非定常性を考慮したロケットエンジン用タービンの高信頼性に関する研究

抄録

To improve the launch capability of rocket, which is the only means for putting man-made objects such as artificial satellites into space, rocket engine turbines are required to have high efficiency and high reliability. In this study, unsteady calculation using Transient Blade Row (TBR) method was performed on the original blade and the optimized blade obtained by blade shape optimization so as to compare the flow fields of the two types of blades and to investigate the resonance caused by the unsteady fluid force. Then, frequency response analysis is performed using unsteady fluid force, and the structural analysis is made using two types of materials (Inconel 718 and Ti-6Al-4V) to determine maximum von Mises stress occurred in the tested blades. It is found that the optimized blade exhibited 4% higher turbine efficiency than the original blade, which is because the exit Mach number from the nozzle is reduced in the optimized blade, weakening the shock wave in the first stage blade so that the generation of entropy of the entire turbine is suppressed. Frequency response analysis was performed using the secondary blade passage frequency (56 EO) component of the nozzle. It is found that there is low risk of the resonance due to the 56EO component because there is no vibration mode excited near the design point in the first stage blade of the optimized blade.