Begell House Inc.
Heat Transfer Research
HTR
1064-2285
31
6-8
2000
Thermal Calculation and Study of Local and Integral Thermal Characteristics of Finned Surfaces with Conjugate Formulation of the Problem
375-379
V. G.
Gorobets
Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine
A technique for thermal calculation of developed heat transfer surfaces in the conjugate formulation of the problem is developed on the basis of integral methods of thermal calculation of the transfer equations for an outer heat carrier. New functional relations for a heat flux removed on the surface with an arbitrary temperature distribution are obtained for a turbulent boundary layer and a developed channel flow with natural convection. Thermal calculation is conducted and local and integral characteristics of a vertical surface with continuous finning in a developed flow of a heat carrier in an inner plane channel and free-convective cooling of the outer finned surface are obtained.
Numerical Simulation of the Effect of Porous Cooling in Aerodynamic Heating of the Elements of Air Ducts and Surfaces by a Hypersonic Viscous Gas Flow
380-387
Alexander
Leontiev
Joint Institute for High Temperatures
V. V.
Nosatov
N. E. Bauman Moscow State Technical University, Moscow, Russia
G. S.
Sadovnikov
N. E. Bauman Moscow State Technical University, Moscow, Russia
D. P.
Frolov
Academy of Civil Aviation, St. Petersburg, Russia
Effectiveness of the conception of porous cooling is diagnosed in numerical stimulation of aerodynamic heating of a wall that is caused by interaction of a generated shock wave and a boundary layer developing along the surface in a hypersonic flow past a wall and a blunt wedge. The developed programming complex based on the solution of the system of the Navier-Stokes and Reynolds equations, which in the latter case is closed by two differential equations of a dissipation two-parameter model of turbulence, by the explicit-implicit finite-difference McCormack method is tested in the solution of a classic problem of interaction between an oblique shock wave and a turbulent boundary layer. The results of calculation are compared to the available data of experimental studies. Numerical prediction of flow characteristics and heat transfer showed a substantial decrease in heat transfer in the case of realization of low-intensity gas injection at the most thermally stressed site of the wall.
Heat and Mass Transfer and Friction in Injection to a Supersonic Region of the Laval Nozzle
388-398
G. P.
Kalmykov
M. V. Keldysh Research Center, Moscow, Russia
Artur V.
Dmitrenko
Department of Thermal Physics, National Research Nuclear University "MEPhI", 31 Kashirskoe Shosse, Moscow, 115409, Russia; Department of Power Engineering, Moscow State University of Railway Engineering (MIIT),
9 Obraztsov St., Moscow, 127994, Russia
Experimental and calculation-theoretical studies on the determination of a flow structure in injection of a foreign gas to a supersonic region of the nozzle are conducted in order to find the possibility of thermal protection of a wall and to reduce losses of specific characteristics due to injection. Experiments are performed on a model engine. Calculation studies are conducted on the basis of a theoretical-calculation method involving a two-scale four-parameter model of turbulence with account for density fluctuations in all equations.
Laminar-to-Turbulent Flow Transition in Directed Injection Through a Perforated Surface to a Laminar Boundary Layer
399-406
A. A.
Klimov
N. E. Bauman Moscow State Technical University, Russia
S. A.
Trdat'yan
N. E. Bauman Moscow State Technical University, Russia
The paper presents the results of an experimental study of the laminar-to-turbulent boundary layer transition in directed injection along the flow and opposite to it. The effect of the value of the angle and intensity of injection on the start and end of the transition was determined. The moment of the start and end of the transition to a turbulent mode was determined by the dependence of the value of a maximum intensity of velocity fluctuations across a boundary layer cross-section on the intensity of injection. The experiments were performed at the angles of injection of 20°, 45°, 65°, 115°, 135°, and 160°. The intensity of injection varied from 0.3% to 3.2%.
