2006 Vol. 21, No. 5

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Investigation of two-phase and multi-cycle detonation
ZHANG Yi-Ning, WANG Jia-Hua, ZHANG Jing-zhou
2006, 21(5): 789-794.
Abstract PDF(450KB) icon1650 icon406
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In order to study the two-phase detonation wave characteristics,a series of experiments at different frequencies were conducted on a pulse detonation engine(PDE) prototype,the diameter and the length of which are 58 mm and 1370 mm respectively.The data of dynamic pressure and ion signal were collected simultaneously in the PDE combustion chamber.The PDE prototype can work at frequency up to 50 Hz with gasoline/air mixture.The two-phase and multi-cycle detonation wave characteristics were described firstly from combustion mechanism.The detonation wave propagated at about 1300m/s,and the width of induction zone is about 30mm.The reaction zone width is about 80mm,and behind the reaction zone there exists reaction delay of liquid fuel drops.Data simultaneous collection can be used to judge whether actual detonation in the PDE combustion chamber occurs.
Influence of density ratio on the discharge coefficient of turbine blade film cooling holes
DENG Ming-chun, ZHU Hui-ren, WANG Xue-wen, XU Du-chun
2006, 21(5): 795-799.
Abstract PDF(304KB) icon1923 icon477
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Discharge coefficients of the film cooling holes were investigated using a large-scale low speed turbine cascade.Discharge coefficients with coolant injection were determined at different density ratio,blowing ratio and Reynolds number.The results show that the influence of density ratio of secondary flow to mainstream flow on discharge coefficients of the film cooling holes is different at different hole array position.The effect of density ratio on suction surface and leading edge is more evident.The data of turbine blade surface film holes discharge coefficients obtained from experiments with small difference in temperature of the secondary and mainstream airflow should be corrected when it was attempted to apply to practice.
Steady heat transfer analysis of multilayer thermal insulations for metallic thermal protection system
YAN Chang-hai, MENG Song-he, CHEN Gui-qing, QU Wei, LIU Guo-qian
2006, 21(5): 800-804.
Abstract PDF(1277KB) icon1731 icon456
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Combined energy equilibrium equation and two thermal flux approximation methods were used to establish the steady heat transfer mathematic model of the multi-layer thermal insulations in the metallic protection system.Radiation attenuation index of fibrous thermal insulations and emissivity of heat insulation screen were optimized by genetic algorithm and experiment that measured the effective conductivity of the multilayer thermal insulation element.The experimentally measured effective conductivity data of the multi-layer thermal insulations validate steady heat transfer model of the multi-layer thermal insulations,which adopt optimized thermal physical parameters.
Experimental investigation on atomization of an air-blast atomizer with plain-orifice nozzle and dual-swirl cup
ZHANG Chi, ZHANG Rong-wei, XU Guo-qiang, LIN Yu-zhen
2006, 21(5): 805-809.
Abstract PDF(344KB) icon1875 icon437
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An air-blast atomizer consisting of a plain orifice nozzle and dual counter-rotating radial swirlers was experimentally investigated to obtain sauter mean diameter(SMD) and Rosin-Rammler distribution parameter at different pressure drops and air-fuel ratios.The mean diameter and distribution parameter of fuel spray were measured by Marlven particle size analyzer.The experimental results show that the SMD and distribution parameter of fuel spray decrease with increasing air pressure drop and air-fuel ratio,and a critical air-fuel ratio occurs in the transitional process,when the actual air-fuel ratio exceeds the critical,the SMD and the distribution parameter change little with changing air pressure drop and air-fuel ratio
Effect of flow parameters and equivalence ratio on the trapped vortex combustor performance
HE Xiao-min, YAO Feng
2006, 21(5): 810-813.
Abstract PDF(632KB) icon1870 icon454
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Trapped Vortex Combustor(TVC) is a simple,compact and high performance gas turbine combustor.The TVC design consisted of two parts,a pilot combustor for stable combustion and a main combustor for power.The effect of a variety of parameters such as inlet temperature,airflow rate and equivalence ratio on the performance of TVC had been studied.Experimental results show:(1) the ignition of the TVC is independent of the main airflow rate in the range of 0.45～0.7 kg/s;(2) the lean blowout limit is improved with a decrease in airflow rate and with a increase of inlet flow temperature of 360～510 K;(3) combustion efficiency improves with the increase of equivalence ratio to the maximum value of 99% in the range of overall equivalence ratio between 0.34～0.4.
