SBIR-STTR Award

Compact, high energy storable propellant thrusters are needed for a wide variety of applications from sattelite control to space missions to missile defense systems. As the thrusters are made smaller, higher performing, with more intense energy release and are needed to operate in more extreme environments, combustion instability becomes a more difficult problem. This program brings to bear the most recent university work in linear and nonlinear instability modeling and takes that knowledge to practical application using data from a current highly tested small divert thruster to provide preliminary verification. The approach is to use linear and non linear studies of combustion gain combined with latest absorber damping technology to provide practical design criteria for these small energetic combustors. The results will include the preliminary design criteria and a proposal for a Phase II hot fire demonstration of the thruster design with this criteria.

The Phase I of this effort encompassed extensive data review and preliminary analysis to define the instability in the subject class of thrusters, identify key factors contributing to the unstable behavior, and outline a plan for the resolution of instability. These key factors were identified as: Mon level in the oxidizer, propellant temperature, and the thruster start conditions. The Phase I effort concluded that the cavity, chamber, and combustion models must be improved to reliably predict stability; an accurate simulation of the thruster start conditions on the flight vehicle is required to have confidence in the stability predictions; both injector and cavity changes must be investigated to ensure problem resolution; and that hot fire testing is required for a high confidence solution. This program will provide the stability model development and the simulation of the start transient conditions for altitude operation. These models will be verified against existing test data. In addition test article designs will be generated and test hardware will be built. Detail test plans and procedures will be drafted and a trade study will be conducted to select the optimum test site. Actual testing is deferred to a future activity associated with this program.

Keywords:
Divert Thrusters, Combustion Instability, Storable