On the interaction of sound with steady heat communicating flows

This paper presents a theoretical and numerical investigation of the interaction between sound waves and non-diffusive, quasi-one-dimensional, subsonic flows with only steady heat communication. It is first shown that a steady heat communicating flow can attenuate or generate sound even in the absence of mean flow acceleration. The relative significance of sound generation by the heat addition induced acceleration of density or entropy inhomogeneities and the effect of steady heat communication on the incident acoustic wave is then found. It is shown through scaling arguments that at high frequencies mean flow acceleration effects are negligible and the only significant sound generating mechanism involves steady heat communication. At low frequencies, however, the two mechanisms are more comparable.