1989 Vol. 4, No. 2

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ON MECHANISM OF ENHANCED HEAT TRANSFER OF FLUIDS WITHIN PIPES BY OSCILLATION
Cao Yuzhang, Zhao Lingde, Zhu Gujun
1989, 4(2): 105-109,193.
Abstract PDF(466KB) icon1501 icon61
Abstract:
Theoretical and experimental studies show that axial oscillation of a fluidwithin pipes can lead to enhancing heat transfer of the fluid. The enhancement multiple of hey ans-fer is a function of (△x/R)2, Womersley number (Worn) and Prandtl number (Pr). Under lerinar conditions, intensive mixture of fluid lumps is impossible. It can be considered that the heat trans’er of the oscillated fluid is completed in form of conduction. In the case of lower Womersley number. the velocity and displacement profiles of the fluid are paraboloids. Normal temperature gradient on the displacement profile for the oscillated fluid is greater than that for the static fluid. Also, the effective conduction area of the oscillated fluid is greater than that of the static fluid. Therefore, the conductive heat transfer rate of the oscillated fluid is obviously greater than that of the static fluid. The oscillation is only the means to make a enhanced area of heat transfer and enhanced temperature gradient continuously. According to this mechanism, the relation of (a1/a) - 1∝ (△x/R)2 is derived . Also, the effects of Womersley number, Prandtl number and wall of the pipe on the enhanced heat transfer are elaborated in this paper.
APPLICATION OF THE BOUNDARY ELEMENT METHOD TO UNSTEADY HEAT TRANSFER PROBLEMS
Ding Jing
1989, 4(2): 110-114,193.
Abstract PDF(389KB) icon1498 icon46
Abstract:
The boundary element method is applied to analyzing temperature field transient distribution on aeroengine turbine blades. It is possible to calculate the thermal stesses and life span of the blade and to check the blade strength according to the temperature field determined by this method. The temperature distributions on a set of different sections in a turbine blade at several instants have been calculated.
MODELLING FOR EXHAUST POLLUTION PERFORMANCES OF A SINGLE OR A VAPORISER TUBE COMBUSTOR
Li Huiying, Liu Lin, Tang Ming, Wang Mongji
1989, 4(2): 115-120,193-194.
Abstract PDF(615KB) icon1357 icon40
Abstract:
On the basis of experimental study on exhaust emissions in a single tube combustor and a vaporiser tube combustor, a theoretical analysis and mathematical modelling are made by using heterogeneous Well Stirred Reactor Analysis (WSR). Considering rea! combustion processes and different combustion structures, the General Reactor Analysis and Simulation Program (GRASP) are improved and supplemented. A new method is put forward to process the distribution of mixture mass with different φand to determine exit flow parameters in the primary zone. This paper aiso deals with the secondary air flow and its mixture with primary gases, the local fuel-rich treatment and the calculation of equilibrium temperature and compositions, in this way, the GRASP has been developed from one only for a simple model combustor to a modification able to predict 17 emission compositions and combustor exit temperature for two real gas turbine comb tors. The results predicted by the modified GRASP are in good agreement with measured data. The prediction also confirms the conclusion drawn from experiments that the emission pollution performance of the vaporiser tube combustor is better than that of the single tube combustor. Moreover, it is found that the errors in prediction of the exit temperature are one of the reasons which cause the errors in NOX prediction.
EFFECTS OF FUEL CHEMICAL PROPERTIES ON EXHAUST SMOKE FROM GAS TURBINE COMBUSTOR
Jin Rushan, Lefebvre A. H.
1989, 4(2): 121-126,194.
Abstract PDF(601KB) icon1619 icon33
Abstract:
The state-of-the-art of the study on soot formation and exhaust smoke From gas turbine combustor has been reviewed with stress on the effects of fuel chemical properties. Based on a great amount of experimental data obtained on a variety of gas turbine combustors. the best correlation parameter representing the fuel effect has been determined as SP-0.92(100-Δx)-0.4, where SP is smoke point,V is the naphthalene content ( in percentage) of the fuel.
