Showing papers in "Journal of Propulsion Technology in 2003"

Multi-fault diagnosis for turbo-pump based on neural network

Abstract: The multi fault phenomena erists frequently in the turbo pump system of liquid rocket engine. The feature expression of common fault of turbo pump was studied for building up the standard fault pattern and satisfying the needs of neural network study and diagnosis. According to the problem of BP neural network, the method of multi fault diagnosis and classification using parallel BP neural network was studied. The results show that the parallel BP neural network can solve the difficult problem of multi fault diagnosis of turbo pump.

Optimal acceleration control of turbofan engine with genetic algorithm

Abstract: An optimal acceleration control law, verified in the whole envelope, is studied for variable geometry turbofan engine based on genetic algorithm (GA) and control design with inequality constrains is discussed in this paper. Combining discrete model with GA, the method is achieved via analysis of the characteristic and performance requirements of engine speedup process. The control scheme is stable, fast and applicable to acceleration optimization. Simulations show that this control methodology can obtain more satisfactory acceleration characteristic of the engine.

Numerical simulation of the form and development of rocket gas near flow field

Abstract: The complicated wave system exists around the near region of the solid rocket motor. The interaction between expansion and compressed wave is the important part of correlated study on plane-missile and missile-warship. The distribution of the pressure and temperature field of complicated wave system is the direct factor which causes the dynamical and hot impact. It is difficult to study the complicated properties of jet flow field by means of experimental method. A method of numerical analysis was applied to study the wave system existing in near rocket gas field and the initial shock wave of high-unexpanded gas jet flow. The properties of the near region of gas flow field have obtained from the numerical result. The data accord with those given in reference and provide helpful information.

Experimental study on the mean flow behind EBMC flameholder

Abstract: In order to study the flow fields behind the Edge Blowing Mixture Curtain (EBMC) flameholder, the detailed near-wake flow behind the EBMC flameholder and the V-gutter flameholder was measured by using 2D cross-correlation on-line PIV in a low speed wind tunnel. The effect of the dynamic parameters and the direction of the jet on the flowfield of the novel flameholder was also investigated. It was revealed that the time-averaged flow field of the EBMC flameholder is similar to that of the V-gutter flameholder, while the jet enlarges the recirculation zone and it increases the turbulence intensity and mass flow rate of the recirculation zone, which would benefit the combustion. It was also found that the momentum ratio of the jet to the main flow is a primary dynamic parameter that affects the flow field of the novel flameholder.

Transient characteristics during shutdown operation of liquid feed line for attitude control propulsion subsystem

Abstract: One dimensional equations for liquid transients in propellant feed lines were considered. By means of the finite difference scheme of characteristic method, the transient flows were simulated for the attitude control propulsion subsystem during shutdown operation. The effect of different condition on dynamic behavior was investigated. The calculated results are identical with test data-the maximum transient pressure in front of the injector is equal to three times of the tank pressure. The results are valuable for designers. It shows that the method can be used to analyze dynamic performance of complex propulsion system consisting of numerous pipes, valves and thrusters.

Measurement of pressure and temperature in exhaust jet during launching stage of rocket

Abstract: Impinging effect of rocket exhaust jet should be considered comprehensively in overall design of rocket weapon system. Rational design for structure and strength of the equipment in shock-affect zone according to exhaust jet characteristics can help to achieve effective flow bypass and protection function. Flow parameters of exhaust jet on a lean steel platform were measured in the experiment during a practical launching. The maximum stagnation pressure and temperature, and distribution of pressure and temperature exhaust jet on the platform were obtained. The dangerous zone behind launch tube is determined from these data.

