Experimental and numerical investigation of impinging jet array heat transfer on a smooth and v-shaped ribbed surface

The flow field and heat transfer from smooth surfaces and surfaces with V-shaped ribs (V-SR) was studied experimentally with a Laser-Doppler Anemometry (LDA) system and infrared thermal imaging technique. In addition, the phenomenon was investigated numerically using CFD. Heat transfer results from these surfaces under impingement of a circular jet array (5x3) are presented. The velocity profiles were measured at Reynolds number of 10,000 and at H/d equal to 3 and 12. Along the target plate, different boundary layer profiles were obtained. Positions of maximum radial and axial velocities and turbulence intensities have been determined. The heat transfer results have also been compared with those of a smooth surface under the same flow conditions to determine the enhancement in the heat transfer coefficient. Nusselt numbers are higher for the V-SR surfaces as compared to smooth surfaces.