Experimental research of 1+3/2 contra-rotating turbine aerodynamic performance

Vaneless contra-rotating turbine is one of the key technologies of the high performance engine. Experimental research was conducted to investigate aerodynamic performance of 1+3/2 contra-rotating turbine. The experiment was tested over three phases: first the alone high pressure turbine(HPT) experiment, second the HPT and low pressure turbine(LPT) with axial gap enlarging between them, and finally HPT and LPT with normal axial gap. In the normal gap experiment, the condition of LPT was confirmed by HPT performance curve by converse calculation. Research shows that LPT has little effect on HPT performance; HPT throat decreases while LPT throat increases, which leads to HPT expansion ratio increasing at the constant total expansion ratio. HPT expansion ratio changes very little during the total expansion ratio varying; however LPT expansion ratio changes greatly. The turbine efficiency is mainly determined by HPT, and the LPT is generally relative low. Enlarging axial gap between HPT and LPT has little influence on LPT performance.