Experimental investigation on thermal characteristics of hot surface by synthetic jet impingement

Abstract

This paper analyses the thermal behavior of impinging synthetic jet by employing various orifice shapes such as circular, square, and rectangular for a given hydraulic diameter. The effect of thickness of orifice plate on heat transfer behaviour is studied in this investigation. An electromagnetic actuator is used as an oscillating diaphragm for the generation of synthetic jet. A stainless steel (SS) foil (AISI-304) with 0.05 mm thickness is used as the test specimen. It is heated by DC power source (APLAB, L-3260). The surface temperature of the test specimen is measured by using a thermal imaging technique during synthetic jet impingement. Tests are carried out for wide range of Reynolds number (Re = 1183–5448), different values of jet-to-plate distance (z/d = 0–30), various orifice plate thicknesses (t = 1.6–5 mm), for a given hydraulic diameter of the orifice. The peak value of the heat transfer coefficient is found to be 16.1 times more than the heat transfer coefficient for natural convection. A correlation is proposed for Nusselt number. © 2019 Elsevier Ltd