Numerical Simulation of Pressure Fluctuations in the Thermo-acoustic Transducer

Abstract

The article describes the features of numerical simulation of acoustic oscillation excitation in the resonators with a foam insert (regenerator) to study the excitation of thermo-acoustic oscillations in the circuit of small-sized engine model on the pulse tube.

The aim of this work is the numerical simulation of the emerging oscillations in thermoacoustic engine resonator at the standing wave. As a basis, the work takes a thermo-acoustic resonator model with the open end (without piston) developed in DeltaEC software. The precalculated operation frequency of the given resonator model, as a quarter of the wave resonator, is ν = 560 Hz.

The paper offers a simplified finite element resonator model and defines the harmonic law of the temperature distribution on regenerator. The time dependences of the speed and pressure amplitude for the open end of the resonator are given; the calculated value of the process operating frequency is approximately equal to the value of the frequency for a given length of the resonator. Key findings, as a result of study, are as follows:

1. The paper shows a potential for using this ESI-CFD Advanced software to simulate the processes of thermal excitation of acoustic oscillations.

2. Visualization of turbulent flow fluctuations in the regenerator zone extends the analysis capability of gas-dynamic processes.

3. Difference between operating frequency of the process simulated by ESI-CFD Advanced and frequency value obtained by analytical methods is about 4%, which is evidence of the model applicability to study the acoustic parameters of thermo-acoustic transducers. Experimental results have proved these data.