Evgeny Zametaev

Stationary and Transient Thermal Analyses of Cryogenic Liquid Rocket Combustion Chamber Walls

A comparative study of stationary and dynamic thermal analyses of a typical rocket combustion chamber wall during a full cycle including pre cooling, hot run, post cooling, relaxation is presented. Furthermore, the influence of the different thermal fields on the following analyses are shown: 1. Nonlinear structural analysis of the combustion chamber wall with cyclic thermal and mechanical loading 2. Post processing life time estimation of the combustion chamber wall

Comparison of Finite Element analysis and experimental results of a combustion chamber type TMF panel test

The inner liner of a regeneratively cooled wall of a main stage rocket combustion chamber is extremely loaded by the high temperature of the hot gas and the pressure difference between the coolant and the hot gas. A cyclic operation of such a chamber usually causes a LFC failure of the wall structure after a very low number of cycles. For the tests presented in this paper, cyclic laser heating is (as replacement for the hot gas) applied to an actively cooled small section of the hot gas wall of the real engine - the so called TMF panel. Optical measurements during such TMF panel tests provide essential validation data for CFD, thermal, structural and fatigue life analyses: The 2d measurement of the thermal field of the heat loaded structure provides - together with the measurement of the temperature, pressure and mass flow rate of the coolant of the TMF panel - data for the combined validation of the CFD analysis of the coolant flow and the thermal analysis of the wall structure. The measurement of the deformation of the thermally loaded structure provides - together with the already determined temperature distribution and the above mentioned pressure measurements of the cooling channels - data for the validation of the structural analysis of the thermally loaded structure. Counting the number of laser loading cycles (laser on-off) until the TMF panel fails (by cracks appearing on the laser loaded side of the cooling channels) provides data for the validation of (either post processing or damage parameter based) fatigue life analyses of thermally loaded structures.

Comparison of 2d and 3d Structural FE-Analyses of LRE Combustion Chamber Walls

A coupled thermal and structural 3d quasi stationary Finite Element (FEM) analysis of a typical rocket combustion chamber wall during a full cycle including pre cooling, hot run, post cooling and relaxation is presented. The results of this 3d analysis are compared with the results of 2d plane strain and 2d generalized plane strain analyses. Finally, a post-processing method is applied in order to estimate the combustion chamber life time. This life time estimation method takes into account the standard Low Cycle Fatigue part as well as additional parts – accounting for the quasi static (or ratcheting) fatigue and the thermal degradation of the chamber wall material.

LRE Chamber Wall Optimization Using Plane Strain and Generalized Plane Strain Models

A method for the optimization of rocket combustion chamber walls with respect to the life time is presented. This method can be split into four main parts: P1) Determination of the thermal field within the combustion chamber wall and the cooling channel during the hot run phase by a steady state thermo-fluid mechanical analysis; P2) Analysis of the nonlinear deformation of the combustion chamber wall under cyclic thermal and mechanical loading using a 2d plane strain or a 2d generalized plane strain model; P3) Estimation of the life time of the combustion chamber wall by a post processing method and P4) Application of a mathematical optimization procedure (gradient free or Conjugate Gradient method). This strategy is used to analyse the thermal load induced deformation process and life time of a typical rocket combustion chamber and to optimise selected geometry parameters of the combustion chamber wall.