Validation of the A5 SCA Waterhammer model
- Paper number
IAC-07-C4.I.08
- Author
Mr. Felipe Dengra, Astrium GmbH, Germany
- Year
2007
- Abstract
The ARIANE 5 upper stage attitude control is performed by SCA (Système de Contrôle d'Attitude). It is a blow-down hydrazine system using gaseous nitrogen as pressurant. SCA also performs roll control of the entire launcher during the EPC thrust phase, after booster separation. The SCA development was performed by EADS-ST, funded by ESA under CNES responsibility. This paper aims to be in possession of a mathematical model able to correctly simulate fast transient flow phenomena that could eventually take place in SCA. The impact of this phenomenon, commonly known as waterhammer, is of vital importance when designing any hydraulic system. High pressure peaks could mechanically damage the piping in the network, leading to, in the worst of the cases, a complete failure of the whole system. The analysis has been carried out using a 1D thermo fluid flow software package able to account for two-phase flow modelling. Experimental results using water as test fluid for rapid valve closures were available and were used to validate the computations. This paper will compare numerical against experimental results taking into account the main frequency of the oscillations, the amplitude of the first and successive peaks and the surges’ damping rate. In addition the paper will contain a description of the physical modelling used in the code (sonic velocity calculation, spatial and temporal grid discretisations, two-phase flow modelling, solver method, etc…) and an overview of other potential applications of this code in the liquid space propulsion field.
- Abstract document