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Thermophysics and Aeromechanics

2008 year, number 4

1.
Modelling of icing of flying vehicles in climatic wind tunnels

G.P. Klemenkov1, YU.M. Prikhodko2, L.N. Puzyrev3, A.M. Kharitonov4
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
4 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: icing, climatic wind tunnel, anti-icing system
Pages: 563-572

Abstract >>
Various forms of icing of flying vehicles are considered. Dimensionless parameters of similarity are chosen and justified. The necessity of creating a climatic wind tunnel for modelling the icing processes is grounded. A possible structural scheme of the climatic wind tunnel is given. It seems reasonable to develop a small-scale test bench for testing methods aimed at generating a uniform field of concentrations of supercooled droplets of a given size and for identifying the efficiency of various anti-icing systems and coatings.
																								



2.
Estimation of energetic efficiency of heat supply in front of the aircraft at supersonic accelerated flight. Part 1. Mathematical models

A.F. Latypov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia, latypov@itam.nsc.ru
Keywords: freestream heating, gliding flight, efficiency, scramjet, exergy method, optimal trajectory
Pages: 573-584

Abstract >>
Fuel economy at boost trajectory of the aerospace plane was estimated during energy supply to the free stream. Initial and final flight velocities were specified. The model of a gliding flight above cold air in an infinite isobaric thermal wake was used. The fuel consumption rates were compared at optimal trajectory. The calculations were carried out using a combined power plant consisting of ramjet and liquid-propellant engine. An exergy model was built in the first part of the paper to estimate the ramjet thrust and specific impulse. A quadratic dependence on aerodynamic lift was used to estimate the aerodynamic drag of aircraft. The energy for flow heating was obtained at the expense of an equivalent reduction of the exergy of combustion products. The dependences were obtained for increasing the range coefficient of cruise flight for different Mach numbers. The second part of the paper presents a mathematical model for the boost interval of the aircraft flight trajectory and the computational results for the reduction of fuel consumption at the boost trajectory for a given value of the energy supplied in front of the aircraft.
																								



3.
Modelling of streaky structures and turbulent-spot generation process in wing boundary layer at high free-stream turbulence

G.R. Grek1, M.M. Katasonov2, V.V. Kozlov3
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: straight wing, boundary layer, streaky structures, turbulent spot, high turbulence level
Pages: 584-598

Abstract >>
Results of an experimental study of turbulent breakdown in gradient boundary layer at high freestream turbulence are reported. For the first time it is shown that, like the flat-plate boundary layer, the wing boundary layer at high freestream turbulence is modulated with streaky structures. One of possible mechanisms underlying the generation of turbulence spots in wing boundary layer is modelled assuming the interaction of streaky structures with high-frequency waves. Qualitative and quantitative data concerning the evolution of streaky structures in swqpt-wing boundary layer and in swept-wing boundary layer are presented. Certain differences between the evolution of streaky structures in wing boundary layer and in flat-plate boundary layer are revealed.
																								



4.
Harmonics of Tollmien - Schlichting waves in a compressible boundary layer

G.V. Petrov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia, smorodsk@itam.nsc.ru
Keywords: boundary layer, stability, nonlinearity, transition to turbulence
Pages: 599-602

Abstract >>
The harmonics of Tollmien-Schlichting waves in a compressible boundary layer of a plate are computed with the aid of nonlinear parabolized stability equations. At the (downstream) growth of the second harmonic amplitude up to the values of the order of the basic harmonic amplitude, the amplification rate of the latter is shown to increase abruptly. A similar rapid deviation from the results of the linear theory characterizes the onset of the boundary-layer transition to turbulent state. Computations are carried out for the Mach numbers М = 0.01 and 2.
																								



