Multi-pendulum modeling of propellant sloshing via parameters optimization

Abstract

In this paper, the modeling about propellant sloshing is conducted using pendulum model with parameters optimization technique. First of all, the dynamics about multiple pendulum model is introduced. The pendulum model used in the modeling is two types. First is most basic single pendulum model, second is coupled multiple pendulum model. Among them, the multiple pendulum model has complicated calculation process because each pendulum mass is coupled with each other. However, it can represent complex motion of fluid than single pendulum model. To exactly represent the sloshing using the pendulum model, the proper parameters have to be determined. And parameters optimization technique can be a solution for this purpose. Among the many types of optimization algorithms, the PSO algorithm is used as a fast calculation. The differential equation of multiple pendulum having coupling term can be solved by integration method only like RK4, and it takes a lot of calculation time. Therefore a fast calculation performance of PSO algorithm is necessary. To use the parameters optimization, a data can be a reference is needed. This data and the environments of actually and currently operating system are set similarly. And the two kind of systems are considered in order to the data analysis. First system is COMS-1 which is currently operating GEO satellite in South Korea. This system has a small vertical and horizontal acceleration characteristics. Second model is Ariane 5 ECA launch vehicle of Europe. The maximum horizontal acceleration assumed in this system is half the vertical acceleration. If parameters optimization algorithms is conducted into the environments obtained by two kind of actual model, the pendulum model is the same as the sloshing appearing in each environment. After that, the comparison between the CFD data and the obtained pendulum model data and analysis about each model is conducted.