Exhaust Gas Analysis of a Rotating Detonation Engine using Tunable Diode Laser Absorption Spectroscopy

摘要

Two different test sections (ducts), with optical ports for optical fibers, were mounted to the exhaust end of two rotating detonation engines (RDE's). The test sections were used to obtain velocity, temperature and water concentration from the exhaust flow of the RDE. These measurements were obtained with time-division-multiplexed tunable diode laser absorption spectroscopy (TDM-TDLAS). The spectroscopic system used to take these measurements used two diode lasers to scan across spectroscopic absorption features of H_2O near 1.3 μm (≈ 7,435 to 7,442 cm~(-1) and 7,465 to 7,471 cm~(-1)). These features were analyzed to obtain the temperature and H_2O concentration as well as the velocity of the exhaust of the RDE. The combustion of C_2H_4 from a Hencken burner was also studied to provide a check for the temperature measurements. It was found that after the RDE reached a steady state condition the temperature and H_2O concentration remained relatively constant with standard deviations of 50 K and 0.08 moles/m~3 respectively. The combustion products of the RDE were also found to have an average velocity of 364 m/s with velocity fluctuations of approximately 110 m/s.