Effect of nano nickel powders on thermal decomposition characteristics of NH4ClO4

Abstract: γ-ray radiation synthesis method was successfully used to prepare the nano nickel powders. The thermal decomposition characteristics of NH4ClO4 (AP) influenced by nano nickel powders was investigated by TG-DTG,DSC experiment under linear temperature increasing condition and isothermal TG experiment. The results show that nano nickel powders had greater influence on the decomposition characteristic of AP than superfine-nickel powders. Nano nickel powders increase the decomposition rate of low temperature stage decomposition of AP and decrease the peak temperature of high temperature stage decomposition of AP. The thermal degradation kinetics of AP and mixture of AP/n-Ni was studied by using TG analysis at heating rate of 5,10,20,30℃ per minute. The results show that nano nickel powders decrease the apparent action energy of the thermal decomposition of AP. The action mechanism of nano nickel powders affecting the thermal decomposition process of AP was described as bridge site effect and deinhibition effect.

Mechanism of the deteriorated processability in boron-fuel-rich HTPB propellants

Abstract: By X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR) and viscosity measurement, it is affirmed that the poor processability in boron-contained HTPB propellants is originated from the gelation between the HTPB and boron surface impurities, namely boric acid and boric oxide, so as to form borate The theory of critical reaction degree is used to explain the mechanism of the deteriorated processability

Modularization modeling and simulation for the transients of liquid propellant rocket engines

Abstract: To prefigure the test processes of different test schemes of liquid rocket engines, and optimize their configuration, a new methodology of modularization modeling and simulation for the transients of liquid propellant rocket engines (LPRE) was studied. A pipe-volume module disassembly method for fluid line systems was presented. By using it, LPRE was disassembled into 21 typical components and their simulation mathematical models were developed. A configuration matrix for combination systems, which describes their module components and relationships among them, was presented. The methods for assembling and connecting module components as well as for solving the modules combination systems were developed, respectively. Based on research results, a modularization modeling and simulation software for the transients of LOX/LH2 staged combustion cycle liquid rocket engines (LRETMMSS) is developed. The transient analysis of the start-up process of a model LH2/LOX rocket engine is modeled and solved by using LRETMMSS and the computed results agree well with test data.

Study of experimental method for ablation of insulator of SRM with high acceleration (I)

Abstract: The mechanism was analyzed for the influences of high acceleration on the internal flow field and the ablation of insulator of SRM. A new method was developed which includes two parts. The first part is to solve the three-dimension two phase flow field of SRM under high acceleration condition by numerical simulation method and the second is to establish the ablation model of insulator by ablation experiment using flow field simulation equipment. Based on these studies the technique of insulator design and ablation prediction for SRM under high acceleration condition can be developed. The key technique is to develop a flow field simulation experimental method. Several projects were discussed and the siphon device seemed to be more feasible. To demonstrate the feasibility of this method, two phase flow field in siphon was analyzed by using numerical simulation method. The results showed that the siphon device can congregate particles to generate two phase flow with high density particles.

Effect of boron coated with AP on the rheological properties of slurry of fuel-rich propellant

Abstract: Four types of boron coated with AP on the rheological properties of the slurry containing 30% boron were investigated. The experimental results revealed that the rheological properties of the slurry of boron coated with 20% AP are obviously different from the others, of which the viscosity is 2.2 kPa·s and the yield value is smaller than 300 Pa after 6 h. This demonstrates that the slurry has a good fluidity and can be casted. The best rheologocal properties were ascribable to the appreciate amount of coating AP, the integrated surface of coated boron and the shape of global particle.

Conceptual design of multi-cycle pulse detonation engines

Abstract: The purpose of this study is to develop a new method based on the multi-cycle detonation results. Fully developed repetitive C-J detonation waves are produced successfully by PDE model with its diameter 50mm using gasoline as fuel and air as oxidizer. The structural parameters of PDE are determined, which are more similar to the actual situation. It is found that experience constant (K) is not a fixed value and it decreases with increasing of the frequency by some function. When the frequency is increased to some extent, the experience constant (K) decreases flatly and tends to a fixed value of 3.90. According to the experimental function obtained, the experience constant (K) of single-cycle detonation equals to 5.35 by calculation.

