2015 Vol. 30, No. 12

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Structure Strength and Vibration
Influence of the shroud's radial position on vibration characteristics of the fan blade
HONG Jie, WEN Min, MA Yan-hong, ZHANG Da-yi
2015, 30(12): 2817-2823. doi: 10.13224/j.cnki.jasp.2015.12.001
Abstract PDF(948KB) icon1210 icon653
Abstract:
The influence of the shroud's radial position on the vibration characteristics of the fan blade considering its dynamics design requirements was investigated. Mechanical model of the shrouded fan blade was built based on beam theory, and the first order natural frequency was obtained using Rayleigh method. Further the influence of the shroud's radial position on the first order natural frequency was also acquired. The influence of the shroud's radial position on the contact status and vibration characteristics was also investigated by the nonlinear finite element method with contact elements. The results reveal that the stiffness and the first order natural frequency are maximal while the relative shroud's radial position is 0.75. The vibration characteristics for multi-modes are best while the relative shroud's radial position is 0.55-0.68. The pressure of the contact surface of the shroud decreases for the increasing of the relative shroud's radial position, and the tangential contact stiffness first increases and then decreases for the increasing of the shroud's radial position.
Multi-level design and optimization of turbine joint structure
SHEN Xiu-li, ZHANG Ye, LONG Dan, DONG Shao-jing
2015, 30(12): 2824-2832. doi: 10.13224/j.cnki.jasp.2015.12.002
Abstract PDF(843KB) icon1455 icon575
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For the optimization design of aero-engine turbine joint structure, a 3-step optimization method was developed based on different levels and requirements:basic parameter optimization for 2-D model of joint, joint structure optimization for 3-D model with disk and multidisciplinary optimization of aerodynamics and structural strength for disk. The 3-step optimization process was iterative; in the first step, the basic parameters were built; the secondary step was established on former results, while some important parameters influencing the disk can be taken into account. When the second step cannot meet the requirements or make the best result, the multidisciplinary optimization was conducted, the outlines of turbine flow path were designed according to aerodynamics analysis, and the 3-D turbine blades were introduced. Through the multidisciplinary optimization of aerodynamic and structural strength, the optimum solution can be obtained to realize the relatively best result of the two disciplines. The results show that, after the optimization the max radial stress of the joint structure dropped by 12.7% in the first step, the mass of turbine decreased by 6.9% in the second step and the comprehensive result of aerodynamic and structural strength increased by 2.4% in the third step while meeting the requirements of design.
Identification of modal damping of composite cylindrical shell based on sliding-envelop method
LI Hui, XUE Peng-cheng, XU Zhuo, SHEN Peng-fei, WEN Bang-chun
2015, 30(12): 2833-2839. doi: 10.13224/j.cnki.jasp.2015.12.003
Abstract PDF(830KB) icon1289 icon521
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Due to the complexity of the damping mechanism of composite cylindrical shell, there is no practical and effective method to identify such structural damping.A modal damping test method based on sliding-envelop method was proposed.First, damping test principle and overall plan of sliding-envelop method for modal damping of composite cylindrical shell were clarified in details.Then, its test procedures in the actual test of modal damping of composite cylindrical shell were summarized.At last, a composite cylindrical shell coated with constrained layer damping materials was used as a study object, and its modal damping were well identified and the relation between external excitation level and modal damping was discussed.Test results showed that the maximum variance obtained by the proposed method corresponding to the first five orders damping result was less than 0.02%, and the damping results had good repeatability, thus ensuring high testing precision.
Dynamics similarity criteria of rotor dynamic with gyroscopic effect
WANG Yong-liang, SUN Li-quan, CUI Ying, HAN Yu
2015, 30(12): 2840-2847. doi: 10.13224/j.cnki.jasp.2015.12.004
Abstract PDF(877KB) icon1379 icon679
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In order to study the dynamics similarily of actual rotor system with gyroscopic effect similar to the corresponding scaled model, the dynamic similarity criteria for rotor-support system considering gyroscopic moment were derived by using dimensional analysis method, and the similarity ratios of physical variables of actual rotor system and model were obtained. And the correctness of dynamics similarity criteria of rotor system with gyroscopic effect was verified by solving the analytical solution of critical speed for a Jeffcott rotor system at different similarity ratios, and by studying the similarity of critical speeds and modes for an actual rotor system based on the finite element simulation software ANSYS. It shows that the natural frequency of actual rotor system is similar to its scaled model in similarity speed, and the critical speed is similar for rotor system considering gyroscopic moment, simple support and Rayleigh proportional damping.
