Advanced Injector Designs for Hydrocarbon Liquid Rocket Engine Components

Combustion instability is one of the greatest development risks for liquid propellant engines. The risks arise in development of a stable injector design from a variety of sources - limited modelling capabilities, poor scalability and the high cost ofappropriate component test facilities. Sierra Engineering believes that much of the empirical data on the injection element's driving characteristics can be obtained using a single full-sized injection element in a combustion chamber of the same diameteras the full-scale chamber. Our proposed two-phase approach demonstrates the validity of the concept. Phase I covers the modification of standard analysis tools for application to this approach and application of the tools to develop an appropriate singleelement chamber conceptual design. Phase II is the validation task, covering the critical design, fabrication and testing of a single-element engine. We propose that the well-characterized 0100 injection elements be used during the initial conceptvalidation. Subsequent testing would include large gas-liquid elements appropriate for ox-rich staged combustion engines currently of interest to both the Air Force and NASA. The goal of this SBIR is the design and demonstration of a reduced thrust testarticle capable of duplicating the full-scale engine combustion stability characteristics. Combustion instability and steady state performance modelling will be key to the success of both of these programs, and other National Aerospace Initiative boosterengine programs. Improved predictive tools and reduced scale test methodologies capable of affording early combustion stability characterization are essential for risk mitigation. The successful completion of the proposed work will provide the governmentand the industry with both tools and methodologies.