Flamelet modeling of turbulent jet non-premixed flame

Abstract: A turbulent jet non premixed flame was numerically simulated by the combination of a two scale k e turbulence model, the scalar joint PDF transport equation and the laminar flamelet model The velocity field results calculated by several different k e turbulence models were compared The joint PDF equation of mixture fraction and turbulence frequency was derived And with the assumption of linear relation between turbulence frequency and scalar frequency, the probability distribution of scalar dissipation rate was obtained Consequently, the species concentration and temperature were computed according to the ensemble average of the laminar flamelets The numerical results were compared with results from direct chemical reaction calculations and the experimental data

Chemical kinetics analysis for nozzle performance

Abstract: The nozzle performance of a small LRE for space propulsion was calculated using chemical equilibrium and chemical kinetic methods. For small LRE, kinetic loss is larger and nozzle performance is closed to frozen state. Kinetic loss is mainly produced in the divergence area near throat. High area ratio tends to have larger kinetic losses.

Intelligent damage-mitigating and life-extending control techniques for reusable liquid-propellant rocket engines

Abstract: A survey on the techniques of intelligent Damage-Mitigating (DM) and Life-Extending (LE) control for Reusable Liquid-propellant Rocket Engines (RLRE) was presented. Firstly, the fundamental concepts and principles on DM and LE control were clarified. Then, the key technologies including system modeling and analysis, damage modeling and estimation, and techniques on design and realization of the DM controller and LE control algorithms were analysed in details. The key technology problems and trend were also indicated.

Effects of recess on coaxial injector's discharge coefficient and performance

Abstract: An analytical model and methodology to characterize the behavior of an atomization and chemical reaction spray produced by a coaxial injector with recessed central tube were presented in this paper A type of coaxial injector element was calculated using this model Calculated results of injector discharge coefficients are in rather good agreement with firing data LOX mass percent vaporized in recession zone is less than 15% Nevertheless, coaxial injector with LOX post recession can significantly change gas-to-liquid injection velocity ratio and momentum ratio, which affects injector combustion performance Recessing LOX post results in extra recession pressure loss (06MPa when MR=1) and variations of injector discharge coefficients of oxidizer and fuel

Effect of primary rocket parameters on the performance of RBCC (rocket based combined cycle) in ejector mode

Abstract: Applying 3-D turbulent finite volume numerical algorithm validated, different operation status of Rocket Based Combined Cycle (RBCC) model with different structures and working conditions of primary rocket were simulated in ejector mode It was found that: 1, by increasing the chamber pressure of the primary rocket, the second air mass flow rate, the total thrust of the model and the mixing efficiency will increase 2, the shape of primary rocket nozzle can affect the ejector-mixing efficiency dramatically However, with the promise of providing enough primary mass flow, cone-shaped primary nozzle can be utilized in the rectangular main duct of RBCC model, which will not bring obvious reduction to the system performance 3, by increasing primary nozzle number, the mixing quality will improve 4, the expansion half-angle of primary nozzle can not change the second mass flow rate But can affect the mixing efficiency and thrust of primary rocket 5, the change of area expansion ratio of the primary nozzle will not effect second mass flow rate But it will change the mixing efficiency

Numerical study on chemical mechanism in supersonic H_2/Air mixture gas flow

Abstract: The flow of H 2/Air mixture ignited by a blund body shock was simulated numerically with an uncoupled non equilibrium method, based on N S equations and ENO scheme. The application of method was simple in structure and efficient for modifying to multi component and multi reaction chemical mechanism. The comparisons of superdetonative and transdetonative speeds were made with 7 species and 8 reactions chemical mechanism introduced by Evans and Schexnayder, 9 species and 19 reactions chemical mechanism and 13 species and 32 reactions chemical mechanism introduced by Jachimowski. The second chemical mechanism without reactions about N atom was suitable to simulate H 2/Air combustion which flight Mach number was below 7.

