Experimental investigation of auto-ignition of ethylene-nitrous oxide propellants in rapid compression machine

Considering the available experimental investigations of auto-ignition behaviors of N2O-C-2 hydrocarbons propellants are limited in high-temperature regime, in the work the ignition delay times for N2O-C2H4 propellants have been measured under the conditions of T-C = 885-940 K, P-C = 2.5-4.3 MPa, phi = 1.05 and 1.35 using the rapid compression machine experiments. Then the relational expression between ignition delay time and condition factors is derived as lg tau(ig) = 11.78(1000/T-c) -0.26P(c) -0.83 phi -9.41 by linear fitting. The expression can be used to predict ignition delay times of N2O-C2H4 propellants in practice. Moreover, the calculated ignition delay times by three kinetic models are compared with experimental data. The results show that these models can well predict ignition behaviors at high temperature regime, but fail at low-temperature regime. Through temperature sensitivity analysis, at high-temperature regime the N2O decomposition reaction has the highest sensitivity coefficient and dominated the overall reaction. While at low-temperature regime, the oxidation reactions of N2O and hydrocarbons become more important steps. For better prediction of low-temperature ignition behaviors, the low-temperature oxidation mechanism of N2O and hydrocarbons needs further development, and the kinetic parameters of the highly sensitive reactions should be improved.

Automated summary

In this study, ignition delay times of N2O-C2H4 propellants were measured under specific conditions and an expression was derived to predict ignition delays. The analysis showed that at high temperatures, N2O decomposition reaction has the highest sensitivity coefficient, while at low temperatures, oxidation reactions of N2O and hydrocarbons become more important. Further development of low-temperature oxidation mechanism is needed for better prediction of low-temperature ignition behaviors.