CFD study on mean flow engine for wind power exploitation

Highlights: → We present a type of mean flow acoustic engine useful for wind power exploitation. → Numerical simulation was carried out based on large-eddy simulation of turbulence. → Impacts of flow velocity and Strouhal number on acoustic field were illustrated. → Critical acoustic pressure amplitudes occur at certain Strouhal numbers. -- Abstract: Acoustic oscillation can be induced in a closed branch tube by a mean gas flow in a trunk tube passing the opening of the branch tube. Based on this principle, novel aerodynamically driven generator and thermoacoustic refrigerator can be manufactured. Large-eddy simulation (LES) of turbulence was applied to simulate aerodynamically driven acoustic oscillation in a mean flow engine (MFE) with a cross-junction configuration. It is shown that a standing-wave acoustic field is established inside the closed branch tube at certain mean flow velocities. Different acoustic and hydrodynamic modes occur with the increase of mean flow velocity. Furthermore, Strouhal number has strong effects on acoustic and hydrodynamic modes of the MFE. Under present computational conditions, critical acoustic pressure amplitudes in the first and fifth acoustic modes occur when St = 0.39 and St = 0.94 respectively. It would be beneficial to design MFEs operating in the third acoustic mode to obtain strong acoustic oscillation.