A part-load performance analysis method for gas turbines based on the stage by stages model of the power turbine

Abstract In existing calculation studies of gas turbine part-load performance, the multi-stage power turbine (PT) is usually considered as an integral whole, and the variation rule of power and efficiency of the PT’s front/rear stage with load cannot be obtained. Therefore, the 6-stage PT of LM2500+ gas turbine is divided into 2 sub-turbines to be investigated by establishing the gas turbine part-load performance model based on the stage by stages method of the power turbine in this paper. The model is used to calculate the part-load performance of the LM2500+ under the fuel flow strategy (FF) and the first sub-turbine variable area nozzle (VAN) strategy. The results show that the relative errors of the mass flow rate, pressure ratio and thermal efficiency calculated by the model compared to the experiment data are all within 3.5 %.Under the FF strategy, the degree of mismatch in PT front/rear stage gradually increases as the load decreases from 100 % to 0.0 %, with the share of the first sub-turbine power increases from 22 % to 130 %, and the second sub-turbine efficiency decreases from 0.876 to −0.126. The adoption of the VAN strategy further exacerbates the degree of mismatch between the PT front/rear stages.