Surge Margin Enhancement for a Centrifugal Compressor

Turboshaft engines are subject to various transient modes, necessitating a compressor with very high surge margin. Therefore, many devices were proposed in the past, and some of them including a recent one with a vaneless cavity by Allied Signal Engines, demonstrated impressive surge margin enhancement. However, there ahs been no detailed investigations on understanding the flow mechanism leading to the improvement of surge margin, or the optimization of cavity location and size, due to a lack of instrumentation capable of measure unsteady localized flows. Therefore, an innovative flow measurement concept is proposed for systematic research to obtain improved centrifugal compressor surge margin. The concept consists of a laser velocimeter and high frequency pressure transducers used between feasibility of the measurement concept. In Phase II this measurement concept will be applied to a small scale compressor, which would lead us to a promising cavity geometry and location. The most promising cavity (or cavities) will then be tested in a full scale compressor or a gas turbine to demonstrate its (or their) full potential. The research will be performed in collaboration with Allied Signal Engines throughout Phase I and Phase II of the project