Showing papers in "Journal of Propulsion Technology in 2000"

Experimental study on mechanism of initial shock wave in jet flow

Abstract: An experimental study was presented to find out the formation mechanism of initial shock wave The generation and development of this phenomena was studied, and the results could be used as a reference for decrement of the harmf shock wave Laser Moire Deflectometry instrument was used in this experiment to display the formation of the initial shock wave field In the meantime, piezoresistance pressure transducers were used to measure the shock wave overpressure Through analysis of the experiment results gotten by these two methods, the physical essence of initial shock wave and its general development rules were deduced In near field, the overpressure is harmful to loading equipment

Acoustic emission experimental study on meso-damage mechanism of HTPB propellant

Abstract: By way of measuring the Acoustic Emission (AE) signal of HTPB composite solid propellant in condition of uniform speed,the mecro mechanism of meso damage and its propagation of HTPB composite solid propellant were studiedThe results of AE test show that AE cumul energy corresponds to two stages of generation and propagation of meso damage of HTPB composite solid propellantA physical model describing meso damage propagation of HTPB composite solid propellant was put forward and it has explained the mecro mechanism for the phenomenon varied from the strain speed after the destraction of the HTPB composite solid propellant

Simulated tests and data acquisition system for aerospike nozzle

Abstract: To find out the performance characteristic of aerospike nozzle, the simulated tests were a aerospike engine unit using solid propellant. The experimental system and data acquisition system for simulated tests of an aerospike nozzle unit including the software of the data acquisition were presented in detail. The method of data handling was also showed summarized.Typical experimental results, which can be used as a reliable basis for the design and development of advanced aerospike engines and also can be used to validate the theoretical and numerical computation, are also showed.

Research on accelerated reliability growth test (I)presentment of a new direction

Abstract: Accelerated Life Testing(ALT)and Reliability Growth Testing(RGT)were summaried Based on these analysis,Accelerated Reliability Growth Testing(ARGT)——a new direction of reliability engineering was presented And the main problems encountered in the study of ARGT were proposed The approaches for these problems were given

Thermal decomposition characteristics of aluminum-magnesium fuel-rich propellant

Abstract: By means of various thermal analytic methods,such as DSC, DTA, TG and DTG, the thermal decomposition characteristics of the aluminum magnesium fuel rich propellant and its main ingredients were investigated The thermal decomposition characteristics of AP/KP mixture are determined by the thermal characteristics of two oxidazers However, the thermal decomposition reaction of KP in the mixture can be catalyzed by AP decomposition The thermal decomposition process of the aluminum magnesium fuel rich propellant is a combination of the thermal decomposition reactions of AP, KP and the HTPB binders

Propagating process of cracks on polysulfide propellant during combustion

Abstract: Investigated the various factors which affect the propagating process of the crack in polysulfide propellant sample Combustion experiments were conducted for samples with cracks and the combustion process is measured by the X ray real time radiography system (RTR) The states of stress and strain of the various parts in the sample with cracks were analysed and computed by the viscoelastic finite element method (FEM) The possibility of the crack propagation was predicted by the J integral fracture criterion Theoretical analysis and experimental result show that the chamber pressurization rate,the crack dimensions and the boundary condition have stronger effects on the propagation of the crack These results will have certain value the criterion determination of propellant failure

Estimation of formation enthalpy of thermoplastic polyurethane binder for novel thermoplastic propellant

Abstract: In order to calculate the specific impulse of novel propellant with thermoplastic polyurethane (TPU) synthesized as binder, method and data developed by Van Krevelen and Chermin together with the theory of cohesive energy of polymers, were applied to estimate the formation enthalpy of TPU Relationship between formation enthalpy and content of hard segment of TPU was quantitatively obtained Results of formation enthalpy of TPU were then adopted to calculate the energetic performances of TPU/aluminum/ammonium perchloride propellant system Results show that specific impulse reaches the maximum value as 2 59 kN·s/kg when the system consists of 14% TPU, 62% AP , 24% Al

Experimental investigation of heat transfer coefficients on the inclined multihole film cooling wall

Abstract: Using the method of constant heat flux, the convective heat transfer coefficients were investigated experimentally in the inclined multihole film cooling The main factors influencing the convective heat transfer include the blowing ratio,row to row spacing,hole to hole spacing and arrangement for inclined multihole The ranges of these parameters were:main fluid Reynolds number about 17 000 and blowing rates from 1 to 4 Measuremerts were done for 4 variant test plates The results indicated that the convective heat transfer coefficient increases greatly with film cooling and with the increasing of blowing rates for the same plate; the hole to hole spacing is more important than the row to row spacing for film cooling at the same condition

