Pressure vessel priming analysis for a regulated liquid propulsion system

An investigation was performed to determine the pressure transient levels and time required to reach pressure equilibrium in a regulated liquid propulsion system due to the priming of a propellant tank during system initiation.An experimental fluid flow test setup was designed and fabricated using a pressure vessel to house distilled water as a propellant simulant for liquid hydrazine and high-pressure gaseous nitrogen as the pressurant.A snubber orifice was installed downstream of the high-pressure gaseous nitrogen bottles to protect a regulator from high-pressure transients,prior to the regulation of incoming gas to beginning of life propulsion system propellant tank conditions.Experiments were conducted to measure pressure transients and time to pressure equilibrium by varying initial system pressures,snubber orifice diameter,and system ullage volume.A mathematical model was developed and compared against the experimental regulated system priming results to predict the system pressures and time to reach system pressure equilibrium during the pressurization period for regulated propulsion systems given initial conditions.

A Comparative Study of Genetic Algorithm Parameters for the Inverse Problem-based Fault Diagnosis of Liquid Rocket Propulsion Systems

Fault diagnosis of liquid rocket propulsion systems （LRPSs） is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be significantly enhanced by exploiting an efficient fault diagnosis system. Currently, inverse problem-based diagnosis has attracted a great deal of research attention in fault diagnosis domain. This methodology provides a new strategy to model-based fault diagnosis for monitoring the health of propulsion systems. To solve the inverse problems arising from the fault diagnosis of LRPSs, GAs have been adopted in recent years as the first and effective choice of available numerical optimization tools. However, the GA has many control parameters to be chosen in advance and there still lack sound theoretical tools to analyze the effects of these parameters on diagnostic performance analytically. In this paper a comparative study of the influence of GA parameters on diagnostic results is conducted by performing a series of numerical experiments. The objective of this study is to investigate the contribution of individual algorithm parameter to final diagnostic result and provide reasonable estimates for choosing GA parameters in the inverse problem-based fault diagnosis of LRPSs. Some constructive remarks are made in conclusion and will be helpful for the implementation of GA to the fault diagnosis practice of LRPSs in the future.

Multidisciplinary Design and Optimization of Satellite Launch Vehicle Using Latin Hypercube Design of Experiments

The design of new Satellite Launch Vehicle （SLV） is of interest, especially when a combination of Solid and Liquid Propulsion is included. Proposed is a conceptual design and optimization technique for multistage Low Earth Orbit （LEO） bound SLV comprising of solid and liquid stages with the use of Genetic Algorithm （GA） as global optimizer. Convergence of GA is improved by introducing initial population based on the Design of Experiments （DOE） Technique. Latin Hypercube Sampling （LHS）-DOE is used for its good space filling properties. LHS is a stratified random procedure that provides an efficient way of sampling variables from their multivariate distributions. In SLV design minimum Gross Lift offWeight （GLOW） concept is traditionally being sought. Since the development costs tend to vary as a function of GLOW, this minimum GLOW is considered as a minimum development cost concept. The design approach is meaningful to initial design sizing purpose for its computational efficiency gives a quick insight into the vehicle performance prior to detailed design.

Transient simulation of a differential piston warm gas self-pressurization system for liquid attitude and divert propulsion system

In order to obtain the dynamic characteristics of a differential piston warm gas selfpressurization system for liquid attitude and divert propulsion system, a transient model is developed using the modular modeling method. The system includes the solid start cartridge,pressure-amplified tank with liquid monopropellant, liquid regulator, gas generator, and pipes.The one-dimensional finite-element state-variable model is applied to the pipes and the lumped parameter method is adopted for the other modules. The variations of the system operation parameters over time during the startup, steady-state, and pulsing operational processes are obtained from the transient model, and the characteristics of starting time changing with different system parameters are also analyzed. It is shown that the system startup process can be divided into three distinct processes. The starting time monotonically changes with variations of the liquid regulator parameters, first decreasing and then increasing with the mass change of the solid propellant charge of the start cartridge, initial gas cavity volume of the pressure amplified tank and initial gas cushion of the propellant tank. The starting time can be reduced to less than 1.0 s（0.68–0.75 s for the current system）. For meeting the deviation requirements of ±10% of the steady-state propellant tank pressure, the positive deviation requirement is assured by the self-locking pressure and the negative deviation can be assured within an allowable maximum propellant tank volume flowrate（1.6 times the design value for the proposed system） for downstream thrusters for a designed system. The results from the simulation are useful as a guide for further system design and testing.

Actuation of Liquid Flow by Guided Acoustic Waves on Punched Steel Tapes with Protruding Loops

In a biomimetic approach the feasibility of liquid flow actuation by vibrating protruding structures excited via guided acoustic waves is investigated.Inspired by periodically beating cilia the loop part of a punched metallic hook-and-loop tape with tilted protruding loops was used as a waveguide for plate waves in water.Such waves were excited in the frequency range of 110 Hz to 220 Hz by directly coupling the tape to a loudspeaker membrane.A flow generated in the tilt direction of the loops with velocities up to 60 mm s 1 was visualized by ink droplets deposited on the tape.The phenomenon persisted,when the protruding length of the loops was reduced by decreasing the protrusion angle.However,after closing the punch holes near the loops with sticking tape streaming could not be observed any longer.The same happened with open punch holes when the ink was replaced by glycerol.Low-frequency acoustic streaming around vibrating sharp edges is proposed as an explanation for the observed phenomena.Applications are expected with respect to the modification of flow profiles and the enhancement of transport processes along and across liquid-solid boundaries.