Conjugate problem of heat transfer in a laminar boundary layer with injection

The author examines two conjugate problems of heat transfer in the laminar boundary layer at the boundary of a semi-infinite porous medium on the assumption that fluid filters continuously through the porous surface and that the injection velocity varies as x^–1/2, where x is the distance in the direction of flow.     

Buoyancy effects on the laminar boundary layer heat transfer along vertically moving cylinders

Abstract

The effects of buoyancy forces on the laminar boundary layer flow and heat transfer along vertically moving cylinders are analyzed for the cases of prescribed surface temperature and prescribed wall heat flux in power of streamwise distance. Local similarity solutions are obtained to show the effects of buoyancy parameters and the transverse curvature of the cylinder on the surface friction and heat transfer rate.     

Generalization of data on convective heat transfer with vaporization to a turbulent boundary layer

Dimensionless complexes describing heat transfer from a plate on evaporation from the surface are derived on the basis of the integral momentum and energy relationships for a turbulent boundary layer.     

Non-similarity solution and correlation of transient heat transfer in laminar boundary layer flow over a wedge

With a comprehensive and rigorous method, this paper has successfully examined the transient heat transfer in a steady and two-dimensional (2D) laminar boundary layer flow on a wedge with sudden change of thermal boundary conditions of uniform wall temperature (UWT) and heat flux (UHF). Additionally, a correlation of unsteady forced convection was also formulated through an exact solution of transient heat conduction (ξ=0) and the similarity solutions of a steady forced convection on a wedge (ξ=1) in this study. Particularly, for the wedge with −0.198838?ξ?1, the deviation of the wall temperatures estimated by correlation is less than 7.5% within full time of 0?ξ?1 comparing with numerical results in the case of UHF ranging from Pr=10⁻⁴ to 10⁴.     

层流状态下纳米流体的对流传热特性

通过数值模拟的方法研究了层流状态下雷诺数、体积分数、颗粒和基液种类以及颗粒粒径对纳米流体对流传热特性的影响。研究结果表明,纳米流体的对流传热系数明显高于基液,并且与基液和颗粒的性质、颗粒的体积分数及颗粒粒径密切相关。纳米流体的对流传热系数随着颗粒和基液热导率的增加、颗粒体积分数的增加以及颗粒粒径的减小而增大。研究发现,对于一定体积分数的Cu-水纳米流体,在层流状态下对流传热系数的提高程度基本保持一致,与雷诺数大小无关。     

The laminar boundary layer,taking into account radiative energy transfer

The integral-differential energy equation is solved, taking into account the viscous dissipation, convection, thermal conductivity, and radiative transfer, without restrictions on the optical thickness of the boundary layer. Comparison of the calculated results with the solution obtained without taking into account the absorption makes it possible to evaluate the relative role of absorption. The influence of radiation on the enthalpy profile and thickness of the boundary layer is investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 5, pp. 829–835, November, 1969.     

Flow in a laminar boundary layer under intensive injection and radiant heat exchange

An asymptotic solution has been obtained for the system of boundary layer equations with intense injection of a foreign absorbing substance for optically thick and thin boundary layers taking account of the influence of a magnetic field. Analytical formulas are presented which permit computation of the temperature, concentration, and heat flux profiles.     

Effect of boundary conditions on the heat transfer law for a turbulent boundary layer

The heat transfer at an impermeable plate has been experimentally investigated under various boundary conditions. The conservativeness of the heat transfer law St₀=f(Re _T ^** ) is demonstrated for a monotonic increase of temperature and heat flux along the surface.     

Quasisteady approach in calculations for convective heat transfer

An equation is derived for determining the limits of applicability of the quasisteady approach in thermal calculations involving the cooling of metal plates in liquids and gases.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 5, pp. 857–860, November, 1976.     

Calculating heat transfer in the region of an attached boundary layer

A method is proposed to calculate heat transfer after a diaphragm in a circular pipe. Satisfactory agreement is obtained between the calculated results and test data obtained with different ReD and Pr numbers and different ratios of pipe diameter to diaphragm diameter.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 5, pp. 709–713, November, 1984.     

