Concave wall heat transfer characteristics with longitudinal pressure gradients and discrete wall jets

Abstract

The effects of free stream velocities, longitudinal pressure gradients and discrete wall jets on concave wall heat transfer characteristics have been examined in wind tunnel and water channel flows at momentum thickness Gortler numbers from 5 to 30 at the initial station. It was shown that longitudinal vortices became supressed with increasing free stream velocities. The pressure gradient parameters of up to 0.75 x 10(-6) resulted in a regular vortex structure and caused mean heat transfer coefficient to increase. The pressure gradient parameter of 1.8 x 10(-6) was sufficent to suppress the vortex development so that there was no heat transfer augmentation above that of flat plate values. Measurements with blowing parameters of up to unity showed that the streamwise vortices and the wall temperature patterns were controlled by the jets so that maximum Stanton numbers exceeded minimum values by a factor of around three. With blowing parameters larger than unity, the interaction between the streamwise vortices and the wall jets caused irregularities in wall temperature patterns so that the streamwise variation of Stanton number remained nearly unchanged.