2009 Vol. 24, No. 12

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Experimental study on combustion instability of lean premixed swirl flame
GUO Zhi-hui, WANG Shuai, LI Lei, ZHANG Cheng-yu, SUN Xiao-feng
2009, 24(12): 2367-2642.
Abstract PDF(1162KB) icon1762 icon625
Abstract:
An experimental study was conducted on combustion instabilities in a lean-premixed swirl-stabilized combustor at atmospheric pressure and temperature.The result shows that the combustion instability occurred in the model combustor is self-excited under longitudinal oscillation mode,the premixing section resonates with the combustor at the unstable mode of the system,and the oscillation frequency depends on the whole system.The equivalence ratio was identified to have major impact on the onset of instabilities.With equivalence ratio increase,the combustion was transited from stable to unstable states,and reached a limit cycle at last.In the occurrence of instability,the flame became much shorter and penetrated into the corner recirculation.The instability mechanism probably stems from the strong interaction between flame dynamics and flow oscillations inside the combustor,but more work is needed to provide an in-depth physical understanding of the mechanisms to initiate and sustain combustion instabilities.
Experimental investigation on drag of strut
SU Yi, LIU Wei-dong
2009, 24(12): 2643-2648.
Abstract PDF(831KB) icon1571 icon495
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Experiments were conducted in a scramjet direct-connected wind tunnel facility with a combustion heater,which supplies Mach 2.7 airflow with a total temperature of 1 337 K.The drags of struts with different heights(H=37.5,71mm) and sweepback angles(0°,30°,45°) were studied by a thrust-measuring system.Experimental results in cold flow indicate that,the drag of strut rises with increase of height and declines with increase of sweepback angles.The drags of struts under combustion condition of different fuel equivalence ratios were investigated.It is found that the drag of strut under combustion condition is less than that in cold flow,and declines with increase of fuel equivalence ratio.
Steady thermal analysis of regeneratively cooled scramjet
JIANG Jin, ZHANG Ruo-ling, LE Jia-ling
2009, 24(12): 2649-2654.
Abstract PDF(1618KB) icon1967 icon495
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In order to analyze the heat transfer in the regeneratively cooled scramjet,three-dimensional internal computational fluid dynamics(CFD) platform and computational program of domestic aviation kerosene properties were incorporated to develop a three-dimensional thermal evaluation code.The code was used at Ma=4.9 operating condition as well as Ma=5.86.The numerical results show the local high temperature areas of scramjet.The code was also used to study the effects of coolant distribution on the scramjet cooling.
Two-dimensional numerical simulation of reactive flow in aero-engine combustor with detailed chemical kinetic mechanisms
HOU Kuan-xin, LIU Yong, ZHAO Jian-xing
2009, 24(12): 2655-2660.
Abstract PDF(737KB) icon1448 icon468
Abstract:
The paper presented a numerical simulation of turbulent flow in a reduced aero-engine combustor model with the detailed chemical kinetic mechanisms of n-C7H16.Under the two-dimensional body-fitted grid,the turbulent characteristics were estimated by k-ε equations,the reacting rate was estimated by eddy dissipation concept(EDC) model.In the paper the reacting model was perfectly stirred reactor(PSR),the concentrations of the major components and thermal flow results were gotten,and the relationship between some certain components validated the feasibility.The results of the EDC model basically agree with the one-step reactions with EBU-SRK(eddy break up-simplified reaction kinetics) model.
Jet structures and phase transition process of supercritical aviation kerosene fuel injection
GAO Wei, LIN Yu-zhen, LIANG Huo-sheng, XU Quan-hong
2009, 24(12): 2661-2665.
Abstract PDF(620KB) icon1527 icon576
Abstract:
The injection of supercritical RP-3 aviation kerosene fuel into a quiescent atmospheric environment was experimentally investigated to study the jet structures and phase transition process near the nozzle exit.It was found that supercritical kerosene jets injected above the critical point underwent ideal-gas-like expansion and exhibited visible Mach disk shock structures.The axial location of the Mach disk increased with the injection pressure,and the injection temperature had little effects on the axial location of Mach disk.The phase transition process analysis revealed that the supercritical kerosene fuel was penetrated into the gas region from the supercritical region directly at the nozzle exit,without going through two-phase region at higher injection temperature.Fuel condensation phenomenon occurred in the nozzle and fuel entered two-phase region when fuel was injected near the critical point.
