Sensitivity Analysis on Brayton Cycle Gas Turbine Performance

Abstract

This paper evaluates the performance of a Brayton cycle gas turbine, in terms of power output and conversion efficiency. Sensitivity of this performance to the realistic value of each input variable considered is analyzed. Sensitivity is evaluated by introducing a parameter, defined as the ratio between the logarithmic differential of the power output or efficiency functions and the logarithmic differential of each variable considered. These analytical functions and their derivatives correspond to a gas turbine model developed by the authors. The above-mentioned sensitivity parameter can be also evaluated by means of a numerical procedure utilizing a common gas turbine power plant computational model. The values calculated with the two procedures turn out to be substantially the same. Finally, the present analysis permits the determination of the weight of the input variable and of its value on the obtainable numerical performance. Such weights are found to be less important for some variables, while they are of marked significance for others, thus indicating those input parameters requiring a very precise verification of their numerical values.