Begell House Inc.
Heat Transfer Research
HTR
1064-2285
33
1&2
2002
Local Heat Transfer Downstream of a Turbulent Separation of Any Intensity
8
Eleonora Ya.
Epik
Institute of Engineering Thermophysics of National Academy of Sciences of Ukraine (IET NASU), 2a Zhelyabov Str., 03057, Kyiv, Ukraine
The results of generalization of experimental data for heat transfer in relaxing boundary layer downstream of a turbulent separation of any intensity in turbulized flows are presented. On the basis of analysis of determining criteria responsible for heat transfer intensification a new criterion of separation intensity Tu is proposed. This criterion is determined by the difference of kinetic turbulence energies at the edge of a dynamic boundary layer and in the external flow. Using this criterion, the similarity equation for the calculation of heat transfer intensification in relaxing turbulent boundary layer is recommended.
Heat Transfer in Separated Hypersonic Gas Flows at Moderate Reynolds Numbers
8
V. P.
Provotorov
N. E. Zhukovskii Central Aerodynamic Institute, Zhukovskii, Moscow Region, Russia
Dmitry Valentinovich
Ivanov
N. E. Zhukovskii Central Aerodynamic Institute, Zhukovskii, Moscow Region, Russia
Ivan Vladimirovich
Egorov
Central Aerohydrodynamic Institute (TsAGI), 1, Zhukovsky Str., Zhukovsky,
Moscow Region, 140180, Russian Federation
Alexander Ivanovich
Erofeev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Street, Zhukovsky,
Moscow Region, 140180, Russian Federation
Separated hypersonic flows of rarefied gas over a flat plate with a vertical barrier and over a comer of compression are investigated at Reynolds numbers Re Ј 1.5·104. A kinetic approach (solution of the Boltzmann equation) and a continuum approach (solution of the Navier-Stokes equations (NSE)) are used. It is shown that in solution of the kinetic problem the point of separation is located more downstream, than in the NSE case. When using slipping boundary conditions for NSE the nonmonotonous change in the distribution of heat flux over the surface takes place in the preseparation region of flow; the peak value of the heat flux distribution is more obvious in the solution of the kinetic problem.
About a Two-Component Laminar Boundary Layer a on Permeable Plate
5
V. V.
Faleev
Voronezh State Technical University, Voronezh, Russia
A. E.
Blazhkov
Voronezh State Technical University, Voronezh, Russia
S. V.
Faleev
Voronezh State Technical University, Voronezh, Russia
A. I.
Zhitenev
Voronezh State Technical University, Voronezh, Russia
An approximate solution of the problem of heat and mass transfer on a permeable wall with discontinuous boundary conditions for a nongradient flow is considered. An expression is given for the function of concentration for the case of uniform continuous injection through a longitudinal permeable inset. Moreover, a particular solution is obtained for the energy equation for a laminar boundary layer on the plate with a thermally insulated starting length.
Multi-Equation Turbulence Model for a Free Convection Boundary Layer
6
A. F.
Fedotov
Samara State Aerospace university, Samara, Russian Federation
Yu. S.
Chumakov
State Technical University, St. Petersburg, Russia
A multi-equation turbulence model for free-convective boundary layer near a vertical flat plate is developed. Attention was specially paid to description of the mean squared temperature fluctuations and correlation of fluctuations of longitudinal velocity and temperature. An algebraic relation taking account of specific features of a free-convective flow was used to model the projection of a turbulent heat flux into a normal to a solid surface. The numerical results obtained are in good agreement with experimental data.
Hydrodynamics and Heat Transfer of a Liquid Metal Tube Flow in Transverse Magnetic Field
8
L. G.
Genin
Moscow Power Institute (Technical University), 14 Krasnoarmeiskaya str., Moscow, 111250, Russia
Vyacheslav G.
Zhilin
Incorporated Institute of High Temperatures (IIHI) of the Russian Academy of Science, 13/19 Igorskaya str., Moscow, Russia
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
Yurii P.
Ivochkin
Moscow Power Engineering Institute; and Joint Institute for High Temperatures of the Russian Academy of Sciences, 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
We carried out experimental investigations of heat transfer for a liquid metal flow in a horizontal tube in a transverse magnetic field. The experimental technique made it possible to avoid the influence of contact thermal resistance on the metal-wall interface on the measurements of heat-transfer coefficients. The buoyancy effects were taken into account. An equation is suggested which approximates the obtained data on the mean Nusselt number. Comparison with earlier experimental results is made.
Enhancement of Heat Transfer in Vertical Openended Channels in Natural Convection of Gas
5
Yu. F.
Gortyshov
A. N. Tupolev Kazan State Technical University, Kazan, Russia
Igor A.
