1988 Vol. 3, No. 2

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A DYNAMIC CHARACTERISTIC ANALYSIS OF A BLADED DISK ASSEMBLY
Gao Deping, Zhang Yisong, Yi Liyan
1988, 3(2): 97-100,183.
Abstract PDF(441KB) icon1383 icon386
Abstract:
The dynamic characteristics of a bladed disk assembly are calculated by means of sector elements of thick plates and wave propagation technique of periodical structure. The method saves greatly the computing time and the storage of computer. The vibration characteristics between the bladed disk assembly and the single blade or disk are compared and the influences of the variation of geometric parameters of the bladed disk assembly on its vibration characteristics are considered. Some conclusions are drawn which will play an important part in further research on the vibration control of an aeroengine. A bladed disk assembly of an actual compressor is analyzed in this paper,and the results obtained coincide with the experimental data. Therefore, the presented method is applicable to the practical engineering.
INTEGRATED STRESS ANALYSIS OF A BLADED DISK ASSEMBLY
Yin Zeyong, Liu Jun
1988, 3(2): 101-104,183-184.
Abstract PDF(504KB) icon1557 icon379
Abstract:
The integrated finite element stress analysis for a bladed disk assembly has been carried out, using the cyclic symmetric model with contact surfaces. The model consists of a sector of the disk and a blade attached to this sector. The technique employed has the following features. l.The contact of blade root and disk groove is taken into account in the analysis by incorporating three-dimensional contact relations at tde contact surfaces into stiffness equations of the model. Consequently,in comparison with the results obtained separately from analysis of the blade or the disk,the displacements and stress fields ac-quired in both the blade and the disk are more accurate. 2.ln order to avoid the assumption for certain boundary conditions,the cyclic symmetric relations are employed at the corresponding boundaries of the disk sector. 3.Several different kinds of elements are applied to modeling the structure. For comparison five other simplified models are also evaluated.
AN EXPERIMENTAL INVESTIGATION ON THE BISTABLE BEHAVIORS OF A FLEXIBLE ROTOR-SQUEEZE FILM DAMPER SYSTEM
Zhu Changsheng, Feng Xinhai, Xu Jiankang
1988, 3(2): 105-108,184.
Abstract PDF(499KB) icon1547 icon485
Abstract:
The bistable behaviors of resonance type occurred near main resonance speed of the system is investigated,based on experiments of a flexible rotor-squeeze film damper system. The influences of unbalance speed,radial clearance ratio, centralizing spring stiffness and acceleration process on the behaviors are considered. It is shown that the squeeze film damper is effective only within a certain unbalance range. If the unbalance is large enough, the bistable operation may occur. The larger the unbalance, the centralizing spring stiffness or the radial clearance ratio is, the more the possibility of occurance of the bistable operation.
THE BISTABLE BEHAVIORS OF A RIGID ROTOR WITH SQUEEZE FILM DAMPER
Yan Litang, Zhang Shiping, Li Qihan, Zhao Fuan
1988, 3(2): 109-112,184-185.
Abstract PDF(479KB) icon1668 icon421
Abstract:
The bistable behaviors of the rigid rotor with centralizing spring and squeeze film damper are studied by means of calculations and experiments. The bistable behaviors are characterized by the variations of eccentricity, transmissibility and Lagging phase angle. The results calculated and experimental data are in a good agreement. The bistable operation of the rotor canbe eliminated at operating speeds if only the bearing parameters including the length and clearance of the film damper,and the stiffness of the centralizing spring are chosen properly over a certain unbalance range of the rotor.
A LOW CYCLE FATIGUE LIFE PREDICTION METHOD FOR BOLT HOLES OF DISK
Wang Lusheng, Gong Mengxian, Liang Cairong, Ru Meixiu
1988, 3(2): 113-116,185.
Abstract PDF(453KB) icon1617 icon491
Abstract:
A LCF(Low Cycle Fatigue)Life prediction method is provided on the basis of systematic experimental investigation, in which the median and reliability LCF Lives to crack initiation for the bolt holes of rotating disk can be predicted precisely by statistic data of smooth round bar specimen LCF lives to failure. The study shows that the LCF life to crack initiation for bolt holes of disk usually depends on the maximum strain history appliod to the critical points of the bolt holes, and the strain gradient influence on the LCF life to crack initiation can be neglected as usual. In addition, the study also indicates that the median LCF life usually depends on the steel chemical composition and its thermal treatment.
