1989 Vol. 4, No. 3

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AN OPTIMUM DESIGN OF CROSS-SECTIONAL SHAPE OF BEVEL GEAR
Guo Xinyhui, Han Erzhong, Yan Shiying
1989, 4(3): 201-204,289.
Abstract PDF(530KB) icon1379 icon12
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The optimum design of a high speed bevel gear has been accomplished. Atfirst, the sensitivity matrix of natural frequencies of the bevel gear is obtained in relation to desge variables. And then the optimum peruturbation on aeration procedure is applied to the dynamie optim design of a high speed bevel gear. Some resulls satisfying frequencies cunstrsunts are ootaned. The result with smallest weight is selected. And me effect of proess accuraey on natural freqaencies the bevel gear are discussed. The results of the experiments on the bevel gear manufactured sa the the optimum oesign. s a success.
FRETTING FATIGUE——Stress distribution and prediction of crack location in dovetail joints
He Mingiian
1989, 4(3): 205-208,289.
Abstract PDF(544KB) icon1495 icon14
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In reference o the research results of Oxford University in U. K. author designed a more simple dovetail joints specimen to model a blade to disc joint in a typical gas turbine and improved the analysis method. The epecimen has been analysed and tested. The remlts are cetter than the previous ones of Oxford Lniversity.Correctness and effectual ness of the analysis method are verified by tests. The method enables to determine the stress and temperature fields in the contact surface and the nearby area, to estimace the state in interface (stick, slip, or separation), and to know how much energy comsumed for friction r. the contact surface. Therefore, it is, possible to predict distribution of fretting damage arong the nter face and the location of crack which will spread.
RELIABILITY TESTING TECHNIQUE OF BLADING FATIGUE WITH CONFIDENCE LEVEL
Zhuang Zhongliang, Gao Deping, Lu Qixin
1989, 4(3): 209-212,289.
Abstract PDF(467KB) icon1580 icon15
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During reliability testing of binding fatigue, it is necessary to consider neronly its reliability, bul also its confidence, characteristics of specimens. simulation technique ana so on simultaneously. In this view, a reliability testing technique with confidence level is presented which can estimate blading fatigue life more reasonably. This technique also can be applied to predicting fa-tigue life of other mechanical parts.
STATISTICAL FA RE PREDICTION MODELS FOR ST UCTURAL CERAMICS
Yang Xiaoguang, Xiong Changbing
1989, 4(3): 213-217,290.
Abstract PDF(630KB) icon1499 icon17
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The Weibull/PIA(Principle of Indepent Action) and Batdorf models are ap-plled to statistical analysis of fracture strength of structural ceramic components with crack in body under multiaxial stresses. As an example, the probability of failure distributions for H. P. Silicion Nitride disk fracture strength under high speed rotation has been estimated numerically with a finite element method on the basis of the model parameters obtained r'rom 3-point bending experiments of H. P. Silicion Nitride, and compared with experimental data available from literature. The results indicate the considerable superiority of the Batdorf model over the Weibull/PIA model in accuracy and confirm the non-conservative nature of the latter.
A MULTI-OBJECTIVE OPTIMUM DESIGN METHOD FOR A RADIAL-AXIAL FLOW TURBINE WITH THE OPTIMUM CRITERIA OF BLADE TWIST AT OUTLET OF BLADES
Chen Lingen
1989, 4(3): 218-222,290.
Abstract PDF(688KB) icon1393 icon14
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This paper provides a multi-objective optimum design method for a radial-axial flow turbine stage. The method takes the parameters in mean radius,α1、β2、μ、and m=u2/w2cosβ22, and the criteria of blade twist at the outlet of the blades as design variables, and selects the internal efficiency in the design conditions and the total weight of the turbine stage as objective functions. The model presented is a nonlinear multi-objective programming problem of two objective functions with 29 constrained functions and 6 variables. The mathematical model for optimization and some analytical results of single- and multi-objective optimization for a variety of twisted blades are also presented in this paper. The numerical results demonstrate the validity and effectiveness of the method.
COMPUTATION OF THE DETACHED SHOCK SHAPE IN A SUPERSONIC OR TRANSONIC CASCADE
Hua Yaonan
1989, 4(3): 223-227,290.
Abstract PDF(525KB) icon1498 icon10
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A method is presented for determining the shape of the detached shock andthe fiowfield in the supersonic entrance region on an arbitrary stream surface of revolution. The e-quation of characteristics and the corresponding equation of compatibility are derived. The shape of the detached shock obtained is taken as the initial- value curve to calculate the fiowfield in the supersonic entrance region by means of the method of characteristics. As an application of the present method, three stream surface of revolution in a transonic compressor roto have been calculated. The results show that the method is effective and useful to determine rapidly the shape of the detached shock wave as well as the fiowfield parameters in the supersonic entrance region. including the unique incidence angle in a supersonic or transonic compressor blade row.