Film cooling and superposition method for double row dust-pan shaped holes
ZHU Hui-ren, GUO Tao, XU Du-chun
2006, 21(5): 814-819.
Abstract PDF(551KB) icon1754 icon472
Abstract:
Film cooling effectiveness for injection from single row and double row dust-pan shaped holes has been studied experimentally.The differences of cooling performance between single row and double row holes were described.Results show that the optimal blowing ratio of injection from double row holes is higher than that of injection from single row holes.In the case of higher blowing ratio,the traditional superposition calculation method under-predicts the film cooling effectiveness of double row injection based on that of single row hole injection.The modified superposition calculation method is given in the present paper.
Experimental investigation on heat transfer in shrouded rotating disk with high-positioned air inflow
XU Guo-qiang, ZHANG Sheng, LUO Xiang, DING Shui-ting, TAO Zhi, LEI Bin
2006, 21(5): 820-823.
Abstract PDF(326KB) icon2013 icon464
Abstract:
The heat transfer characteristics of the rotor-stator disk system were investigated experimentally.The distributions of temperature on the rotating disk surface,local and averaged Nusselt number of the rotating disk were obtained from the test.Conclusions are drawn as follows:The temperature gradient near disk center is insignificant;the Nusselt number at the inner radial position is almost invariable;and at outer radial position is increased with the increase of inlet mass flow coefficient.The averaged Nusselt number is dramatically increased with the increase of inlet mass flow coefficient.
Large-eddy simulation of turbulent spray combustion in an annular combustor
YAN Ying-wen, ZHAO Jian-xing, ZHANG Jing-zhou, LIU Yong
2006, 21(5): 824-830.
Abstract PDF(1685KB) icon1711 icon495
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In three-dimensional arbitrary curvilinear coordinate system,an Eulerian-Lagrangian two phase large-eddy simulation(LES) approach was employed to predict instantaneous gas-liquid two-phase turbulent combustion flows in an annular combustor.Three dimensional body-fitted grid was generated by using an elliptical grid generation procedure.The k-equation sub-grid scale model was used to simulate the sub-grid eddy viscosity,the EBU combustion sub-grid scale model was used to determine the chemical reaction rate,the six-heat flux model was applied to predict the radiant heat transfer.The gas phase was solved with SIMPLE algorithm and hybrid scheme in non-staggered grid system.A Stochastic Separated Flow formulation was used to track the droplet trajectories velocities,size and temperature history by using Lagrangian equations of motion and thermal balance.To avoid the need for detailed calculations in the near wall regions,wall functions was extended to the body-fitted coordinate system.The calculated and measured temperature profiles at outlet plane were in reasonable agreement.It shows that system,in arbitrary curvilinear coordinate system,and an Eulerian-Lagrangian two phase LES formulation may be used to investigate turbulent two-phase reacting flows and combustion process in combustors.
Interior local heat transfer!characteristics of midchord region due to sparse film cooling holes
ZHANG Jing-yang, CHANG Hai-ping, XU Lei, GAO Hou-feng
2006, 21(5): 831-836.
Abstract PDF(413KB) icon1848 icon457
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The cooling flow and heat transfer in the midchord region of turbine blade are very complex as a result of the reciprocity among the impinging jet,initial cross-flow and outflow from film cooling holes.Experiments are carried out in order to acquire the local and average heat transfer characteristics for various impinging Reynolds numbers,density flow ratios of film outflow to initial cross flow,density flow ratios of initial cross flow to impinging jet flow and impinging distance to impinging jet hole diameter when complex flows exist.Moreover,the variations of local Nusselt number and average Nusselt number characteristics in the whole target surface and different regions of that have been discussed so as to disclose the incidence of the sparse film holes to the interior heat transfer in the midchord of turbine blade.