Experimental study of the characteristics of flame jet in crossflow
GAO Wei, LIN Yu-zhen, ZHANG Chi
2009, 24(12): 2666-2670.
Abstract PDF(1095KB) icon1573 icon541
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The characteristics of flame jet into crossflow were experimentally investigated.The influences of the parameters of jet and main flow on jet penetration depth and temperature characteristics were studied under atmospheric pressure and temperature.The temperature field of jet flame and an expression of jet penetration depth were attained.Results show that the temperature of the flame jet decreases and boundary of the jet is widened along the jet trajectory.The penetration depth of jet flame increases with increasing ratio of jet and main flow's momentum.And,the penetration depth of jet flame was larger than cool jet under the same ratio of momentum.
Design and experimental research on 6 cm-diameters head-swirl micro-combustor
YAO Shang-hong, LEI Yu-bing, ZHU Yan
2009, 24(12): 2671-2677.
Abstract PDF(1637KB) icon1944 icon514
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The concept of new form of combustor named as head-swirl micro-combustor was studied to improve the performance of the micro-combustor.The experiment on the ambient temperature and pressure was carried out,the resistance characteristic shows that the combustor couldn't get into modeling state.The characteristics of the limit blow-out show that,the head swirl takes great advantage in keeping the fire stabilization,and the loading parameter is more satisfactory than that without the head swirl,the combustion efficiency is 0.8 at most,the major reason to the low efficiency is attributed to the short residual time for gas to stay in the combustor.The structure of head-swirl is successfully used in the micro-combustor design.
Numerical investigation on two parallel flows mixing excited by synthetic jets
NIE Meng-meng, ZHANG Jing-zhou, TAN Xiao-ming
2009, 24(12): 2678-2682.
Abstract PDF(1073KB) icon1584 icon473
Abstract:
Numerical investigations on two parallel flows mixing process excited by the synthetic jets were performed to understand the effects of synthetic jet excitation parameters on the mixing process.As compared to the mixing flow field without synthetic jet excitation,the synthetic jets induce a complicated vortex structure in the mixing flow field through periodical blow-entrain action.These vortexes generate convective mixing between two parallel flows,making it helpful to shorten the length of primary flow core.As the synthetic jet excitation frequency or excitation amplitude increases,the vortex intensity and the mixing effectiveness are obviously enhanced.
Prediction of transitional flows using an improved low-Reynolds-number turbulence model with transition sensitivity
YAN Ming, SU Xing-yuan, WEI Ran, SHENG Chun-hua
2009, 24(12): 2683-2688.
Abstract PDF(1806KB) icon1747 icon546
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The paper presented the initial development of an improved two-equation low-Reynolds-number(LRN) turbulence model with transition sensitivity,based on the Launder-Sharma(LS) turbulence model.Several modifications were made for LS model's disadvantage on realizablity and stagnation point anomaly.The improved model only uses local variables.No need of calculating wall distance,y+ and boundary layer integral parameters makes it can be used for a wide range of flows,and this feature also makes it more easily implemented into general-purpose computational fluid dynamics(CFD) codes.The numerical simulation results of T3A test,a zero pressure gradient transitional flat plate boundary layer flow experiment,with detailed experimental data shows that the improved model can predict transitional flow,including an appropriate response to freestream turbulence intensity variety.
Effect of bowed and swept rotors on wake transportation in a transonic compressor
MAO Ming-ming, SONG Yan-ping, WANG Zhong-qi
2009, 24(12): 2689-2694.
