Impact of injection distribution on cryogenic rocket engine stability

Abstract

The present publication addresses the actions taken to stabilize the combustion chamber assembly using a porous injector head described in a former publication2 and the test campaign during which the success of these measures was demonstrated. The first part of this paper deals with the nature of the reported combustion instability. A phenomenological explanation for its occurrence is presented and supported by experimental data. As a measure to counter this instability, two approaches were taken. First, a hydrogen cooled bae segment and second a modification of the injection distribution of the injector head with respect to the presumed cause of the instability. While the bae segment did not prove successful, the test runs with the modified injection pattern demonstrated the stable operation of the 80mm porous injector head over the whole range of operating conditions at hydrogen injection temperatures as low as 45 K. 1. Introduction