Study of the Coefficient of Heat Transfer in a Tube Gas Flow with Unsteady Flow
407-413
V. M.
Kraev
Moscow State Aviation Institute (Technical University), Moscow, Russia
Study of heat transfer in unsteady turbulent flows is stipulated by the necessity to improve power systems and plants in the elements of which nonstationary nonisothermal flows are realized.
As is found in earner studies [1,2], nonstationary conditions substantially affect convective heat transfer. A study of a physical picture of turbulence, construction of a mathematical model for its description and development of correct engineering techniques for calculating hydrodynamic processes and heat transfer under the conditions of hydrodynamic nonstationarity are urgent.
The earlier conducted experimental studies of the structure of turbulent gas flows [3] showed a strong difference between the profiles of an axial velocity, axial and radial fluctuations and correlations of them in deceleration and acceleration of the flow on their quasistationary values. The authors of [3] confirmed the results of [2] indicating that flow acceleration increases, whereas deceleration decreases the coefficient of heat transfer.
Influence of the Inlet Velocity Profile on the Efficiency of Film Cooling
414-418
V. A.
Kudryavtsev
Central Institute of Aircraft Engine Manufacturing, Moscow, Russia
A. I.
Mayorova
P. I. Baranov Central Scientific Research Institute of Aircraft Engines, Moscow, Russian Federation
A length of the initial section of an element of the system of film cooling in a uniform velocity profile formed under real conditions at the outlet from the mixing device is studied. It is shown that efficiency of film cooling is determined by the profile of its averaged velocity rather than by the level of turbulence of a cooling flow.
High-Turbulent Gas Screen in a Supersonic Nozzle
419-427
V. P.
Lebedev
S. S. Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
V. V.
Lemanov
Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Viktor I.
Terekhov
Kutateladze Institute of Thermophysics, Laboratory of Thermal and Gas Dynamics, Russian Academy of Sciences, Siberian Branch, 630090,1, Acad. Lavrent'ev Avenue, Novosibirsk, Russia; Novosibirsk State Technical University, K. Markx av., 20, Novosibirsk, 630073, Russia
An effect of initial turbulence of the flow on characteristics of a gas screen in the Laval nozzle is studied experimentally. The effect of flow acceleration on turbulence behavior is considered, the distribution of turbulence is compared with the theory of rapid transformation. The distribution of static pressure, adiabatic temperature of a wall, coefficient of recovery, and the parameter of gas screen efficiency along the nozzle length is measured. An integral method is suggested for calculation of the efficiency of screen cooling on the calculated flow modes in the nozzle. The method allows for a longitudinal pressure gradient, compressibility, nonisothermicity and degree of flow turbulence.
Conjugate Heat and Mass Transfer in a Porous Wall with Coolant Injection
428-434
M. I.
Osipov
Bauman Moscow State Technical University, Moscow, Russia
A. V.
Gushchin
N. E. Bauman Moscow State Technical University, Russia
R. N.
Dadonova
All-Russia Institute of Aviation Materials, Moscow, Russia
Distributions of temperature along and across the wall are obtained as a result of the development of physical and mathematical models of the problem of conjugate heat transfer in a gas flow along the wall with a porous section of a finite length and coolant injection. Porous ceramic specimens on the basis of A12O3, Si3N4, SiC were used in the experiments. The problem was solved numerically in two-dimensional approximation by the method of finite elements using a specially-developed computer program.
Local Heat Transfer Around the Perimeter of a Complex-Shape Channel in Stagnation Zones of Rod Bundles
435-443
N. V.
Paramonov
Moscow State Aviation Institute (Technical University), Russia
An original technique of the experimental study which allows one to obtain distribution of the local coefficient of heat transfer around the perimeter of a complex-shape channel is suggested. This requires the solution of a number of problems of a methodical character, and to eliminate or considerably reduce heat overflows around the perimeter, i.e., by the walls of the complex-shape channel, and also to suggest the technique of transfer the data from the model experiment on large-scale mockups of rods to natural conditions. Experimental studies of local heat transfer in stagnation zones of complex-shape channels as applied to the interrod space of bundles of woven rods of fuel elements of nuclear reactors are made by the developed technique. Reduction of the local coefficient of heat transfer in stagnation zones of the channels by 25−35% compared to heat transfer on the remaining part of the perimeter is revealed.
