Numerical Simulation of the Actuation System for the ALDF's Propulsion Control Valve

A numerical simulation of the actuation system for the propulsion control valve (PCV) of NASA Langley Aircraft Landing Dynamics Facility (ALDF) was developed during the preliminary design of the PCV and was used throughout the entire project. The numerical simulation is based on a predictive model of the PCV that was used to evaluate and design the unique actuation system. The PCV is a one-of-a-kind valve that controls a 1.7-millionIb thrust water jet used in propelling a 108,000-1 b test carriage. The PCV can open and close in 0.300 s and deliver over 9000 gal of water per second at pressures up to 3150 psi. The actuation system of the PCV is a complicated mechanical-fluid power system designed for moving large masses at a high rate of acceleration. The design concept for the PCV was unique and it was built without the benefit of prototypes to verify the engineering design. The results of the numerical simulation of the PCV were used to predict transient performance and valve opening characteristics, specify the hydraulic control system, define transient loadings on components, and evaluate failure modes. The unique actuation system operated as the design intended and met the required performance without modification, largely because the results of the numerical simulation determined the required engineering parameters used to design the PCV. The mathematical model used for numerically simulating the mechanical fluid power system is described. Numerical results are demonstrated for a typical opening and closing cycle of the PCV. The computed results are shown to agree well with operational measurements. Finally, a summary is given on how the model was used in the design process. This paper demonstrates the advantages of having a predictive model for designing a complicated mechanical-fluid power system.