Investigation of the Effect of Acoustic Waves on the Convective Heat Transfer Characteristics of Coal Powder Particles under Deep Peak Adjustment

This study employs numerical simulations to investigate the influence of acoustic parameters on convective heat transfer around coal particles, aiming to enhance heat transfer efficiency in pulverized coal combustion. The results reveal that acoustic pulsations significantly amplify the amplitudes of both lift and drag coefficients—amplitudes that increase with higher sound pressure levels (SPL) and frequencies—thereby intensifying vortex shedding at the particle rear. The introduction of acoustic waves induces a multi-peaked frequency spectrum in vortex shedding: the shedding frequency increases with acoustic frequency, while the peak amplitudes grow with rising SPL. Acoustic waves enhance heat transfer by disrupting the thermal boundary layer and promoting vortex shedding. It is further proposed that the dominant effect of acoustic parameters is governed by the ratio ε of the acoustic Reynolds number to the background flow Reynolds number: within the range 0.49 < ε < 1.94, the local Nusselt number distribution is primarily influenced by SPL; whereas within 3.87 < ε < 7.73, acoustic frequency becomes the dominant factor. This research elucidates the coupled mechanisms by which acoustic parameters affect convective heat transfer around coal particles, offering theoretical insights for improving heat transfer efficiency in coal combustion systems.