1991 Vol. 6, No. 2

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HYDROQUENCH OF ALUMINIZED COMPOSITE SOLID PROPELLANTS
Yin Jinqi, Wu Xinping, Li Zhaozhong, Wang Youhong, Wang Ang
1991, 6(2): 97-100,185.
Abstract PDF(225KB) icon1556 icon504
Abstract:
The extinction process of three kinds of aluminized composite propellants by liquid injection has been experimentally investigated,according to the liquid quench model of solid propellant proposed by the authors.The experimental results indicate that(1)The liquid quantity requirment(LQR in g/cm 2)for reliable extinction varies significantly with the energy of propellant in the relationship of LQR ∝ 0 1Q f(Q f〔kJ/g〕the heat relased by the propellan at constant volume);(2)The extinction speed increases and LQR decreases with increasing liquid injection pressure drop;(3)LQR increases with increasing combustion chamber pressure for propellants having positive pressure exponents.In addition to LQR,there exists a non-dimensional parameter which summarizes the effects of energy and burning rate characteritics of propellants,liquid injection pressure drop,liquid properties and combustion chamber pressure on the liquid uqench process.If the parameter is less than a critical value,the extinction of propellant by liquid injection is not obtainable.The examination by means of the scanning electron microscopy demonstrates that the appearance of the burning surface quenched by liquid are different from those by extinguished by rapid depressurization.The surface profile is porous and a lot of oxidizer particles are dissolved during liquid quenching.This fact exerts an influence on the reignition of the quenched burning surface for stop/restart solid rocket motors.
CALCULATION OF TEMPERATURE COEFFICIENTS FOR THERMODYAMIC FUNCTION
Tian Deyu, Weng Wujun, Liu Zhengyuan
1991, 6(2): 101-104,185.
Abstract PDF(226KB) icon2177 icon601
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Temperature coefficients for themodynamic function are determined by means of a simultaneous least-squares fitting of heat-capacity,enthalpy、entropy,which are described as polynomical equations in temperature.After some mathematical treatments and programming,exact numerical solutions can be obtained.Even some of solution errors are less than those given in reference[1]、[2].The first and systematical calculation of the temperature coefficients for combustion products of the copper element has been completed.The function ensures the equal values at the cross point of the two temperature intervals(such as 100K).In fact,this method provides the reliable data of the temperature coefficients for the calculation of the propellant performance.
RESEARCH ON IGNITION CHARACTERISTICS OF HIGH-ENERGY IGNITERS
Li Lu
1991, 6(2): 105-109,186.
Abstract PDF(264KB) icon1773 icon484
Abstract:
The experimental research on the ignition characteristics of aluminum-potassium perchlorate ignition charge were carried out with CO 2 laser as heat source.The effects of the weight percentage of aluminum in the ignition charge,the radiation intensity,the additive of sulphur powder and the initial temperature of the test sample on ignition delay were investigated experimentally.The expperimental results show that under the conditions of a fixed radiant heat flux,the ignition delay is the shortest,as the weight ratio of alumiinum to potassium perchlorate approaches 50%.The ignition delay decreases sharply by adding 2%(weight)of sulphur into the ignition charge.The ignition delay decreases as the radiant heat flux and the initial temperature increase.There seems to exist a minimum of the radiant heat flux in the case of a fixed weight percentage of aluminum and a given initial temperature.It is impossible to ignite the sample successfully if the heat flux is inferior the minimum.The external energy for ignition is the smallest at the optimal heat flux.An ignition model for aluminum-potassium perchlorate ignition charge is established on the basis of experimental observiations and theoretical analyses.The heterogeneous reaction is regarded as the most important process in the model.The governing equations of the model can be solved numerically.The analytical results correspond to the experimental data satisfactorily.
IMPLICIT SCHEME IN ONE-DIMENSIONAL TIME-DEPENDENT TWO-PHASE TRANSONIC FLOW FIELD COMPUTATION
Pei Ming, Zhang Zhongqin, Zhang Zhenpeng
1991, 6(2): 110-114,186.
