Impact of injection distribution on cryogenic rocket engine stability

The present publication addresses the actions taken to stabilize the combustion chamber assembly using a porous injector head described in a former publication and the test campaign during which the success of these measures was demonstrated. The first part 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 baffe segment, and second, a modification of the injection distribution of the injector head with respect to the presumed cause of the instability. While the baffe segment did not prove to be successful, the test runs with the modified injection pattern demonstrated the stable operation of the 80-millimeter porous injector head over the whole range of operating conditions from 50 to 90 bar at hydrogen injection temperatures as low as 45 K.     «

The present publication addresses the actions taken to stabilize the combustion chamber assembly using a porous injector head described in a former publication and the test campaign during which the success of these measures was demonstrated. The first part 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 hyd...     »