5.
Experimental studies of influence of the turbulent flow structure on temperature distribution in a compact heat exchanger

B.V. Perepelitsa
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, perep@itp.nsc.ru
Keywords: turbulence, flow structure, corrugated sheets, wall temperature, contact points, gap
Pages: 603-609

Abstract >>
Results of experimental investigation of temperature distribution over the surface of a complex heat exchanger (the Frenkel packing type) are presented. Measurements were carried out in the air flow between two sheets with triangular corrugations directed at 90° to each other. Measurements were carried out by the microthermocouples glued on the heated outer surface. The effect of Reynolds numbers, a gap between corrugated sheets, and substitution of one corrugated sheet by the smooth one on temperature distribution over the heat exchanger surface in the turbulent air flow is analysed. According to the performed experiments, there is a significant effect of a gap and applied perturbations on the type of temperature distribution over the perimeter of a heated cell.
																								



6.
Flow separation behind a rib in a channel with laminar flow

V.M. Molochnikov1, N.I. Mikheev2, A.A. Paereliy3, K.R. Khairnasov4
1 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia, vmolochnikov@mail.ru
2 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
3 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
4 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
Keywords: combined measurements, flow visualization, flow separation, laminar-turbulent transition, space-time structure, integral scale, large-scale vortical structures
Pages: 611-621

Abstract >>
Visualization data and results of combined measurements of flow quantities in flow with separation past a rib at nominally laminar regime of channel flow are reported. In the separation region, the flow is found to be essentially three-dimensional and unsteady, exhibiting a distinct cellular structure and flow zones with transverse motion. It is shown that the rib-induced flow separation gives rise to low-frequency fluctuations of flow velocity and initiates the turbulence transition in the channel flow. The critical Reynolds number at which flow instability starts developing in the channel is estimated. It is shown that at Reynolds numbers higher than the critical Reynolds number the linear integral scale of flow velocity fluctuations in the channel is defined by the duct size.
																								



7.
Unsteady film cooling with imposed nonuniform pulsations of the main flow

T.YU. Izmodenova1, N.N. Kortikov2, N.B. Kuznetsov3
1 Klimov JSC, St. Petersburg, Russia, tizm@mail.ru
2 Saint-Petersburg State Polytechnic University, Saint Petersburg, Russia, n-kortikov@yandex.ru
3 Klimov JSC, St. Petersburg, Russia
Keywords: unsteady film, cooling efficiency, main flow pulsations, Strouhal number
Pages: 623-628

Abstract >>
Effects of the main flow pulsations on the unsteady adiabatic film cooling efficiency were investigated. The possibility of using the critical value of the modified Strouhal number for the single-row perforation to identify the quasi-steady flow in the double-row perforation was proved. The penetration of disturbances into the perforation channels due to “plunger” effect was observed. The influence of the imposed pulsations on the adiabatic film cooling efficiency was shown to be weaker for the double-row perforation as compared to the single-row perforation.
																								



8.
Turbulent gas-dispersed flow in a pipe with sudden expansion: numerical simulation

V.I. Terekhov1, M.A. Pakhomov2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, erekhov@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, pakhomov@ngs.ru
Keywords: gas-dispersed flow, turbulent flow, flow separation, simulation
Pages: 629-642

Abstract >>
A mathematical model was developed to simulate two-phase gas-dispersed flow moving through a pipe with axisymmetric sudden expansion. In the model, the two-fluid Euler approach was used. The model is based on solving Reynolds-averaged Navier - Stokes equations for a two-phase stream. In calculating the fluctuating characteristics of the dispersed phase, equations borrowed from the models by Simonin (1991), Zaichik et al. (1994), and Derevich (2002) were used. Results of a comparative analysis with previously reported experimental and numerical data on two-phase flows with separation past sudden expansion in a plane channel and in a pipe are given.
																								



