Numerical Simulation of Minor Losses in Oscillating Flow

Introduction Thermoacoustic devices operate on conversion of heat into acoustic energy and vice versa for use in heat engines or refrigerators [2]. Normally the conversion between thermal and acoustic energies is realised by oscillating gas flow. The main advantages are lack of moving mechanical parts and use of non polluting inert gases as working medium. The present efficiency levels are as high as 49% of the Carnot efficiency [3] but the efficiency levels need further improvement to take them to commercial scales. Significant improvement can be achieved by reducing losses in pipe bends, expansions or entrances (other than in a straight passage) which are generally termed as minor losses. Minor losses in oscillating flows can dissipate significant acoustic power in thermoacoustic heat pumps and refrigerators [2]. Numerical simulation of minor losses can help in improving the design of thermoacoustic devices. In this work, we investigate performance of Reynolds-Average Navier-Stokes (RANS) method in capturing minor losses in incompressible oscillating flow by comparing with available experimental data.