Abstract PDF(1274KB) icon1365 icon437
Abstract:
The unsteady 3-D flow fields in a transonic compressor at design point were simulated numerically to study the effect of the bowed and swept rotors on rotor wake fluctuation intensity and transportation progress.The results show that,as compared to the baseline,all three types of bowed or swept rotors weaken the fluctuation intensity of tip leakage vortex and the top fluctuation core of wake at rotor outlet,thus quickening the dissipation during downstream transportation and helping to reduce the unsteady disturbance on the top of stator.The fluctuation intensity of the middle part of swept or bowed rotor wake increases to some extent,and the middle-part low energy fluid of rotor wake intends to move downwards during transportation,so the stator is disturbed stronger at mid-span and near hub.
Numerical investigation of impeller-diffuser interaction in a centrifugal compressor
LIU Yang-wei, LIU Bao-jie
2009, 24(12): 2695-2702.
Abstract PDF(1095KB) icon2391 icon521
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Steady and unsteady simulations were conducted to investigate the complicated flow in a transonic centrifugal compressor with splitter blade.Results from the steady and unsteady simulations were compared and the interactions between impeller and diffuser were studied in detail.The results indicate that the impeller/diffuser interaction can affect a range of 30% impeller chord for impeller trailing edge on impeller performance and whole chord length on diffuser performance.The potential effects of the diffuser caused an unsteady pressure disturbance for the impeller exit,leading to the unsteadiness of impeller load,tip leakage flow and losses.While the unsteadiness of impeller exit flow caused periodical variation of inlet flow conditions for the diffuser,and the inlet flow angle was found to be the most significant parameter in setting diffuser performance,resulting in significant unsteadiness of blade load and total pressure recovery coefficient.
Coupled heat transfer simulations of a transonic vane by taking account of transition flows
WANG Qiang, GUO Zhao-yuan, ZHOU Chi, YAN Pei-gang, FENG Guo-tai, WANG Zhong-qi
2009, 24(12): 2703-2710.
Abstract PDF(2457KB) icon1511 icon499
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The Abu-Gharmam Shaw(AGS) transition model and a one-equation intermittency transition model were added into the Navier-Stokes(N-S) solver,HIT-3D,so as to investigate the effect of laminar-turbulent transition on predicting thermal load of vane.The test case was 5411 run of NASA-MARKⅡvane,a transonic turbine vane.The full turbulent models and transition models were employed by the coupled heat transfer simulations.The results show that the transition model can predict the transition process in the boundary layer near the vane,and that the simulations with such models lead to thermal load matching well the experiments.Since the grids cells near the vane surface are coarse,the simulations with the intermittency equation lead to results worse than those with the algebraic transition model.
Aerodynamic performance of a highly-loaded low-pressure turbine profile
LUO Hua-ling, QIAO Wei-yang, XU Kai-fu
2009, 24(12): 2711-2718.
Abstract PDF(1485KB) icon1516 icon475
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Based on Lantry-Menter transition model,aerodynamics of a highly-loaded low-pressure(LP) turbine profile with a Zweifel lift coefficient of 1.2 at different freestream turbulence intensities and Reynolds numbers,both under steady and unsteady inflow conditions,were numerically investigated in this paper.The numerical results show that,the freestream turbulence intensity has remarkable effects on the boundary layer flow on the profile suction surface and the profile loss at low Reynolds numbers under steady inflow conditions.At low Reynolds numbers and low freestream turbulence intensity,the unattached separation flow existing on the suction surface near the trailing edge leads to the rapid increase of the profile loss relative to that at high freestream turbulence intensity.The suppression of the separation bubble by upstream unsteady and periodic wakes can further reduce the profile loss at low Reynolds numbers.It can be concluded that the current LP turbine design system should take into account and make well use of the true environment characteristic of high freestream turbulence intensity in LP turbines.
Controller partitioning method for integrated flight/vectoring propulsion control
LI Yan-shuang, SUN Jian-guo
2009, 24(12): 2714-2820.
