Session: 01-03-02: Advanced Manufacturing for Aerospace Structures

Paper Number: 107212

107212 - Finite Element Analysis of the Thermo-Mechanical Behavior of Liquid Rocket Engines Thrust Chambers 

The Italian Ministry of University and Research (MIUR) funded the Hyprob Program to develop regeneratively cooled liquid rocket engines, which adopt liquid methane and liquid oxygen. Indeed, the employment of methane as propellant for liquid rocket engines, together with oxygen, allows to reach very good performances in terms of high vacuum specific impulse and high thrust-to-weight ratio performances. Furthermore, methane is relatively easy to store, and is characterized by low toxicity, availability and production cost, as compared to hydrogen or kerosene and mono-propellant systems.

In a long-term perspective, such a propulsion technology may cover a wide range of propulsion systems, from launcher main stages up to small thrusters.

 

In the present study, the authors focus on the final ground Demonstrator that will be able to produce a 30 kN thrust in flight conditions (a ground fire test is foreseen in a very near future in AVIO Colleferro). In particular, the thrust chamber is composed of an inner structure made of CuCrZr precipitation hardened alloy and an external cold structure made of electrodeposited Nickel. In order to obtain the aforementioned thrust level, very high chamber pressures (about 50 bar) and consequently high thermal fluxes and gradients are expected inside the thrust chamber. To maintain the inner structure temperature in a range acceptable for the selected material, the chamber must be regeneratively cooled. In this process the fuel is employed to cool the inner structure, passing through axial cooling channels, before being injected in the thrust chamber. In such a way, even though temperature levels are lowered, very high thermal gradients occur in the structure separating the hot gas heat fluxes from the cooling channel where the fuel temperature is considerably lower.

 

Then, very complex and high-fidelity numerical models have been adopted to accurately simulate the thermo-mechanical behavior of the thrust chamber cooling channels, also considering plasticity, creep and low cycle fatigue phenomena. More in detail, the plasticity effects have been studied adopting the von Mises yield criterion, the Prandtl Reuss flow rule and both non linear isotropic and kinematic hardening behavior with respectively the Voce and Chaboche models. Low cycle fatigue evaluations have been carried out adopting multiaxial fatigue criteria considering non proportional loading effects (e.g. Wang Brown and Smith, Watson and Topper), while both primary and secondary creep stages (combined time hardening), have been taken into account. A cumulative damage model, considering the effects of plastic instability (thermal ratcheting), creep and fatigue, has been employed to evaluate the number of cycles to failure.

The finite element analyses have been conducted by means of ANSYS code to predict with a good accuracy level the thrust chamber service life.

Presenting Author: Michele Ferraiuolo CIRA

Presenting Author Biography: Michele Ferraiuolo took his degree in Mechanical Engineering in 2002 at the Second University of Naples. He is now a Research engineer at the Italian Aerospace Research Centre (CIRA). The main topic of his work is the Re-entry vehicle’s Hot Structures design. Moreover, in the frame of the PhD studies, he has developed new thermostructural design methodologies in order to decrease the computational time needed to perform a complete design of the thermal structures.
Recently he has worked on the Stress Analysis on the structural components of an Unmanned Aerial vehicle. From 2010 he is responsible for the Mechanical and Material Processes for the Hyprob-Bread Project, whose main goal is to design build and test a 30 kN regeneratively cooled thrust chamber. From February 2015 he is head of the “Technologies and design of hot structures and thermal control” lab. under the Materials and Structures department.

Authors:

Michele Ferraiuolo CIRA
Bruno Rizzo University of Salerno
Roberto Guglielmo Citarella University of Salerno
Venanzio Giannella University of Salerno
Michele Perrella University of Naples