1994 Vol. 9, No. 1

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A METHOD FOR DETERMINING AIRCRAFT ENGINE GROSS THRUST IN FLIGHT
Lian Xiaochun, Chen Fuqun, Shen Shaoying, Liu Xuanwin
1994, 9(1): 1-4,105.
Abstract PDF(285KB) icon1746 icon478
Abstract:
Abstract A method,“gross thrust model”,is developed to determine gross thrust of jet engine and afterburning turbofan engine in flight testing.This model is able to determine the gross thrust of modern engines with an acceptable degree of accuracy only by using a few of pressure measurements.The gross thrust model is based on a one dimensional analysis of flows in mixer,afterburner and nozzle.Some correction coefficients are required to account for three dimensional effects,the effects of friction and mass transfer,as well as the effects of the simplifying assumptions used in the theory.The correction coefficients in the model are K,C and E.Both K and C are constants,whereas E varies with engine operating conditions.In order to determine the reasonable coefficients K,C and E,it is necessary to acquire engine testing data in the altitude facility at flight conditions as much as possible.A comparison was made between the data determination from the gross thrust model and the gross thrust measured from the altitude facility for engine J85 GE 21 at H=7620m, Ma 0=0 90.It demonstrates that the accuracy of the gross thrust model is about 3 0 percent and depends on the pressure difference between the total pressure of the turbine discharge and the static pressure of the nozzle inlet.
AN EXPERIMENTAL STUDY OF AERODYNAMIC PERFORMANCE AND AEROACOUSTIC CHARACTERISTICS OF A SERIES OF PROP-FANS
Wang Po, Ren Liyun, Peng Zeyan
1994, 9(1): 5-9,105.
Abstract PDF(1354KB) icon1909 icon415
Abstract:
Abstract Aerodynamic performance and aero acoustic characteristics of straight (un sweep)、forward sweep and backward sweep blade with different installed angles have been investigated experimentally under the take off condition.From their comparative study the following conclusions have been drawn.(1)An optimal prop fan design should be made by combining both high aerodynamic performace and low aerodynamic noise;(2)Blades with sweep have potentials for noise reduction;(3)Tip load reduction prop fan blade design would be benefit to lowering the noise level as well as to the prop fan efficiency improvement.
A HIGH-ORDER ACCURACY TVD EULER SOLVER FOR 3D FLOWS IN TURBINE CASCADES
Gu Fahua, Wang Zhongqi, Yang Hong, Feng Guotai
1994, 9(1): 10-14,106.
Abstract PDF(412KB) icon2030 icon408
Abstract:
Abstract A third order accuracy implicit approximate factorized TVD code is developed using Chakravarthy-Osher scheme to solve the steady flows in annular turbine cascades.The governing equation is the 3D Euler equations in arbitary curvilinear coordinate systems in terms of cylinder coordinate system velocity components.Beam-Warming factorization and upwind difference are adopted to discretize the implicit term,and the explicit one is discretized by Chakravarthy-Osher TVD numerical fluxes.The boundary condition is obtained from extrapolation.The resulted algebraic equations are tridiagonal block matric system and solved by sweeping in each direction.So the scheme is a 5 point implicit AF scheme of first order temporal and third order or second order spacial accuracy depending on the two TVD factors.Two examples are presented,the first verifies the calculation of third order scheme with a low speed wind tunnel experiment,the second compares the third order scheme with the second order one.The examples indicate that the code results in numerical solutions agree with the experiment,and the third order scheme has little difference from the second order one in the solutions,but it decreases the convergent residual greatly.Also it is showed that the two schemes do not agree with each other very well in the throat of the cascade where the flow velocity is equal to the local sound speed.
A METHOD OF USING TVD SCHEME TO CALCULATE INCOMPRESSIBLE FLOWS SEPARATELY
He Jun, Feng Qin, Yan Chuanjun, Liu Songling
1994, 9(1): 15-18,106.
