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The analysis of acoustic radiation from piping systems is complicated by the presence of multiple excitation sources; for example, mechanical valve vibration, acoustic near- and farfields, and the random pressure field of fully-developed turbulent flow will normally act together. This latter pressure field is well defined, and was chosen as the excitation for an initial parametric investigation of the response of and radiation from piping systems. An intermittent induced-flow pipe facility, mounted across an anechoic chamber, was used to obtain extensive measurements of the radiation from steel and P.V.C. pipes for a wide range of flow speeds and several pipe wall thicknesses. Theoretical predictions compare favourably with experimental measurements. The main conclusions are: the acoustic power radiation is resonant and well-described by considering only acoustically fast pipe vibration modes; this radiation is proportional to the modal loss factors and to the fifth power of flow Mach number. Comparisons between excitation by fully developed flow and propagating acoustic fields are given, which demonstrate their relative importance.

Tne theoretical basis for an analytical model developed to predict the interior noise levels of high-speed propeller-driven airplanes is presented. Particular er@asis is given to mdeling the transmission of discrete tones t h r o w a fuselage element into a cavity, estimates for the mean and standard deviation of the acoustic power flow, the coupling between a non-homoEeneous excitation and the fuselwe vibration response, and the prediction of maximum interior noise levels. The model allows for convenient examination o f the various riies of the excitation and fuselage structural characteristics on the fuselage vibration response and the interior noise levels, as is required for the desip of model or Orototwe noise control validation tests

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