“Green propellants” as a hydrazine substitute: experimental investigations of ethane/ethene-nitrous oxide mixtures and validation of detailed reaction mechanism

Abstract

Mixtures of hydrocarbons and nitrous oxide are known as green propellants and could replace the highly toxic hydrazine and hydrazine derivatives as rocket fuel, since they are non-toxic and easier to handle, but still have a high specific impulse. Possible hydrocarbon candidates are ethane or ethene. To check the applicability of the two reaction systems, C2H6/N2O and C2H4/N2O, experiments are a prerequisite for accurate predictions under various conditions that are of great importance for the design of safe and reliable thrusters. Therefore, experimental literature data obtained from ignition delay times and laminar burning velocities were used to validate and optimize a new reaction mechanism, which is designed for C0–C3 and nitrogen oxides formation. To achieve a better predictive power of the detailed mechanism, the Arrhenius parameters of three reactions were adjusted: N2O + H ⇌ N2 + OH, N2O (+ M) ⇌ N2 + O (+ M), and NH + NO ⇌ N2O + H. A good agreement was achieved between simulation and experiment for ignition delay times at various pressures and equivalence ratios in a broad temperature range before and after the mechanism optimization. However, the laminar burning velocities in the whole measured range of the equivalence ratio for all pressures and dilutions showed a significant improvement after the optimization.

Nitrous Oxide: Oxidizer and Promoter of Hydrogen and Hydrocarbon Combustion

“…Numerous studies examined the combustion rate of various fuels with N 2 O, delivering a large body of measured and computed burning velocities at ambient initial conditions or under different operating conditions. Experimental data were obtained by using stationary flames anchored on burners, as either conical flames ,,,− or flat flames. ,− Nonstationary flames were examined in closed vessel experiments, by making synchronous records of the pressure and flame radius. ,,,,,,,,,,− …”

“…Two extensive studies on H 2 –N 2 O flames, neat or diluted with N 2 , CO 2 , Ar, and He, were using a Bunsen-type burner and delivered the laminar burning velocity of H 2 –N 2 O at ambient temperature and variable initial pressures, between 10 and 760 mmHg. , The reference burning velocity of the stoichiometric H 2 –N 2 O mixture at ambient pressure was S u,0 = 390 cm s –1 . , Other fuels were also studied: carbon oxide, ethylene, , and acetylene, sometimes in the presence of promoting additives like Fe­(CO) 5 for CO or inerting additives like N 2 and CO 2 for H 2 or C 2 H 4 . ,, Recent studies describe high-pressure burners, , working at pressures up to 10 bar and using the cone angle method as a straightforward tool for burning velocities determination. One has to mention that the laminar burning velocities obtained by this method are influenced by the flame stretch, because of flame front curvature and/or flow divergence; therefore, their results are to be examined with care.…”

“…One has to mention that the laminar burning velocities obtained by this method are influenced by the flame stretch, because of flame front curvature and/or flow divergence; therefore, their results are to be examined with care. Still, the burning velocities from these papers were used since the beginning for understanding of the chemistry of H–N–C–O reactions in flames and for validation of kinetic models. ,,, …”

“…130,132 Other fuels were also studied: carbon oxide, 134 ethylene, 61,63 and acetylene, 133 sometimes in the presence of promoting additives like Fe(CO) 5 for CO 134 or inerting additives like N 2 and CO 2 for H 2 or C 2 H 4 . 61,131,132 Recent studies describe high-pressure burners, 63,69 working at pressures up to 10 bar and using the cone angle method as a straightforward tool for burning velocities determination. One has to mention that the laminar burning velocities obtained by this method are influenced by the flame stretch, because of flame front curvature and/or flow divergence; 167 therefore, their results are to be examined with care.…”

Study on the Flame Acceleration and Transition from Deflagration to Detonation of N2O/C2H4/CO2

“…At the critical temperature, it has a strong ability to dissolve hydrocarbons, ammonia and other fuels, so the propellant with nitrous oxide and fuel blends (NOFBX) can be prepared by low-temperature liquefaction [7,14,15]. Compared with monopropellant hydrazine and its derivatives, NOFBX can offer high specific impulse, low cost, wide availability and environmental friendliness [6,16,17]. Moreover, they have high vapor pressure at ambient tem-perature and self-pressurizing capability applicable to a wide range of space vehicle [18].…”