Abstract PDF(796KB) icon1530 icon484
Abstract:
The controller partitioning problem for the integrated flight/vectoring propulsion control was presented in detail,and an analytical controller partitioning was obtained using a stepwise procedure.Based on the results of the analytical controller partitioning,an optimization scheme for controller partitioning using nonlinear least-squares method was proposed.The optimization scheme proposed in this paper is quite effective and easily realizable.Then,an optimal controller partitioning was obtained using the optimization scheme for the integrated flight/vectoring propulsion control.The experiments on many nonlinear simulation examples demonstrate that the performance of closed-loop system with the optimal partitioned subcontrollers is almost the same as that achieved by the centralized controller,indicating that the controller partitioning scheme discussed in this paper is quite suitable and successful.
Performance numerical investigation of double-channel fan/compressor
LI Xiao-juan, JIN Hai-liang, GUI Xing-min
2009, 24(12): 2719-2726.
Abstract PDF(2539KB) icon1521 icon481
Abstract:
A core and bypass combined calculation method of full-speed performance and surge boundary of the multi-stage double-channel fan/compressor was established.The circumferentially averaged Euler equations with two modeling source terms were employed to reduce the overall computation effort,while modeling blade force and friction force were employed along with incidence angle and deviation angle proposed by NASA SP-36 to model the two source terms.By combining with Koch surge boundary model,the simulation program was conducted for the overall aerodynamic performance of one transonic fan stage and a high bypass ratio fan/compressor.As compared with experiment and 3-D simulation,the results show the circumferentially averaged method can fulfill the requirement of practical application.
Linear stability model of rotating stall based on direct numerical techniques:Part Ⅰ—Theoretical model and algorithm
HOU Rui-wei, SUN Xiao-feng
2009, 24(12): 2727-2734.
Abstract PDF(2507KB) icon1639 icon498
Abstract:
A linear stability model of rotating stall in axial flow fan/compressors was presented based on direct numerical methods to Navier-Stokes equations,which was described as an eigenvalue problem.The inception point of rotating stall can be predicted by the model without requiring more experimental or empirical relations as input data.Two different methods,finite difference method and spectral collocation method,have been proposed to discretize the eigenvalue equation and the relevant comparison and analysis also have been given in the present investigation.
Linear stability model of rotating stall based on direct numerical techniques:PartⅡ——A simplified model and its applications
HOU Rui-wei, SUN Xiao-feng
2009, 24(12): 2735-2740.
Abstract PDF(2435KB) icon1608 icon486
Abstract:
A two-dimensional linear stability model was presented,which can be used to estimate the inception point of rotating stall in axial flow compressors by solving the eigenvalues,the effects of the blade rows in compressors on the flow field have been modeled by body force source terms in the momentum equations.Two methods,finite difference and spectral collocation methods,have been used to discretize the eigenvalue equations.The validations of model have been performed in two different cases,and the results show that the simplified model is able to predict the stall onset point of low-speed axial compressors.
PNS-NS combined method for solving two-dimensional powered airbreathing hypersonic vehicle's flowfield
HE Xu-zhao, LE Jia-ling, SONG Wen-yan
2009, 24(12): 2741-2747.
Abstract PDF(796KB) icon1427 icon480
Abstract:
To improve the computational efficiency of airbreathing hypersonic vehicle's flowfield,a combined computational fluid dynamics(CFD) method,which combines space marching method for parabolized Navier-Stokes(PNS) equations and time iteration method for Navier-Stokes(N-S) equations,was used to simulate airbreathing hypersonic vehicle's flowfield.Space marching method was used to solve the PNS equations in the supersonic dominated regions,and time iteration method used to solve the N-S equations in the stream direction separation or subsonic dominated regions.For solving the two-dimensional(2-D) airbreathing hypersonic vehicle's flow field with chemical reaction,the combined CFD procedure can get the same results with the same accuracy and also improve computational efficiency for several folds as compared with traditional time iteration methods.
Investigation of nozzle vector control using synthetic jet actuator
LIU He, DONG Jin-zhong, WU Nai-ming, ZHAO Xin-jun, LIU Chang
2009, 24(12): 2748-2755.