Research state of electric propulsion and its development prospect

Abstract: The basic theory and technical state of all kinds of electric rocket engine were discussed According to its operation features and application examples, the application situation of all its kinds were analyzed It is forecasted that the electric propulsion has great prospect in aerospace applications

Propulsion system stability control for super-maneuvering flight

Abstract: A study of propulsion system stability control for super maneuvering flight was carried out.In order to enhance engine stability at post stall,a scheme of stability control through adding fan pressure ratio control loop was proposed,and a algorithm for pressure ratio command was given.Based on aircraft model and nonlinear engine model,simulation was done and the results verified the validity of stability control concept.

Nonlinear analysis for high frequency combustion instability in rocket engine

Abstract: A nonlinear physical model to probe into driving mechanism of combustion instability in rocket engine was presented.The nonlinear relation between combustion and acoustic process was studied. The mathematics model was deduced from the basic control equations for reaction fluid dynamics.“Averaging Method”was used to analyze the mathematical equations. Bifurcation and chaos were found in this nonlinear system.The effects of physical parameters on the combustion instability with this physical model was discussed.

Characteristic of a new damped flexible support in turbopump rotor for engine

Abstract: In order to determine the support characteristic for rotor dynamic of LOX/LH 2 turopump in high pressure staged combustion rocket engine,an investigation was carried out for the characteristic of new damped flexible support with the radial force of less than 10 kN and bearing preloaded force of 980 N～2 205 N By means of experiments and computation,the effects of some factors on the characteristic for the support system were emphasized and those factors include:deformation,stress distribution,limited element model of turn back squirrel cage flexible support;damping characteristic of metal rubber damper;dual rolling bearings and their preloaded force.

Two types of bowed blades in turbine stage

Abstract: In order to control second flow in cascade, three-dimensional design technique of the blade bowed circumferencially and the blade bowed in its chord-normal direction was successfully applied to the modern turbomachinery design Depending on numerical simulation and experiment,different physical principium between the blade bowed circumferencially and the blade bowed in its chord-normal direction was analyzed.The design rule for two types of bowed blades in turbine stage was summavized It points out that two types of bowed blades can control second flow, but their physical principiums are different

Optimal statistical clustering for high dimensional fault sample using evolution strategies

Abstract: A clustering algorithm based on Evolution Strategies was proposed to make analysis on high dimensional data of liquid rocket engine propulsion system In order to prevent the solution population from premature convergence, the dynamic fitness adaptation technique and all sharing function were introduced An adaptive regulation scheme for evolution control parameters was specially presented for clustering analysis of high dimensional data A local clustering deadlock can also be overcome by the deadlock check and cluster recombination collapse strategies This algorithm was used in the optimal clustering analysis for the 560 data samples of 14 sorts of common faults, each of 68 dimensions, which were simulated for a liquid rocket engine In addition, comparison with fuzzy Kohonen clustering networks (FKCN) has also been made,based on IRIS data The simulation results show that the evolution strategies based on clustering algorithm is superior to other non evolutionary clustering algorithms, particularly when the data is of high dimensions

Experimental research of casing treatment on single stage transonic fan

Abstract: Three types of different casing treatment were designed for new developed single stage transonic fan. They are arc curved skewed slot casing treatment, axial skewed slot casing treatment and counter vortex slot casing treatment. By using real time data gathering and test system of the aero engine test bed, the detail measurement of single stage transonic fan performance with and without different casing treatments were made. Research results show that a further improvement is obtained with arc skewed slot than other casing treatments in stall margin and peak efficiency.

Computation of two-phase flow with droplet vaporization in ramjet

Abstract: For computation of the flow field established in the chamber of solid liquid rocket ramjet,the block implicit algorithm was used to solve the Navier Stokes equations for gasThe separated flow model and continuum formulation model were used to characterize the flow and vaporization of dropletsFor droplet flow,a special approach was tried to represent the law of mass conservation and the size changing of the dropletsIt was demonstrated that the solution was rapidly convergent and the numerical results were qualitatively correct

