Radiation Efficiencies of Engine Components for Engine Noise Prediction

This paper describes the work undertaken to measure and evaluate the radiation efficiencies of various components of a diesel engine.

Using a small reverberant room, values of radiation efficiencies were determined in one-third-octave bands in the frequency range 200 Hz to 5 kHz for the following components - cylinder head, inlet manifold, exhaust manifold, lubricating oil filter and fuel filter.

Each component was excited in turn and measurements were taken of the velocity of vibration on the surface of the component and the sound pressure level produced in the reverberant field. The radiation efficiency could then be evaluated knowing the average absorption coefficient and surface area of the room and the surface area of the component.