Influence of time dependent effects on the estimated life time of 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 and relaxation is presented. Furthermore, the influence of the different thermal fields on the following analyses is shown: · Nonlinear rate independent or rate dependent structural analysis of the combustion chamber wall with cyclic thermal and mechanical loading · Post processing life time estimation of the combustion chamber wall A series of stationary one dimensional thermo-fluid mechanical analyses provide the coolant side film coefficients during the pre-and post cooling and the hot run phase. For the purpose of a comparative study, these film coefficients are used to determine the boundary conditions for either a series of stationary analyses or for a transient analysis of the thermal field in the combustion chamber wall during a full cycle. The resulting thermal fields at different stages of the loading cycle are applied as thermal boundary conditions for a Finite Element analysis of the nonlinear deformation of the combustion chamber wall under cyclic thermal and mechanical loading. This structural analysis is either performed by assuming a rate independent material or by assuming rate dependent behavior according to Peirce. Finally, a post-processing method is applied in order to estimate the life time of the combustion chamber.