Numerical Study of the Entrance Effects in an Oscillatory Flow of a Standing-Wave Thermoacoustic

Siti Hajar Adni Mustaffa; Fatimah Al-Zahrah Mohd Saat; Ernie Mattokit

Authors

Siti Hajar Adni Mustaffa Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia
Fatimah Al-Zahrah Mohd Saat Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia
Ernie Mattokit Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia

Keywords:

Oscillatory flow , entrance region , turbulence , standing-wave , thermoacoustics

Abstract

Entrance effect and formation of the vortex structure play a vital role in understanding the flow physics at the channel entry especially in oscillatory flow inside the channel between thermoacoustic stack plates. The aims of the current study are to investigate the effect of flow frequency on the structure of the vortex shedding at the end of the stack plates and also the effect of the vortex formation at the end of the plates associated with “entrance effect”. The methods used are CFD simulation with ANSYS FLUENT as a solver. The flow was solved using laminar model and two-equation Shear-Stress Transport (SST) k-ω turbulence model. The “entrance effect” and vortex flow phenomena has been studied for two drive ratios, DR (defined as ratio of maximum pressure amplitude to mean pressure) which are 0.65% and 1.0% at two frequencies of 13.1 Hz and 23.1 Hz. The results shows that at higher frequency, the entrance length becomes shorter. This can be emphasized that flow frequency plays a significant role as it affected the entrance length and vortex formation and structure of the flow.