Heat transfer enhancement in laminar flow over flat plate using small pulsating jet

Abstract

A technique of heat transfer enhancement over a heated plate using a water injection to disturb a laminar boundary layer is presented in this paper. The water jet was injected from the heated surface to the mainstream flow, having turbulence intensity of 1% through a 1 mm diameter hole. After the injection, a turbulent spot playing an important role on the heat transfer enhancement was generated artificially and investigated experimentally using thermochromic liquid crystals coated on the hot wall. In this study, contours of temperature and heat transfer coefficient were presented when the Reynolds number in the mainstream flow was varied as 117,000, 158,000, and 199,000 under the constant heat flux condition. The results show that this technique can increase heat transfer capability between the hot plate and freestream flow. The results from this research were found to be an important information that will be able to increase the efficiency of heat exchanger in the future.