Network Flow Simulation of Fluid Transients in Rocket Propulsion Systems

Abstract

Fluid transients, also known as water hammer, can have a significant impact on the design and operation of both spacecraft and launch vehicle propulsion systems. These transients often occur at system activation and shutdown. The pressure rise due to sudden opening and closing of valves of propulsion feed lines can cause serious damage during activation and shutdown of propulsion systems. During activation (valve opening) and shutdown (valve closing), pressure surges must be predicted accurately to ensure structural integrity of the propulsion system fluid network.In the current work, a network flow simulation software (Generalized Fluid System Simulation Program) based on Finite Volume Method has been used to predict the pressure surges in the feed line due to both valve closing and valve opening using two separate geometrical configurations. The valve opening pressure surge results are compared with experimental data available in the literature and the numerical results compared very well within reasonable accuracy (< 5%) for a wide range of inlet-to-initial pressure ratios. A Fast Fourier Transform is preformed on the pressure oscillations to predict the various modal frequencies of the pressure wave.The shutdown problem, i.e. valve closing problem, the simulation results are compared with the results of Method of Characteristics. Most rocket engines experience a longitudinal acceleration, known as "pogo" during the later stage of engine burn. In the shutdown example problem, an accumulator has been used in the feed system to demonstrate the "pogo" mitigation effects in the feed system of propellant. The simulation results using GFSSP compared very well with the results of Method of Characteristics.

Dynamic modeling and simulation of an integral bipropellant propulsion double-valve combined test system

“…Majumdar [48] use a model with two nodes and one branch to simulate the blown-down process of a pressurized tank. Comparison of simulation results with isentropic analytical solution verifies the effectiveness of the Generalized Fluid System Simulation Program (GFSSP) [49]. The venting air tank problem is modeled here by a modularization system composed of 1 gas volume (GVol1), 1 gas injector (GI1) and 1 fluid source (FS1) as shown in Fig.…”

The spectral element method as an efficient tool for transient simulations of hydraulic systems

“…Fast variations of the volume flow in a pipeline system give rise to pressure waves propagating through the pressure lines and causing problems like noise, vibrations, or in the worst case, even pipe collapse. These transient hydraulic effects constitute a major risk in various areas like cooling-water systems, pumped-storage power plants or even in the feed lines of liquid rocket engines [1,2,3,4].…”

Analysis of Energy Consumption Model and Energy Consumption Characteristics of Electric Vehicle

“…With global warming, energy crisis and air pollution in the city is increasing, energy saving and emission reduction situation facing traffic field is becoming more and more serious. The development of city low carbon transportation system with low energy consumption, low emission and low pollution characteristics has become the inevitable choice to realize the sustainable development of the city traffic [1][2]. In the process of using zero pollution, low noise and high energy efficiency, the role of electric vehicles in the construction of low carbon traffic is expected in the cities of various countries.…”

“…the traditional Galerkin method. Equation(3)is obtained by substituting equation(2) into integral equation(1). When the remainder term n r in equation(3)is zero,     conveniently get a more accurate numerical solution,   x r n needs to be as close to zero as possible.…”