Mass- and Momentum-Conserved Secondary Injection Model (MMC-SIM) for Thrust Vector Control Analysis

Abstract

A mass- and momentum-conserved secondary injection model (MMC-SIM) is presented for thrust vector control (TVC) analysis in axisymmetric nozzles. TVC modelling provides fast thrust vector predictions for control and design applications. MMC-SIM addresses a key limitation in prior models - the lack of mass conservation, which often compromised accuracy through assumed jet exit conditions. Using a semi-empirical approach based on the blunt-body analogy, MMC-SIM uniquely incorporates both mass and momentum conservation for thrust vector predictions. Computational fluid dynamics (CFD) simulations were performed to verify that MMC-SIM captures the underlying physics of the flow, including boundary layer separation and the pressure distribution. MMC-SIM shows strong agreement with experimental results, yielding average and maximum lateral force prediction errors of 3.3% and 4.8%, respectively. Compared to current models, MMC-SIM halves the maximum error on the pressure-driven lateral force. MMC-SIM is highly suitable for integration into six degree-of-freedom rocket flight simulation programs.