Measurement of vibroacoustical energy flow through straight pipes

The measurement of vibroacoustical energy flow through straight pipes has been investigated. At frequencies below the cut-on of n=3 shell waves the energy propagates in a limited number of waves. The stnicture-borne energy in these waves can be determined from acceleration measurements on the pipe surface, provided that appropriate accelerometer configurations are chosen to separate the different waves. The energy flow in each wave can then be determined using a two-channel cross-spectral density method. It appears to be impossible to determine the fluid-borne energy flow from acceleration measurements, due to the transverse axis sensitivity of the accelerometers. Experiments on a cooling water pipe of a shipboard diesel engine indicate that energy flow measurements are feasible, although further investigations are necessary to achieve a practicable and reliable method