EXPERIMENTAL INVESTIGATION ON LIQUID FILM THICKNESS OF ATOMIZING CHANNEL
Liu Zhigang, Wang Jiahua
1989, 4(2): 127-129,198.
Abstract PDF(290KB) icon1265 icon27
Abstract:
In order to find out the fuel distribution on the surface of the atomizing channel, the resistance sensor are used for measurement of the liquid film thickness. The principle of the measurement is described. The thickness and the wave frequence of the liquid film on the surface of the atomizing channel have been measured in the conditions of different air velocities, widths of the channel, injection pressure and diameters of nozzles.
AN EXPERIMENTAL RESEARCH ON MIXTURE PRESSURE LOSS IN COMBUSTOR
Mo Lixiao
1989, 4(2): 130-132,199.
Abstract PDF(296KB) icon1602 icon38
Abstract:
Mixture of cold air flow from annular pass through holes with main flow(cold or hot stream) has been researched experimentally. The momentum exchange for annular pass air flow through plain or plunge circular holes into main flow has been studied experimentaaly on a rectagular test section in a simulated combustion chamber. The momentum exchange increases the pressure loss of the main air stream near the jet holes. The results show that the mixture pressure loss of combustor with plunge circular holes is 1 to 1. 5 time as large as that of the combustor with plain circular holes. Therefore, the combustor with plunge circular holes is favourable to combustion and may reduce the length of the combustor.
COLD FLOW MEASUREMENTS FOR A DOUBLE SWIRLER COMBUSTOR
Zhang Qingfan, Zheng Qingping, Sao Yiming, Zang Xiaomei
1989, 4(2): 133-134,199.
Abstract PDF(233KB) icon1749 icon47
Abstract:
The cold flow patterns in a double swirler combustor have been measured byusing a six-orientation hot-wire probe technique. The results show that the central recirculation zone for counter-rotating swirling is different from that of co-rotating swirling. A better pattern in the central recirculation zone for combustion will be obtained if the swirler angles of both the outer swirler and the center swirler are chosen reasonably.
EXPERIMENTAL RESEARCH ON SWIRLING COMBUSTION EFFICIENCY
Huang Xianjian, Tan Haoyuan, Cui Wei
1989, 4(2): 135-136,199.
Abstract PDF(229KB) icon1487 icon29
Abstract:
This paper describes the experiments of combustion performances in twokinds of swirling augmentor models. The combustion efficiencies and stabilizing limits have been measured. The length of flame have been observed. The experiments of swirling combustion under small swirl angles have been completed, in which the flame could not been stabilized in recirculation zone. Results, show that the efficiency of swirling combustion increases approximately 20% in comparison with that of V-flameholder and the length of flame is obviously shortened.
INVESTIGATION ON UNSTEADY FLOW FIELD AND ENDWALL BOUNDARY LAYER IN AXIAL FLOW COMPRESSOR WITH HOT WIRE ANEMOMETER
Lin Qixun, Guo Ningfang, Li Ysping, Xiao Ningfang
1989, 4(2): 141-144,195.
Abstract PDF(345KB) icon1489 icon70
Abstract:
The measurement method of rotating stall is presented. The oifferencebetween two signals and its frequency are determinea correcry on the basis of the spectrum analysis. Then, the number of rotating stall regime, its spread velocity and is for tained. The methods of the two-dimensional unsteady flow measurement are described. The.ocits distribution of the unsteady flow, for example a rotating stall cell, is obtained. A rotating gie a re method is applied to measuring the two-dimensional boundary layer. The results meater ehind a single rotor and a stator are shown in the paper. The contamination from dirt, the influeru of air flow temperature and the boundary layer flow field disturbance caused by probe hole had been consid-ered.
