Effects of sound on local transport from a heated cylinder

Abstract

The steady transport of heat from a horizontal circular cylinder supported in a standing transverse sound field was investigated. Experimental conditions were chosen to allow ready comparison with solutions of the momentum and energy equations. Local heat transport was studied, it being more sensitive to sound fields than overall transport. Experiments were performed with a heated cylinder in an anechoic chamber and a laser schlieren-interferometer was used to obtain local measurements of temperature gradients in the air surrounding the cylinder. Sound field intensities ranged up to 142 db. The convection was analyzed in the equations for mean motion using the Reynolds stresses generated by the sound to represent the effect of the sound field. The velocity and temperature fields of the mean motion were represented as an azimuthal series of functions of the radial coordinate, and the solutions computed at finite Grashof and streaming Reynolds numbers for conditions at the bottom stagnation region. Substantial agreement was found between experimental transport and the computed solutions for horizontal sound fields. The analysis showed that the effect of the sound field is significantly greater at the moderate Grashof numbers (0 (10 3)) used in the experiments than predicted by a boundary layer analysis ( Gr → ∞) for otherwise similar conditions. The results support the hypothesis that effects of sound and vibrations can be accounted as the influence on the mean motion of Reynolds stresses associated with the oscillations.