Experimental Study on the Alteration of Cooling Effectivity Through Excitation-Frequency Variation Within an Impingement Jet Array with Side-Wall Induced Crossflow

摘要

The influence of in-phase variation of the excitation frequency of a 7 by 7 impinging jet array between f = 0 and 1000 Hz on the cooling effectivity is investigated experimentally. Liquid crystal thermography is employed to measure a 2-dimensional wall-temperature distribution, which is used to calculate the local Nusselt numbers and evaluate the global and local heat transfer. The cooling effectivity of the dynamic approach is determined by comparison with corresponding steady blowing conditions. The results show that the use of a specific excitation frequency allows a global cooling effectivity increase of more than 50%.