Since hybrid propulsion is being developed for space launch vehicles, there is a strong need for understanding the physical mechanisms causing hybrid rocket combustion instability. The project's objective is to develop and demonstrate a Liquid Oxygen Hybrid Motor Combustion Stability Test Bed. This test bed consists of a 10,000 pound thrust liquid oxygen/polybutadiene hybrid rocket motor that has the capability to modify the injector, forward chamber and nozzle so that the effect of injector design, forward chamber design, fuel lining, fuel formulation, combustion pressure and mass flux on acoustic and non-acoustic hybrid combustion instabilities can be evaluated. This test bed simulates the large-scale injector/forward chamber effect on liquid oxygen atomization and vaporization that is critical to understanding hybrid rocket stability. This work involves designing, building, and testing several innovative liquid oxygen injectors and 10K hybrid motors. Extensive data is gathered on the dynamic performance of the injectors and combustion chamber, and compared with other industry hybrid propulsion research and development. The combustion stability analytical models, test data, and stability boundary maps resulting from this project help to ensure that hybrid boosters can be designed to operate smoothly throughout their entire operating regime.The results from this project apply directly to the design and development of small and large-scale liquid oxygen hybrid boosters for commercial and government space launch vehicles. The diversity of hybrid rocket motor applications includes sounding rocket motors, upper stage motors and boost propulsion for expendable launch vehicles. Ultimately, the safety, environmental cleanliness, and low cost of hybrid boosters could lead to its use as an upgrade for the solid rocket motors used on the Space Shuttle or for boost propulsion on the next generation launch vehicle.hybrid propulsion, combustion stability or instability