CBS finite element method with approximate boundary conditions for panel flutter
LI Kai-lun, WEI Yun, ZHANG Mei-lin, ZHANG Jia-zhong
2015, 30(12): 2848-2856. doi: 10.13224/j.cnki.jasp.2015.12.005
Abstract PDF(953KB) icon1089 icon556
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In order to simplify the solving process of Euler equation for panel flutter, approximate boundary conditions were successfully introduced into CBS (characteristic-based split) finite element method to simulate the panel flutter. The impact of moving boundary was treated as normal boundary conditions for Euler equation. From analysis, it is found that:first, the results by approximate boundary conditions agree very well with those by moving boundary method, and the application of approximate boundary conditions is more convenient; then, Euler equation, rather than 3rd order piston theory is able to capture the pressure jump caused by sharp points at the ends of panels; finally, CBS finite element method with approximate boundary conditions has potentials and advantages in solving the fluid-structure interaction problems of small deformation of slender bodies in inviscid compressible flows.
Failure analysis and prediction on the open-hole tensionof domestic carbon fiber composite
XIAO Meng-li, ZHANG Yong-bo, WANG Zhi-hua, FU Hui-min, YANG Xin
2015, 30(12): 2857-2862. doi: 10.13224/j.cnki.jasp.2015.12.006
Abstract PDF(802KB) icon1170 icon548
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Based on the research of the failure mode and damage mechanism of the notched domestic carbon fiber composite laminates and the experimental analysis, finite element models were established. Then the effect of different failure criterias on the residual strength of notcked domestic carbor fiber composite laminates was studied in the corresponding finite element model. Through the comparison between experimental data and simulation results, it was found that the two-dimensional model could predict the residual strength of the notched domestic carbon fiber composite laminates accurately, the relative error between numerical simulation result and experimental data of failure load was 7.9%,while the relative error of tensile modulus was 5.6%.
Structure and dynamics analysis of low pressure rotor in geared turbofan
YAN Wen-zhong, LIAO Xin, CAO Chong, HONG Jie
2015, 30(12): 2863-2869. doi: 10.13224/j.cnki.jasp.2015.12.007
Abstract PDF(719KB) icon1340 icon612
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Takeing the low pressure rotor in geared turbofan as object, the influences of structural parameters (i.e., supporting scheme and stiffness of supporting point) of low pressure rotor on its dynamics were studied by building simplified model of low pressure rotor and quantifying its dynamics through structural efficiency evaluation parameters. Meanwhile, the optimization design of the supporting scheme and stiffness of supporting point was carried out based on the relationship of the structural parameters and dynamics of the rotor. The optimization design of the supporting scheme and stiffness of supporting point was presented. As a result, it indicates that the dynamics performance of the rotor is optimal when the supporting scheme is 1-0-1 and stiffness of supporting points is 5.84×107N/m and 5.90×107N/m, respectively. At that moment, the angular non-deformability of the rotor is pretty good, and the distribution of the first two critical rotational speeds satisfies the requirements for resonance margin design and is limited within a small speed extent as well.
Effect of operating conditions on turbine rotor blade creep life
LI Na, YANG Xiao-guang, SHI Duo-qi, HU Xiao-an
2015, 30(12): 2870-2875. doi: 10.13224/j.cnki.jasp.2015.12.008
Abstract PDF(754KB) icon1339 icon595
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Based on Larson-Miller parameter, the effects of high pressure turbine relative rotational speed, flight altitude H and radial temperature distribution factor (RTDF) on turbine rotor blade creep life were analyzed quantitatively when these parameters deviated from design condition. The results show that when high pressure turbine relative rotational speed is reduced by 2% from its reference value, both the blade temperature and blade stress decrease by 6%. The creep factor increases substantially from 1 to around 186 in terms of blade root. With the increase of H, blade temperature increases and blade stress decreases. In terms of blade root, when H is deviated from its reference value, the creep factor is reduced under the combined action of temperature and stress. Far away from the blade root, the effect of temperature is more important and creep factor increases with the decrease of H. When RTDF reduces, the blade temperature decreases and creep factor increases.
Structure of non-contact shape control based on hierarchical genetic algorithms
ZHANG Xiao-fei, ZHENG Shi-jie, WANG Hong-tao
2015, 30(12): 2876-2881. doi: 10.13224/j.cnki.jasp.2015.12.009
Abstract PDF(752KB) icon1010 icon524
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Taking the non-contact shape control of a beam bonded with PLZT photostrictive actuators on its surface as an object, a control method was proposed by combining the structural topology optimization and hierarchical genetic algorithms. In this method, the topological distribution of photostrictive actuators and the light intensity were chosen as design variables, and the shape errors between the desired shape and the achieved shape of beam bonded with PLZT photostrictive actuators were taken as the fitness function. The distribution of PLZT photostrictive actuators and the light intensity were optimized by using structural topology optimization, hierarchical genetic algorithms and finite element method. The performance of the presented method for shape control was assessed in comparison with that of the conventional genetic algorithm. The results demonstrate that the speed of the evolution of the presented method has been improved by more than 91% and the errors between the desired shape and the achieved shape have been reduced by over 76% compared with the conventional genetic algorithm.
