Advanced Optical Patternator for Performance Prediction of Bipropellant Thrusters

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.