critical region

A.B. Kaplun1, B.I. Kidyarov2, A.B. Meshalkin3, A.V. Shishkin4
1 Kutateladze Institute of Thermophysics SB RAS, kaplun@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS
3 Kutateladze Institute of Thermophysics SB RAS
4 Kutateladze Institute of Thermophysics SB RAS
Keywords: equation of state, compressibility factor, critical region, heat capacity, carbon dioxide, helium-4
Pages: 359-368

Abstract >>
The compressibility factor was calculated in a wide range of parameters including the critical region using the equations of state obtained previously for real gas and conditions and limitations formulated by the authors for the form (structure) of the equation of state. It was determined that maximal deviations of compressibility factor values calculated by these analytical equations from the experimental (tabulated) values occur mainly within the critical region. A corresponding correction was introduced into the initial equation, and the analytical equation accurately describing experimental data in a wide range of real gas state parameters, including the critical region, was derived. It was shown by the example of analysis of high-accuracy experimental data on thermal properties of helium in the critical region that data description by the proposed analytical equation is at least as good as that obtained by the equation of fluctuation theory (scaling). It is shown that the proposed equation meets the classical conditions at the critical point.
																								



2.
Speed of sound and ideal-gas heat capacity of freon R-236ea

S.G. Komarov1, V.A. Gruzdev2, S.V. Stankus3
1 Kutateladze Institute of Thermophysics SB RAS, gamma@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS
3 Kutateladze Institute of Thermophysics SB RAS
Keywords: R-236ea, vapor, speed of sound, ideal-gas heat capacity, ultrasonic interferometer
Pages: 369-371

Abstract >>
Speed of sound in the gaseous freon R-236ea with the purity of 99.68 mol. % has been measured by the method of ultrasonic interferometer in the range from 263 to 423 K and at pressures from 17 kPA to 4.2 MPa. Errors of temperature, pressure, and speed of sound measurement were estimated to be within +/- 20 mK, ± 1.5 kPa, and ±(0.1+0.2) % respectively. Temperature dependence of ideal-gas heat capacity of R-236ea has been calculated on the basis of the obtained data.
																								



3.
Studies of thermal resistance of mixtures in a wide temperature range. 1. Experimental techniques

A.V. Baginsky1, D.V. Volosnikov2, P.V. Skripov3, A.A. Smotritsky4
1 Kutateladze Institute of Thermophysics SB RAS
2 Institute of Thermophysics UB RAS
3 Institute of Thermophysics UB RAS, pavel-skripov@bk.ru
4 Institute of Thermophysics UB RAS
Keywords: heat exchange in solutions, metastable state, thermal conductivity, thermal resistance, method of thermal waves, impulse heating
Pages: 373-379

Abstract >>
Experimental techniques for investigation of heat transfer in liquid mixtures of different types complimenting each other have been presented. The main attention is focused on the measurements under conditions of pulse heating. The paper opens the set of papers dealing with the elucidation of features characteristic of the heat transfer in pulse superheated mixtures, including metastable states with respect to the liquid-vapor and liquid-liquid equilibriums.
																								



4.
Gas motion through porous objects with nonuniform local distribution of heat-release sources

V.A. Levin1, N.A. Lutsenko2
1 Institute of Automation and Control Processes, Far-Eastern Branch of RAS, Vladivostok, Russia
2 Institute of Automation and Control Processes, Far-Eastern Branch of RAS, Vladivostok, Russia, NickL@inbox.ru
Keywords: porous medium, heat release, gaseous cooling, numerical modelling
Pages: 381-391

Abstract >>
The gas motion through porous objects in the gravity force field with a non-uniform distribution of heat sources, which may arise as a result of natural or man-caused catastrophes (as the damaged power unit of the Chernobyl NPP), is investigated. The influence of different parameters of the heat-releasing zone on the process of cooling of such objects is analyzed with the aid of computational experiment. It is shown that the porous element heating is affected not only by the height of the heat-releasing zone and the heat-release intensity therein but also by the distance of the heat-releasing zone from the element inlet as well as by the width of the heat-releasing zone. The phenomenon of a reduction of the porous element heating with increasing distance of the heat-releasing zone from the porous element inlet is revealed. An ambiguous dependence of the porous object heating on the width of the heat-release zone is identified: at a growth of the heat-releasing zone width, the heating of the element may both increase and decrease depending on the distance of the heat-release zone from the element inlet.
																								