MEASUREMENT OF THREE-DIMENSIONAL FLOW IN TURBOMACHINERY WITH A SINGLE SLANTED HOT-WIRE
Li Yuchun, Jiang Haokang
1989, 4(2): 145-149,195.
Abstract PDF(445KB) icon1530 icon35
Abstract:
An improvement to measuring three-dimensional mean flow field in turoo-machinery with a single slanted hot-wire is presented. The method features high accuracy and broad angular measuing range. In order to obtain the three-dimensional flow field, the single slanted wire sets in several positions around the probe axis. The data are sampled with the help of a high speed data acquisition system and the phase-locked ensemble average technique. Then, the three- dimensiorial mean flow field is calculated by means of a data processing program developed by the authors. A periodic three-dimensional flow field at the exit of an axial-flow compressor rotor successfully measured. A proof calculation against the calibration data shows that the errors in velocity measurement are less than one percent of the mean velocity and the errors in the flow direction are less than one degree.
MEASUREMENT OF THREE-DIMENSIONAL MEAN AND TURBULENT FLOW FIELD WITH A DOUBLE SLANTED HOT-WIRE PROBE
Chen Fan, Jiang Haokang
1989, 4(2): 150-154,195-196.
Abstract PDF(489KB) icon1554 icon45
Abstract:
A method to improve the measurement of three-dimensional mean and turbulent flow field with a double slanted hot-wire probe is presented. A prominent feature of the method is that the coefficients of direction t and h are determined according to the directional characterisitics of the wires. Therefore, there is no need to measure the flow direction at each measuring point prior to the velocity measurement along this predetermined direction.
PRIMARY EXPERIMENTAL INVESTIGATION ON EROSIVE BURNING IN A NOZZLELESS SOLID PROPELLANT ROCKET MOTOR
Zhang Chaocai, Sun Xuquan, Lu Zhenzhang
1989, 4(2): 158-160,200.
Abstract PDF(266KB) icon1852 icon35
Abstract:
A new apparatus for investigating the erosive characteristics of the nozzlelesssolid propellant rocket motor by interruption of burning is presented. The erosive characteristics of HTPB composite propellant are obtained. The curves p-t computed with the erosive characterisitcs are compared with the experimental data. The experimental results show that the erosive characteristics of nozzleless rocket motors are similar to those of the rocket motor witha nozzle.
EFFECTS OF AXIAL VELOCITY DENSITY RATIO ON CASCADE PERFORMANCES
Liu Qianzhi, Yan Ruqun
1989, 4(2): 161-164,196.
Abstract PDF(381KB) icon1881 icon52
Abstract:
In turbomachinary cascade flows, the effects of Axial Velocity Density Ratio (AVDR) on cascade performances are very important. The theoretical and experiment of the problem are presented in this paper. The theoretical correlations of mafor cascade mances with AVDR are obtained. The comparisons of calculations and exper s are ir good agreemens
PREDICTION OF SPANWISE LOSS DISTRIBUTION OF COMPRESSOR ROTOR WITH A SEMIEMPIRICAL LOSS MODEL
Fan Sixin, Chen Maozhang
1989, 4(2): 165-168,196.
Abstract PDF(396KB) icon1575 icon39
Abstract:
Systematically checking calculations have been conducted to compare thesemiempirical loss models available in literatures for compressor rotors. It is found that neither the accuracy nor the scope of feasibility of these models can meet the demand of engineering prediction. A new model is developed on the basis of powered averaging of these models and employing the part-span damper loss model. The model can give quite accurate estimation for the spanwise loss distribution of a rotor, and has been successfully used in a streamline curvature method to predict the loss and flow field of an axial compressor rotor.
EXPERIMENTAL INVESTIGATION ON CHARACTERISTICS OF SINGLE AND TANDEM BLADE CASCADES WITH DOUBLE-CIRCULAR ARC PROFILE
Zhuang Biaonan, Guo Bingheng
1989, 4(2): 169-172,197.
