Hypergolic ignition of hydrogen peroxide with various solid fuels

An experimental investigation was conducted to determine the hypergolic ignition delay time and behavior of various solid fuels containing sodium borohydride with high-grade hydrogen peroxide. It is shown that the hypergolic reaction between sodium borohydride and hydrogen peroxide provides the heat necessary to cause the ignition and combustion of the fuels. Ignition delay times between 5.5 ms and 10 ms were measured for tests performed at ambient conditions. The hypergolic ignition has also been studied at elevated pressures, resulting in decreased ignition delay times for most cases. Ignition delay times as short as 2.93 ms were measured for tests at 10 bar. The theoretical specific impulse of the tested fuels was found to be comparable to other liquid hypergolic propellants as well as common hybrid rocket combinations. Additional tests were conducted using radial oxidizer injection over a hollow cylindrical surface to prove that the hypergolic ignition of the selected fuels is certain. Approximated ignition and combustion delay times averaged 23.1 ms. The results imply that in a hypergolichybrid rocket configuration, short ignition delay times can be achieved, thus eliminating the need for a separate ignition system.