Popov
Tupolev Kazan National Research Technical University – Kazan Aviation
Institute, 10 K. Marx Str., Kazan, Tatarstan, 420015, Russia
V. V.
Olimpiev
Kazan State Power Engineering Institute, Kazan, Russia
B. B.
Kostylev
A. N. Tupolev Kazan State Technical University, Kazan, Russia
In this paper we present results of experimental study of hydrodynamics and heat exchange in vertical open-ended cylindrical empty and intensified channels with natural convection of gas (self-draught). The boundaries of the regimes of flow are revealed and the results of generalizations of heat transfer are given. The expediency of natural convection heat exchange enhancement with laminar regime of flow is shown.
Natural Convection Heat Transfer of a Horizontal Isothermal Cylinder with Combined Boundary Conditions
6
S. E.
Gusev
Kaluga State Pedagogical University, Kaluga, Russia
O. S.
Shokhina
Kaluga State Pedagogical University, Kaluga, Russia
The aim of this work is to investigate heat transfer of a horizontal isothermal cylinder placed in an infinite volume of liquid. A part of its surface is under isothermal conditions and a part of its surface under adiabatic conditions. Four cases are considered. The results of numerical and semi-integral study of local and average heat transfer from the isothermal part of the cylinder surface are given. Comparisons with experimental data known from the literature are given.
Numerical Investigation of Tornado Enhancement of Heat and Mass Exchange Processes in Flow Past Projections in Concave Surfaces
9
Alexander
Leontiev
Joint Institute for High Temperatures
P. A.
Baranov
Saint-Petersburg State University of Civil Aviation, Saint-Petersburg, 196210, Russia
Within the framework of multiblock approach, using a finite-volume algorithm based on the physical-process splitting concept and developed for the solution of three-dimensional nonstationary Navier-Stokes equations, a numerical analysis of spatial separated flow playing a dominant role in the mechanisms of heat transfer enhancement is carrier out. Special attention is given to computer identification of self-organizing jet-vortical structures. The correctness of the developed approach is checked in comparison of numerical and physical results for a turbulent flow in a channel with a lune. The structure of a vortical flow in the vicinity of the lune on a flat wall is numerically analyzed. The connection between reorganization of a vortical structure in the asymmetric lune growth of thermal output is found out.
Numerical Simulation of the Effect of Porous Cooling of Bodies in Hypersonic Flow
8
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
The efficiency of the concept of porous cooling is checked in numerical simulation of aerodynamic heating of a wall as a result of interaction of a generated shock wave with a boundary layer developing along the surface as well as in a hypersonic flow past a blunt body. The calculated results are fitted to the available experimental data. Numerical prediction of flow and heat exchange characteristics demonstrated a substantial decrease in heat transfer when a low-intensity blowing of gas was applied in the most thermally stressed part of the wall.
Characteristics of Flow and Heat Transfer in a Turbulent Twisted Flow
11
Sergey
Kharlamov
Tomsk State University, Tomsk Polytechnic University
In the present paper the results of numerical investigation of turbulent flow and' heat transfer of incompressible fluid twisted in a circular cylindrical tube by the rotating wall technique are given. Analysis of transfer processes is made on the basis of the low-Reynolds number version of the TRS-flows turbulent model with the kL-base. Authenticity of the results is estimated by comparison with existing experimental data.
Effect of Vortex Structures on the Boundary Layer of External Flow Around Bodies
4
I. I.
Kovalev
Academic Scientific Complex "A. V. Luikov Heat and Mass Transfer Institute" National Academy of Sciences of Belarus, Minsk, Belarus
Numerical simulation of a slot-and-jet vortex generator and its effect on the wall boundary layer is considered. The existence of unsteady flow regime is shown, with initiation of unsteady votrices which separate from the jet and are carried by outer flow. When moving downstream, they deform the longitudinal velocity profile and reduce local skin friction. The considered slot-and-jet vortex generator is shown to be an effective way of overall friction reduction in its vicinity.
A New Probe for Combined Measurements of the Parameters of Turbulent Flow and Heat Transfer
6
A. K.
Saikin
Department of Power Engineering of the Kazan' Science Center, Russian Academy of Sciences, Kazan', Russia
Nikolay I.
Mikheev
Hydrodynamics and Heat Transfer Laboratory, Research Center for Power Engineering Problems, Kazan Scientific Center of the Russian Academy of Sciences, 2/31 Lobachevsky st., Kazan 420111, Russia
A. P.
Kozlov
Department of Power Engineering of the Kazan' Science Center, Russian Academy of Sciences, Kazan', Russia
Valery M.