Abstract PDF(1214KB) icon1962 icon421
Abstract:
Abstract The Total Variation Diminishing (TVD) schemes have been adapted to incompressible flow computations.Considering the characters of the computation in the incompressible flow,a new method is given that the TVD sheme is used with separating the continue equation from momentum equations.The continuum governing equations are discretized on a modified nonstaggered grid.In the momentum equations,the convective terms are discretized by a third order TVD scheme,and the others are done by central finite difference scheme.The pressures are solved by pressure substitiution.Furthermore,a pressure correction procedure and the Gauss-Seidel centrally symmetric iteration algorithm are used to enhance the convergence rate.As a result,the code containing those methods has been applied to computation of two typical flow problems:the channel flow problem and the lid driven cavity flow problem.A comparison of the present results with the literature data is also given in good agreement.It is shown that the TVD scheme is not only applicable to incomprssible flow computation,but also it yields higher accuracy than the non TVD scheme.
A NEW COMPREHENSION ON STATOR CASCADE UNDER ROTATING STALL
Zhu Junqiang, Liu Zhiwei, Li Jun
1994, 9(1): 19-23,106.
Abstract PDF(332KB) icon1864 icon486
Abstract:
Abstract Onset points of rotating stall,time average performance and flow fields after stall appearing,as well as the unstable behaviors for a single stage axial flow compressor and an isolated rotor have been measured successfully with hot film probes and a three hole cylindrical pressure probe containing fast response transducers.On the basis of many experimental data,the influences of stator cascade in the single stage compressor on the whole time average characteristics and the cessation behavior of rotating stall,as well as the stalled flow field have been elaborated in detail.When a single stage compressor enters the unstable condition,the roles of the stator cascade,such as postponing the appearance of rotating stall,as well as modifying the stalled flow field and cessation form,have been analysed.There is an obvious difference of the unstable behavior between the single stage axial flow compressor and the isolated rotor.At high rotor speed (>0 85),a nonrecoverable stall phenomenon appears for a single stage compressor,but it does not appear for an isolated rotor at any speed.
HEAT TRANSFER FROM SHROUDED ROTATING DISK WITH CENTRIC AIR INFLOW
1994, 9(1): 24-26.
Abstract PDF(198KB) icon1493 icon437
Abstract:
Abstract An air cooled turbine disk was investigated as the model of a rotating disk near a shrouded stator with centric inflow of cooling air.The heat transfer performance of the rotating disk was experimentally studied in consideration of rotational Reynolds number Re、mass flow coefficient C w、gap ratio G and shrouded clearance ratio G s.The disk diameter is 360mm and its maximal rotational speed is 3600rpm.The disk was electrically heated at the outer radial side.One of the disk surfaces was cooled by air and the another surface was adiabatic.Temperature of heated side and cooled surface was measured.Mean Nusselt number of cooled surface has been obtained by using numerical method.For large Reynolds number,the mean Nusselt number is slightly affected by the Reynolds number.Increasing mass flow coefficient can enhance the capacity of heat transfer.The effects of G and G s are small.An emperical correlation of the heat transfer coefficient of rotating disk is proposed.
A NUMERICAL SIMULATION OF SPANWISE MIXING IN MULTI-STAGE AXIAL-FLOW COMPRESSOR
1994, 9(1): 27-30.
Abstract PDF(1122KB) icon1731 icon482
Abstract:
Abstract By incorporating contributions of the under/over turning attributed to secondary flow,through flow calculations of spanwise mixing for S2 stream surface are accomplished on the basis of a turbulent diffusion model.The Gallimore-Cumpsty mixing model and the Baldwin-Lomax turbulent model are employed respectively to estimate the effects of turbulent diffusion.The deviation angle is predicted according to Carter′s 2D rule with addition of Robert′s correction model.The method mentioned above is applied to two 3 stage axial flow compressors.The calculated results are closer to the test data than those of Gallimore and Adkins-Simth′s mixing calculations.
A FINITE ANALYSIS SOLUTION OF VISCOUS COMPRESSIBLE TURBULENT FLOW IN A CASCADE
1994, 9(1): 31-34.
