HEAT TRANSFER FROM THE REAR OF BLUFF OBJECTS TO A LOW SPEED AIR STREAM

Abstract : The local heat transfer by forced convection from the base surface of a blunt obstacle in a variety of configurations has been measured. The data are satisfactorily correlated by an equation, where the properties are evaluated at the mean film temperature. The coefficient C depends upon the configuration and the location on the rear surface. Devices that close the dead-air space, or reduce its size, reduce the value of C. Thus, C has practically the uniform value 0.20 for a flat-plate strip at 90-degree angle of attack; but at 25-degree angle of attack it changes from 0.09 sub 3, where the apparent free streamline changes direction through an obtuse angle, to 0.18 where the apparent free streamline changes direction through an acute angle.