Abstract PDF(1960KB) icon1694 icon572
Abstract:
Novel fluidic actuators based on synthetic jet technology were used to experimentally investigate the effectiveness on the flow vector control.In the proper conditions,the primary jet's vector could change at angles exceeding 30 degrees.It is proved that the alteration of flow vector angle is correlated with not only the actuator parameter,the flow velocity and flow rate,but also with the downstream wrap sucking field with low pressure,which is formed by the action of "vortex pair" during the actuator operating.It is also closely correlated with the coupling effect between the vortex pair and the free shearing layer.This is treated as the mechanism of vector control.
Analysis of mode transition with thrust smoothing of small turbine/ramjet combined cycle engine
HUANG Hong-chao, WANG Zhan-xue, CAI Yuan-hu
2009, 24(12): 2756-2762.
Abstract PDF(2121KB) icon1962 icon509
Abstract:
The goal of this study is to establish mathematical model for computing performance and analyzing the thermodynamic parameters variation of turbine/ramjet combined cycle engine during mode transition.Firstly,the computed flow charts of performance and thermodynamic parameters of combined engine,and the criteria of determining design parameters of combined engine were given.Secondly,according to computed performance and thermodynamic parameters along flight trajectory and design limitations,such as the Mach number at ramjet burner entrance＜0.3,the reasonable mode transition periods were optimized,and geometry parameters of critical section were given.Thirdly,the effects of opening area of mode transition valve on thermodynamic parameters,especially the relations of total and static pressure,were analyzed.The quantitative opening area of mode transition valve along flight trajectory were given for satisfying the criteria of thrust smoothing.At last,the thrust and specific impulse of turbine/ramjet combined cycle engine were calculated along flight trajectory.
Experimental investigation of short isolator with a full ramp under asymmetric incoming flow
CAO Xue-bin, ZHANG Kun-yuan, JIN Zhi-guang
2009, 24(12): 2763-2767.
Abstract PDF(603KB) icon1477 icon472
Abstract:
An isolator with a full ramp was designed to improve the performance of the isolator or to reduce the length of the isolator.The ramp was placed on the lower wall at the isolator entrance.Experiment was conducted in Mach 1.98 at the isolator entrance.Experimental results indicate that,the length of the shock train is reduced by 19.8 percent for the rectangular isolator with the full ramp.The length of shock train in the isolator without a ramp is 13.87 times the height of the isolator entrance,but the length of shock train in the isolator with the full ramp is reduced to 11.12 times the height of the isolator entrance under the same back-pressure cases.The maximum back-pressure is improved by 8.45 percent for the isolator with a ramp which can withstand a maximum back-pressure of 3.85 times static pressure,but the isolator without a ramp could only withstand a maximum back-pressure of 3.55 times static pressure.
Design and application of engine test gas path fault diagnosis system
ZHU Da-ming, ZHU Zhi-li, TANG Hai-long
2009, 24(12): 2768-2772.
Abstract PDF(476KB) icon1911 icon456
Abstract:
A gas path fault diagnosis system was established with the whole engine test data for the study.The system functions and the implementation flow chart were described.The fault diagnosis and optimal adjustment module was established using failure mode and adjustment model.And then taking a dual-shaft turbofan engine as an example,numerical experiments were conducted for noise and results analysis.Finally,the development of the system was discussed.
Investigation of drag reducing in three-dimensional sidewall inlet
WEI Yong-bin, ZHANG Kun-yuan
2009, 24(12): 2773-2779.
Abstract PDF(1107KB) icon1386 icon493
Abstract:
Two sorts of three-dimensional sidewall inlets: standard inlet,and low drag inlet developed by taking some measures of decreasing drag in the standard inlet,had been investigated with methods of wind-tunnel experiments at Ma0 =5.3 and numerical simulations.The results show that the measure of decreasing drag is effective and pressure drag decreases about 4.7% and friction drag decreases about 4.9% at Ma0 =5.3;the additive drag can be turned into additive thrust and total drag decreases about 4.7% at Ma0 =5.3.Here,the collectivity performance is also improved.
Simulation analysis of a car interior flow field
XU Xiao-ming, ZHAO You-qun
2009, 24(12): 2780-2783.