5.
Three-dimensional non-stationary processes in a vertically falling film of a viscous liquid

E.A. Demekhin1, S.M. Shapar2, E.N. Kalaydin3
1 Kuban State University, Krasnodar, Russia, edemexin@mail.ru
2 Kuban State University, Krasnodar, Russia
3 Kuban State University, Krasnodar, Russia
Keywords: liquid films, solitons, 3D waves
Pages: 393-400

Abstract >>
Three-dimensional wave processes in vertically falling films of viscous liquid are considered. The 3D localized perturbations, which are studied insufficiently, are of a particular interest. The numerical method for watching evolution of initial perturbations was developed. The final stage of this evolution is formation of the 3D localized structures: solitons. The boundaries of 3D soliton stability were determined.
																								



6.
PIV measurement of mean and pulsating velocities in a gas-droplet jet with low concentration of dispersed phase

V.I. Terekhov1, D.YU. Starodumova2, K.A. Sharov3
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, terekhov@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: submerged jet, two-phase flows, PIV, phase discrimination, turbulent pulsations
Pages: 401-407

Abstract >>
A Particle Image Velocimetry (PIV) system was used to perform an investigation into the effect of low concentration of dispersed phase on time-average and pulsating characteristics of the flow over the self-similar part of a two-phase jet emanating into ambient space filled with the same fluid. A phase discrimination procedure based on reflected intensity was introduced into routine practice. Distributions of mean and pulsating velocities in the carrier and dispersed phases of the gas-droplet jet were obtained. In spite of low concentration of the dispersed phase, large droplets present in the flow were found to reduce the intensity of velocity pulsations in the gas phase.
																								



7.
Influence of dispersed phase on the turbulent structure of submerged axisymmetric impact jet

A.P. Belousov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, abelousov@gorodok.net
Keywords: turbulent flows, gas-liquid flow, PIV/LIF method, impact jet, spectrum of turbulent
Pages: 409-414

Abstract >>
The PIV/LIF method was used to experimentally examine turbulent characteristics of a submerged gas-saturated axisymmetric impact jet. A novel method to analyze the dynamics of vortex formations is proposed, making it possible to obtain spectral characteristics of turbulent motion at low sampling frequency. A comparison of data obtained with theoretical models is reported.
																								



8.
Specific features of unsteady processes in the front regions of streaky structures in the boundary layer on a nonswept wing

V.N. Gorev1, M.M. Katasonov2, V.V. Kozlov3
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS Novosibirsk State University, Novosibirsk, Russia, gorev_vasiliy@ngs.ru
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS Novosibirsk State University, Novosibirsk, Russia
3 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS Novosibirsk State University, Novosibirsk, Russia
Keywords: boundary layer, laminar-turbulent transition, streaky structures, Tollmien ? Schlichting waves, forerunners, wave packets, ?-structures, wind tunnel
Pages: 415-425

Abstract >>
Under conditions of a model experiment in nonswept-wing boundary layer, forerunner wave packets were obtained in the flow regions preceding the fronts of streaky structures. A model to describe the formation and development of the fronts is proposed. An external-flow pressure gradient is shown to be a necessary condition for forerunner growth. Besides, the spatial geometry of the forerunners and the evolution of this geometry in the course of downstream development of the wave packet were studied.
																								



9.
Analysis of possible improvement of acceleration of a high-velocity air-breathing flying vehicle

YU.P. Goonko1, I.I. Mazhul2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia, mazhul@itam.nsc.ru
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia, mazhul@itam.nsc.ru
Keywords: supersonic velocities, small-scale flying vehicle, aeropropulsive characteristics, acceleration characteristics, parametric analysis
Pages: 427-441

Abstract >>
Results of parametric calculations of the total aeropropulsive characteristics and characteristics of acceleration of a small-scale high-velocity flying vehicle with an air-breathing engine are presented. Integral parameters of acceleration from the flight Mach number М = 4 to М = 7 are determined, namely, the time, required fuel stock, and range. A schematic configuration of the vehicle is considered, which allows studying the basic parameters, such as the forebody shape, the angles of surfaces of compression of the stream captured by the inlet, angles of external aerodynamic surfaces of the airframe, relative planform area of the wing panels, and relative area of the nozzle cross section. A comparative estimate of the effect of these parameters shows that it is possible to improve the characteristics of acceleration of vehicles of the type considered.
																								



