Experimental Study of Acoustic Resonances in the Side Cavities of a High-Pressure Centrifugal Compressor Excited by Rotor/Stator Interaction

Abstract

Under unfavorable conditions aerodynamic and aeroacoustic excitation mechanisms may lead to fatigue failures of centrifugal compressor impellers. The mechanisms for consideration are, for example, the arising pressure patterns due to rotor/stator interactions, the so-called Tyler/Sofrin modes, or acoustic resonances in the compressor housing. In a research program, a high-pressure radial compressor has been equipped with a multiplicity of sensors to investigate the excitation and interaction mechanisms in a complete centrifugal compressor stage. The current paper deals with the experimental detection of acoustic resonances in the compressor side cavities and the excitation of these acoustic eigenmodes due to Tyler/Sofrin modes. In this context the test rig and the installed instrumentation are briefly described. The methods of measuring as well as the analyzing techniques for detecting acoustic resonances and evaluating the measurements are presented. In addition, acoustic eigenmodes have been calculated by the finite-element method for the representative numerical test rig parameters. Results are presented and compared to the experimental findings. The accomplished experiments are the first available in open literature showing that the fluid core rotation in the compressor side cavities plays a crucial role for the prediction of the acoustic eigenfrequencies with respect to the rotor frame of reference. Without taking into account the effect of fluid rotation, large deviations between predicted (simulated) and measured acoustic eigenfrequencies would be the result.

Weak Defect Identification for Centrifugal Compressor Blade Crack Based on Pressure Sensors and Genetic Algorithm

“…Support vector machine has been proved to have good performance on shaft crack classification and prediction, therefore, it was tried to diagnose the blade damage of a helicopter [ 8 ]. At the same time, König conducted a series of studies on the rotating impeller failure mechanism through a pressure pulsation signal, which provided good results and confirmed that the vibration information of the blade can be reflected in the pressure pulsation signal [ 9 , 10 ]. However, most of the research is focused on the gas turbine currently, although there exists a certain similarity between centrifugal compressors and gas turbines.…”

Experimental Investigation of Vibrational and Acoustic Phenomena for Detecting the Stall and Surge of a Multistage Compressor

“…Noise is a less complex and dangerous threat than vibrations but recently the study of aeroelasticity is becoming more popular in order to examine some aerodynamic and aeroacoustic aspects [6], and to design acoustic treatments. Interesting examples, with application to stall and surge conditions, are provided by the work of Vahdati et al [7] and that of Schoenenborn and Breuer [8].…”

The technique ofdithering—a parameter study

“…The different effects of adding dither to a wanted signal are experimentally depicted. Examples where the method of dithering finds application in actual measuring tasks can be found in the studies of Petry et al [7,8] as well as of König et al [9,10]. These papers contain investigations about marginal pressure fluctuations in a high-pressure radial compressor.…”