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. Theo retical prediction of its sound field is problematic. This paper descr ibes a vibro-acoustic reciprocity technique for the experimental predi ction of sound radiated by the engine. The basis of the technique is t he evaluation of the surface volume velocity distribution of the sourc e by nearfield intensity measurement and of the transfer functions bet ween the volume velocity and the pressure at a receiver point by a rec iprocal measurement technique. The principal advantage of this techniq ue is that it avoids direct vibrational velocity measurement. This pap er describes the method and a laboratory experiment which demonstrates its application.