Fluid modeling of propellant motion via parameters optimization

Abstract

This thesis covers a methodology to find a modeling for fluid motion using parameters optimization. The motion of a propellant can be divided by two motion according to the target model, one is the sloshing motion in gravity environment and the other is floating fluid motion in micro-gravity environment. And, the general method to model the propellant motion is composed of two methods. First calculates a huge amount of computation using CFD, second is alternative modeling method using fluid mechanics analysis obtained from very simple conditions. In case of the method using CFD directly, although it can model the fluid in a very high accuracy, it takes a very long computation time. The method using alternative modeling is focused on the computation time than the accuracy. In order to compensate for it, in this thesis, the proper alternative modeling is calculated using param-eters optimization method. This method has small computational time and calculation load rather than CFD method and high accuracy than classical alternative modeling. For the method validation, three kind of situa-tions are assumed. Currently operating geostationary satellite is referred for weak sloshing environment. The environment of launch sequence about typical launch vehicle is applied for strong sloshing environment. At this time, three types of alternative modeling obtained from pendulum modeling are used. And, background environment of launch vehicle upper stage are mainly simulated for the fluid modeling in micro-gravity con-dition. The alternative modeling for this is related to potential field method. Eventually, optimal parameters are obtained using the modeling about each environments and parameters optimization in each environment. The performance validation is conducted through CFD data comparison.