Numerical investigation of two-phase reacting flows in annular combustor domes with swirl cup
CAI Wen-xiang, HU Hao-sheng, ZHAO Jian-xing
2006, 21(5): 837-842.
Abstract PDF(1931KB) icon1723 icon465
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In arbitrary curvilinear coordinate system,numerical simulations of three-dimensional and two-phase reacting flows in annular combustor domes with the swirl cup are performed.The block-structured grids are generated by solving a system of elliptic partial differential equations.The gas phase equations are solved in an Eulerian frame of reference.Modified k-ε model is employed to describe the turbulent characteristics.Modified Eddy Dissipation Model-Arrhenius turbulent combustion model is used to determine the reaction rate.To consider the influence of heat radiation,the six flux model is applied to the predictions of radiant heat transfer in the combustor.The liquid phase is treated in a Lagrangian frame of reference with the particle trajectory model.Hybrid scheme and SIMPLE algorithm are used to solve the finite-difference equations in non-staggered grid system.The couple of the gas phase and the liquid phase is adopted by the Particle Source in cell Method(PSIC).The calculating swirl number is in agreement with experimental data.Predictions show that the influence of different geometries of the swirl cup on combustor flow characteristics is considerable.So the combustion performance may be improved by the optimum design of the swirl cup.
Study on vaporization rate of a mini Г-vaporizer under atmospheric pressure condition
LIN Yu-zhen, LIU Jun, XU Quan-hong, WEI Wen-bo
2006, 21(5): 843-847.
Abstract PDF(1404KB) icon1368 icon469
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Experimental study of vaporizing characteristics of a mini engine's "Г" type vaporizer was presented.The experiments were conducted under the atmospheric air pressure.The main factors of the vaporization rates including the Air/Fuel Ratio(AFR),vaporizer inlet air temperature and the velocity of the airflow within the vaporizer were studied extensively.From the test results,it can be concluded that the AFR and the vaporizer inlet temperature are the important parameters to the fuel vaporization rates,and the increasing of the AFR and the inlet air temperature will cause an increase of the vaporization ratio.
Reliability sensitivity investigation of impact-rub for rotor-stator systems
ZHANG Yi-min, LIU Qiao-ling, LI He, WEN Bang-chun
2006, 21(5): 848-853.
Abstract PDF(383KB) icon1903 icon419
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On the basis of the impact-rub dynamics equations of Jeffcott rotor-stator systems with imbalance,the reliability sensitivity investigation of rotor-stator systems of rotating machinery under impact-rub is presented.Techniques from Kronecker algebra,matrix calculus,fourth moment analysis,probabilistic perturbations,reliability theory and sensitivity technique are employed to systematically develop the mathematical and numerical expressions for reliability sensitivity analysis of rotor-stator systems.The effects of shaft stiffness and damping, stator stiffness and damping,radial clearance and stator radial stiffness on reliability sensitivity are studied and discussed.The numerical results are obtained.
Vibration performance of contact system of labyrinth assembly
ZENG Liang, LI Lin
2006, 21(5): 854-861.
Abstract PDF(387KB) icon1876 icon427
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The analysis of contact system vibration is complex due to its non-linearity and chaotic behaviors in the process.This paper formulates the equivalent linear model of labyrinth assembly by introducing local contact rigidity and using vibration mechanical theory.The vibration performance of contact system of some types of labyrinth assembly is simulated with variable damper size,circumferential numbers and size of interference fit by using FEM software.The simulation results confirmed the validity of the proposed simplified model and relevant theory analysis.
Investigation of disk LCF life prediction and its experimental verification
WANG Wei-guo, GU Yuan-xing, QING Hua, TENG Guang-rong
2006, 21(5): 862-866.
Abstract PDF(1522KB) icon2189 icon571
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A simplified Walker strain model was presented to predict the disk Low Cycle Fatigue(LCF) life for unsymmetrical loads and the main life regions.The effect of number of life critical regions in each disk was taken into account in the life prediction.A series of axial strain-controlled LCF tests of GH4133 bar specimens were conducted.An experimental turbine disk was designed,and the high temperature LCF test of the rotor was carried out on the spin test rig.The result indicates that the disk LCF life prediction method is effective,and the accuracy of the life prediction is within the targeted scatter band of two compared to the turbine disk LCF test data.
