Compressor performance deterioration with operating time has been analyzed and a method for the description of actual scaled map curves is discussed. These curves are obtained from actual operating point data from the monitoring system. Suitable scaling functions have been introduced. An inverse stage stacking technique solution has been adopted to obtain reference quantities to be used with generalized curves. In order to account for machine peculiar real phenomena, shape factors have been introduced for best fitting of given data.
An example is presented to discuss the deteriorated compressor map and the influence of mass flows extracted from bleeds.