Abstract PDF(436KB) icon1672 icon518
Abstract:
Abstract A finite Analysis Method is further extended to numerical calculation of viscous compressible turbulent flow on the basis of experience of incompressible turbulent flow calculation.The viscous compressible turbulent flow fields in a single and a tandem cascades with Mach number up to 0 72 are numerically studied in a curvilinear coordinate system by means of the Finite Analysis Method.The study shows that the Finite Analysis Method has good numerical stability and accuracy,and it is suitable for viscous compressible turbulent flow calculation.
A NEW APPROACH TO BLADE DESIGN ON STREAM SURFACE OF REVOLUTION
1994, 9(1): 35-38.
Abstract PDF(240KB) icon1766 icon383
Abstract:
Abstract A new approach is provided for blade design on stream surface of revolution based on a novel image plane theory of cascade blading.A flow solver in differential integral formulation for analyzing the flow field of a given geometry is transformed into a design method by coupling with a contour modification model.In this method the classical slip condition is replaced by other boundary conditions.In such a way the prescribed velocity or pressure distribution can be imposed directly on the blade.Since the blade shape is compatible with the velocity requirement,a nonzero velocity component normal to the blade wall evolves from the flow calculation.This normal velocity is then used to reset the wall parallel to the new flow field,using a transpiration technique.The procedure is repeated until the calculated velocity distribution converged to the required one.Numerical results of an actual turbine nozzle show that the present method can provide a practical blade without strict requirement for its initial shape.Another important aspect of this method is the ability to design and analyze a blade with identical code.
MULTIVARIABLE AND MULTICONSTRAINT OPTIMIZATION FOR TRANSONIC AIRFOIL DESIGN
1994, 9(1): 39-42.
Abstract PDF(971KB) icon1361 icon396
Abstract:
Abstract An efficient optimization design method for transonic airfoils is developed by coupling the direct search EXTREM optimization method to a reliable aerodynamic analysis method.The aerodynamic analysis method is based on combination of full potential and viscous boundary layer flow analysis including calculations of laminar and turbulent boundary layers,natural or fixed transition prediction and separation prediction.The drag coefficient at design Mach number is considered as objective function and a set of smooth shape functions are adapted to fitting the basic goemetry.By using the numerical optimization method,supercritical airfoils or conventional low speed airfoils can be modified to be transonic airfoils which have the lower drag coefficient at transonic speeds.The presented method is attractive for practical engineering application because of its quick convergence.
EXPERIMENTAL RESEARCH ON AN APPARATUS FOR MEASURING ALFORD FORCE
1994, 9(1): 43-46.
Abstract PDF(746KB) icon1409 icon440
Abstract:
Abstract A lateral destabilizing force (Alford force) emerges as a rotor of an axial turbomachinery is offset in relation to its case.Existence and mechanism of the Alford force have been verified and researched in literature.However it is very difficult to measure the stationary destabilizing forces and especially the rotational destabilizing forces for lack of an effective test apparatus and efficient measuring methods.As a result of investigation on the experimental measuring methods for years,a testing apparatus has been designed and established through several practical tests and improvements.Therefrom the destabilizing forces under various conditions are successfully measured.
A SEMI-ANALYTICAL SOLUTION FOR DYNAMIC RESPONSE OF COMPOSITE PLATES IN HAMILTON SYSTEM
1994, 9(1): 47-50.
Abstract PDF(223KB) icon1284 icon418
Abstract:
Abstract Hamilton canonical equations have been derived by introducing the canonical functions in time direction,and a semi analytical method for the dynamic response of composite plates is provided.By separation of variable,conventional finite element discretization can be applied in the plane of lamina,and the exact solution in thick direction is deduced by the state space control method.Continuity of diplacements and stresses is ensured by applying the transfer matrix method,and the relational expression in the upper and lower surfaces is established,then the solution is obtained by means of the shot method.The results indicate that the number of variables is reduced greatly and the accuracy of the solution is enhanced.
RESEACH ON CONTACT CHARACTERISTICS OF AIRCRAFT SPIRAL BEVEL GEARS
1994, 9(1): 51-54.
