BEHAVIOR OF AERODYNAMIC SOUND OF SPUR GEARS - (DETERMINATION OF SIMILARITY LAW AND SOURCE LOCATIONS)

Tooth mesh frequency sound generated aerodynamically in the region of meshing was investigated to determine the general characteristics of t he sound emission as well as its detailed source locations. Sound pres sure response measurement for various facewidths revealed that emissio n is expressed in terms of a similarity law as a function of a paramet er b/lambda, the ratio of facewidth to wavelength of the sound. The ef fect of dimensions such as the module and number of teeth were derived by means of a dimensional analysis with respect to pumping action of the cavity between driving and driven gears. Throughout several kinds of experiments, one source was located at the middle of the meshing ex it, which becomes prominent as the axial air flow reaches a certain sp eed. Another source is estimated to spread over both faceends, of whic h the radiation characteristics are closely related to the distributio n and the solid boundary of the gear pair.