A method for reducing strain-life curve of low cycle fatigue
ZHANG Guo-dong, SU Bin, WANG Hong, ZHONG Bin, XU Chao
2006, 21(5): 867-873.
Abstract PDF(239KB) icon2718 icon442
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Based on Manson-Coffin equations of low cycle fatigue(LCF) under strain controlled to acquire strain-life curve,a new technique for determining strain-life curve of LCF is developed.When fatigue life is shorter than 5000 cycles,experimental data of LCF under strain controlled are used.But when fatigue life is longer than 5000 cycles,experimental data of high cycle fatigue(HCF) under stress controlled are employed.This new method of combining LCF with HCF allows to avoid long fatigue life with small strain test under strain controlled,thus test expenses may be saved and test time shortened.Experimental data of LCF and HCF are reduced by new method for superalloy GH141,at temperature 760℃. Strain-life curves obtained by simply Manson-Coffin equation and by new method are in good agreement.The new method combining by LCF with HCF can be used to get strain-life curve of LCF.
Effects of mean stress and its scatter on vibrational reliability of structures
Chen Li-wei, Wang Yan-rong
2006, 21(5): 874-878.
Abstract PDF(307KB) icon1767 icon449
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Based on traditional structural vibration analysis,the effects of mean stress and its scatter have been introduced into the vibrational reliability model of structures by use of Goodman curve and the interference theory of stress and strength.Combined with other relative parameters' scatter,the vibrational reliability model has been established separately while considering mean stress to be deterministic and stochastic,and the corresponding formulations and procedures for reliability computation have been presented.Compared with Monte-Carlo simulation,the numerical results indicate that the model proposed in this paper is reasonable and feasible,meanwhile they also indicate that reliability decreased as the mean stress and/or its scatter increased.
Parallel computing of series solution of precise integration for structural dynamic response
LI Yuan-yin, JIN Xian-long, ZHANG Xiao-yun, LI Gen-guo
2006, 21(5): 879-883.
Abstract PDF(1437KB) icon1662 icon456
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Storage requirements of precise integration method were discussed.Series solution of the method suits dynamic response analysis of large-scale structures much better than other methods.Parallel computing of series solution has been researched and implemented.Time integration of precise integration method includes two items.The first item was computed serially and the second item was computed in parallel.Then a corresponding flowchart was given.Load distributed strategies were discussed for the parallel algorithm.The unbalanced distribution of time steps was implemented.The strategy can decrease the waiting time of the initial value for each processor.The final example shows that parallel algorithm of series solution has high speedup.
Experimental and numerical study of jet mixing enhancement with wedged nozzle
LIU Xin, JIANG Nan
2006, 21(5): 884-890.
Abstract PDF(968KB) icon1420 icon455
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Experimental flow field measurement of the circular and various wedged turbulent jets has been carried out.Simultaneously,standard k-ε model has been employed in the numerical simulation of the mean flow fields of various turbulent jets corresponding to the measured values.Comparison research has been performed to analyze the fragmentation and enhanced mixing effect of the nozzles with different number of wedge on the multi-scaled turbulent eddy structures in the free jet flow.The experimental and numerical results show that the energy distribution of wedged jets in space is different from that of the circular jet with the energy at the center being transported sidewise.Furthermore,due to the wedges not only the eddy structures at the wedge tines in the near field are broken up,but also the interactions such as eddy structures rejoining and entrainment take place at different locations normal to the flow along the longitudinal development of the jets.
Numerical study of conical vortices space evolvement on a flat roof
LI Peng-nian, ZOU Zheng-ping, CHEN Xue-rui, GU Zhi-fu
2006, 21(5): 891-896.
Abstract PDF(1142KB) icon1352 icon445
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Using the computational fluid dynamics software FLUENT,wind load and conical vortices of a building were simulated with the v2-f turbulence model and k-ε turbulence model.The wind angle of attack is 40° relative to the eave of the building.It shows that the v2-f turbulence model can give fairly good results compared to the experimental pressure data.With the increase of x,the sizes of the conical vortices on the flat roof increase firstly and then fall off when they arrive at the ackside of the building.Simultaneously conical vortices and the vortex shed from the lateral wall of the building have great interaction.Also it gets the immanence relation of the space evolvement,intensity and positions of the conical vortices on the flat roof.
