Accidental Excitation of Acoustic Resonances from Balance Holes on Rotating Disk
Abstract
During commissioning of an open-casing test rig, a loud (above 105 dB) high pitch “squealing” sound occurred at speeds above 3,000 rpm. All elements of the rig were removed except the bearings yet the noise persisted. Microphone measurements show the sound occurring in the frequency range between 3,000 and 5,000 Hz, while proximity sensors and accelerometers showed very small amounts of vibration of the shaft in this frequency range. After investigations into bearing rub proved negative, the cause of the sound was determined to be an excitation of acoustic resonances arising from air passing over the balance holes on the seal disk. Duct tape placed over the balance holes completely eliminated the noise. An investigation into vortex shedding, confirms that a Strouhal number of 0.4 shows vortices will begin to form on the disk at speeds of 3,000 rpm at a frequency of 3,500 Hz.
Description
Case StudyCollections
Citation
Kerr, Tommy; Rimpel, Aaron; Simons, Sarah (2021). Accidental Excitation of Acoustic Resonances from Balance Holes on Rotating Disk. Turbomachinery Laboratory, Texas A&M Engineering Experiment Station; Texas A & M University. Libraries; Texas A & M University. Libraries. Available electronically from https : / /hdl .handle .net /1969 .1 /196756.