The Dynamic Charateristic Study About Pipe System For Conveying Fluid Propellant

Control of conveying pipe vibration has been and being studied widely which is a world problem. Aiming at the conveying-alcohol pipe system of a certin model gas generator in our school rocket engine field laboratory, this paper does a series of simulation studies using AMESim, analyses and summarizes the results of simulations, and at the same time implements some waterhammer experiments, and compares the results with the ones of simulations.First,the dynamic characteristics of pipe is simulated, the influence to waterhammer which is brought by the flow area of the valve, response time, the length of the pipe before and after the valve, the hydraulic pressure fluctuating in the trunk, and the high frequency pressure fluctuating in combustion chamber is analysed. The simulation shows that the valve throttle area should be little as possible but must be more than 40% of pipe section area; when the total length of pipe is same, and the flow quantity is enough, pipe before primary valve should be thin and long, and the pipe after primary valve should be thick and short,the upriver and downriver small pressure fluctuation will badly lead to waterdrammer pressure rising, and spending more time in establishing pressure and flow quantity. Compute the ability that reducing vibration of six measures. Believe that setting gas pressure accumulator is the effective measure. Base on the model of accumulator,design a new-style accumulator which can consume energy by appending a damper on the spring accumulator.The whole model of gas generator experimental system is established, all kinds of work states are simulated, the interaction between two branch pipes is analyzed. Its effect is simulated when setting a gas pressure accumulator near the valve. Believes that gas pressure accumulator can absorb waterhammer pressure effectively, but it needs more time to achieve stable state. The consume-energy accumulator can not absorb one of opening valve effectively, but it can achieve stable state quickly. Combination of the two style accumulators will be a nice choice.The results of simulation is validated by the experiments, but some errors between ones of experiments and ones of simulation still exist that they occur generally when experiments begin. The reason lies in the practically structure of the valve that it's a 2-D or 3-D structure, but the model using is just 1-D and can't simulate the valve exactly. The experiments prove that the effect of the gas pressure accumulator absorbing waterhammer pressure is better than one of the Helmholtz filter, so this paper advises to set gas pressure accumulator to reduce vibrations. Different-diameter pipes can reduce waterhammer pressure also; the key is the matching between pipe and valve which is important.