Effect of Cavity Volume on the Flow-Excited Acoustic Resonance of a Shallow Cavity in a Pipe-Line

The effect of cavity volume on the aeroacoustic source generated by fully developed pipe flow through an axisymmetric shallow cavity is investigated experimentally. Nine cavity sizes are studied in three different groups of length, L, to depth, H, ratios (L/H = 1, 2 and 3) with three different cavity volumes for each group of L/H. The Sound Wave Method (SWM) is used to measure the aeroacoustic sources as function of the Strouhal number. This methodology does not require knowledge of the details of the unsteady flow-sound interaction in the cavity region because it considers the cavity as a black box with a dipole sound source or sink. The aeroacoustic source strength and the Strouhal number corresponding to its maximum value are found to increase in a systematic manner as the cavity volume is increased for the same L/H ratio. These results indicate that the aeroacoustic sources of shallow cavities are affected not only by the ratio L/H, but also by the cavity volume.Copyright © 2015 by ASME