Propagation speed of acoustic waves is of vital importance in pipeline leakage detection using acoustic method. However, the wave front shape and thermodynamic process of leakage acoustic waves in gas-liquid stratified flow remain unclear, which restricts the proper calculation of sound speed in this flow pattern. This paper presents a simulation study using CFD software Fluent to investigate the propagation process of leakage acoustic waves in stratified flow. The leakage acoustic waves are generated in different fluid phases and small time-step simulation is implemented to study the pressure behavior during the wave propagation. The results show that leakage acoustic waves propagate as single plane wave in gas-liquid stratified flow and the propagation process is nearly adiabatic. The value of polytropic exponent when calculating the sound speed in gas phase should be 1.4. Further, experimental study is conducted to verify the simulation results. Influencing factors including pressure and void fraction are considered. The present results contribute to the proper selection of sound speed calculation model in stratified flow, which can improve the leakage detection accuracy in gas-liquid stratified flow pipelines.
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