Measurement of multispecies concentration and gas temperature in an ammonium-dinitramide-based thruster by tunable diode lasers

Abstract

In this paper, quantitative experiments were made to measure the concentration of key intermediate products (CO, NO, and NO) and the gas temperature for combustion flow based on near-infrared and mid-infrared laser absorption spectroscopy. This paper used the developed diagnostic system to study two main ignition modes of a real 1-Newton thruster based on ammonium dinitramide (ADN): steady-state firing and pulse-mode firing over a feed pressure of 5-12 bar. The steady-state firing experiments distinguished the whole process into catalytic decomposition stage and combustion stage, experimentally demonstrating the combustion kinetics mechanism of an ADN monopropellant. Experiments for pulse-mode firing showed the measured multispecies concentration and temperature were consistent with pulse trains, verifying good performance for the thruster pulse-mode firing operation. The performance of the thruster was given based on the optical measurements, and characteristic velocity for the ADN-based thruster standard operation was higher than the corresponding 1-Newton hydrazine thruster.

Preliminary study on direct measurements and diagnostics for chemical reaction dynamics of NOx by using laser wavelength modulation spectroscopy

“…For example, Almodovar et al [7] used tunable diode LAS (TDLAS) for in situ detection of high-temperature gas temperature and NO concentration measurements, further explaining the temperature dependence of NO collisional spreading. Zeng et al [8] quantified the concentrations of key intermediates CO, N 2 O, and NO and gas temperatures during the combustion of ammonium dinitramide (ADN) using TDLAS in the near and mid-infrared bands. Shang et al [9] determined the key product NO of CH 3 NO 2 by the TDLAS technique and investigated the pyrolysis process of CH 3 NO 2 in heated excitation tubes at about 3.5 atm and 1013-1418 K. However, studies on the measurement of key substances during NO oxidation by O 3 are very limited.…”