Abstract PDF(254KB) icon1348 icon489
Abstract:
A computational model with an implicit numerical integration scheme is successfully applied to computation of the one-dimensional time-dependent two-phase transonic flow field in nozzleless solid propelland rocket motors.In addition,this achievement provides the basis of integrative performance calculation for all kinds of solid rocket motors.We introduce a concept of equivalent ignition channel,which simplified the treatment of headstream boundary conditions.When deducing the expressions of the elements in the coefficient matrix,we get derivatives before we replace the differential with finite difference.This approach not only makes the expressions succinct,but also saves the time of computation.In the inverse operation of the matrix in two-phase flow computation,the characteristics of the matrix are taken into account,and therefore the computation time is further shortened.Two numerical examples are given.Comparison of the calculations with the motor tests shows a good agreement between the calculated and the measured values.
CORRELATION BETWEEN CONDENSED PHASE REACTION AND BURNING RATE OF AP/HTPB PROPELLANT
Zhang Wei and, Zhang Ren
1991, 6(2): 115-117,190.
Abstract PDF(174KB) icon1520 icon544
Abstract:
The effects of transition metal oxides TMO on the thermal decomposition characteristics of AP and AP/HTPB propellants and on the burning rates of AP/HTPB and AP/Al/HTPB propellants are studied.The results show that the burning rate of AP/Al/HTPB/TMO propellant depends on the thermo-decomposition characteristics of AP/TMO and burning rate of AP/HTPB/TMO propellant depends on the thermo-decomposition characteristics of itself.The results also indicate that the aluminum decreases the burning rate of the propellant.It is suggested that the aluminum reduce the rate of condensed phase reactions and the stress effect of AP thermal decomposition properties on the burning rate of aluminized propellant.
A NEW DISTORTION SCREEN AND ITS APPLICATION
Ma Jiaju
1991, 6(2): 118-120,190-191.
Abstract PDF(222KB) icon1921 icon479
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A new distortion screen,“simulation poles”,is proposed for simulation of steady state pressure distortion patterns.It is composed of a number of round poles with same diameter,the depth inserted into flow field may be adjusted steplessly during the test.The author applied it to scale simulator of an axisymmetrical random frequency turbulence generator,in result the examinatorial pattern was successfully simulated.Practice of its applicalion proves that the simulation poles are simpler,less consumptive in energy and man-hour and more accurate in simulation than the traditional distortion screen.
DEVELOPMENT OF ENGINE FAULT EQUATIONS
Fan Zuomin, Sun Chunlin, Lin Zhaofu, Gao Haichuan
1991, 6(2): 121-125,187.
Abstract PDF(253KB) icon1405 icon475
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The engine diagnosis problem lies in solution of the engine fault equations which express the relationships between the measurements and a large set of possible but improbable mulfunctions.The engine fault equations are generally underdetermined and can be solved by the aid of Main Characteristic Parameter Model(MCPM)suggested by the authors.The engine fault equations are based on engine fault samples and can be called empirical fault equations.The empirical fault equations are similar to fault equations obtained by single factor experiments,but the engine fault samples are used instead of the results of special experiments.Differing from the small change equation,the empirical fault equations are easily obtained and are of great use for diagnosis of such faults which are difficult to be diagnosed by employing small change equations.Some practical examples of engine fault diagnosis are also given.The fault diagnosis results obtained from are very satisfactory.
FUZZY CLUSTERING ANALYSIS OF GAS TURBINE ENGINE MISSION PROFILES
Cheng Dejing
1991, 6(2): 126-128,191.
Abstract PDF(181KB) icon1728 icon465
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In order obtain engine mission profiles from a vast amount of flight test,the fuzzy matrix of the membership function of engine mission profile samples is established according to the theory of fuzzy sets and boolean algebra behaviours.The fuzzy matrix is examined by using sqaure method for meeting the equivalent conditions.When it meets equivalent conditions,the dynamic clustering is carried out by selecting various threshold values.The clustering analysis of the mission profiles for an actual engine has been completed by the complicated and enormous fuzzy caleulation based on statistical data of the engine loads measured in fiight test.The clustering method of three parameters(flight altitude,Mach number and angle of throttle lever)is first employed in the clustering analysis and the results abtained are satisfactory.
