CASE-HISTORY - COMPUTATION OF NORMALIZED DYNAMIC MESH FORCE AND TRANSMISSIBILITY SPECTRA FOR VIBROACOUSTIC CONTROL OF ROOTS-TYPE SUPERCHARGER SYSTEMS

A linear dynamic finite element model of a geared supercharger is deve loped by following a systematic step-by-step modal based modeling and test-analysis correlation procedure. This entails analyzing and valida ting each major component individually, and combining them into a syst em representation. The assembled model is utilized to compute the norm alized dynamic mesh force and vibration transmissibility response spec tra assuming a uniform amplitude spectrum of gear transmission error e xcitation. It is shown in this paper how these response functions can be used to identify critical controlling parameters for the purpose of developing noise and vibration control strategies. An example case of a three-lobe rotor system is discussed to demonstrate the salient fea tures and limitations of this proposed vibro-acoustic design methodolo gy. Even though this study is aimed at analyzing the dynamics of super chargers with emphasis on gear whine, its proposed method is quite gen eral and can be applied to other high-speed geared machinery. (C) 1998 Institute of Noise Control Engineering.