Estimating the Influence of Compressor Blade Erosion Wear on the Compressor’s Integral and Local Characteristics

Assessment, monitoring, and prediction of the technical condition of gas turbine unit (GTU) assemblies and components are among the key matters that have to be dealt with during the operation of GTUs. In this connection, various prediction systems that use statistical, experimental, and calculated data on the change in the axial compressor (AC) characteristics resulting from the occurring erosion are becoming of great demand. The article describes an approach to the development of models of erosively worn blades on the basis of freely accessible statistical data on the failures of units as a consequence of a blade compressor’s erosion. The article also proposes a body of mathematics for specifying the blade wear degree, introducing the change in the eroded profile chord, and considering the wear nonuniformity along the blade height. The statement of the problem of numerically studying how the erosion degree and pattern affect the compressor stage performance parameters is described. The outcomes from intermediate studies on comparing different geometrical models of erosion are presented along with assessment of their applicability for flow computations in elaborating a prediction model. The results of computations of a transonic compressor stage have been obtained for different erosion wear degrees of its blading in a wide range of operation modes, and the revealed degradation pattern of the stage integral and local characteristics is analyzed. It has been found from analyzing various erosion wear degrees for the stage considered that, if there is an erosion wear, the compressor pressure ratio may drop by up to 3.31%, the ratio of temperatures by up to 1.55%, the adiabatic efficiency by up to 1.15% (abs.), and mass flowrate at the stage choke line up to 1.26%. With decreasing the rotor rotation frequency, the wear influence decreases, and the change in integral characteristics do not exceed 0.10% for the isodrome (a constant rotation frequency line) 70%. The article briefly outlines possible methods for analyzing the results for constructing the correlations between the erosion wear degree and the change in the compressor integral characteristics and also promising lines for development of studies.