Transient Thermal and Structural Analysis of the Liquid Rocket Turbopump Turbine

Abstract

A turbopump unit is a key component of the liquid rocket engine assembly. Generally operated by an impulse-type turbine with supersonic hot gas for a gas generator cycle engine, it pressurizes liquid oxygen and fuel to attain high specific impulse. The turbine is exposed to hot gas while rotating at a high speed and experiences severe thermal and mechanical loads during the operation. Its structural integrity must be assured through thermal and structural analyses of the turbine. To investigate non-steady heat transfer characteristics from the hot gas to the turbine blade, the heat transfer of supersonic hot gas flow to the complicated turbine blade geometry is solved through a three-dimensional CFD analysis. The distribution of gas temperature, pressure and velocity on the blade surface are obtained by the CFD analysis with appropriate convection heat transfer coefficients to be used for the structural analysis of the turbine rotor. The thermal stress due to material expansion and mechanical stress due to centrifugal loads are considered in the analysis. The three-dimensional transient stress distributions of the turbine blades, shroud, and disk are obtained by a finite element analysis. Finally, the overall results are examined to evaluate the strength safety of the turbine.