Preliminary Analysis Method for Large Amplitude Liquid Slosh in Air-Launched Space Launch Vehicles

摘要

The air-launch of space launch vehicles from aircraft potentially increases operational flexibility and payload mass compared to conventional ground-launch, and several vehicles in development are pursuing this alternative. Existing air-launched orbital systems use solid motors, but new entrants propose to use liquid engines for increased performance. The introduction of liquid propellants into air-launched orbital vehicles is a significant engineering challenge that requires new analytical techniques. Specifically, the release, reorientation, and ignition transient incites large amplitude slosh that may expose engine intakes and affect vehicle stability. Computational fluid dynamics (CFD) can be used to study isolated scenarios but is too expensive to couple with Monte Carlo trajectory simulations. A preliminary analysis method is presented that uses a single second order differential equation to rapidly calculate inertial properties and forces on the tank structure. Model parameters are calibrated using a single high fidelity reference simulation. The viability of the reduced-order model is then evaluated by comparing it against CFD for a scenario different than the calibration case.