Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance

Abstract

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid–structure interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point toward an acoustic resonance originating from separated flow in the variable inlet guide vanes (VIGV). A detailed investigation based on highly resolved wall-pressure data confirms this conclusion. This paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. This paper contains a concise categorization of flow-induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.

An Overview of Time-Domain Computational Methods for Aeroelastic Instabilities of Multi-Stage Compressor

“…Moreover, the result shows that a spatial "lock-in" event where the circumferential order of the part-span rotating stall shifts to match that induced by the vibration mode. This type of interaction has been reported in recent experimental and computational investigations by Kielb et al (2003) and Holzinger et al (2016).…”

Investigation Of Mild Surge In A 1.5-Stage Transonic Axial Compressor

“…The TCD has been operated by the Institute of Gas Turbines and Aerospace Propulsion since 1994 and its rotors, mostly representative for aero engines, are throughout prone to aero-elastic effects such as flutter, non-synchronous vibrations and related aeromechanical coupling. This is reported in numerous studies, both experimentally and numerically (Holzinger et al 2016, Brandstetter et al 2018, Jüngst 2019, Möller 2019.…”

Influence of Gap Detailing on Calculated Unsteady Non-Adjacent Blade Row Aero-Forcing in a Transonic Compressor Stage

“…The compressor blade is representative for a first stage blade of a two-spool aero engine high pressure compressor. The test rig is described in [1] and a schematic overview is given in Fig. 1.…”