Assignment of the compressor performances at mathematical modelling of the aviation gas turbine engine
Efficiency of aviation engine mathematical model (EMM) application at various stages of the engine creation substantially depends on accuracy and «physical» descriptions of working procedure in air-gas channels of the engine and its units. As now the course of creation of the aviation gas turbine engine (GTE) and the aircraft works can depend on reliability of the engine parameters and performances estimation, increase of EMM accuracy is rather important problem. One of the most significant components of the gas turbine engine mathematical model accuracy is accuracy of the basic engine units’ performances; in particular, elements of the compression group (fans and compressors). In article features of the assignment of compressor performance with air extraction from its air-gas channel in gas turbine engine mathematical model are considered. It is shown that the distributed air extraction can lead to appreciable compressor performances exfoliation, especially to its part located behind a place of extraction; it is necessary to consider at the aviation gas turbine engine parameters computation. For this purpose the relative extracted air flow, and also part of the compressor work from enter to an air extraction place are defined. These parameters allow calculating the physical air flow, enthalpy and temperature of extracted air. As show results of the numerous experiment-calculated researches, now widely used simplified technique of air compressor extracted air enthalpy definition can lead to considerable errors in GTE parameters calculation. The main reason of wrong calculation aviation GTE parameters is discrepancy of methodical approaches to independent estimated and/or experimental definition of units’ performance to how this performance is used in engine mathematical model. That correctly to use the performance of engine units (for example, compressor cascades) in integrated engine mathematical model, it is necessary to know, how they were characterization and that is understood as value of this or that experimentally received parameters have been received. Techniques of the compressors' cascades tests results handling for its characterization, calculation of the air extractions’ parameters, and also the turbine power for a drive of the considered compressors' cascade in core and gas turbine engine system are presented.