AN ACOUSTIC METHOD FOR MEASURING CHARACTERISTICS OF ROTATING STALL IN A COMPRESSOR
Sun Xiaofeng, Hu Xongan, Feng Yucheng, Zhou Sheng
1991, 6(2): 129-130,191.
Abstract PDF(146KB) icon1535 icon538
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According to analysis of the characteristics of frequency and propagation of the sound generated by the rotating stall,an acoustic measuring method is developed,in which the characteristic parameters,such as the number and propagation speed of stall cells,are measured.Compared with existing methods,this method is a untouched measurement so as to avoid not disturb ance of the flow field.The primary experimental results obtained on a transonic axial-flow compressor facility demostrate the feasibility of this method.
EXPERIMENTAL INVESTIGATION ON JET NOISE
Zheng Keyang and, Gui Xingmin
1991, 6(2): 131-133,191.
Abstract PDF(182KB) icon1719 icon550
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The correlation of sound power with jet velocity is studied in this paper.It is indicated that Both Lighthill's and Lilley's formulas fit experimental data very well when Mach number of jet Maj>0 4,but the diviation between the results obtained from the formulas and experimental data is not so negligible as Maj<0 4.The authors propose substituting sixth power of the jet velocity instead its eighth power in the formulas.The direction sensitiveness and the frequency spectrum of jet noise have been investigated enperimentally.
TECHNIQUE FOR DIGITAL PROCESSING OF COHERENT IMAGES OF PARTICLES
Fang Jinyan, Yan Chuanjun and, Wang Hongji
1991, 6(2): 134-136,191-192.
Abstract PDF(215KB) icon1373 icon577
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An approach,known as Edge Tracking Method,has been developed in particular,which searches out the outer edge and the central spot edge of the coherent image of a particle.The processing procedure of the digital images and its program have been worked out in detail.Finally,the outer size and the central size a particle image are determined by means of the presented technique,then the particle size and its position are calculated by means of the Three-Dimensional Judgement Technique.The results obtained are reasonable.
A DISTRIBUTED FIVE-HOLE PROBE RAKE ON STATOR BLADES FOR ROTOR EXIT MEASUREMENT OFA COMPRESSOR
Lin Qixun, Shi Chunying, Pan Gengsen
1991, 6(2): 137-138,192.
Abstract PDF(144KB) icon1655 icon610
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Each tube of five-holes probe will be placed at the same radius on five different blades of stator.The diameter of the probe and the wall proximity effect are decreased.The distributed five-hole probe rake has been verified experimentally.Its dynamical frequency response is enhanced seven times.Its characteristics are improved.The parameter measurement of each rotor exit in a multistage compressor becomes practicable.
FINITE ANALYTIC SOLUTION OF TURBULENT FLOW FIELD THROUGH CASCADE OF AIRFOIL
Xu Diao and, Wu Guochuan
1991, 6(2): 139-143,187.
Abstract PDF(895KB) icon1412 icon595
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The finite analytic method is used in the present study to calculate the turbulent flow field described with Navier-Stokes equations in body-fitted curvilinear coordinate system.The finite analytic method invokes the analytic solution of governing partial differential equations in formulating the algebraic equations that relates a nodal value in an element to its neighbouring nodal values.The major feature of the finite analytic method is its ability to simulate automatically the upwind influence of neighbouring nodal values according to direction and magnitude of convection.It is shown that the finite analytic method has good numerical stability and accuracy.The turbulent flow fields through a two-dimensional channel and a cascade of airfoil are numerically simulated by using finite analytic method in the present study.The k-ε turbulence model and wall function method are also employed.The agreement of numerical solution with experimental data is quite good.
