Stress and deformation analysis of the turbine in liquid rocket engine using fluid-thermal-structure coupling method

The turbine is widely used in the aerospace industry such as liquid rocket engine (LRE). The turbine in LRE is under extreme conditions of high temperature gradient, high pressure and high rotation speed. The safety assessment of the turbine during operation is essential in the design period. In this paper, the stress and deformation analysis of the turbine in LRE based on threedimensional fluid-thermal-structure coupling method is investigated. First, the unsteady flow and heat transfer analysis of the turbine is performed using Computational Fluid Dynamic (CFD). The time average method is applied to obtain the pressure and temperature results. Then, temperature and pressure results obtained from CFD calculation are assigned as thermal and aerodynamic loads through coupling analysis. Finally, the stress and deformation distributions of rotor are analyzed under different load conditions using Finite Element Method (FEM). The results of this paper can provide some references for the turbine design in LRE. INTRODUCTION The turbine is widely used in the aerospace industry such as liquid rocket engine (LRE). In LRE, the turbine is under extreme conditions of high temperature gradient, high pressure and high rotation speed rotating that involves complex aerodynamics, heat transfer, and structural deformation. Considering the characteristics of its complex fluid-thermal-structural coupling, combining the CFD and FEM to obtain the temperature distribution became the research focus. Sun et al. [1] showed the difference between heat transfer computation and experiment of rotating cavity which includes a buoyancy model driven. Tian et al. [2] computed on experimental model and the computational results were similar with the experiment. Tian also found the similar circulation flow model, and 2 the results of tangential velocity and radial Nu distribution were qualitative similar with the experimental data. A.Gunther et al. [3] carried out the CFD/FEM coupling transient analysis of the mid-plate temperature distribution and thermal conductivity of the two-cavities rotating geometries. The results showed that the prediction of surface temperature distribution is quite accurate, but the error of heat flux is relatively large. The turbine rotor is simultaneously subjected to mechanical and thermal load. The stress analysis for the turbine in LRE is usually necessary for safety and reliability. Some numerical analysis on fluid-thermal-structural coupling of turbine blade have been proposed. Ho and Paull [4] described a method to implement aerodynamic heating models into a finite element code for thermal-structural and thermal-structural-vibrational analyses of a hypersonic engine. A combined effect of varying dynamic pressure and thermal loads was considered, and thermal-structural vibrational response of an engine was studied. Shen et al. [5] conducted a fluid-thermal-structure coupled analysis and an optimization of a turbine mortise/disc. In their work, a complete multidisciplinary method containing fluidthermal-structure of the mortise/disc was formed, taking influence of the fluid flow and heat transfer into account. Krishnakanth et al. [6] carried out finite element analysis for the structural and thermal analysis of gas turbine rotor blades. They found that the temperature had a notable effect on the overall stress in the turbine blades. Other relevant works involving multidisciplinary analysis and optimization design of gas turbines can be found in references [7–11]. In this paper, the ANSYS software is used for a fluid-thermal-structural coupling analysis the turbine in LRE. At first, an unsteady flow analysis is conducted to obtain temperature distribution and the aerodynamic pressure on the turbine. The time average unsteady method is applied to obtain the pressure and temperature results. After that, the stress and deformation analysis are then conducted considering three cases of loads: thermal load, aerodynamic load combined with centrifugal load, and all the three types of loads. Unlike the previous studies, this paper systematically studied the three cases to ensure the safety and reliability of the rotor in LRE. NUMERICAL METHOD AND COMPUTATIONAL MODEL COMPUTATIONAL MODEL AND BOUNDARY