Experimental and numerical analysis of heat transfer within cavity working under highly non-stationary flow conditions

Cavities and gaps are a common design element of a lot of types of machinery and equipment. The fluid flow over a cavity may generate acoustic waves, which may have both negative and positive implications. This paper is focused on the possibility of improving the heat transfer conditions using the phenomenon of the acoustic wave generation. The operating conditions of a system including an acoustic generator are analysed both numerically and experimentally. A measuring stand and the applied measuring techniques are presented. The sound pressure level characteristic is determined and then compared with the results of a numerical simulation performed for different models. Additionally, the Schlieren technique is used to determine flow structure within the cavity. The second part of the paper concentrates on the analysis of the impact of a change in the acoustic generator scale on the propagation of waves and heat transfer conditions. Changes are observed in the acoustic wave key parameters. Distributions of the heat transfer coefficient values are determined for the generator individual walls. A reduction in scale involves changes in frequency, the sound pressure level and the heat transfer coefficient mean value.