Experimental Heat Transfer and Cooling Effectiveness over an Effusion Wall with Internal Jet-Array Impingement: Influence of Hole Arrangement

The arrangement pattern of film and jet impingement holes plays an important role in heat transfer and cooling characteristics of an effusion cooling system. This study provides a multifaceted and integrated comparison of inline and staggered film-jet impingement cooling systems, concerning heat transfer coefficients, adiabatic cooling effectiveness, and conjugate heat transfer characteristics. Detailed adiabatic cooling effectiveness contours are mapped by applying Pressure Sensitive Paint (PSP). Heat transfer coefficients are measured using a steady heat flux method with a film foil heater. Furthermore, a conjugate heat transfer method evaluates the combined cooling effects of internal jet impingement, in-hole convection, solid conduction, and external film cooling, and the resulting temperatures on the external surface of the effusion wall are measured through an infrared (IR) camera. Results demonstrate that in the range of blowing ratios M = 0.3−2.0, adiabatic effectiveness peaks at M = 0.6 for both configurations of hole arrangement, and then decreases with further increasing the coolant flow rate. Nevertheless, increasing the blowing ratio continuously improves overall effectiveness. The staggered hole cooling geometry exhibits higher adiabatic and overall effectiveness levels relative to the counterpart. Though local distribution patterns of heat transfer coefficients are quite different for the two hole arrangements, their laterally-averaged values are approximate to one another.