Abstract PDF(556KB) icon1344 icon440
Abstract:
Car models were built by software CATIA.In consideration of the flow field characteristics of a car aerodynamics,three-dimensional incompressible Navier-Stokes equations and RNG(renormalization group) k-ε model were used in simulation.Second-order upwind difference scheme was applied to obtain the physical quantities of control pedal.The cooling air inlet of engine compartment was placed in the front of car,simulation on three different removal modes of cooling air was implemented to select a superior ventilation mode by comparing with aerodynamic characteristics of car.The flow inlet of cab was placed between the hood and windshield,simulation on three different removal modes of flow inside the cab was implemented to select a superior ventilation mode.Interior flow of engine compartment has greater impact on drag coefficient,interior flow of cab has greater impact on lift coefficient.
Comparison between distance test method and TIC method for simulation results
FU Hui-min, CHEN Jian-wei
2009, 24(12): 2784-2788.
Abstract PDF(1771KB) icon1574 icon474
Abstract:
According to dynamic consistency test of simulation results,comparative analysis of distance test method and TIC(Theil's inequality coefficient) method was given.As the rejection regions for dynamic simulation result test were obtained at a given level of significance by the distance test method,quantitative test of dynamic consistency was realized.TIC coefficient was used to test the simulation result consistency,but the coefficient could be affected by selection of coordinate origin,causing possibly misjudgement.Therefore,the method cannot realize quantitative test,nor realize effectively qualitative test.The comparative analysis shows that the distance test method will not be affected by dimension and selection of coordinate origin,and reach a high credibility of test results.
Dynamic performance analysis of low pressure turbine(LPT) component with damping-sleeves
ZENG Liang, WANG Xiao-li
2009, 24(12): 2789-2795.
Abstract PDF(1238KB) icon1522 icon480
Abstract:
The natural characteristics and dynamic response of low pressure turbine(LPT) component with damping-sleeve was analyzed by elastic and contact mechanics.For different disturbing forces(single radial exciter and rotating radial exciter),the damping-sleeve has shown great effect in vibration control with the action of "frequency-transfer" and friction damping.The simulation results confirm the validity of the proposed model and method.There are best parameters of damping-sleeve,which lead to the best effect of vibration control.The vibration control of damping-sleeve differs from various modal shapes of LPT component.Some suggestions are given for the design of labyrinth air seals in vibration control according to the analysis.
Real-time performance reliability prediction for civil aviation engines based on Brownian motion with drift
REN Shu-hong, ZUO Hong-fu, BAI Fang
2009, 24(12): 2796-2801.
Abstract PDF(1625KB) icon1701 icon552
Abstract:
This paper studied the civil aviation aircraft engine.The reliability of the engine has been studied by the performance degradation theory and stochastic process methods.Firstly,the reliability model based on Brownian motion with drift was built by analyzing the performance degradation process of the engine.Then,the degradation-time prediction method for current degradation signals was developed by using the characteristic of Brownian motion.These models were applied to practical situations.It is shown that the proposed methods are feasible and the prediction accuracy meets the needs of the project.Also,it provides a foundation for scientific management of engine fleet of airlines.
Computational modified model and experimental verification of compressive strength of the X-cor sandwich
DANG Xu-dan, XIAO Jun, TAN Yong-gang, LI Yong, YUAN Yong-hu
2009, 24(12): 2802-2807.
Abstract PDF(1071KB) icon1367 icon390
Abstract:
The generation process of residual stress during the curing process of X-cor sandwich was described,and the analytical results indicate that carbon fiber Z-pins are subject to residual tensile stress.In consideration of the effects of residual stress,Z-pins were treated as beams upon an elastic foundation,then a sort of compressive strength computational modified model of X-cor sandwich was proposed and its compressive strength was computed.The X-cor sandwich samples of different density,diameter and angle of Z-pins were made for compressive strength experiments.Through contrast between experimental and computational results the computational model was verified.The residual stress increases as the Z-pin's diameter and density become bigger,or decreases as the Z-pin's angle increases.
