This research develops an advanced optical patternator method to predict the characteristic exhaust velocity of bipropellant thrusters, aiming to bridge the gap between cold-flow diagnostics and hot-fire performance prediction. The method combines scattered light and planar laser-induced fluorescence techniques to enable noncontact high-resolution spray characterization, overcoming fundamental limitations of conventional mechanical patternators. Experiments conducted under well-controlled conditions support theoretical analysis and demonstrate that the optical approach achieves performance equivalent to mechanical patternators over a wide range of mixture ratios. Furthermore, the predicted characteristic velocities show excellent agreement with hot-firing test data, confirming the validity of the proposed framework. The optical method enables real-time measurements with an approximately 90% reduction in evaluation time, achieving performance prediction within a 5.2% error relative to hot-fire test results, highlighting its potential in reducing development costs while maintaining quantitative reliability for thruster design applications.
Tominaga et al. (Sun,) studied this question.