Heat is the final form of energy, and about 1/3 of Japan's primary energy supply is exhausted to the environment without being effectively used and discarded as waste heat. One of the methods for recovering waste heat is a thermoacoustic engine, which can reuse heat for electricity and cooling. There are few examples of visualization of non-linear phenomena by numerical analysis, and it has not been sufficiently studied. The purpose of this study is to visualize the fluid behavior downstream of the stack of a thermoacoustic engine and to clarify the effect of vortex shedding on the temperature field.The self-sustained oscillation was reproduced by two-dimensional numerical analysis using the compressible solver of OpenFOAM. The calculation model was composed of two heat exchangers, a stack, and a 4m-long resonator with an open end. The buffer region on the side of the open end was also included in this calculation.&nbsp;As a result, a pressure amplitude of 4 kPa and a flow velocity amplitude of&nbsp;10 m/s were obtained by giving a temperature difference of 450 K.&nbsp;The vorticity field and temperature field were visualized and&nbsp;the obtained results show that the vortex downstream of the stack changed from symmetric to asymmetric near the peak of the flow velocity. Changes in the vortex structure caused by the unsteady flow caused irregular and non-uniform temperature field. It is also suggested that the vortex affects the heat transfer between the heat exchanger and the fluid.&nbsp;Keywords: Flow visualization, Oscillatory flow, Numerical simulation, Vortex shedding

Numerical Simulation of Vortex Shedding Downstream of a Thermoacoustic Engine Stack

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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