Simulation on hydromechanical controller of modern aero-engine
XU Min, WANG Xi, ZENG De-tang, XUE Min-dong
2009, 24(12): 2808-2813.
Abstract PDF(1308KB) icon1724 icon458
Abstract:
The accurate simulation of aero-engine hydraulic mechanical controller was investigated by combining the computer technique and numerical simulation.A set of components library was founded,and then the whole control system of aero-engine was simulated accordingly.This simulation method was applied to the control system design of an aeroengine.Simulation results show that the requirement for controller is satisfied.
Calculation and analysis on film thickness of the slippers based on hydrostatic bearing in the aeronautical fuel piston pump
HE Bi-hai, SUN Jian-guo, YE Zhi-feng
2009, 24(12): 2821-2827.
Abstract PDF(676KB) icon1735 icon469
Abstract:
The friction pair between swash plate and slipper is very important in the aeronautical fuel piston pump,and has great effect on the service life of the piston pump.Variation laws of the film thickness with rotor angle,angle of swash plate,pocket pressure and pressing force were obtained.The differential equations of the variation of the film thickness were established,hence the dynamic law of the film thickness in one period was further obtained.By the calculation method of the film thickness,the lubrication condition in one period between swash plate and slipper can be obtained,offering a theoretical basis for the design of the slippers in aeronautical fuel piston pump.
Gas dynamic resonance performance of circle injector
YU Nan-jia, CAI Guo-biao, ZHANG Guo-zhou
2009, 24(12): 2828-2833.
Abstract PDF(561KB) icon1699 icon427
Abstract:
By means of analysis of the trailing flow field structure of different circle injectors,the relationship between the position of shock wave specific to injector diameter,and the pressure of inlet flow/pressure of environment was determined.From numerical simulation of circle injector with cylinder resonance tube and cone resonance tube,it is concluded that the necessary condition the intense resonance can occur within resonance tube lies in the position of resonance tube's entrance in the expand wave field;and if the position is in shock wave field,the resonance can not occur within resonance tube.Now the region where resonance occurs can be gained from free jet flow field by means of numerical simulation.The best matching between injector and resonance tube was obtained by analyzing the resonance heating performance variation with different diameter injectors.
Design and experiment research for oxygen-rich preburner of FFSC
LI Mao, JIN Ping, WU Zhi-qi, YU Nan-jia, CAI Guo-biao
2009, 24(12): 2834-2838.
Abstract PDF(744KB) icon1890 icon506
Abstract:
A design scheme of oxygen-rich preburner with division combustion,downstream dilution and nickel coatings was presented based on the full flow staged combustion(FFSC) rocket engine cycle.The firing sequence of fuel-rich starting-up and oxygen-rich shutting-down was designed and 26 times experiments were completed.The influence of the different downstream dilution flux on the uniformity of the product temperature was investigated primarily.The results show that the structure of preburner is rational,and the reliability of ignition and security of structure are reached.The distribution of the product temperature is influenced remarkably by downstream dilution in the experiments.And,an optimum downstream dilution flux exists.
Rattling response of vibration lapping of spiral bevel gear
YANG Jian-jun, DENG Xiao-zhong, FANG Zong-de
2009, 24(12): 2839-2844.
Abstract PDF(724KB) icon1514 icon475
Abstract:
The torsional vibration model of vibration lapping process for spiral bevel gear under displacement excitation was established,and the method of local maps between pre-impact and post-impact states was introduced.The Poincaré map relation was deduced in consideration of the oblique-impact vibration between teeth under the influence of sliding friction.The calculation method for Lyapunov exponent of vibration lapping system of spiral bevel gear was obtained.The dynamic response for a given gear lapping system with the change of excitation parameter was analyzed by employing phase plane plots,Poincaré map,Lyapunov exponent and bifurcation plot compositely.The results show that,with the increase of excitation amplitude,the gear lapping system exhibits a period from doubling route to chaos in single-side tooth impact state,and the period window can be found in chaotic region.With the continued increase of excitation amplitude,a double-side tooth impact phenomenon of the lapping system appears.

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