9.
Relaxation auto-oscillations in a fluidized bed

V.G. Tuponogov1, A.F. Ryzhkov2, A.P. Baskakov3, O.A. Obozhin4
1 Ural State Technical University, Ekaterinburg, Russia, tuponogov@mail.ustu.ru
2 Ural State Technical University, Ekaterinburg, Russia
3 Ural State Technical University, Ekaterinburg, Russia
4 Ural State Technical University, Ekaterinburg, Russia
Keywords: gas slugs, surface velocity, cavity on the surface, annular particle streak, voidage variation, Ergun equation, cycle of oscillations
Pages: 643-657

Abstract >>
Oscillations of nonuniform fluidized bed in the slugging regime are considered. A nonlinear one-dimensional model of bed oscillations is developed and investigated, including the equations of the bed surface motion and the oscillations of the pressure drop in the bed for the phase of the surface ascent and for the phase of its fall. A quasi-discrete process of the gas escape from the layer with large bubble and the relaxation (discontinuous) type of oscillations of the bed surface and of the pressure, which are related to the above process, are shown based on the model analysis, the obtained numerical solutions, and the comparison with experiment.
																								



10.
Measurement of the wave characteristics of a film under the effect of external perturbations

E.A. Chinnov1, A.D. Nazarov2, A.F. Serov3
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, nazarov@itp.nsc.ru
Keywords: heat transfer intensification, wave characteristics, artificial perturbations on the film surface, thermocapillary-wave regime of rivulet formation, changes in relative amplitudes of large waves
Pages: 659-665

Abstract >>
The effect of artificial perturbations on structure formation in the water film flow over a vertical plate with a heater was studied experimentally. To measure the film thickness an eight-channel capacitance probe was used. It is shown that artificial perturbations on the liquid film surface can change the distance between rivulets from the values corresponding to the thermocapillary-wave regime of rivulet formation to the values related to the thermocapillary regime. The distance between the rivulets can be changed at Reynolds numbers higher than those corresponding to the thermocapillary regime. Artificial perturbations do not change significantly the relative amplitude of large waves, but they affect the character of amplitude dependence on the heat flux density.
																								



11.
Criterion of homogeneous boiling-up of superheated liquids

G.V. Ermakov1, E.V. Lipnyagov2
1 Institute of Thermal Physics UB RAS, Ekaterinburg, Russia, ermakov-german@mail.ru
2 Institute of Thermal Physics UB RAS, Ekaterinburg, Russia
Keywords: waiting time for boiling-up of superheated liquid, theory of homogeneous stationary nucleation, theoretical and empirical work of critical nucleus formation
Pages: 667-675

Abstract >>
It is difficult to eliminate the effect of vessel walls and impurities in practical studies of boiling-up of strongly superheated liquids. Therefore, some doubts are always cast upon validity of experiments and their agreement with the classical theory of homogeneous stationary nucleation, impairing the verification of theoretical considerations. This paper reports main results of the theory of homogeneous nucleation and presents formulas for calculating the work of formation of a critical nucleus by an incline of the accessible superheating boundary on isobars and isotherms. Matching of experimental and theoretical values of the work of formation was considered as the homogeneous boiling-up criterion. Calculations by isobars and isotherms were made for some liquids. The theoretical values of the work of formation of a critical nucleus were 1.23-4.5 times higher than the corresponding empirical values for all the liquids, i.e., they were much higher than the calculation error. Thus, boiling-up of the studied liquids was not homogeneous and, hence, it did not correspond to the classical theory of nucleation.
																								



12.
Numerical and analytic investigation of the dynamics of hollow droplet impact onto substrate

A.N. Cherepanov1, O.P. Solonenko2, V.V. Bublik3
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, ancher@itam.nsc.ru
Keywords: hollow metal droplet, substrate, impact, mathematical model
Pages: 677-688

Abstract >>
A numerical and analytical model is proposed for the impact of a hollow melt droplet onto the surface of a solid polished substrate. The model is based on integral laws of the mass and energy conservation of the colliding droplet, it accounts for capillary and adhesion properties of the melt. The main parameters of the high-velocity deformation of a hollow particle have been computed: the variation of its height, shell thickness, and the contact spot diameter up to the moment of the spreading droplet solidification as well as the pressure variation inside the droplet until the moment of the shell rupture. The critical pressure value at which the rupture occurs is estimated by a formula characterizing the spherical shell strength. Quite a fair agreement of the computed values of the final diameter of the splat of a spread and solidified droplet with the data of physical experiment  is shown.
																								



