COMBUSTION AND PERFORMANCE STUDIES OF GLYCIDYL AZIDE POLYMER AND ITS MIXTURES AS HYBRID ROCKET FUEL

摘要

The combustion of glycidyl azide polymer (GAP) was investigated. The GAP fuel tests were conducted in a strand burner with nitrogen gas purge and in a lab-scale hybrid rocket with gas oxygen as oxidizer. In the strand burner, at intermediate pressure range 3-6 MPa, burning rates of both cured and uncured GAP were nearly the same and strongly depend on the chamber pressure. At pressure larger than 6 MPa, uncured GAP shows less dependence on pressure, and the GAP ratio of mixtures begins to have dominant role on burning rate. Transition pressure region was observed, which was in between the pressure dependence to composition dependence. The fluctuating burning rate was the main appearance in the transition pressure region. The Zel'dovich formula shows good prediction for burning rate at intermediate pressure range, but has much deviation at high pressure due to the surface instability. A smaller sample tube can restrict the burning surface from twisting, and the resulting burning rate shows good agreement with Zel'dovich formula prediction. Uncured 100% GAP can reach its maximum burning rate at certain pressure less than 10 MPa. Based on the assumption that condensed phase reaction is the only heat source which dominates the burning rate, the prediction of maximum burning rate of GAP mixture is also possible. In a lab-scale hybrid rocket test, GAP/PEG solid fuel demonstrated a very good burning rate under mild chamber pressure and oxygen flux. Instantaneous burning rate was successfully measured by ultrasonic techniques, and the results implied complex internal ballistic behavior.