Lateral Vibration Reduction In High Pressure Centrifugal Compressors
Abstract
Recent designs of high and medium pressure centrifugal compressors show a well-behaved response to forced vibration and an adequate margin to self-excited vibration. This can only be achieved by an extensive rotor dynamic analysis and wide practical experience. A number of sophisticated computer codes to calculate the response and the stability of complex rotors are widely used. One problem with the application of these programs is the realistic estimation of data for aerodynamic excitation. It is the purpose of this paper to discuss the different types of excitation that occur in a multistage centrifugal compressor with shrouded impellers and to evaluate their importance with respect to lateral vibrations. The main source for self-excitation is found to be the labyrinth seals. A simple one-dimensional aerodynamic theory to calculate the destabilizing lateral forces of the labyrinths is presented. It is shown that the tangential velocity of the leakage gas strongly influences the excitation. Simple devices which may be installed in nearly any compressor reduce the excitation by reducing the fluid rotation in the labyrinth annulus. Stability tests for a number of different centrifugal compressors have been carried out on a test bed. The stability limits have been determined by increasing the pressure level at constant speed until subsynchronous vibration occurs. The measured stability limits agree well with those theoretically predicted using calculated labyrinth data.
Description
LectureSubject
TurbomachinesCollections
Citation
Jenny, R.; Wyssmann, H. (1980). Lateral Vibration Reduction In High Pressure Centrifugal Compressors. Texas A&M University. Gas Turbine Laboratories. Available electronically from https : / /hdl .handle .net /1969 .1 /163733.