Measurement uncertainties encountered during gas turbine driven compressorfield testing

Field testing of gas turbine compressor packages requires the accurate dete rmination of efficiency, capacity, head, power and fuel flow bl sometimes l ess than ideal working environments. Nonetheless, field test results have s ignificant implication for the compressor and gas turbine manufacturers and their customers, Economic considerations demand that the performance and e fficiency of an installation are verified to assure a projects return on in vestment. Thus, for the compressor and gas turbine manufacturers, as well a s for the end-user, an accurate determination of the field performance is o f vital interest. This paper describes art analytic method to predict the m easurement uncertainty and, thus, the accuracy, of field rest results for g as turbine driven compressors. Namely, a method is presented which can be e mployed to verify the validity of field test performance results. The equat ions governing the compressor and gas turbine performance uncertainties are rigorously derived and results are numerically compared to actual field te st data. Typical field test measurement uncertainties are presented for dif ferent sets of instrumentation. Test parameters that correlate to the most significant influence on the performance uncertainties are identified and s uggestions are provided on how to minimize their measurement eri ors. The e ffect of different equations of state on the calculated performance is also discussed. Results show that compressor efficiency uncertainties can be un acceptably high when some basic rules for accurate testing are violated How ever, by following some simple measurement rules and maintaining commonalit y of the gas equations of slate, the overall compressor package performance measurement uncertainty can be limited and meaningful results can be achie ved.