Effects of water hammer on propulsion systems

An experimental research program was conducted to evaluate pressure transient levels in liquid monopropellant propulsion system configurations and propellant manifolds generated by water hammer effects resulting from a priming event. This was accomplished through the development of a water hammer experimental setup using distilled water as a propellant simulant for hydrazine. Multiple test elements were evaluated using different internal diameters, line lengths, and flow control valves, at both atmospheric and sub-atmospheric pressure levels. Based upon experimental results, it was determined that the internal diameter, line length, valve flow coefficient, and valve opening response time all contributed to the pressure magnitude of the priming event. It was observed that water hammer pressure levels may be minimized and equally distributed throughout a propulsion system manifold using a ring layout, independent of line geometry, valve flow coefficient, and valve opening response time.