Numerical Simulation Of Waterhammer In Shutting Liquid Rocket Engine

Liquid rocket engine system contains lots of control valves, water hammer and pressure surge aroused in the propellant pipelines while valves’operating during engine working period. This problem consequently makes pipeline seal invalid, propellant leakage, even lose engine power. To improve the engine working reliability, it’s important to study the water hammer phenomena and pressure transient discipline in order to depress and eliminate the influence of water hammer pressure and give reasonable design for liquid rocket engine and propellant systems.This paper firstly presents the mathematic theories of Method of Characteristic (MOC) and difference method that is the fundamental preparation for water hammer numerical simulation. In the process of simulating, FLOWMAER is adopted as the solver. FLOWMASTER is a widely used tool for solving pressure transient problems, which is programmed on the basis of MOC and involved kinds of loss coefficient data, such as pipe, elbow, transition and valve. It makes the results of water hammer numerical simulation more accuracy to fit the actual water hammer pressure. In the paper a new idea is presented that explain how to use CFD method to gain the loss coefficient and flow coefficient of the special valve and five-pass pipes by solving tow-dimension and three-dimension N-S formula. It’s practically effective in the propellant pipeline system water hammer simulation because there are usually composed a lot of non-standard fittings in the liquid rocket engine system.This paper also considers cavitations as an important aspect in the numerical process, the calculation results is terrified by rocket engine hot-run experiment data. The numerical simulation is proved to be reliable by comparing calculation data with experiment data. Further more, the pressure transients difference between two locations, one is on the end of the pressure measuring pipe and the other is in front of the closing valve, has analyzed by a series of calculation results. Finally some methods of depressing and eliminating water hammer in the pipeline are stated on the basis of calculation and analysis.The numerical simulation method and calculation results in the paper provide the reference for liquid rocket engine design; also give reasonable approaches to access water hammer in pipelines including non-standard fittings.