Variable Geometry Compressors for Improvement of Gas Turbine Part Load Performance

The variable geometry compressor has been studied to determine if it can offer the prospect of a solution to the part load performance problem which is mechanically simpler and hence less expensive than current modifications. The two most common modifications of this type are the variable geometry turbine and General Motors' Power Transfer scheme. The former is the better known, but the latter has been gaining acceptance and may now indeed have more potential than the variable geometry turbine. However, when one realizes that both these methods may become less attractive as turbine inlet temperatures are raised to improve performance, modification at the cold end of the engine seems to present a reasonable alternative.

The proposed variable geometry compressor cycle is designed around part load conditions, with maximum power being obtained by opening the guide vanes and increasing the rotational speed of the compressor. Although its performance is not competitive with current engines utilizing variable geometry turbines or Power Transfer, the variable geometry compressor does seem to offer increased potential as the trend towards higher turbine inlet temperatures continues.