Optical Observation for the Impingements of Nitrogen Tetroxide/Monomethylhydrazine Simulants

Abstract

The spray phenomena of doublet and triplet impingements of nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) simulants were studied by the planar laser induced fluorescence technique. The total flow rates of the simulants were controlled at ∼8.00 g/s to simulate the operations of a 5-lb f rocket, and the ratios of the mass flow rates (O/F) of NTO and MMH simulants were varied from 1.0 to 2.4. Statistical analysis was employed to examine the probability distributions of the mass of individual simulants at 10 mm downstream from the impinging point. The distributions of local mixture ratios and flame temperatures were deduced, and the estimation of characteristic exhaust velocity was performed. The results revealed that the breakup and mixing of the impinging jets were closely related to the momentum flux ratio of the jets and the surface tension of the liquids. The triplet impingement was superior in symmetry and uniformity of the spray than that of the doublet impingement, and its mixing was less sensitive to the momentum flux ratio and showed a better mixing effect than doublet impingement at higher O/F ratio conditions. With the detailed distribution information provided by the optical technique, the optimum C* occurred at O/F = 1.18 with doublet impingements for the operation of a 5-lb f NTO/MMH rocket.