Mixed H_2/H_∞ output feedback control of aeroengine based on LMI

Abstract: According to the shortage of H ∞ controllers in time-domain performance, mixed H 2/H ∞ control problem was investigated For a species of systems with structured perturbations, the sufficient and necessary condition that there were mixed H 2/H ∞ controllers and the method to design a controller were presented The simulation results for a certain double spool turbojet aero-engine reveals that the robust control with no static error for both rotational velocity of low-pressure rotor and temperature at low-pressure turbine outlet in the same time can be realized And the dynamic performance character of closed loop system is also improved evidently

Experimental investigation on gas dynamic performance of caret inlet under takeoff condition

Abstract: An experimental investigation was carried out for caret inlet′s gas dynamic performance as well as the effect of inlet cowl lip thickness on the performance under takeoff condition The flow characteristics of the inlet and their influence on inlet exit distortion of total pressure were analyzed by means of static pressure distribution along each side of the inlet wall and total pressure contour plots of inlet exit It is shown that there are two counter rotating vortices at inside corner(weaker) and outside corner(stronger) separately on the bottom cowl lip.As a result , the high and low total pressure domains were rotated more than 90 deg from inlet face to exit face of caret inlet It is also shown that the thickness of caret inlet outside and bottom side cowl lips has great influence on its total pressure recovery and total pressure distortion The experimental results may be used in practical design of the caret inlet

Effect of mixing tube area and position on performances for lobed ejector

Abstract: Experimental research for four mixing tubes with different sectional area and different axial distance for a axisymmetric lobed nozzle was conducted to investigate the effect of area ratio A m/ A p and axial distance L mp between lobed nozzle and mixing tube on the aerodynamic performances for a lobed exhaust system. The results show that the pumping coefficient increase and synthetic aerodynamic performance of the system can be improved with the increase of A m/ A p.The pumping coefficient and pressure loss coefficient of the system also increase with L mp increase.The slope of pressure loss coefficient with L mp change is different in different range, and the synthetic aerodynamic performance be worse with L mp increase.

Effect of nano metal powder on thermal decomposition characteristics of glycidyl azide polymer

Abstract: The effects of nano metal powders(Cu,Ni),super fine metal powders(Al,Ni) and normal metal powders(Cu,Al) on the thermal decomposition characteristics of glycidyl azide polymer (GAP)was investigated.DSC results shown that there are two exothermal peaks on DSC curve of GAP/metal powder, in which the peak at higher temperature resulted from metal reacting with oxygen is influenced by atmosphere, while the one at lower temperature resulted from GAP decomposition has no relation with atmosphere The effects of copper powder on GAP is the greatest in different metal powders The thermal decomposition peak temperature of GAP decreases 33 2 ℃ in the presence of nano copper powder, and decreases 12 9 ℃ in the presence of normal copper powder However,for other metal powders, their influences on thermal decomposition characteristics of GAP are rather small In GAP/ nano copper samples, the influence of nano copper on thermal decomposition characteristics becomes weak with the decrease of the nano copper, while there is no linear relation between nano copper and its influence degree on GAP TG results show that metal powders do not change the stage of GAP decomposition,while it influence the GAP mass loss temperature Lastly,the mechanism for the effects of namo copper on thermal decomposition characteristics of GAP is analyzed

Effect of ethanolamine derivative aids on rheological properties of HTPB propellant slurry

Abstract: The effects of TEA(triethanolamine),BF 3 and TEA·BF 3 complex on rheological properties of Al/HTPB, AP/HTPB, AP/Al/HTPB composites slurry were studied by rotational viscometer.The results show that shear rate exponent n decreases due to the hydrogen bonding effect and TEA-Al reaction in presence of BF 3, and the coefficient K of shear viscosity increases with HTPB-BF 3 interaction,so that the apparent viscosity increase sharply under low shear stress and the flowability and leveling of HTPB propelland slurry is poor.

Effect of temperature and rotational speed on radial clearance of turbine blade tip

Abstract: The calculation method for radial clearance of turbine blade tip considering the effect of temperature and rotational speed is developed in this paper. The transient change of turbine blade tip clearance during the whole flight is computed by means of ANSYS finite element program. To calculate radial displacement the influence of temperature and rotational speed on the turbine and the effect of temperature on the case are considered. The methodology presented in this paper can lay some foundations for further study to control radial clearance of turbine blade tip.

Fibre-optic image viewing system applied to combustion test

Abstract: The principle,main components and function of the fibre-optic image viewing system were described. The internal flame of combustor in different operating conditions can be observed using this system. The flame image was recorded and analyzed systematically.Some measures for improvement for test process were suggested. The viewing system can be an aid in the future design of more durable combustors.