Effects of Various Geometric Features on the Performance of a 7:1 Pressure Ratio Deeply Scalloped and Split Radial Turbine in a Gas Turbine Engine.

A 2 MW gas turbine engine has been developed for the distributed power market. This engine features a 7:1 pressure ratio radial inflow turbine. In this paper, influences of various geometry features are investigated including turbine tip and backface clearances. In addition to the clearances, the effects of the inducer deep scallop and exducer rounded trailing edge are investigated. Finally, geometric features associated with a split rotor (separate inducer and exducer) are studied. These geometry features are investigated numerically using CFD. Part of the numerical results is also compared to experimental data acquired during engine test to validate the CFD results. Results indicated that for this specific turbine, the influences of the exducer radial tip clearance, inducer axial tip clearance, and even scalloped blade backface clearance all have negligible influences on performance. In all cases, 1% increase in clearance only attributes to approximately a 0.1% lower efficiency. This finding is very different from former published papers with low pressure ratio turbines, indicating different flow physics apply for a turbine with a relatively high-pressure ratio. [ABSTRACT FROM AUTHOR]