SOLUTION FOR TWO DIMENSIONAL INVISCID TRANSONIC CASCADE FLOWS WITH MULTIPLE-GRID ALGORITHM
Sheng Chunhua, Wang Licheng
1989, 4(3): 228-232,291.
Abstract PDF(1255KB) icon1777 icon10
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This paper gives an efficient form of multiple-grid scheme and presents a"prediction-correction " method for processing the boundary conditions on a solid wall. The conver-gency and the stability of the scheme can be further improved by using local time stepping and residual smoothing. Finally, two-dimensional inviscid transonic cascade flows are calculated. The comparisonbetween the calculated and the measured results shows that this scheme possesses very fast convergence speed and satisfactory accuracy.
APPLICATION OF UPWIND FACTOR METHOD TO TRANSONIC CASCADE CALCULATION
Wang Lichteng, Zhang Huimin, Lu Xiaoling
1989, 4(3): 233-236,291.
Abstract PDF(368KB) icon1639 icon12
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In this paper the upwind factor method is extended to treating the two-dimensional transonic flows. The Navier Stokes equations with k-e turbulence model are discretized in a non orthogonal body-fitted coordinate system, and the upwind factor method is employed to ensure the numerical stability of the scheme. The maximum local time step is determined by the criterion that the cofficients in discretized equations must be non-negative.The numerical experiments are carried out for DFVLR transonic cascade for inlet Mach number of 0. 82 and 1. 05. and numerical results are compared with the experimental data in good agreement. Also, the numerical results are compared with the results calculated with a four stage Range Kutta time stepping scheme of an Euler code.
A NEW HYBRID SCHEME OF FLUX VECTOR SPLITTING HARTEN'S TVD AND ITS APPLICATION
Wang Baoguo, Chen Naixing
1989, 4(3): 237-240,291.
Abstract PDF(445KB) icon1577 icon15
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A new high-resolution hybrid implicit scheme for solving the unsteady Euterflow equations to abtain steady solutions is provided in curvilinear coordinates. This scheme is mainly based on Steger-Warming' s implicit flux vector splitting technique and Harten' s numerical flux fura tion. With the hybrid scheme, we obtain the discrctized linear system with diagonally dominant coeff ctent matrix which enhances the convergence rate by use of the Line Gauss-Seidel relaxation procedure including backward and forward sweeps.The numerical procedures were applied to three examples for steady transonic flows in a channel. Computational results shows the convergence rate is very high due to the very big time steps. The scheme is capable of obtaining weak solutions for system of hyperbolic conservation equations. It also can exclude expansion shocks and lead only to physically relevant solutions. The new algorithm reaches steady shock solutions on the-grid with a one or two point monotone transition.
DERIVATION OF DIMNESIONLESS EQUATIONS FROM METHOD OF ANALYSIS OF DIRECTIONAL UNIT SYSTEM
Qiu Xuguang
1989, 4(3): 241-244,292.
Abstract PDF(442KB) icon1654 icon13
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In this paper the dimensionless equations are derived from the method ofanalysis of directional unit system, and two examples are presented in illustration. The important priciple is suggested that the choice and treatment of the unit system in the similarity theory is quite differ from those of public unit systems such as SI system or engineering unit system, even though all they must conform to the Gauss' s rule of selection of unit system. For the former the flexibility and the particularity is necessary, because in the similarity theory the particular and actually phenomenon is investigated, and for the latter the invariance and the universality is necessary. as it is based on possibility of occurrance of all phenomena.
APPLICATION OF FINITE ELEMENT METHOD TO CALCULATING STRESS FIELD IN NOZZLE INSERT OF SOLID ROCKET MOTOR
Sun Jufang
1989, 4(3): 245-249,292.
Abstract PDF(500KB) icon1714 icon13
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The finite-element methcxl is applied to analyzing the two-dimensional stressfield in the graphite insert of a composite nozzle under pressure and transient temperature loads in a solid rocket motor. The mechanical models, basic approaches and numerical examples are presented in this paper. The anisotropy of the material is considered in the computation. A compression technique of variable bandwidth is applied to the stiffness matrix [K] of the integral structure in order to save main storage. The calculated results are agreed with the experimental data very well.
EROSION EVALUATION OF NOZZLE THROAT INSERTS
Deng Yuejun, Cai Er, Feng Wenlan
1989, 4(3): 250-252,296.