Abstract PDF(3505KB) icon1488 icon477
Abstract:
Abstract A method is proposed for analyzing contact characteristics of aircraft spiral bevel gears.The effects of loads,misalignments and deflection of their supports on the tooth bearing and transmission error of spiral bevel gears have been investigated with the present method.The conclusions of this work are as follows:(1)The disalignment and deflection of the supports exert an evident influence on the contact pattern and the displacement curve of the spiral bevel gears.(2)The gears are sensitive to the position changement of △G and △Σ,but insensitive to △P and △E.(3)For the sake of acquiring optimum parameters of gears and cutters,the contact characteristics of spiral bevel gears can be analyzed with this method during design of the gears.
NUMERICAL AND EXPERIMENTAL ANALYSES OF DYNAMIC ROOT STRESSES OF HELICAL GEARS
1994, 9(1): 55-58.
Abstract PDF(546KB) icon1671 icon475
Abstract:
Abstract A method for calculating dynamic root stresses of helical gears is proposed,based on local mesh refinement approach of tooth root,analysis of dynamic behaviours of gear transmission system and 3 D FEM.In order to improve greatly the accuracy of computation,following factors are taken into consideration:simultaneous engagement of three pairs of teeth;influence of deformation of rims and webs of gears;influence of deformation of shafts and bearings;gear base pitch errors and tooth profile errors.The transient responses of dynamic root stresses are replaced by the root stresses under dynamic loads.In this case it is possible to avoid the complicated natural vibrational behaviours and dynamic response analyses of gear teeth.Experiments of the dynamic root stresses of the helical gears are carried out to verify the validity and reliability of the presented numerical method.The calculated results are in agreement with experimental ones.The calculations and the experiments show that the distributions of the dynamic root stresses of the helical gear teeth in meshing have basically three stress peaks.The maximum dynamic stress of the tooth root and stress fluctuations will increase with the increase of the rotational speed.As the input torque increases,the dynamic stresses of tooth root increase.But their dynamic stress factors have a decreasing tendency as the elastic deformation of the gear structure will increase with increasing the input torque.
AN EXPERIMENTAL STUDY ON INTERNAL BALLISTIC PERFORMANCE OF AN IMPULSIVE SRM WITH A LARGE VALUE OF L 
1994, 9(1): 59-62.
Abstract PDF(532KB) icon1819 icon436
Abstract:
Abstract An experimental study on internal ballistic performance of an impulsive SRM with a large value of L  for a middle way guidance system of a long range rocket has been completed at a dynamic ground test,such as static firing test,dynamic spinning test and ambient temperature limitation test.The tests show a good agreement of experimental data with the predicted ones.It is indicated from experimental results that the major performance of the impulsive SRM meets the requirements of dynamic testing with the rocket guidance system,but also is associated with some evident features of the impulsive SRM with large value of L .
A STUDY OF SWIRLING SOLID ROCKET MOTOR
1994, 9(1): 63-66.
Abstract PDF(838KB) icon1679 icon396
Abstract:
Abstract The effect of swirling on solid rocket motor performance is investigated analytically and expermentally.The investigation on burning rate sensitivity in detail is completed.The prediction programs of transient burning rate,steady state burning rate and internal ballistic performance are established,the calculation results are compared with the experimental data.The effect of propellant ingredients on the swirling solid motor performance is also revealed.Through a series of researches,the following conclusions are reached:if the aluminium content of the propellant remains constant,the greater the diameter of aluminium particles,the higher the burning rate sensitivity;if the diameter remains constant,the greater the content,the higher the sensitivity.For a high burning rate propellant,there exist a higher threshold of acceleration and a lower burning rate sensitivity.For star grain motor,the effect of swirling flow on its internal ballistic performance is smaller,than in the motor with conocyl grain.The prediction results of the theoretical model are consistent with the experimental results.The theoretical model can be applied to engineering design.
INTELLIGENT CONTROLLER AND ITS APPLICATION TO AEROENGINE
1994, 9(1): 67-70.
