Combustion Chamber Code Activities in Germany.

Lampoldshausen 961126

Inner liner temperature variation caused deformation localisation effects in a multichannel model of a generic LRE wall structure

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. The development and flight qualification of such components includes on top of many other actions thermal, structural and fatigue life analyses of chamber wall structures. Often, these analyses are based on half cooling channel + half fin Finite Element models of a tiny chamber wall section with symmetry conditions at the centerline of the cooling channel and the centerline of the fin. However, injector vicinity caused chamber wall temperature variations in circumferential direction of the chamber wall may cause localization effects of the deformation of the inner liner of chamber wall structures. Exemplary, an injector vicinity caused 20 K wall temperature variation is taken into account by a three-channel model. The influence of this variation to the distribution of the circumferential strain distribution as well as to the post processing determined fatigue life is shown