THE EFFECTS OF PRESTRESSING OVERLOAD ON LOW CYCLE FATIGUE AND da/dN
Hou Jingyung, Liu Shaolun, Xie Jizhou
1988, 3(2): 117-122,185.
Abstract PDF(527KB) icon1739 icon385
Abstract:
The effects of prestressing overload on dow cycle fatigue and fatigue crack growth rates da/dN of titanium alloy TC-11 and Ni-base superalloy GH33A for gas turbine disks were investigated at room temperature and 633K. The experimental results show that the low cycle fatigue crack initiation life is increased by prestressing overload treatment within the range of low cycle fatigue life 5×103 to 5×104,but the effect of the prestressing overload on fatigue crack propagation life Np is not obvious. In addition, an empirical expression is formulated to estimate the fatigue life of side edge notched (SFN) specimen under prestressing overload as Sm（Nf/r） = c. When this expression is employed to estimate the fatigue life of a notched specimen prestressed, it is only necessary to know the conventional fatigue S-N curve.
A CICULAR CONE SURFACE SHAPING METHOD FOR FAN BLADE
Han Minghui, Lu Yajun
1988, 3(2): 123-126,186.
Abstract PDF(533KB) icon1161 icon391
Abstract:
A new method,circular surface shaping method,has been developed to shape the sheet metal twisted blade. By changing the conical point angle and the location of the blade on the conic surface, this method can satisfy the various radial law and make the shaped blade meet the specifications of its aerodynamic design much better. The shortcoming of the existing cylinder shaping method that leads the inlet flow incidence to deviate from its permitted range can be overcome. In addition,the forwardswept blade shape can be obtained by contro-ling the blade location on the circular cone surface. As a result, a new design and manufacturing method is provided for sheet metal twisted blade shaping. The method is of great practical and economic value.
EXPERIMENTAL INVESTIGATION ON INDUSTRIAL MODIFICATION OF WZ-5 AEROENGINE TO RUN ON MEDIUM BTU GAS FUEL
Liu Gaoun, Wang Huafang
1988, 3(2): 127-130,186.
Abstract PDF(445KB) icon1855 icon378
Abstract:
The present work aims at industrial modification of WZ-5 aeroengine to runon medium BTU gas fuel which is a typical waste gas come from chemical fertilizer production. The medium BTU gas fuel contains 50% of H2,20% of CH4 and H2, and its low heating value is 3000kcal/Nm3. Four injectors have been designed and tested in the combustor of the engine. Three of them have quite good performance, the injector with slat-shape opening at its end is unsuitable because of unacceptable temperature distribution at the exit of the combustor. It is also shown that there is the potentiality for the modified combustor to be improved as the medium BTU gas fuel contains a certain amount of H2.
A STUDY ON EVAPORATION AND COMBUSTION OF OIL/WATER EMULSIFIED FUEL
Zhang Qingfan, Su Ke
1988, 3(2): 131-134,187.
Abstract PDF(443KB) icon1601 icon382
Abstract:
The evaporation and combustion processes of RP-2 aviation kerosene/water and No2 diesel oil/water emulsified fuel are studied experimentally and analytically. The micro-explosion processes of suspended droplets are demonstrated by high-speed photography and also testified by abrupt temperature variaition measured with the suspended thermo-couple. A steady state frozen model for an oil/water droplet is adopted to calculate droplet evaporation and combustion. The micro-explosion is assumed to occur as the droplet temperature reaches so called "superheat temperature" , which is from 550K to 580K. The calculated results are in good agreement with experimental data. The micro-explosion makes life-time of droplet cut down significantly, and formation of NOx and soot suppressed by water emulsification. Finally, influences of some parameters, such as ambient pressure and temperature, water content, initial tempersture of fuel, and relative velocity of droplet to gas on micro-explosion are investigated.
CALCULATION OF COMPRESSIBLE FLOW AND HEAT TRANSFER ON A ROTATING DISK
Wu Dingyi, Liu Songling
1988, 3(2): 135-139,187.