Abstract PDF(232KB) icon1643 icon527
Abstract:
Abstract An intelligent controller for aeroengine at steady state and acceleration is designed,which consists of a characteristic model、characteristic identification、characteristic memory、inference engine and rule base.The results of its simulation show that the intelligent control is better in dynamic quality than Fuzzy control and PID control.
HOLOGRAPHIC INTERFEROMETRY FOR DENSITY FIELD OF SUPERSONIC FLOW
1994, 9(1): 71-74.
Abstract PDF(237KB) icon1575 icon480
Abstract:
Abstract An approach for accurate measurement of density distribution in the inflow field between supersonic blades is provided by means of holographic interferometry and digital image processing system.It is a non contact measuring method without interference from the measuring instrument.This approach has advantages of high accuracy of measurement,good feasibility in acquiring and processing data,as well as possibility to collect the information of the whole flow field at the same time.Finally,the density distribution in the flow field of supersonic blades is obtained by using this approach.
MATCHING OF PLAIN INJECTOR FUEL DISTRIBUTION WITH BARCHANE DUNE FLAMEHOLDER
1994, 9(1): 75-78.
Abstract PDF(711KB) icon1519 icon416
Abstract:
Abstract The effects of air stream velocity,fuel injector pressure drop and flameholder radial position on fuel distribution of vertical spraying from a plain orifice injector in high speed transverse air stream are experimentally investigated for a barchane dune flameholder.The fuel concentration distribution is measured by means of heating sampling probe and infrared analyzer.The experimental data are compared to the fuel distribtuion of horizontal spraying from the injector.The rcsults show that the vertical spraying is superior to the horizontal one in matching with the barchane dune flameholder,and the manner of fuel spraying relative to air stream is the key factor for fuel distribution to match barchane dune flameholder well.
SOLUTION OF 2-D TRANSONIC CASCADE FLOW WITH EFFECTIVE FLUX VECTOR-SPLITTING IMPLICIT SCHEME
1994, 9(1): 79-82.
Abstract PDF(212KB) icon2047 icon439
Abstract:
Abstract A one step effective flux vector splitting implicit scheme is developed,which features simplicity of no approximate factorization and no block bidiagonal system of equations.The scheme provides a significant enhancement in computational efficiency because it has advantageous characteristics in creation of higher order numerical implicit items.The Euler flow of a two dimensional cascade is calculated numerically by using the above scheme,and the results show that it has good convergence and accuracy of shock wave capture.
A STUDY ON AN ANNULAR STATIONARY CASCADE WITH BOWED AND TWISTED BLADES
1994, 9(1): 83-85.
Abstract PDF(178KB) icon1904 icon616
Abstract:
Abstract In this paper,a 3D Euler solver and a direct problem code of S stream surface are applied to numerical analysis of the flow field in an annular stationary turbine cascade with bowed and twisted blades.Also,an experimental study on this cascade is made by blowing on an annular cascade test rig to verify the two calculation programs and to research the flow mechanism in the cascade.Numerical results show that the effect of blade bowing in circumferential direction is mainly reflected in the front of cascade and blade bowing has little influence on the flow beside blade pressure surface.After comparing the calculated results with the experimental data,it is found that in respect of circumferentially averaged flow parameters at the cascade exit,the 3D Euler solver is more precise in predicting the pressure distribution but less precise in predicting the flow angle distribution than the code of S stream surface.The experimental data verify the effect of blade bowing on the flow around blade hub,and show great losses occurring near blade tip due to excessive camber angle of blade profile and improper bowing of blade stacking line in that region.Some difference between the calculated results and the experimental data demonstrates that a more reasonable loss model and a more precise lag angle model should be worked out if a good design for turbine cascade with bowed and twisted blades is expected by means of an Euler solver or a throughflow code.
A NUMERICAL CALCULATION OF AXISYMMETRIC COMBUSTION GAS JET
1994, 9(1): 86-88.
