Patent ID: 7647778
Filing Date: 2010-01-19
Classification: F02C,F05D

Abstract:
1. A method of controlling a gas turbine engine to reduce an imbalance between compressor stages, the gas turbine engine comprising at least two compressor stages each having an associated bleed device and an associated pressure sensor for determining a pressure in the compressor stage, and at least one of the compressor stages having an associated shaft from which power can be extracted to drive an electrical device or auxiliary device, the method comprising: measuring a pressure in each of the at least two compressor stages using the measuring devices to provide pressure parameters; measuring a speed of the shaft; extracting power from the shaft to drive the electrical device or auxiliary device; comparing the pressure parameters to at least one reference value to determine a first bleed device schedule to reduce an imbalance in the gas turbine engine caused by the power extracted from the shaft, the first bleed schedule having at least one first bleed device value representing a first amount the bleed device is opened; comparing the speed of the engine shaft to the at least one reference value to determine a second bleed device schedule to reduce an imbalance in the gas turbine engine caused by the power extracted from the shaft, the second bleed schedule having at least one second bleed device value representing a second amount the bleed device is opened; and comparing the first bleed device value to the second bleed device value and using the bleed device schedule having the lowest bleed device value to open the bleed device to reduce the imbalance.