10.
Aerodynamic characteristics and parameters of the cone base region at transonic speeds

A.N. Mikhalev
Ioffe Physical-Technical Institute, St. Petersburg, Russia, mikhalev@mail.ioffe.ru
Keywords: ballistics, barotrace, Mach number, transonic and supersonic flows, near wake, separation zone, laminar and turbulent flows, Reynolds number
Pages: 443-451

Abstract >>
Aerodynamic characteristics of a sharp cone with the semi-apex angle of 15° are investigated by the methods of ballistic modelling in the Mach number range from 0.5 to 3.7, which are computed under the assumption of their almost linear behavior at the angles of attack up to 10°. Using the direct shadow pictures the geometric characteristics of near wake are measured and analyzed within the considered transonic and supersonic range. They provide the basis for semi-empirical computation of integral parameters of the base cavity: the pressure, density, and temperature.
																								



11.
Investigation of separation properties of turbulent boundary layer at its sequential interaction with shocks of different strengths

M.A. Goldfeld1, YU.V. Zakharova2, N.N. Fedorova3
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
3 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: boundary layer, shock wave, expansion wave, interaction, separation zone
Pages: 453-461

Abstract >>
The results are presented for numerical modelling of two-dimensional flows with large pressure gradients in a wide range of freestream parameters (М = 2−4, Re1 = 5−30⋅106 1/m) and the intensities of perturbing factors. Computations were performed with the use of averaged unsteady Navier - Stokes equations of a viscous heat-conducting gas. The structure of a turbulent boundary layer at its passage through a single shock and a system of shocks of different strengths, which lie at a fixed distance from one another, was investigated numerically. In the case of the boundary layer passage through a system of shocks, the influence of the first interaction on the structure and separation properties of the boundary layer behind the second shock was investigated. The presence of a preliminary shock was shown to improve the boundary layer capability to withstand separation ahead of the secondary interaction region.
																								



12.
Numerical analysis of vortex dynamics and unsteady turbulent heat transfer in lid-driven square cavity

S.A. Isaev1, P.A. Baranov2, A.G. Sudakov3, N.A. Mordynsky4
1 St. Petersburg State University of Civil Aviation, St. Petersburg, Russia, saev3612@yandex.ru
2 Open Joint-Stock Battery Company "Rigel", St. Petersburg, Russia
3 St. Petersburg State University of Civil Aviation, St. Petersburg, Russia
4
Keywords: convective heat transfer, vortex dynamics, turbulence, circulation flow, incompressible viscous fluid, square cavity, URANS, MSST, VP2/3 package
Pages: 463-475

Abstract >>
Based on the solution of unsteady Reynolds equations (URANS) closed with the aid of differential equations for shear stresses transport (MSST), the evolution of the vortex structure in a square cavity with a moving lid and an unsteady turbulent heat transfer in the air medium are computed while maintaining constant temperatures of the hot moving and cold motionless walls (Re = 5⋅104). The phases of the development of dynamic and thermal processes are analyzed.
																								



13.
On the manifestation of multi-component diffusion in a laminar boundary layer with foreign blowing

V.V. Lukashov1, S.V. Zhilivostova2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: multi-component diffusion, boundary layer, foreign blowing
Pages: 477-482

Abstract >>
Specific features of laminar diffusion boundary layer on permeable surface with isothermal helium blowing into airflow are experimentally examined. Measured profiles of helium, nitrogen, and oxygen concentrations show that the proportion between the volume molar fractions of N2 and О2 varies across the boundary layer. At high intensities of helium blowing into air a difference from binary diffusion obeying the Fick law is observed. Our estimates show that, in boundary layer with foreign blowing, manifestation of effects due to multi-component diffusion is possible.
																								