An efficient method for increasing mass flow capture ratio of a three-dimensional sidewall compression scramjet inlet
JIN Zhi-guang, ZHANG Kun-yuan
2006, 21(5): 897-902.
Abstract PDF(679KB) icon1657 icon424
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For a typical backward-sweep sidewall compression scramjet inlet with two ramps and mid-located sidewalls,a modified inlet with higher mass flow capture ratio was designed by reducing the second ramp angle and using circular arc compression surface.The flow filed was numerically simulated and comparisons were made between the modified inlet and the typical one at the free stream Mach number of 6 and 4.Numerical results indicate that most of the performance parameters of the modified inlet are obviously improved and the mass flow capture ratio is greatly increased by using the new method.At Mach 6 incoming condition,the mass capture ratio of the modified inlet was 0.87,which was 14.5 percent higher than that of the typical one;at Mach 4 incoming condition,the mass flow capture ratio was 0.69,19% percent higher than that of the typical one.
Experimental study of a serpentine inlet under ground running
JING Jian-peng, GUO Rong-wei
2006, 21(5): 903-908.
Abstract PDF(451KB) icon1630 icon470
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Experiments of a serpentine inlet under ground running have been done and described in this paper.The study was performed in a low speed wind tunnel with an independent air-pumping system.It contains air-pumping tests at zero and different speeds of the free stream.The results show that:(1)When the inlet Mach number of the flow at exit increases,the total pressure recovery decreases,and the circular steady total pressure distortion coefficient,turbulence intensity and synthesis distortion increase.In comparison with the results measured in highspeed wind tunnel tests for the serpentine inlet at the same exit Mach number,the total pressure recovery is lower and the circular steady total pressure distortion coefficient,turbulence intensity and synthesis distortion are larger.(2)Under ground air-pump running,when the serpentine inlet is running at the exit Mach number Mae=0.45,the total pressure recovery coefficient equals 0.90,circular steady total pressure distortion coefficient equals 9.24%,turbulence intensity equals 4.6%,and synthesis distortion equals 13.85%,so it can be seen that the distortion of the flow delivered by the inlet may be too large to fit the engine.(3)When the air-pumping system and the wind tunnel are operating together,as it happens when the plane is ground taxiing,the performance of the inlet is getting better with the wind speed increasing.
Bandwidth influence on frequency spectrum analysis of high speed fan noise
JIN Peng, WANG Tong-qing
2006, 21(5): 909-913.
Abstract PDF(1138KB) icon1945 icon466
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Components of Blade Passing Frequency(BPF) are the important elements of fan noise.In the spectrum analysis of noise signal,it was discovered that different analysis bandwidth made a significant difference in the BPF component value.In this paper,the Fast Fourier Transform(FFT) processes with different bandwidth for the same record of noise were discussed.Because the result of SPL is the energy sum within a bandwidth,while the range of BPF variation due to the varying rotating speed exceeds the bandwidth,the variation of bandwidth will make the SPL different.Finally,a method for determining the fan noise spectrum was introduced.
Numerical simulation of stator clocking effect in a low speed compressor
QI Lei, ZOU Zheng-ping, CHEN Fu, XU Guo-qiang, DING Shui-ting
2006, 21(5): 914-922.
Abstract PDF(1266KB) icon1649 icon527
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The unsteady flow in a low speed compressor with repeated stages was simulated by numerical simulation of 3-D viscous flow.The influence of clocking and the interaction of wake,boundary layer and leakage vortex were discussed.The results show that only a 0.1% overall efficiency variation due to clocking of the second stage stator is found,and it is considered that the clocking effects in low speed compressor is not distinct.The unsteady flow indicates that the upstream wake can influence the boundary layer,wake and leakage flow of the downstream flow.
Design optimization of compressor blades using parallel genetic algorithms
WANG Guang-wen, ZHOU Zheng-gui, HU Jun
2006, 21(5): 923-929.