Detection of compressor stall based on wavelet analysis

Abstract: Stall in engine compressor will result in variation of pressure in its compressors, which is regarded as a singularity of signal. Considering the good performance of wavelet analysis in time and frequency domain, a method based on multi scale wavelet transform was proposed to detect the compressor stall, which is based on the fact the wavelet transform of a signal will take its modulus maximum at its singular point in transform domain. As a result, the engine stall is detected precisely through the method developed in this paper.

Combustion flow in ejecting mode of strutjet engine (I) Flow simulation in simultaneous mixing and combustion

Abstract: A configuration of strutjet engine in ejecting mode was investigated with numerical simulation. The flow structure and features of ejecting mode in static sea-level and zero to 1 Mach conditions were analyzed in detail. The performance results show that the strutjet engine gets thrust enhancement with Mach number greater or equal to 0.7. It is concluded that the StarJet engine of this configuration can be used as the propeller of air-launched missile and the thrust enhancement in lower range of Mach number including zero Mach needs to be optimized with multiple elements.

Starting and acceleration control law design for a missile turbojet engine

Abstract: In order to meet the request for a certain missile turbojet engine that it should start in a large airspace under windmilling condition, the localization of the control system's old control plan of the engine was analyzed and a new control plan was brought forward in this paper by dint of introducing a additional control input parameter According to the new control plan, a control law of the turbojet engine was investigated and designed Through the result of validate test on ground bed and simulated altitude and Mach number test, it showed that the demand of starting and acceleration in a large airspace under windmilling condition for the engine was satisfied So it can be said that the new control plan is feasible for the engine, and it was succeeded in designing a control law for the digit electronic control system of a certain turbojet engine at the first time

Aerodynamic stability analysis of inlet total pressure distortion for turbofan

Abstract: Adistortion generator with a moveable sliding board generated the distorted flow field. The inlet total pressure distortion tests were completed on a dual spool turbojet engine. A multiple distortion index " W " equal to the sum of circumferential uneven degree and the turbulence of total pressure was employed to measure the inlet flow distortion. The engine was tested at four rotor speeds, 80%, 85%, 90% and 95%. The maximum value of multiple distortion index and the sensibility coefficients of the total pressure distortion of the tested engine were determined.

Circular leading edge with a flat for compressor blades

Abstract: To improve the leading edge shape, weaken the suction spike and reduce or eliminate the separation bubble, the circular leading edge with a flat was investigated both numerically by using CFD and experimentally by using hydrogen bubble visualization technique in a water tunnel. Definition and criteria for flat design are also discussed. It is found that the double suction spikes on the flat edges are much weaker than the single spike that appears on a circular leading edge. At high incidence, the separation on downstream of the leading edge is weaker in the case with a flat, and the blade performance is improved by comparing it with the case of circular leading edge without a flat. The improvement is similar to or better than that with an elliptical leading edge, but the circular leading edge with a flat has an advantage of being more tolerant with manufacturing inaccuracy thus more acceptable for the practical application than that with elliptic leading edge.

Test system for FADEC of a aeroengine

Abstract: To study the performance characteristic of FADEC which is the most important components in the control system of a certain aeroengine, a test system reflecting the performance characteristic was established. In consequence the system outline, hardware , software and data acquisition and handling were discussed in detail. A control software can be concluded from the data based on the test system, which will be used in the FADEC system design. The simulation results show that the system has the advantages of being convenient and practical.

Performance monitoring and fault diagnosis of engines based genetic algorithm

Abstract: According to the problem on calculating the synthetic exponent characterizing the whole performance of engine by using the synthetic weighted method, the weights of every parameter are difficult to be determined. To solve this problem, a method of determining the weights of every parameter by genetic algorithm is presented. The synthetic exponent gained by GA is more sensitive and exact than the one gained by the expert investigated method in reflecting the whole performance of the engines. Meanwhile, this method improves the rate of identifying whether the performance of the engine is normal or not, finds the potential forepart fault of engine and prevents the spread of the fault. The validity of the method is testified by monitoring certain type of turbine-fan engine.

