Humidity Effects on Gas Turbine Performance

Moisture in the intake air of a gas turbine can affect its operation and performance in two different ways: by possible condensation in the inlet and by changing the gas properties throughout the cycle. Condensation can be controlled by restricting engine operation with limits on relative and absolute humidities. Two fundamental correction approaches for the effects of humidity on major engine parameters were investigated; they were found to compare very well. Both methods correct parameters as a function of absolute humidity, yielding corrections of between 0.1 and 0.8%, for high humidity test conditions. Additional operational, engine-specific humidity corrections were examined: some notable differences were observed. Recommendations are made for the correction of major performance data for absolute humidity.