13.
Mathematical modelling of damp porous material drying in diffusion approximation

U.R. Ilyasov1, D.E. Igoshin2
1 Nizhnevartovsk Branch of Southern-Ural State University, Nizhnevartovsk, Russia
2 Sterlitamak State Teacher Training Academy, Sterlitamak, Russia, navydimka@rambler.ru
Keywords: mathematical modelling, drying, heat and mass transfer, vapor, water, volumetric moisture content, porosity, diffusion, thermal conductivity, self-similar problem, shooting
Pages: 689-697

Abstract >>
The problem of drying a porous permeable material is considered. Self-similar solutions are derived for the process of the moisture diffusion transport. The dependence of drying intensity on the porous medium initial state as well as on the parameters of external effect is investigated.
																								



14.
On the mathematical modeling of processes of peat firing and smoldering

A.N. Golovanov1, A.S. Yakimov2, A.A. Abramovskikh3, YA.R. Sukov4
1 Tomsk State University, Tomsk, Russia
2 Tomsk State University, Tomsk, Russia, YakimovAS@mail.ru
3 Tomsk State University, Tomsk, Russia
4 Institute of Monitoring of Climatic and Environmental Systems SB RAS, Tomsk, Russia
Keywords: peat, drying, water, pyrolysis, friction
Pages: 699-710

Abstract >>
Based on a mathematical model of a porous reacting medium the statement and mathematical solution are presented for a problem of the peat smoldering rise as a result of the effect of a lower seat of fire. It is found that at moderate temperatures T ≤ 750 K the firing and smoldering of the initial reagent are determined by the intensity of the external burning seat as well as by the processes of the peat drying, pyrolysis, and the oxidation reaction of the coked fixed bed.
																								



15.
Analysis of the properties of heat radiation of the axisymmetric semitransparent systems with permeable boundaries

N.A. Rubtsov1, S.D. Sleptsov2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, sleptsov@itp.nsc.ru
Keywords: heat radiation, semitransparent medium, permeable boundaries
Pages: 711-719

Abstract >>
Numerical analysis of hemispherical values of absorptive, transmitting, and reflective abilities of a flat layer and absorptivity of a sphere is presented in this paper depending on the optic thickness and refractive index.
																								



16.
Development of carbon-carbon nozzle extension for liquid fuel rocket motors

M.I. Sokolovsky1, S.N. Petukhov2, YU.P. Semyonov3, B.А. Sokolov4
1 SPA "Iskra", Perm, Russia
2 SPA "Iskra", Perm, Russia
3Korolev RSC "Energy", Moscow, Russia
4 Korolev RSC "Energy", Moscow, Russia, iskra@iskra.perm.ru
Keywords: liquid fuel rocket motor (LFRM), carbon-carbon extension
Pages: 721-727

Abstract >>
Successful experience of RSC "Energy" and SPA "Iskra" in the development of carbon-carbon extension for oxygen-kerosene liquid fuel rocket motor has been summarized. Methodological approach that served to completion of carbon-carbon extension development in full and at comparatively small expenses has been described. Results of practical application of carbon-carbon extension for liquid fuel rocket motor 11D58М have been presented within the framework of International Space Program "Sea Launch".
																								



17.
Thermal conductivity and thermal diffusivity of tantalum at in the temperatures range from 293 to 1800 K

I.V. Savchenko1, S.V. Stankus2
1 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia, gamma@itp.nsc.ru
2 Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: laser flash method, tantalum, thermal conductivity, thermal diffusivity, high temperatures
Pages: 729-732

Abstract >>
Thermal diffusivity of polycrystalline tantalum at the temperatures range from 293 to 1800 K has been measured by the laser flash method with the error of 2−4 %. Thermal conductivity has been calculated with the use of reference data on density and heat capacity. Approximating equations and tables of reference data for the temperature dependence of heat transfer coefficients have been obtained; comparison with the published data has been carried out.