Calculation of the Power of a Heat Source Necessary to Destruct an Obstacle
444-451
A. N.
Pervyshin
Samara State Aerospace University, Russia
Generalized results of theoretical and experimental studies of the process of obstacle material heating to the assigned temperature by combustion products issuing from the generator of supersonic jets are presented. In all types of heat sources this process usually precedes onset of material cutting, but it also has an individual engineering implementation, e.g., in thermal treatment. A method for calculation of a minimum power of a heat source or fuel consumption in generators of supersonic jets depending on a thickness and thermophysical properties of the material is suggested and confirmed experimentally. Energy parameters of a heat source which provide cutting of a material of any thickness are determined and corresponding restrictions for sources of smaller power are given.
Numerical Simulation of Conjugate Heat and Mass Transfer in Combination of Penetrating and Convection-Screen Cooling of a Blunt Body
452-458
Dmitry L.
Reviznikov
Moscow Aviation Institute, Volokolamskoe Shosse 4, 125993 Moscow, Russia; Dorodnicyn Computing Centre, Federal Research Center "Computer Science and Control" of Russian Academy of Sciences, 44, b. 2, Vavilov st., Moscow, 119333, Russia
Anatoly F.
Polyakov
Department of Heat Transfer, Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, Moscow 127412, Russia
A conjugate thermogasdynamic problem of combined transfer of momentum and heat in a high-temperature gas boundary layer and in a shell-design metal body containing a porous nose part is solved numerically. Particular emphasis is placed on nonuniformicities of distribution of parameters of longitudinal conjugate mass transfer. A combined effect of a porous screen, longitudinal heat conduction, a factor of nonisothermicity on the efficiency of cooling is analyzed.
Calculation of Hydrodynamics and Heat Transfer in a Transient Separating Bubble on a Plane Surface
459-465
Philippe R.
Spalart
Boeing Commercial Airplanes P.O. Box 3707, Seattle, WA 98124, USA
Michael Kh.
Strelets
New Technologies & Services St-Petersburg 197198, Russia
A. K.
Travin
Russian Scientific Center “Applied Chemistry”, St. Petersburg
M. L.
Shur
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180,Moscow region; and Russian Scientific Center “Applied Chemistry”, St. Petersburg, Russia
The results of numerical investigation of flow and heat transfer in a transient “separating bubble” formed on the wall of a plane channel, through an opposite wall of which liquid is sucked-off, are presented. Calculations are made within a framework of two-dimensional Reynolds equations by means of three different models of turbulence and by the method of direct numerical simulation. In both cases temperature is considered as a passive scalar. It is shown that dynamic characteristics of the considered flow can be calculated within the framework of Reynolds equations rather accurately, whereas the corresponding data on intensity of heat transfer on a wall are underestimated by all the considered models of turbulence by a factor of two.
Heat Transfer in Separation Zones of Turbulized Flows
466-473
Viktor I.
Terekhov
Kutateladze Institute of Thermophysics, Laboratory of Thermal and Gas Dynamics, Russian Academy of Sciences, Siberian Branch, 630090,1, Acad. Lavrent'ev Avenue, Novosibirsk, Russia; Novosibirsk State Technical University, K. Markx av., 20, Novosibirsk, 630073, Russia
Nadezhda I.
Yarygina
S. S. Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Characteristic results of experimental studies of heat transfer in separating flows behind single obstacles (in rectangular trenches, behind a back-step and a single fin with a wide range of geometric dimensions) are analyzed. Applicability limits of some laws of mean heat transfer are presented. A substantial degree of the influence of an external level of a turbulent flow past a fin and a step of various heights on heat transfer and coefficients of pressure in separation and relaxation zones is revealed. Intensification of a maximum coefficient of heat transfer by 15−20% is obtained for both obstacles.