Abstract PDF(509KB) icon1760 icon60
Abstract:
A single cascade and a tandem cascade with double-circular arc profile havebeen designed and investigated .which have same total cord, total camber, constructional inlet and exit angles, and solidity as the reference tandem compressor stator Wade of Turmo Ⅲc gas turbine engine. The inlet Mach number is 0. 3. The characteristics of both single and tandem cascades, such as the dependence of turning angle Δβ and coefficient of total pressure lossω on incidence angle i have been obtained. The experimental data are compared and analyzed.
STUDY ON NONLINEAR DUFFING CHARACTERISTICS OF FLEXIBLE ROTOR WITH SFDB
Meng Guang, Xue Zhongqing
1989, 4(2): 173-178,197.
Abstract PDF(502KB) icon1757 icon42
Abstract:
It is demonstrated theoretically and numerically that the flexible rotor-centralized squeeze film damper bearings (SFDB) system with multiple degrees of freedom has the nonlinear characteristics similar to those of the Duffing equation of one degree of freedom. The bcne curve and amplitude limit curve of the amplitude-frequency response curve of the system are derived. The relations among tne abuve three curves and their effects on bistable response are analyzed. It is found that the number of the intersection points of the bone curve with the amplitude limit curve determines the nonlinear forms of the system responses, and the amplitude limit curve is tangential to the amplitude-frequency response curve at the intersection point. Thus it is revealed how the Duffing and bifurcation nonlinear responses are formed. It is also proved that the squeeze film force will not change the rigid critical speed of the original system, but make the amplitude-frequency response curve de-1 fleet. This deflection always has the characteristics of hard spring,that is, the amplitude-frequency response curve will deflect in the direction of larger rotating speed. When this deflection reaches a certain degree, the bistable response occurs and it may appear in the both sides of the undamped rigid critical speed of the system.
AN ENERGY METHOD FOR CALCULATING THE LOCAL STRESS AT AN ECCENTRIC HOLE IN A TURBINE DISK
Lu Wenlin, Wei Bangxu
1989, 4(2): 179-182,198.
Abstract PDF(349KB) icon1368 icon42
Abstract:
A new method based on energy principle is derived to calculate local stress at an eccentric hole in a turbine disk under the elasto-plastic conditions. This method is not only simpleand practical, but also able to obtain more accurate results than those calculated by the modified Neu-ber method. A numerical example is also presented in this paper.
EXPERIMENTAL INVESTIGATION OF AEROENGINE HIGH-SPEED ROLLER BEARING
Feng Yangyuan, Shao Jiaxing, Zhan Mingxue
1989, 4(2): 183-184,200.
Abstract PDF(235KB) icon1925 icon54
Abstract:
A research work for developing aeroengine high-speed roller bearings with2. 5×106 DN has been completed. At first, a front roller bearing of a turbine rotor on an existing engine was tested to expose its defects as its DN was enhanced. Then, a new bearing 5D2002832N W has been designed to eliminate the these defects, the comparative tests have been carried out. The results show that the new bearing can meet the requirements of the roller bearing working at 2. 5×106 DN, when its design parameters are chosen reasonably.
CALCULATION OF UNSTEADY TRANSONIC FLOW FIELD IN A NOZZLELESS ROCKET MOTOR
Pei Ming, Li Yiming, Xia Xiangxing
1989, 4(2): 185-188,198.
Abstract PDF(366KB) icon1458 icon62
Abstract:
After some treatment of the ignition process, the MacCormark explicit prediction-correction schemes can be adapted to predicting the one-dimensional unsteady flow field and interior ballistics in a nozzleless rocket motor from ignition to the end. The interior ballistics of cylindrical proforated and slab charges in the nozzleless rocket motor are calculated and compared with each other. The predicted results are in agreement with the experimental data. Moreover, the computations reveal that the choking position appears somewhat downstream to the geometric throat position and the thrust increases as the angle of divergence decreases and vice versa.

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