Abstract PDF(445KB) icon1431 icon389
Abstract:
In this paper, "BOX" method is extended to swirling compressible flow on a body of revolution, after the boundary layer equation is non-dimensionalized. The torque coefficients and local heat transfer coefficients in the laminar, turbulent and transitional flow regions on the rotating disk are calculated. The variable air properties are taken into account in the calculation. The investigation shows that the modified two-layer turbulence model is suitable to the calculation of the flow on the rotating disk. An appropriate analytical formulation of the turbulence model and relevant constants are also given.
A PNEUMATIC PROBE WITH THERMISTER
Tang Diyi, Zhu Zhuguo, Xu Guomin, Xu Douchun
1988, 3(2): 140-144,188.
Abstract PDF(505KB) icon1609 icon468
Abstract:
A tiny 5-hole compound probe with NTC-thermister has been developed by the authors for measurement of flow parameters in the compressor. All problems encountered for the thermister to be used in measuring the flow temperature are discussed. The techniques for enlarging the temperature range measured are also considered, such as how to sift out the best thermister, how to apply a highly precise and voltage-stabilizing supply to an unbalanced bridge for transmitting an accurate millivolt signal, and how to set a limit to the self-heating power of the thermister. As a result, the temperature range is extended from 273K to 473K. The probe was tested in a single-stage compressor rig, and its function and performance were verified favorably.
REDUCTION OF EJECTOR NOISE WITH MULTIHOLE NOZZLE
Fang Rensong, Zhang Rongxue
1988, 3(2): 145-148,188.
Abstract PDF(450KB) icon1587 icon376
Abstract:
In order to reduce the noise, an ejector with multihole nozzle is proposed as the primary nozzle, and its design method is presented. For comparison of the aerodynamic performance and the noise characteristics with those of conventional one in subsonic and supersonic ejector systems, the sound power levels and the primary and secondary mass flow rates of the ejectors were measured, and the static thrusts of the ejectors were estimated, based on the measured mass flow rates. The shroud length of the ejector system tested was altered in the experiments so as to study the effect of this parameter on noise and thrust. The exper imental results show that the multihole nozzle ejector system not only reduces noise considerably but also gains better aerodynamic performance due to a shorter shroud. The shorter the shroud, the more noise reduction and greater the static thrust increment can be achieved. For subsonic ejector, the noise reduction is about 14dB and the static thrust increment is about 30% when ratio of shroud length is 7.6. For supersonic ejector, those are about 22dB and 35% respectively when the shroud length ratio is 9.6.
APPLICATION OF ANNULAR INSTABILITY MODEL TO FY-20 LIQUID PROPELLANT ROCKET ENGINE
Yuan Weilan, Zhuang Fengchen, Yang Benlian
1988, 3(2): 149-152,189.
Abstract PDF(433KB) icon1854 icon389
Abstract:
This paper presents computation and analysis of tangential mode of high frequency combustion instability in FY-20 liquid propellant rocket engine by means of the annular instability model. The results show that the tangential mode of high frequency unstable conbustion does not occur in the engine, that coincides with the experimental results. Concrete steps and some effective measures for improving the liquid propellant rocket engine which is weak in the tangential mode of high frequency stability are also described in the paper.
FLOW PERFORMANCE OF REVERSED TANDEM CASCADES WITH DOUBLE-CIRCULAR ARC PROFILE FOR COMPRESSOR STATOR
Zhuang Biaonan
1988, 3(2): 153-157,189.
Abstract PDF(461KB) icon1653 icon378
Abstract:
Blowing experiments have been completed on 21 kinds of reversed tandem cascades with different geometrical parameters. The cascades were designed by the aid of a computer program with reference to the configurations of the tandem cascades of Turmo-IIIc, J69 and J85 compressor stators. The main flow performances were obtained in the form of a group of curves. Three conclusions are drawn as follows. l.The turning angle of the reversed tandem cascade is larger than that of a single blade cascade, while the pressure loss coefficient is smaller. 2.The reversed cascades still possess a better performance even if the incident angle is about -13°. Therefore, they can be suitable for application under conditions of minus incident angles. 3. The relative displacement and the relative axial distance of reversed tandem cascades should be matched well.