Self-Organization, Small-Mode Chaos and Multi-Mode Turbulence
474-483
L. P.
Kholpanov
Institute for the Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka
Laws governing origination of self-organization, small-mode chaos, and multi-mode turbulence are suggested on the basis of an analysis of the solution of the non-linear parabolic equation. Dynamic modes of a wave package are classified. A mechanism of turbulence origination formulated earlier by V. V. Struminskii and B. Yu. Skobelev is substantiated.
Heat Transfer in Origination of an Upper Bypass Transition
484-492
Eleonora Ya.
Epik
Institute of Engineering Thermophysics of National Academy of Sciences of Ukraine (IET NASU), 2a Zhelyabov Str., 03057, Kyiv, Ukraine
V. A.
Grigorenko
Institute of Technical Thermophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine
The results of the study of heat transfer in by-pass laminar-to-turbulent transition (BLTT), arising in the presence of local separation on the leading edge of a flat plate with non-gradient streamlining at an elevated degree of turbulence Tue = 3.6−2.6% are presented. It is confirmed that an upper BLTT characterized by monotonic changes in the coefficients of heat transfer takes place under these conditions. BLTT of this type is diagnosed and its boundaries are determined on the basis of an analysis of distributions of coefficients of friction and heat transfer, velocity profiles, fluctuations and a formparameter. A scheme for calculation of heat transfer in the presence of BLTT that is based on use of turbulent viscosity on the outer edge of a dynamic boundary layer as a main criterion which determines intensity of heat transfer.
Two-Dimensional Laminar Free Convection in the Cavity Having a Shape of a Square with Rounded Angles
493-499
G. V.
Makhnova
St. Petersburg State Technical University, Russia
Evgueni M.
Smirnov
Department of Hydro- and Aerodynamics at the Saint-Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg, 195251, Russia
Vladimir V.
Ris
Peter the Great St.Petersburg Polytechnic University, Polytechnicheskaya 29, St.Petersburg, 195251, Russia
Two-dimensional stationary laminar free convection in cavities obtained by rounding-off the angles of an initially square shape is studied numerically at the Rayleigh numbers of from 104 to 5 · 109 at the following values of the Prandtl number 0.03, 0.1, 0.71, 2, 5, and 10. It is found for the cavities with isothermal vertical and adiabatic horizontal walls that rounding-off of the angles with preservation of the length of isothermal portions leads to an increase in the Nusselt number to 20%. The strongest effect of rounding-off of the angles is in lowering the limit of stability of stationary convection.
Electric Convection and Its Interaction with Convective Flows of a Different Nature
500-508
A. S.
Nenishev
Omsk State Technical University, Russia
M. O.
Myznikov
Omsk State Technical University, Russia
A model of low-conducting fluid (LCF), which is based on a neutral fluid with an admixture of charged particles (positive and negative ions), in an electric field is suggested. The processes of ionization of a neutral component on positive and negative ions and the processes of ionic recombination are taken into account in the fluid volume. Origination of charged particles on the electrodes is described by the equations of surface ionization. The problem of origination and development of electric convection (EC) and heat transfer in a rectangular cavity and a cylindrical cell is solved on the basis of this model. The effect of an electric field on gravity convection and hydraulic resistance and heat transfer in a forced flow in a complex-shape channel is considered.
Structure and Stability of Three-Dimensional Convective Flows
509-514
V. I.
Polezhaev
The Institute for Problems in Mechanics, Russian Academy of Sciences, Prospect Vernadskogo 101, 117526 Moscow
O. A.
Bessonov
Institute for Problems in Mechanics Russian Academy of Science, 117526 , Moscow, Russia
S. A.
Nikitin
The Institute for Problems in Mechanics, Russian Academy of Sciences, Prospect Vernadskogo 101, 117526 Moscow
A spatial structure, origination of secondary flows and three-dimensional effects of concentration nonuniformities that are caused by thermal gravitational convection in a parallelepiped are studied on the basis of the stability theory and numerical solution of three-dimensional nonstationary Navier-Stokes equations.
