Implementation of experimentally derived models in a fast engineering tool for simulation and design of propellant management systems in launcher stages
- Paper number
IAC-09.C4.1.2
- Author
Mr. Arnold van Foreest, Germany
- Year
2009
- Abstract
A well designed propellant management system in rocket stages is of crucial importance for successful launcher design. The main task of the system is to make sure propellant enters the engine under the right conditions. Typically about 90% of the launcher takeoff mass consists of propellant. To make launchers as efficient as possible, propellant weight should be minimized. The most obvious way to achieve this is probably to increase the specific impulse of the engine. But engine performance cannot be increased indefinitely. In fact current rocket engine technology is reaching its limits. The propellant management system can be optimized such that propellant residuals (unburned propellant which for example remains in the feedlines) and loaded propellant are minimized. This is especially important in upper stages, where each kilogram saved can be directly added to the payload. To obtain an efficient design, it is necessary to be able to simulate propellant behaviour and propellant management systems using fast engineering methods (CPU time in order of seconds, maximum a few minutes). This way propellant management can be integrated in the preliminary design phase where different propellant management systems can be compared and a trade-off can be made. At the Institute of Space Systems of DLR (German Aerospace Centre) in Bremen, the SART (Space Launcher Systems Analysis) department is developing a tool for this purpose. In its current form the program PMP (Propellant Management Program) calculates amongst others the required pressurization gas mass, pressure losses throughout the propellant feed system, pressure at all locations, and it includes a simple method for the determination of evaporated propellant mass and self-pressurization. Other models, such as a model for thermal stratification and a model for the simulation of thermodynamic effects caused by sloshing, are to be implemented. Experiments are carried out at Centre of Applied Space Technology and Microgravity (ZARM) in Bremen, Germany, for the investigation of cryogenic stratification and sloshing. Detailed investigations of the experiments are done by numerical simulation with the commercially available code FLOW 3D. Once good numerical results are obtained a more detailed analysis of the problem can be made. Once the problem is better understood, one can try to derive a model to predict the stratification and thermodynamic effects caused by sloshing without the need of 3D CFD solvers. The model can then be implemented into the tool PMP.
- Abstract document
- Manuscript document
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