APPLICATION OF A VIBROACOUSTIC RECIPROCITY TECHNIQUE TO THE PREDICTION OF SOUND RADIATED BY A MOTORED IC ENGINE

An internal-combustion (IC) engine is a complicated noise source. Theoretical prediction of its sound field is problematic. This paper describes a vibro-acoustic reciprocity technique for the experimental prediction of sound radiated by the engine. The basis of the technique is the evaluation of the surface volume velocity distribution of the source by nearfield intensity measurement and of the transfer functions between the volume velocity and the pressure at a receiver point by a reciprocal measurement technique. The principal advantage of this technique is that it avoids direct vibrational velocity measurement. This paper describes the method and a laboratory experiment which demonstrates its application.