Heat Convection in a Fluid Rotating under Conditions of Weightlessness
515-520
V. S.
Yuferev
A. F. Ioffe Physical -Technical Institute of Russian Academy of Sciences, St. Petersburg, Russia
Yu. A.
Polovko
A. F. Ioffe Physicotechnical Institute, St. Petersburg, Russia
Heat convection in a nonuniformly rotating fluid, provided that the size of the container with the fluid is much smaller than the distance between the container and the center of rotation and the gravity force is absent, is considered. It is shown that a fluid flow is induced by the action of two forces: the buoyancy force and the inertia force associated with the angular acceleration of the container. Interaction of these forces leads to a substantial dependence of convection intensity on the angle between the temperature gradient and the radius-vector drawn from the center of rotation to the origin of the coordinate system connected with the container. The results of numerical simulation of three-dimensional convection in a cubic region are presented.
Natural Convection of Water in a Closed Three-Dimensional Rectangular Cavity Heated from Below Near the Point of Density Inversion
521-528
S. P.
Rodionov
Tumen Branch of the Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences, Tumen, Russia
Natural convection of water in a closed three-dimensional rectangular cavity heated from below at about 4°C is studied numerically on the basis of the Navier-Stokes equations in the Boussinesq approximation with account for the dependence of thermophysical parameters on temperature. Main forms of stationary convective flows are found. The effect of geometric dimensions of the cavity on the process of heat transfer is studied. The results of calculations are compared to the solutions obtained on the basis of two-dimensional equations of fluid flow.
Influence of Free Convection on Heat Transfer Along the Length of a Horizontal Heated Tube in a Liquid Metal Flow in a Longitudinal Magnetic Field
529-536
V. G.
Sviridov
Joint Institute for High Temperatures of the RAS, 125412 Izhorskaya st. 13 Bd.2, Moscow, Russia; National Research University "MPEI", 111250 Krasnokazarmennaya st. 14, Moscow, Russia
N. G.
Razuvanov
Joint Institute for High Temperatures of the RAS, 125412 Izhorskaya st. 13 Bd.2, Moscow, Russia; National Research University "MPEI", 111250, Krasnokazarmennaya st. 14, Moscow, Russia
A. V.
Ustinov
Moscow Power Institute (Technical University), Russia
Heat transfer of liquid metal along the length of a horizontal heated tube in a longitudinal magnetic field is studied experimentally. The experiment models the conditions of a thermonuclear reactor of the TOKAMAK type. Three characteristic schemes of heating are considered. Temperature fields, distributions of local and mean coefficients of heat transfer are measured. Considerable influence of free convection on the quantities studied is observed. A longitudinal magnetic field did not reduce the effects of free convection.
Effect of the Lewis Number and Chemical Kinetics in Modeling of Hydrogen Combustion
537-545
E. P.
Volchkov
S. S. Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
L. N.
Perepechko
Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Processes of heat and mass transfer in a turbulent boundary layer in combustion of hydrogen injected from a porous plate to an outer air flow are studied by numerical methods. The used model of turbulence allowed the calculation of the entire flow field including a high-gradient near-wall region. Chemical conversions are modeled by different methods with the aid of equilibrium approximation or a detailed kinetic mechanism. The coefficients of molecular transfer are calculated depending on temperature and composition. Use of kinetics of multistage reactions of formation of the products of hydrogen combustion in air does not lead, in the given case, to noticeable differences in the results. The obtained distribution of turbulent fluctuations allows one to draw a conclusion about flow laminarization in burning. Moreover, the effect of the Lewis number on the position of the flame front and other flow characteristics is analyzed.