14.
Numerical analysis of the spreading and crystallization dynamics of the modified metal droplet on the substrate

A.N. Cherepanov1, V.N. Popov2, O.P. Solonenko3
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
3 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: plasma-sprayed coating, collision of droplet with substrate, crystallization kinetics, supercooling
Pages: 483-489

Abstract >>
A physical and mathematical model is proposed and numerical investigations are carried out for processes of the deformation and non-equilibrium crystallization of a liquid metal drop with modifying refractory solid nano-inclusions at its collision with a solid substrate under the typical conditions of the gas-thermal and also plasma-sprayed coating. An analysis of the formation of splats is carried out depending on the substrate temperature.
																								



15.
Nonlinear non-spherical oscillations of gas bubble under a periodic variation of ambient liquid pressure

A.A. Aganin1, M.A. Ilgamov2, L.A. Kosolapova3, V.G. Malakhov4
1 Institute of Mechanics and Engineering, Kazan Scientific Center of RAS, Kazan, Russia Institute of Mechanics USC, Ufa, Russia, aganin@kfti.knc.ru
2 Institute of Mechanics and Engineering, Kazan Scientific Center of RAS, Kazan, Russia Institute of Mechanics USC, Ufa, Russia
3 Institute of Mechanics and Engineering, Kazan Scientific Center of RAS, Kazan, Russia Institute of Mechanics USC, Ufa, Russia
4 Institute of Mechanics and Engineering, Kazan Scientific Center of RAS, Kazan, Russia Institute of Mechanics USC, Ufa, Russia
Keywords: gas bubble, nonlinear oscillations, potential flow
Pages: 491-502

Abstract >>
A mathematical model is constructed for the bubble dynamics, in which the interphase surface variation is presented in the form of a series in spherical harmonics, and the equations are written with the accuracy up to the squared amplitude of the distortion of the spherical shape of the bubble. In the oscillation regimes close to periodic sonoluminescence of a single bubble in a standing acoustic wave, the character of air bubble oscillations in water was studied depending on the bubble initial radius and the amplitude of the liquid pressure variation. It was found that non-spherical oscillations of bounded amplitude can take place outside the region of linearly stable spherical oscillations. Both the oscillations with a period equal to one or several periods of the liquid pressure variation and aperiodic oscillations are observed. It is shown that neglecting the distortions in the form of spherical harmonics with large numbers (i > 3) may lead to a change of oscillation regimes. The influence of distortions on the bubble surface shape for the harmonics with i > 8 is insignificant.
																								



16.
Influence of resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion

A.V. Potapkin1, D.YU. Moskvichev2
1 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: hydrogen combustion, straight-through flow chamber, resonators, propulsion performance characteristics
Pages: 503-508

Abstract >>
The influence of acoustic resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion was experimentally examined. In the study, resonators having identical throats and different cavity diameters were used. For fixed-volume resonators the best propulsion performance characteristics were achieved in the case in which the cavity diameter differed little from the resonator throat diameter.
																								



17.
Modelling of methanol-to-hydrogen steam reforming with a heat flux distributed along a microchannel

V.V. Kuznetsov1, S.P. Kozlov2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia Novosibirsk State University, Novosibirsk, Russia, vladkus@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia Novosibirsk State University, Novosibirsk, Russia
Keywords: methanol steam reforming, heat and mass transfer, chemical transformation, microchannel, catalytic reaction
Pages: 509-517

Abstract >>
The flow of reacting mixture of methanol and steam in a 2D microslot was studied numerically at activation of the reactions on the channel wall. This modelling was carried out in the framework of Navier - Stokes equations for a laminar flow of multicomponent compressible gas. Correlations between thermal, diffusion, and physical-chemical processes were studied under the conditions of intense endothermic reaction and external heat supply distributed along the channel. It is shown that not only the amount of heat supplied to the reaction zone is essential, but also the mode of heat supply along the channel length is important, which allows optimization of the compact reactor for hydrogen production.
																								



18.
Auto-scanning in plasmatorches with the magnetic-vortex arc stabilization

B.I. Mikhailov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: tube electrodes, scanning, arc fixation, solenoid, erosion, tube electrodes, scanning, arc fixation, solenoid, erosion
Pages: 519-521

Abstract >>
Under consideration is the physical nature of the auto-scanning in plasmatorches with tube electrodes; the exclusive simplicity of this process comparing to the aeromagnetic and gas methods of scanning has been demonstrated.