A DATA ACQUISITION SYSTEM FOR BLADE VIBRATION TEST
Zhang Chengsheng, Song Zhaohong
1988, 3(2): 158-160,190.
Abstract PDF(359KB) icon1278 icon377
Abstract:
A real-time data acquisition system based on IBM-PC for vibration test is provided. The highest sampling frequency of each channel is 100kc/s. There are 16 A/D channels and 2 D/A channels in this system. The tests of frequency spectrum analysis and vibration stress distribution of blade have been completed with this system.
EXPERIMENTAL INVESTIGATION ON FILM-COOLING UNIFORMITY OF DISCRETE HOLES OVER A CURVED SURFACE
Yao Yongqing, Xia Bin, Ge Shaoyen
1988, 3(2): 161-163,190.
Abstract PDF(382KB) icon1763 icon374
Abstract:
The film-cooling uniformity of discrete holes in the direction normal to main stream is investigated by means of heat and mass analogy. At different blowing ratios, the features of the film-cooling uniformity for one row and two rows of discrete holes are compared. It is found that the film-cooling uniformity on the concave surface is better than that on the convex one.
A DESIGN METHOD OF “WIGGLESTRAP” FILM-COOLING CONSTRUCTION OF FLAME TUBE
Li Changlin
1988, 3(2): 164-166,190.
Abstract PDF(318KB) icon1654 icon386
Abstract:
This paper presents a calculation method for the design of three types of "wigglestrap" film-cooling construction, i. e. the square, the trapeze and the double circle arc constructions, which are applied to the flame tube of aeroengine. When the airflow distribution and the cooresponding airflow passage section areas are given, all parameters of the construction can be determined.
A JET THRUST MEASUREMENT METHOD WITH GAS COMPOSITION ANALYSIS
Peng Shiyi
1988, 3(2): 167-168,191.
Abstract PDF(244KB) icon1262 icon482
Abstract:
A new method is proposed which uses composition analysis of gas from engine for determining jet thrust at a given fuel consupmtion. This method has been verified in JT15D engine testing, and the thrust error is about 6.9%.
FLIGHT TEST ON ENGINE SURGE INDUCED BY SIMULATED MISSILE FIRING
Li Shuren
1988, 3(2): 169-171,191.
Abstract PDF(363KB) icon1546 icon409
Abstract:
Based on flight test data of the engine surge induced by simulated missile firing, the behaviors of the surge are analyzed. The space and time response to the surge, the features of the surge course, and the formation and movement of the hammer shock are considered.
EFFECTS OF INLET-GUIDE-VANE WITH VORTEX GENERATOR ON PERFORMANCE OF AIR-INTAKE
Wang Xiaowen, Zhang Shiying
1988, 3(2): 172-174,191.
Abstract PDF(410KB) icon1787 icon373
Abstract:
An experimental investigation has been made on improvement of flow field in an air-intake with inlet-guide-vanes by the aid of vortex generators. Emphasis is placed on the effects of the vortex generator configuration and location on the performance of the air-intake.
EFFECTS OF Al203 DEPOSIT ON PERFORMANCE OF SOLID PROPELLANT ROCKET ENGINE
Fang Dingyou
1988, 3(2): 175-177,192.
Abstract PDF(349KB) icon1450 icon362
Abstract:
The A1203 mass fraction collected from the interior surface of nozzle is correlated with the material of throat insert, combustion pressure and Al content in the propellant. The thrust loss resulted from A1203 deposition should be considered in performance prediction and has been calculated in this paper.
ESTABLISHMENT OF VARIABLE VANE REGULATION LAW
Wang Zhengmu
1988, 3(2): 178-180,192.
Abstract PDF(318KB) icon1747 icon404
Abstract:
An approach to establish optimum regulation law of the variable vane for a turbojet engine is presented. The stable operating boundary of the engine can be determined according to matching with effective flight conditions.
THE 3-D BOUNDARY LAYER ON ROTATING BLADE
Zu Guojun, Chen Maozhang
1988, 3(2): 181-182,192.
Abstract PDF(251KB) icon1502 icon370
Abstract:
The 3-D boundary layer equations with rotation terms are presented in oblique curvilinear coordinates. After treatment of the governing equations, the basic equations are discretized by backwind difference scheme, and the two parts of them are solved by cross iteration.

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