Abstract PDF(1613KB) icon2244 icon454
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Simple Genetic Algorithm is improved with Niche and adaptive operator,the new algorithm called Improved Genetic Algorithm(IGA) is parallelized using WinSock,multithread and Client-Server architecture.Blade profiles are parameterized using Hicks Henne function,2D cascade flow fields are calculated by using NavierStokes equation method.To form software for design optimization of compressor blade profiles,the IGA is combined with the above blade profile parameterization and flow field calculation method.The software can be used for design of compressor blades or improvement of existing blades.In this paper,design of two compressor blade profiles is taken as examples.The inlet Mach number of two cascades composed of the blades is about 0.5 and 0.9,respectively.To insure improvement of cascade aerodynamic performances in whole work ranges,the objective functions are constructed from consideration of both design and off design point performances.In the optimization procedure,three computers are run in parallel to reduce design time.The aerodynamic performances of optimal blades are obviously better than that of the initial blades.
Numerical study on coupled heat transfer of thrust chamber with regenerative cooling
ZHANG Hong-wei, TAO Wen-quan, HE Ya-ling, FENG Zhen-ping
2006, 21(5): 930-936.
Abstract PDF(1852KB) icon2099 icon486
Abstract:
Numerical study on coupled heat transfer of the hot gas,chamber wall and coolant was performed.The two-dimensional Navier-Stokes equations were adopted to describe the hot gas flow,while a reduced one-dimensional model was employed for the coolant flow and heat transfer,and one dimensional heat transfer model was used to calculate the coupling heat transfer through the wall.The N-S equations were discretized by the finite volume method in body-fitted coordinates and the coupling of pressure and velocity was implemented with the compressible form of SIMPLE algorithm.The compressible form of the standard k-ε turbulence model was adopted to simulate the hot gas flow.Radiation of gas stream was also considered and simulated with the FLUX model.Results show that the method adopted in this paper can simulate two dimensional gas flow field well.Moreover, the method can calculate the heat flux through the wall,wall temperature and the temperature increase of coolant quickly.The numerical results are expected to be helpful for the design,especially for cooling scheme design of rocket engines.
Optimization analysis of the main parameters of hydrogen-oxygen FFSC
ZHANG Li-hui, LING Gui-long, DUAN Na, TANG Jia-peng
2006, 21(5): 937-942.
Abstract PDF(388KB) icon1914 icon428
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According to the appointed carrier mission and setting the pay load of the space transportation craft(STC) as objective function,energy characteristic model, mass model and orbit model of the hydrogen-oxygen FFSC(Full Flow Staged-Combustion Cycle) were established,and the numerical method was used to optimize the performance parameters.Through calculation,the veracity of the mass model was verified;optimized engine performance parameters for single stage to orbit were obtained and the optimized results with current level of chamber pressure were presented.This method could provide guidance for the development of the new generation hydrogen-oxygen FFSC rocket engine.
Flow and performance calculation of absorber/thruster of solar thermal propulsion
ZHANG Chun-liang, WANG-ping
2006, 21(5): 943-948.
Abstract PDF(1318KB) icon1811 icon446
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Based on experimental data about large STP(Solar Thermal Propulsion),structural analysis and experimental condition estimation were made.By means of equal wall-temperature model and FLUENT software,inner-flow,heat-transfer and performance characteristics were calculated.Calculation results are in good agreement with experimental data.It has important meaning for design STP.
Dynamic frequency calculation of the spiral bevel gear under prestress
LI Sheng-peng, FANG Zong-de
2006, 21(5): 949-955.
Abstract PDF(653KB) icon1961 icon403
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Being an important part in aero-engine,the spiral bevel gears were frequently destroyed from syntony.A modal analysis of the spiral bevel gears under prestress caused by rotating speed and meshing torque was carried out by ANSYS.Dynamic frequencies of the spiral bevel gears with different geometrical parameters were calculated.The finite element models were established using a design and analysis system of spiral bevel gear which had been developed by ourselves.The result shows that rotating speed and meshing torque have certain effect on dynamic frequency.

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