Laminar Free Convection Over Two-Dimensional and Axisymmetric Bodies of Arbitrary Contour

1974 ◽  
Vol 96 (4) ◽  
pp. 435-442 ◽  
Author(s):  
F. N. Lin ◽  
B. T. Chao
Keyword(s):  
Free Convection ◽  
Experimental Information ◽  
The Body ◽  
Two Dimensional ◽  
Universal Functions ◽  
Body Contour ◽  
Convection Boundary ◽  
Smooth Objects ◽  
Elliptical Cylinders ◽  
Axisymmetric Bodies

A rapid computation procedure is described for the prediction of heat transfer in laminar free convection boundary layers, either two-dimensional or axisymmetrical, over isothermal smooth objects with fairly arbitrary shape. The analysis employs suitable coordinate transformation which makes it possible to express the solutions of the governing conservation equations in terms of a sequence of universal functions that depend on the fluid Prandtl number and a configuration function. The latter is completely determined by the body contour and its orientation relative to the body force that generates the motion. Several of the leading universal functions have been evaluated and tabulated. The theory was applied to a number of body configurations and the results compared well with published analytical and/or experimental information. Some new results are also obtained for the local Nusselt number over horizontal elliptical cylinders and ellipsoids or revolution.

scholarly journals Critical Mach Numbers of Flow around Two-Dimensional and Axisymmetric Bodies

Aerodynamics ◽  
2021 ◽  
Author(s):  
Vladimir Frolov
Keyword(s):  
Mach Number ◽  
Cross Section ◽  
Flow Simulation ◽  
The Body ◽  
Two Dimensional ◽  
Critical Mach Number ◽  
Method Of Integral Relations ◽  
Viscosity Factor ◽  
Mach Numbers ◽  
Axisymmetric Bodies

The paper presents the calculated results obtained by the author for critical Mach numbers of the flow around two-dimensional and axisymmetric bodies. Although the previously proposed method was applied by the author for two media, air and water, this chapter is devoted only to air. The main goal of the work is to show the high accuracy of the method. For this purpose, the work presents numerous comparisons with the data of other authors. This method showed acceptable accuracy in comparison with the Dorodnitsyn method of integral relations and other methods. In the method under consideration, the parameters of the compressible flow are calculated from the parameters of the flow of an incompressible fluid up to the Mach number of the incoming flow equal to the critical Mach number. This method does not depend on the means determination parameters of the incompressible flow. The calculation in software Flow Simulation was shown that the viscosity factor does not affect the value critical Mach number. It was found that with an increase in the relative thickness of the body, the value of the critical Mach number decreases. It was also found that the value of the critical Mach number for the two-dimensional case is always less than for the axisymmetric case for bodies with the same cross-section.

Laminar Mixed Convection Boundary Layer Flow Over Two Dimensional and Axisymmetric Bodies

2013 ◽  
Author(s):  
Sufianu A. Aliu ◽  
Richard O. Fagbenle
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Convection Boundary Layer ◽  
Two Dimensional ◽  
Universal Functions ◽  
Laminar Mixed Convection ◽  
Layer Flow ◽  
Axisymmetric Bodies

Simple and familiar perturbation parameters have been employed in applying the corrected Merk series of Chao and Fagbenle to the laminar mixed convection flow over two dimensional or axisymmetric bodies. The governing ordinary differential equations for the first five sets of the resulting universal functions for the velocity and temperature have been given. Numerical solutions were subsequently obtained and the relevant universal functions tabulated with respect to the ‘wedge parameter’ for mixed convection two dimensional flows and with respect to both the ‘wedge parameter’ and ‘shape parameter’ for the axisymmetric case. Using the wall derivatives of these universal functions, friction and heat transfer in mixed convection flows over two dimensional or axisymmetric bodies have been obtained and used in evaluation of skin friction and surface heat transfer.

Effect of Base Cavities on the Aerodynamic Drag of an Axisymmetric Cylinder

1979 ◽  
Vol 30 (2) ◽  
pp. 400-412 ◽  
Author(s):  
Thomas Morel
Keyword(s):  
Bluff Body ◽  
Aerodynamic Drag ◽  
The Body ◽  
Two Dimensional ◽  
Cavity Depth ◽  
Small Depth ◽  
Ventilated Cavity ◽  
Order Of Magnitude ◽  
Different Depths ◽  
Axisymmetric Bodies

SummaryBase cavities (hollow extensions mounted behind the rear end of a bluff body) are known to reduce substantially the aerodynamic drag of two-dimensional bodies. For axisymmetric bodies their effect is not well established, and the objective of this work was to assess their drag-reducing potential. Experiments were performed using three different types of base cavities, one solid walled and two ventilated, each with six different depths ranging from 0.1 to 0.9 body diameters. All three types of cavities reduced the body drag for small cavity depths, with a maximum drag coefficient reduction of 0.027 being obtained with a ventilated cavity 0.2 diameters deep. The reductions are an order of magnitude lower than those reported for two-dimensional bodies, but are achieved with a much shorter cavity depth. Although the ventilated cavities had a beneficial effect for small depths, at large depths (greater than 0.5 diameters) they had an opposite effect – a very large drag increase. The cause of this increase is as yet not understood. Hot-wire investigation revealed that base cavities suppress wake periodicity. For cavities of small depth this correlated with a reduction in drag, but for large cavity depths the trends of the intensity of the periodic motion and of drag were not always the same.

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