An experimental investigation of heat and mass transfer in a reacting laminar boundary layer on a porous cylinder with propane injection

This paper gives the results of an experimental investigation of heat and mass transfer in a reacting laminar boundary layer on a cylinder through which propane is injected for Re=48 · 10⁴–4.6 · 10⁴. Empirical equations are obtained for St and St_m. The effect of injection on the wall temperature and heat transfer is shown graphically.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 4, pp. 622–632, October, 1969.The author thanks Professor B. M. Smol'skii, Head of the Thermodynamics Laboratory of the Institute of Heat and Mass Transfer, Academy of Sciences of the Belorussian SSR, and also Candidate of Technical Sciences G. T. Sergeev and his colleagues, for help in conducting the experimental investigations described in the paper. The author also thanks the Director of the Laboratory (Delhi) for permission to publish this work.     

An iterative procedure for the oscillatory laminar boundary layer

The problem of small sinusoidal oscillations imposed on a stagnation point flow is considered. This leads to an ordinary differential equation which, in the high frequency limit, has a simple solution. An iterative method (involving a linear integral operator) is developed, starting from this basic solution. This scheme, performed numerically, is ‘under-relaxed’ and this renders it applicable to as wide a frequency range as possible: convergence criteria are discussed in terms of the relaxation parameter. The streamwise velocity profiles computed are compared with those given by an independent method.     

Fabrication of heat sinks by Selective Laser Melting for convective heat transfer applications

In this paper, the forced convective heat transfer performance of heat sinks produced by Selective Laser Melting (SLM) was experimentally investigated. Three heat sinks comprising pin fins of circular, rectangular-rounded and aerofoil geometries were fabricated by SLM from aluminium alloy AlSi10Mg powder. The heat sinks were tested in a rectangular air flow channel for convective heat transfer performance. Experiments performed for Reynolds numbers ranging from 3400 to 24,000 show that the heat transfer performances of the aerofoil and rectangular-rounded heat sinks exceeded those of the circular heat sink. Using the cylindrical heat sink as a benchmark, the average enhancements in the normalised Nusselt numbers were computed to be 15.0% and 21.4% for the rectangular-rounded and aerofoil heat sinks, respectively. It was demonstrated that SLM can be employed to design and fabricate heat sinks of customised geometries for heat sink applications.     

Theory of a periodic laminar boundary layer

A method is proposed for the analysis of a periodic laminar boundary layer, refining the conventional methods of Lin, Rayleigh, and Hill and Stenning and providing a basis for the unification of those methods.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 36, No. 6, pp. 1033–1039, June, 1979.     

Analysis of interactions between shock waves and laminar boundary layers with heat transfer

Summary This paper deals with interactions between shock waves and laminar boundary layers on flat plates with heat transfer. In order to describe this phenomenon the boundary layer is divided into inner viscous layer and outer inviscid layer after Gadd. The boundary layer approximations are assumed to remain valid in the inner layer and the momentum integral equation for the layer is utilized instead of the Pohlhausen's wall condition. In the outer inviscid layer the motion is described by Euler's equation in terms of the isobar coordinates and the deflection angle is determined to match with that at the outer edge of the inner layer. The present theory predicts that self-induced separation does occur for highly cooled wall and yields results in good agreement with the measurement of Lewis et al.With 6 Figures     

Investigation of boundary layer stability in the presence of intense heat transfer

The results of an investigation of the transition of a laminar boundary layer to turbulent in the air behind a shock wave by the thin-film thermometry method are presented. Stabilization of transition Reynolds number is observed with an increase of the intensity of heat transfer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No. 1, pp. 29–33, July, 1971.     

Unsteady convective heat transfer in potential flow

Analytical relations are obtained for the unsteady temperature field in potential flow over a flat plate and a cylinder.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 1, pp. 109–115, January, 1977.     

The effect of temperature-dependent viscosity on free-forced convective laminar boundary layer flow past a vertical isothermal flat plate

Summary The effect of a temperature-dependent viscosity on an incompressible fluid in steady laminar free-forced convective boundary layer flow over an isothermal vertical semi-infinite flat plate is studied. The local similarity solution is used to transform the system of partial differential equations, describing the problem under consideration, into a boundary value problem of coupled ordinary differential equations and an efficient numerical technique is implemented to solve the reduced system. Numerical calculations are carried out, for various values of the dimensionless parameters of the problem, which include a Prandtl number, a mixed convection parameter and a viscosity/temperature parameter. The results are presented graphically and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters. In particular, it is concluded that when the viscosity of a working fluid is sensitive to the variation of temperature, care must be taken to include this effect, otherwise considerable error can result in the heat transfer processes. In the literature, such care is not always evident.