Molochnikov
Hydrodynamics and Heat Transfer Laboratory, Research Center for Power Engineering Problems, Kazan Scientific Center of the Russian Academy of Sciences, 2/31 Lobachevsky st., Kazan 420111, Russia
A new probe for combined measurements of an instantaneous heat flow to a wall, longitudinal component of skin friction vector, and of wall pressure is presented. The design and principle of operation of the probe are described. Results of some tests are presented. The estimated measuring characteristics used have shown that the probe can be used for combined measurements of instantaneous longitudinal component of skin friction vector, pulsations of heat flow to the wall, and of the wall pressure in a turbulent flow.
Correlation Between Instantaneous Hydrodynamic and Thermal Parameters in Turbulent Separated Flow
10
A. P.
Kozlov
Department of Power Engineering of the Kazan' Science Center, Russian Academy of Sciences, Kazan', Russia
Nikolay I.
Mikheev
Hydrodynamics and Heat Transfer Laboratory, Research Center for Power Engineering Problems, Kazan Scientific Center of the Russian Academy of Sciences, 2/31 Lobachevsky st., Kazan 420111, Russia
Valery M.
Molochnikov
Hydrodynamics and Heat Transfer Laboratory, Research Center for Power Engineering Problems, Kazan Scientific Center of the Russian Academy of Sciences, 2/31 Lobachevsky st., Kazan 420111, Russia
Irek A.
Davletshin
Research Center of Power Engineering Problems, Kazan Scientific Centre of the Russian Academy of Sciences, Lobachevsky str., 2/31, Kazan, 420111, Russia
Using combined two-point measurements of an instantaneous heat now to a wall, the longitudinal component of skin friction and wall pressure in a turbulent separated flow, some regularities in the transfer in space of the fluctuations of the parameters were discovered. The data on space-time correlation between the measured parameters was obtained. It is shown that large scale eddies of the mixing layer have an essential influence on this correlation. The mechanism of the interaction of eddies with the wall in different parts of the separated flow is described.
Natural Convection in a Porous Rectangular Duct - the Brinkman Model
17
D. V.
Krishna
Department of Mathematics, Sri Krishnadevaraya University, Anantapur, India
D. V. Prasada
Rao
Department of Mathematics, Sri Krishnadevaraya University, Anantapur, India
The study of buoyancy driven convection How and heat transfer in a porous medium has gained importance owing to its application in the development of geothermal technology, drying technology, insulation technology and many other technological fields. Convective heat transfer in a rectangular porous duct with differentially heated sidewalls is a problem, which has received attention by many investigators. In this paper we discuss the said problem using finite element analysis. The governing nonlinear coupled equations for the momentum and temperature under the Brinkman's model are obtained in terms of the stream function and the temperature. The Galerkin method with eight node serendipity elements is used to obtain the coupled global matrices. These coupled matrices are solved using iterative procedure. The behavior of velocity, temperature and the Nusselt number is discussed computationally for different values of governing parameters, viz., the Grashof number, the Darcy parameter, and the Prandtl number. It is observed that in a two-dimensional convection now through a sparsely packed porous medium, the resultant velocity at any position in the given duct enhances with in crease in either the permeability of the medium or the thermal buoyancy acting on the fluid. In a given duct the influence of the thermal buoyancy exhibits a critical value for G. It is also interesting to know that irrespective of the aspect ratio of the duct, the values of Nusselt number exhibit in variance for all G in low-permeable media. In all ducts with moderate permeability the Nusselt number exhibits a hysteresis behavior for G greater than a critical value.
Hydrodynamics and Heat Transfer of a Three-Dimensional Flow in a Film Cooling System
11
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. A.
Sviridenkov
Central Institute of Aircraft Engine Manufacturing, Moscow, Russia
We carry out experimental investigation of flow and heat transfer in a film-cooling mixing unit as well as numerical calculation on the basis of a 3d equations of turbulent flow. The fact that flow structure is independent of cooler mass flow rate, i.e., Reynolds number, and is determined only by geometry is established. The turbulence and heat transfer depend on both geometry and Reynolds number.
Influence of the Wall Temperature Regime on the Transition to Turbulence in the Boundary Layer with High Level of External Disturbances
7
A. E.
Yakubenko
"Energomash" Science and Production Association, M. V. Keldysh Research Center, Institute of Mechanics at the Moscow State University, Moscow, Russia
A. A.
Pavel'ev
"Energomash" Science and Production Association, M. V. Keldysh Research Center, Institute of Mechanics at the Moscow State University, Moscow, Russia
Valerii G.
Lushchik
"Energomash" Science and Production Association, M. V. Keldysh Research Center, Institute of mechanics of Lomonosov Moscow State University, Michurinsky prospect 1, 119192, Moscow, Russia
The results of numerical investigation of the influence of the external turbulence level, surface-flow temperature ratio, and flow Mach number on transition to turbulence in a boundary layer are presented. It is shown that the critical Reynolds number decreases with increase of the above parameters. The obtained qualitative and quantitative picture of the transition agrees with the available experimental data.