A numerical study on effect of evaporation and condensation of water vapor on acoustic oscillations of a gas parcel with a Lagrangian approach in a thermoacoustic prime-mover

Abstract

Acoustic oscillations of a gas parcel in a wet stack of a thermoacoustic prime-mover are numerically simulated with a Lagrangian approach taking into account Rott equations and the effect of non-equilibrium evaporation and condensation of water vapor at the stack surface. A gas parcel gradually drifts to higher and lower temperature side of a stack in traveling-wave and standing-wave prime-movers, respectively, owing to a shift of phase angle of particle’s velocity with a movement of a parcel according to Rott equations even without evaporation and condensation. It is an alternative acoustic streaming in a narrow tube with temperature gradient along a tube. In a traveling-wave prime-mover, the volume oscillation amplitude of a gas parcel always increases by evaporation and condensation, and pV work done by a gas parcel is accordingly enhanced. On the other hand, in a standing-wave prime-mover, the volume oscillation amplitude sometimes decreases by evaporation and condensation, and pV work is suppressed. ...