Structural and Modal Analysis of the L75 Rocket Engine Turbine Disk at Operating Conditions

Resumo

The development of a biofuel turbopump was initiated at the Institute of Aeronautics and Space (IAE)
in 2013 under Brazilian Space Agency (AEB) support and in the context of the L75 Rocket Engine project. The
turbopump is composed by an oxidizer pump, a fuel pump and a supersonic-flow single-stage turbine. Due to the
high rotational speed and high temperature it is subjected for, the turbine is considered one of the most critical
components of the rocket engine. In this study, an appropriate structural and modal FEM analysis of the turbine
rotor is performed. Temperature and rotational influence on material properties, the temperature gradient,
rotational speed and gas pressure distribution effects are considered. The main failure modes of the L75 turbine
are elastic deformation, plastic deformation, high-cycle fatigue and low-cycle fatigue. It was not considered creep
as a failure mode due to the short life the turbine is designed for. Therefore, a thermo-elastic and a modal analysis
of the turbine rotor are performed using a FEM commercial software, considering actual operation environment
conditions. The results are presented graphically, a discussion is carried out and a design modification is proposed
in order to reach the turbine requirements.