The Second Fundamental Problem in Heat Transfer of Laminar Forced Convection

1962 ◽  
Vol 29 (2) ◽  
pp. 415-420 ◽  
Author(s):  
L. N. Tao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Conformal Mapping ◽  
Boundary Value Problems ◽  
Forced Convection ◽  
Heat Generation ◽  
Analytic Functions ◽  
Transfer Problem ◽  
Fundamental Problem ◽  
Laminar Forced Convection

This paper is concerned with the heat-transfer problem of laminar forced convection in noncircular pipes with arbitrary heat generation and prescribed heat flux at the wall. This class of boundary-value problems with Neumann conditions is approached by the method of conformal mapping. The solutions in terms of two analytic functions are established. This greatly enlarges the possibilities of analyses to many configurations which are otherwise not easily attainable. The example of an indented pipe of cardioid section is investigated in detail.

Experimental investigation of wall heat transfer due to spray combustion in a high-pressure/high-temperature vessel

2021 ◽  
pp. 146808742110072
Author(s):  
Karri Keskinen ◽  
Walter Vera-Tudela ◽  
Yuri M Wright ◽  
Konstantinos Boulouchos
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Pressure ◽  
High Temperature ◽  
High Speed ◽  
Transfer Problem ◽  
Wall Heat Transfer ◽  
Gas Temperature ◽  
Reference Case ◽  
High Pressure High Temperature

Combustion chamber wall heat transfer is a major contributor to efficiency losses in diesel engines. In this context, thermal swing materials (adapting to the surrounding gas temperature) have been pinpointed as a promising mitigative solution. In this study, experiments are carried out in a high-pressure/high-temperature vessel to (a) characterise the wall heat transfer process ensuing from wall impingement of a combusting fuel spray, and (b) evaluate insulative improvements provided by a coating that promotes thermal swing. The baseline experimental condition resembles that of Spray A from the Engine Combustion Network, while additional variations are generated by modifying the ambient temperature as well as the injection pressure and duration. Wall heat transfer and wall temperature measurements are time-resolved and accompanied by concurrent high-speed imaging of natural luminosity. An investigation with an uncoated wall is carried out with several sensor locations around the stagnation point, elucidating sensor-to-sensor variability and setup symmetry. Surface heat flux follows three phases: (i) an initial peak, (ii) a slightly lower plateau dependent on the injection duration, and (iii) a slow decline. In addition to the uncoated reference case, the investigation involves a coating made of porous zirconia, an established thermal swing material. With a coated setup, the projection of surface quantities (heat flux and temperature) from the immersed measurement location requires additional numerical analysis of conjugate heat transfer. Starting from the traces measured beneath the coating, the surface quantities are obtained by solving a one-dimensional inverse heat transfer problem. The present measurements are complemented by CFD simulations supplemented with recent rough-wall models. The surface roughness of the coated specimen is indicated to have a significant impact on the wall heat flux, offsetting the expected benefit from the thermal swing material.

An Experimental Investigation of Heat Transfer and Buoyancy Induced Transition from Laminar Forced Convection to Turbulent Free Convection over a Horizontal Isothermally Heated Plate

1978 ◽  
Vol 100 (3) ◽  
pp. 429-434 ◽  
Author(s):  
H. Imura ◽  
R. R. Gilpin ◽  
K. C. Cheng
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Forced Convection ◽  
Leading Edge ◽  
Finite Amplitude ◽  
Heated Plate ◽  
Transfer Rates ◽  
Longitudinal Vortices ◽  
Turbulent Flow Regime ◽  
Laminar Forced Convection

The flow over a horizontal isothermally heated plate at Reynolds numbers below that at which hydrodynamic instabilities exist, is characterized by a region of laminar forced convection near the leading edge, followed by the onset of longitudinal vortices and their growth to a finite amplitude and finally a transition to a turbulent flow regime. Results are presented for the temperature profiles, the thermal boundary layer thickness, and the local Nusselt number. They are used to identify the various flow regimes. It was found that the transition from laminar forced convection to turbulent convection was characterized by the parameter Grx/Rex1.5 falling in the range 100 to 300. For values of this parameter greater than 300 the heat transfer rates were independent of Reynolds number and typical of those for turbulent free convection from a horizontal surface.

scholarly journals Two conjugate convection boundary-layers of counter forced flow

2018 ◽  
Vol 22 (2) ◽  
pp. 835-846
Author(s):  
Mohamed Mosaad
Keyword(s):  
Heat Transfer ◽  
Boundary Layers ◽  
Conjugate Heat Transfer ◽  
Transfer Problem ◽  
Forced Flow ◽  
Relative Importance ◽  
Counter Flow ◽  
Wide Range ◽  
Convection Boundary ◽  
Laminar Forced Convection

In this study, the conjugate heat transfer problem of two laminar forced convection boundary-layers of counter flow on the opposite sides of a conductive wall is analyzed by employing the integral method. The analysis is conducted in a dimensionless framework to generalize the solution. The dimensionless parameters affecting the thermal interaction between the two convection layers are deduced from the analysis. These parameters give a measure of the relative importance of interactive heat transfer modes. Mean Nusselt number data are obtained for a wide range of the main affecting parameters.

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