Abstract PDF(201KB) icon1854 icon522
Abstract:
Abstract This paper presents an application of Von Mises transformation to all governing equations,initial conditions and boundary conditions in the axisymmetric jet.A Prandtle mixing length turbulent model and an implicit finite difference scheme have been employed,and solution of the equations describing axisymmetric jet has been obtained.The velocity field,temperature field,mass concentration field and density field of combustion gas jet of a typical aircraft at cruising conditions,and composition distribution of combustion gas components has been calculated succeessfully.The algorithm and calculation results could be used to predict the infrared radiant properties of high temperature aircraft nozzle jet.
TECHNICAL NOTES A PRELIMINARY EXPERIMENTAL STUDY ON AERODYNAMIC CHARATERISTICS IN EJECTOR WITH CURVED MIXING DUCT
1994, 9(1): 89-91.
Abstract PDF(186KB) icon1718 icon392
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Abstract A preliminary experimental study on aerodynamic characteristics of internal flow in ejector composed of curved mixing duct and lobed nozzle or round nozzle is presented in this paper.The results show that:(1)in comparison with the lobed nozzle,its ejector pumping efficiency is enhanced up to about 100% and the relative temperature peak value at its mixing duct exit is cut down to about 10% whereas the total pressure loss is almost the same.(2)due to the generation of the secondary flow induced by curved duct and the spreading effect caused by the primary flow impingement to curved walls,the temperature near the trailing edge is obviously higher than that near the front edge at the major axes of elliptical mixing duct exit,while the temperature distribution takes a saddle shape at the minor axes.
STRESS ANALYSIS OF DIRECTIONALLY-SOLIDIFIED AIR-COOLED TURBINE BLADES
1994, 9(1): 92-94.
Abstract PDF(192KB) icon2010 icon460
Abstract:
Abstract A general nonlinear finite element code has been applied to thermoelastic stress analysis of directionally solidified air cooled turbine blades.Therefrom characteristic constants of Ni base superalloys DZ 22 have been analyzed and determined.A constitution model for transversely isotropic materials is established.According to sophisticated construction of the air cooled turbine blade and maximum regime of its ground start,the calculation of its centrifugal stress,thermal stress and sum equivalent stress comprising aerodynamic loads is accomplished by using eight noded brick elements,and automatic mesh generation and postprocessing of computed results are carried out.
MELTING OF CIRCULAR CYLINEDR SUBCOOLED
1994, 9(1): 95-97.
Abstract PDF(202KB) icon1306 icon369
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Abstract A new model of temperature distribution is proposed as a solution for melting of a subcooled solid surrounding a circular cylinder.The simple expressions for the position of phase change interface are derived as a function of time.By comparison,the results are in a good agreement with numerical solutions.The present method is simple and perceivable.The method is valid for phase change problems at large Stefan numbers and different boundary conditions.The results show that the subcooling has a distinct effects on the melting processes,the liquid layer thickness of circular cylinder subcooled is less than that without subcooling,even only a fraction of that at deep subcooling and long melting time,the subcooling also enlarges the difference between cylinder and plane meltings.
AN EXPERIMENTAL INVESTIGATION ON FLOW DRAG IN TUBE WITH INNER FANS
1994, 9(1): 98-100.
Abstract PDF(183KB) icon1856 icon458
Abstract:
Abstract The experimental investigation on flow drag of the air or high temperture gas flows passing through the tube with inner fans.The range of air temperature is from 287 2K to 259 1K and that of the gas tempreature is from 347 3K to 499 7K.The velocity of the flow varies from 7 3 to 41 7m/s.A correlative equation between Renolds number and drage coefficient is formulated,based on all test data.The results calculated with the correlative equation are in good agreement with the data of tests.
AEROENGINE CONTROL SYSTEM OF SINGLE-CHIP COMPUTER
1994, 9(1): 101-103.
Abstract PDF(192KB) icon1863 icon457
Abstract:
Abstract In order to develop a new type of aeroengine control system,a 16 bits single chip computer is used.8098 is specially designed for the speed demand of 16 bits micro controller and the bound condition of 8 bits external bus.It has features of high quality,full function and easy to operate.The system simulation and practical physical simulation test show,that the time response of the digital control system is better than that of hydro pneumatic control system.

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