MODAL CHARACTERISTICS OF CENTRIFUGAL FAN WHEELS AND PROPOSED SEVERITY CRITERIA FOR EXCITATION BY BLADE-PASS PULSATION FORCES

摘要

Centrifugal fans are subjected to dynamic forces from many different sources. These include mechanical forces such as imbalance and misalignment and aerodynamic forces produced as a result of rotating stall, surge, vortex shedding and blades passing the housing cut off point. This paper concentrates on blade-pass pulsation forces and their effect on the structural dynamic integrity of centrifugal fan wheels. A description of all of the standard modes of natural frequencies for double-inlet fan wheels is included. An evaluation criteria is proposed to determine the relative severity of the n-nodal diameter modes of natural frequency to blade-pass pressure pulsations.