Abstract PDF(355KB) icon1491 icon10
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A study has been conducted to evaluate the temperature distribution and recession behavior of graphite nozzles in rocket motors by solving two-dimensional transient heat transfer equations. Flowfield analysis takes in account the effects of A12O3 concentration through the contribution of particles on the stream density and temperature. The analytical model assumes that there is radiant exchange between the gas stream and the wall. An effective emissivity is used in this parallel plate radiation model. The results calculated in radiation and non-radiation conditions are compared for aluminized propellants, and also checked with data of Keswani and Kuo. The laboratory motor tests with double base propellants have been performed for verification of the analytical model. The temperature profiles in the nozzle have Been measured at four locations with Cr-Ni/Ni-Si sheathed thermocouples. The present model is in general agreement with the available experimental data
A SPLINE INTEGRAL EQUATION METHOD FOR ROTATING VARIABLE-THICKNESS DISC
Liu Xingye, Zheng Jianjun
1989, 4(3): 253-255,292-293.
Abstract PDF(407KB) icon1905 icon10
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The integral equations of rotating disc with variable thickness are derived bymeans of the ring fundamental solution of elacticity. Then the integral equations are solved by spline function method. Also, this method is applied to the rotating variable-thickness disc with circular hole. Its computing program is so simple as to work on the IBM-PC computer. Due to the spline interpolation, very high accuracy of the numerical solution can be achieved even if few elements are chosen, The numerical results obtained by this method is almost completely consistent with the exact solution. Obviously, this method overcomes the shortcomings of the finite element method or finte difference method in need of solving huge systems of algebraical equations.
OPTIMIZATION OF DISPERSED ELEMENT NODE SERIAL NUMBER
Liang Cairong
1989, 4(3): 256-258,293.
Abstract PDF(339KB) icon1496 icon11
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The computer time and storage necessary for structure finite-element analysis are mainly dependent on the bandwidth of the general rigidity matrix [K], if its dimension is fixed. According to the sparse characteristic of the general rigidity matrix and the principle of decreasing matrix bandwidth, an optimization of element node serial number is provided. It is simple and suitable for different elements, not only for the single-loop, but also for the multi-loop.
AN INVESTIGATION ON STAGNATION PRESSURE ERRORS DUE TO ROTATION STATE BEHIND A ROTOR
Tang Guocai
1989, 4(3): 259-261,293.
Abstract PDF(367KB) icon1392 icon12
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This paper proposes that the errors in stagnation pressure measurement due torotation state behind a rotor should include perception errors in addition to the weighting error and dynamic response errors. The analysis and experimental data show that the stagnation pressure in wake may be higher than that in the main flow,so the weighting error may be positive. These two conclusions are contrary to the affimation of reference [1]. This paper also puts forward various approaches to minimize the errors due to the rotation state.
ACTIVE CONTROL OF INLET DISTORTED FLOW FIELD IN COMPRESSOR INLET
Xu Liping
1989, 4(3): 262-264,293.
Abstract PDF(448KB) icon1475 icon18
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The feasibility of alleviating the destabilizing effect of the inlet circumferential total pressure distortion on an axial compressor by active control of individually adjustable inlet guide vanes(LAIGV) has been qualitatively analyzed under the parallel compressor hypothesis. The result shows that when the distortion is quasi-steady it is possible to use the actively controlled LA1GV with a relatively simple proportional control scheme to adjust the flow angle, and thus to prevent the compressor entering the unstable state. For a typical blade setting the angular adjustment of LA1GV needed to cope with 10 % total pressure distortion is of only few degrees.
FLIGHT TESTS FOR AIR INTAKE FLOWFIELD AND ENGINE OPERATING STABILITY
Lun Yiyun
1989, 4(3): 265-268,294.
Abstract PDF(502KB) icon1632 icon17
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The operating compatibility between air intake and engine during the flighttests of a supersonic fighter is considered. The flight tests were completed under conditions of huri zontal accelerating flight, uprated and retarded throttles of the engine during horizontal flight and constant-Mach climbing with maximum and augmented thrust rating. The flow conditions at the intake and the tendency of flowfield variation at the inlet of the engine were evaluated by means of six prossure tappings at the variable intake cone and a cross rake pressure probe at the exit of the intake. The technical measures have been taken to cope with the engine troubles and their effects are also described in the paper.
ESTIMATION OF MAXIMUM INSTANTANEOUS DISTORTION WITH A FEW RMS MEASUREMENTS
Liang Dcwang, Zhang Shiying
1989, 4(3): 269-270,294.
Abstract PDF(282KB) icon1453 icon12
Abstract:

A method for estimating the maximum instantaneous distortion with a fewmeasured RMS values of the fluctuation pressures is presented based on reference[1]. This method enables to estimate the maximum instantaneous distortion value by assuming that the turbulence distribu tion is uniform and equal to the average value of s few measured RMS values. A comparison between the maximum instantaneous distortion values measured experimentally and estimated by this method shows that the maximum instantaneous distortion can be estimated by the average value of a few men sured RMS values of the fluctuation pressune with the same accuracy as that obtained by the method reference [1].