FLOWFIELD MATRIX SOLUTION ON S1 STREAMSURFACE IN A CENTRIFUGAL COMPRESSOR
Hua Yaonan
1991, 6(2): 144-148,187-188.
Abstract PDF(313KB) icon1783 icon636
Abstract:
The existing flowfield matrix solution method on S 1 stream surface for the calculation of flowfield in an axial compressor is extended to calculation of flowfield in a centrifugal compressor.The stream function governing equation of fluid flow has been established with respect to non-orthogonal curvilinear coordinates.By the aid of artificial compressibility method,the discretzation of the partial differential equation is accomplished with the standard central difference formula.The set of linear algebraic equations obtained is solved by means of the direct matrix method.The velocities at grid nodes are first determined by integrating the momentum equation and then the densities are obtained from the energy equation.Nine numerical examples of three types of the centrifugal compressors show that the solution obtained by the present method is in good agreement with experimental data,provided that there is no large flow separation in compressors.
EFFECTS OF ASPECT RATIO ON CASCADE PERFORMANCES
Li Ly and, Yan Ruqun
1991, 6(2): 149-150,192.
Abstract PDF(147KB) icon1750 icon517
Abstract:
An experimental research of compressor cascade performances has been completed in the conditions of varing aspect ratios(AR).The results show that AR has a significant influence on cascade losses,pressure ratios and blade loads.Furthermore,the correlations of cascade performance parameters with AR,cascade geometric and aerodynamic parameters are derived.The comparative analysis between the calculated results and the experimental data show that the correlation reveals the rules of variation of cascade performance parameters with the aspect ratio.
PREDICTION OF LONG BLADE FLUTTER IN A STEAM TURBINE
Tao Deping, Yang Xiaodong, Zhou Shen
1991, 6(2): 151-156,188.
Abstract PDF(299KB) icon1907 icon487
Abstract:
The flow characteristics of the last stage of the steam turbine are analysed on the basis of the results obtained from the cascade experiments and flow field calculation.In the case of low volumetric flow rate,the large scale separation occurs in the last stage rotor hub,and the height of separated flow region increases as the volumetric flow rate decreases.Flow separation appears at the blade pressure surface as the bulk flow enters the rotor with large negative incidence.The flow in the rotor can be divided into three regionsa separated hub flow region,an attached-flow region and a separated-flow region.The dimensions of the three regions vary with the flow rate.The flow pattern in the last stage is very complicated.Aseries of deforming actuator disk methods and a numerical method have been developed to predict the blade flutter.The deforming actuator disk method system is applicable to calcalating 2-D and 3-D unsteady flow fields and also to calculating the bending mode and the torsional mode blade flutters.The analytical and numerical deforming actuator disk methods for predicting the blade flutter in a compressor or a steam turbine have been developed in consideration of variability of or invariabiity of the interblade phase angle.The small-disterbance potential amplitude equation is adopted in the numeried method for unsteady flow in the cascade,while the airfoil thickness and bending degree are arbitrary and the rotating finite difference scheme is employed in the calculaton of transonic flow field.The comparison between the computational and the experimental results shows that the presented methods are feasible in prediction of the flutter in blade design.
NUMERICAL SIMULATION OF TRANSITIONAL FLOWS OVER A FLAT PLATE
Jiang Hongde, J.G.Moore and, J.Moore
1991, 6(2): 157-161,188-189.
Abstract PDF(297KB) icon1668 icon475
Abstract:
A new version of one-equation turbulence model for predicting the incompressible,transitional flow over a flat plate is developed.Based on an analysis of the existing one-equation models and some physical features of the transitional flow,both the eddy viscosity and turbulence length scale in the turbulence kinetic energy equation are modified in order to bring the low Reynolds number effect into the new model.The capability of this model for predicting the transitional flow is demonstrated by an extensive numerical testing for flat plate flow under free stream turbulence intensity ranging from 0 03 to 8 percent.Both the start and length of the transition are correctly predicted.Comparison of the calcutated results of both the mean and fluctuating flow properties with experimental data indicates the agreement between them is very good.