Investigation of helium resonance ignitor and kerosene/oxygen ignitor

Abstract: In order to reliably realize the multiple ignition of liquid rocket engine, the gas dynamic resonance ignitor, which creates the ignition resource of high temperature and high energy, was applied to ignite kerosene/oxygen. Two ignitors were developed. The helium resonance ignitor with light and simple structure was powerful and reliable. It can be concluded from experiments that the helium resonance ignitor has good resonance performance even when gas temperature or inlet pressure has large variance, which leads to more application of helium resonance ignitor. The kerosene/oxygen ignitor, which is utilized as an indirect ignition method, is able to multiple ignition and produce ignition torch successfully. Since the flux of kerosene and oxygen and the temperature of ignition torch can be varied in a wide range, the kerosene/oxygen ignitor satisfies various ignition requirements of liquid rocket engines. The present research shows that the helium resonance ignitor and the kerosene/oxygen ignitor characterized with advantages of simple structure, high reliability, and non-poison, etc., are prospective to be applied for multiple ignition of liquid rocket engine.

Combustion property of Nitramine/AP/HTPB propellant under high pressures

Abstract: The combustion property of Nitramine (NA)/AP/HTPB propellant containing aluminium (5%) is investigated under high pressures (15MPa～22MPa). The results show that ferrocene derivant (RMT) can effectively enhance burn rate of propellants and reduce its pressure exponent under high pressures; The propellant burn rates maintain constant with raising the content of RDX; But burn rates of HMX propellant decrease. The pressure exponent of NA/AP/HTPB propellant is reduced to 0.45 under high pressures by means of raising the content of RMT, the fine particle AP or using RMT/chromic acid salt composite catalysts.

Catalysis of nanocomposite CuO·Cr_2O_3 on thermal decomposition of RDX

Abstract: Nanocomposite oxide CuO·Cr 2O 3 with different mass ratio of Cu and Cr was synthesized by solid state reaction method at room temperature, and dispersing agent was added to disperse nanometer particle The particle size, crystal form, and phase were examined with XRD and TEM Average particle size were about 15 nm The catalytic performance of nanocomposite oxide CuO·Cr 2O 3 was determined by DSC The results show that the peak temperature of thermal decomposition of RDX decrease 11 1℃, under the effect of nanocomposite oxide CuO·Cr 2O 3, and the apparent activation energy of the thermal decomposition of RDX decrease 17kJ/mol The catalytic action of nanocomposite oxide CuO·Cr 2O 3 is better than that of nanometer Cr 2O 3 and its mixture

An experimental investigation of film cooling effectiveness on the surface of turbine blade

Abstract: Film cooling effectiveness of single film row at different locations on turbine blade surface was studied experimentally. A three-blade liner cascade in a large-scale low-speed opening wind tunnel was used in the experiment. There were 15 rows of film cooling holes at the surface of middle blade which was made of high quality wood and three rows on the suction surface, six rows on the leading edge and six rows on the pressure surface. Film cooling effectiveness on the blade surface was measured for the cases with mainstream Reynolds number from 250000 to 450000 and blowing ratio from 0.5 to 2.5. The influences of Reynolds number, blowing ratio and the location of film cooling holes on film cooling effectiveness were described.

Experimental investigation of microwave plasma thruster in vacuum

Abstract: Microwave Plasma Thruster (MPT) is a new type of electrothermal thruster. Its characteristics in clude light weight, long lifetime, high efficiency and high specific impulse. Both types of MPT 100W and 1kW incident power at frequency of 2.45GHz and vacuum experimental system are introduced. The characteristics of MPT under vacuum condition are emphatically described. Results of experiment demonstrate that they can reliably start up and steadily operate from 30W to 1kW incident power under vacuum condition. The specific impulse of helium (He) propellants is higher than that of Argon (Ar).