OPTIMUM DESIGN FOR GEOMETRIC PARAM ETERS OF AXISYMMETRIC CONVERGING DIVERGING NOZZLE
Zen Jun, Zhao Jingyun
1989, 4(3): 271-272,294.
Abstract PDF(281KB) icon1696 icon20
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A mathematical model of a axisymmetric converging-diverging nozzle in design conditions is set up by quadratic-regression equation. The thrust force coefficient is taken as objective function. The three geometric parameters (half convergent angle, half-divergent angle, radias ratio of throat curvature to throat) are chosen as design variables. The optimum design is completed py the random-walk method. Then the relationships of the optimum geometric parameters to the designed pressure ratio of the nozzle are obtained. The results provide the basis for designing the axisymmetrie convergent-divergent nozzle of an exhaust system.
EFFECT OF GEOMETRIC PARAMETERS ON INTERNAL PERFORMANCE OF CONVERGENT-DIVERGENT NOZZLE
Zhao Jingyun
1989, 4(3): 273-274,295.
Abstract PDF(290KB) icon1749 icon19
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The efect of geometric parameters on internal performance of convergent-divergent nozzle has been investigated experimentally. The relationships of thrust coefficient and wall static pressure distribution to area ratio, divergent angle, convergent angle and throat radius of curvature are presented in this paper.
AN EXPERIMENTAL STUDY ON ATOMIZATION OF COAL-WATER SLURRY AND EROSION OF ATOMIZER
Cao Minghua, H. W. Glaser
1989, 4(3): 275-276,295.
Abstract PDF(290KB) icon1216 icon12
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An internal-mix atomizer has been specially designed for coal-water slurry.The relationships between its slurry spray characteristics and operating parameters have been studied experimentally. High levels of atomization were achieved by the internal-mix atomizer. The protective layer formed by the rotating flow at high speed in the internal-mix atomizer provides a useful means of protection against erosion, corrosion and deposition.
AN EXPERIMENTAL STUDY ON FUEL SPRAY ATOMISING CHARACTERISTICS OF EVAPORATING PIPE ATOMIZER
Sun Yuezhong
1989, 4(3): 277-279,295.
Abstract PDF(352KB) icon1843 icon17
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This paper summarizes the test research on the atomizing characteristics ofthe evaporating pipe atpmizer. Among all the factors which affect the fuel atomization, the atomizing air speed is the most important, but the fuel-air-ratio and geometrical parameters have certain effects on it as well. The distance of the fuel atomization shortens with the increase of the atomizing air speed.
AN EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER IN ROTATING COOLANT CHANNELS
Wang Baoguan, Ding Xiaojiang
1989, 4(3): 280-282,295.
Abstract PDF(359KB) icon1595 icon10
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This paper deals with a facility and an experimental technique for researching the heat transfer of coolant channels in the rotating turbine blade, and presents the preliminary results of the convective coefficient of the flow parallel to the axis in the rotating conditions. The results show that the effect of rotating on heat transfer is highly enhanced by centrifugal and Coriolis forces. In the conditions of the present tests (Re = 6. 4×104, n= 1000rpm. ), the Nusselt number in the rotating state in about 20 percent higher than that in the stationary case.
FLOW SIMILARITY IN IGNITION PROCESS OF JET ENGINE
Wang Hongming
1989, 4(3): 283-285,296.
Abstract PDF(363KB) icon1622 icon9
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An analytical study on the flow similarity in ignition process is completed inrespect to the effects of the air flow on the local fuel and oxygen distribution near the plug. For lean light off limitation, a momentum criteria is derived from the motion equation of fuel droplet. The criteria states that the ignition velocity rises with the increase of altitude. It is in quite good agreement with the experimental data. Moreover, it can be explained as that the ignition process changes gradually with the decrease of pa into-optimum range when the fuel flow is kept constant. This case is a very conventional fuel control scheme for ignition ot the jet engine.
AN IMPORTANT ROLE OF CONDENSED-PHASE INTERFACE REACTION HEAT IN COMBUSTION PROCESS OF COMPOSITE PROPELLANTS
Zhang Ren
1989, 4(3): 286-288,296.
Abstract PDF(358KB) icon1526 icon9
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The condensed-phase interface reaction heat of AP/HTPB composite solidpropellant and the influence of some burning rate catalysts on the interface reaction heat are studied with the aid of diferential scanning calorimetry. The experiments demonstrate that the catalysts which increase the condensed-phse interface: reaction heat raise the burning rate of the propellant.

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