NUMERICAL SIMULATION OF 3-D VISCOUS FLOW IN NON-AXISYMMETRIC NOZZLE
Ji Yongchun, Ma Tieyou and, Cui Jiya
1991, 6(2): 162-166,192.
Abstract PDF(254KB) icon1442 icon576
Abstract:
The three-dimensional viscous flow in non-axisymmetric nozzle are simulated numerically.MacCormack finite difference scheme is extended to solving three-dimensional Navier-Stokes equations.Local time step technique is adopted in numerical iteration for rapid convergence.The computer memory and CPU time are saved by proper programming.Two examples of simulation are presented.Favorable agreement is shown between computed and measured surface static pressure distributions.
EFFECT OF ABRUPT INLET DISTORTION ON ENGINE STABILITY
Wang Xiaofeng, Wang Naixing
1991, 6(2): 167-169,192.
Abstract PDF(185KB) icon1514 icon485
Abstract:
The unsteady response of a compressor to abrupt change of inlet temperature has been calculated by numerical integration with the“actuator-volume”and the second order delay models.The calculated results are compared with flight test data favourably.The unsteady response of the compressor to abrupt change of inlet pressure(or combined with inlet temperature)has also been calculated in the same manner.The calculated results show that the effects of the abrupt inlet pressure on compressor stability cannot be ignored.
EFFECT OF HEAT-TRANSFER LAW ON FINITE-TIME EXERGOECONOMIC OPTIMAL PERFORMANCE OF A CARNOT ENGINE
Chen Lingen, Sun Fengrui, Chen Wenzhen
1991, 6(2): 170-174,189.
Abstract PDF(243KB) icon1450 icon497
Abstract:
The relationship between optimal efficiency and profit of an endoreversible carnot engine is derived.According to this relationship the finite-time exergoeconomic optimal peroformance of the engine has been considered for three common heat-transfer laws.A number of new universal conclusions have been drawn therefrom.
EXPERIMENTAL INVESTIGATION ON LIQUID-COOLING MECHANISM FOR TURBINE VANE
Liu Dezhang and, Ouyang Ning
1991, 6(2): 175-179,189.
Abstract PDF(919KB) icon1474 icon499
Abstract:
The experimental investigation on liguid cooling mechanism was carried out with water through an even-heated adiabatic straight pipe.The flow pattern,the heat transfer coefficient along full-flow-path,and the correlation between them,have been studied.In order to imitate the actual working conditions of the cooling passage of turbine vane,the heat transfer flux,the coolant inlet parameters,and the pipe angle are changeable.Some empirical formulas for come-to-saturated point Z B and come-annular point Z N have been derived and several useful conclusions have been drawn for engineering application.
DEVELOPMENT OF AN EFFICIENT OIL FILM DAMPER FOR IMPROVING THE CONTROL OF ROTOR VIBRATION
Zhang Shiping and, Yan Litang
1991, 6(2): 180-184,190.
Abstract PDF(259KB) icon1637 icon556
Abstract:
An efficient oil film damper,known as Porous Squrrze Film Damper(PSFD)is developed from the normal squeeze film damper(SFD)for effective and reliable rotor vibration control.The outer race of the PSFD is made of permeable sintered porous metal materials.The permeability of PSFD under squeeze effect makes it possible for the oil to permeate through the porous outer race,so that the characteristics of squeeze film forces are improved,in particular,as the amplitude of eccentricity is rather great.The nonlinearity of squeeze film forces could be reduced due to PSFD permeability,and the relations between oil film stiffness coefficient and damping coefficient of squeeze film forces could be improved.Investigation demonstrates that:The cavitated SFD high nonlinear oil film stiffness forces,which lead to many undesirable nonlinear vibration characteristics,lessen due to the permeability of PSFD,and the damping forces are relatively enhanced by PSFD.The nonlinear vibration characteristics of SFD system such as bistable jump phenomenon are greatly improved and even eliminated at higher unbalance level with the PSFD system.The PSFD can operate effectively under greater unbalance loads as compared with the SFD system.

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