Free Convection Heat Transfer From Spheroids

Abstract

Measurements of the heat transfer by free convection from isothermal spheroids to air are reported. The range of Rayleigh number, Ra, covered was sufficiently large that both thick boundary layer effects (at low Ra) and turbulence (at high Ra) affect the heat transfer. Data are reported for one prolate spheroid and two oblate spheroids. The results of an approximate method of analysis, which accounts for both thick boundary layers and turbulence, are also given. These are compared to the present measurements, and to earlier measurements for spheres. Excellent agreement with experiment is found. Correlation equations, from which average heat transfer rates can be calculated, are also given. These are thought to be valid at all Rayleigh numbers over a large range of eccentricity.