Study on vibration control of rotor with semi-active cage-type tuned mass damper
HUANG Xiu-jin, HE Li-dong, HUANG Wen-chao
2015, 30(12): 2882-2887. doi: 10.13224/j.cnki.jasp.2015.12.010
Abstract PDF(749KB) icon1179 icon512
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An application of tuned mass damper (TMD) in the semi-active vibration control of rotor system was proposed,which also had been studied. And a kind of semi-active cage-type tuned mass damper was designed without changing original supports of the rotor system. The section switch control technique based on the rotor speed was put forward.Based on laborary virtual instrument engineering workbench (LabVIEW), a closed loop system for the natural frequency regulation was developed for semi-active vibration reduction in which cage-type TMD was adjustable according to different rotor speeds. The single span rotor TMD test rig was built and the experimental study has been carried out. Experimental results show that rotor vibration is well controlled with the section switch control technique of the semi-active cage-type TMD when the rotor goes through the critical speed, the vibration damping effect reaching up to 83.4%, which helping to avoid the extra resonance peak caused by TMD.
Combustion Heat and Mass Transfer
Experiment on laminar combustion characteristics of RP-3 kerosene
ZENG Wen, CHEN Xin, MA Hong-an, LIU Yu, CHEN Xiao-xiao, HU Er-jiang
2015, 30(12): 2888-2896. doi: 10.13224/j.cnki.jasp.2015.12.011
Abstract PDF(1091KB) icon1266 icon573
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In order to illustrate the combustion characteristics of RP-3 kerosene, the laminar combustion velocity and Markstein length of RP-3 kerosene were investigated experimentally in a constant volume combustion bomb.The experiments were performed at four different pressures:0.1, 0.3, 0.5 and 0.7MPa, three different temperatures:390, 420 and 450K, and over the equivalence ratio range of 0.6-1.6.The influences of three crucial parameters:initial temperature, initial pressure and equivalence ratio on the flame structure, laminar combustion velocity and Markstein length were investigated.The results showed that increasing the initial temperature or decreasing the initial pressure could lead to an increase in the laminar combustion velocity of RP-3 kerosene.With the equivalence ratio increasing from 0.6 to 1.6, the laminar combustion velocity increased initially and then decreased gradually.The highest laminar combustion velocity was measured at fuel rich condition (equivalence ratio of 1.2).Furthermore, decreasing the initial pressure or equivalence ratio could increase the stability of the flame front, which is established by increased Markstein length.The effect of the initial temperature on the Markstein length is not clear; with the increase of the initial temperature, the Markstein length has a decreasing trend at some conditions for the equivalence ratios of 0.9-1.1, and an increasing trend over the equivalence ratios range of 1.2-1.5.
CFD simulation and experiment of transient spray for an air-assisted injector
YANG Hai-qing, CHEN Mao-jie, HUANG Li-ping, HU Chun-ming
2015, 30(12): 2897-2903. doi: 10.13224/j.cnki.jasp.2015.12.012
Abstract PDF(798KB) icon1516 icon580
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In order to research the transient spray characteristics of the air-assisted injector and verify the accuracy of the simulation model, the spray characteristics of the air-assisted injector were investigated by CFD simulation and experiment. The CFD simulation had been carried out that the transient injection with different back pressure and inject pressure was simulated. The spray development in the constant volume bomb had visualized by the high speed camera. The SMD of the fuel droplets in the atmospheric environmenthad measured by the laser particles test device. The results show that the high speed compressed air from the injector and the fuel are strongly coupled, and the vortex ring structures come out in the downstream; the increased average rate in experiment by reducing 0.2MPa of back pressure is 3.62 times than increasing 0.2MPa of inject pressure; the average error of average rate between experiment and simulation is 9.94%; the SMD average error of the outlying of injector between experiment and simulation is 4.33%.
On-line parameters measurement of combustion flame in engine using radiation spectroscopy
YANG Bin, GUI Xin-yang, ZHOU Wu, JIANG Yong-jun, QIN Fei, CAI Xiao-shu, HE Guo-qiang
2015, 30(12): 2904-2909. doi: 10.13224/j.cnki.jasp.2015.12.013
Abstract PDF(720KB) icon1117 icon502
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For the non-intrusive, on-line and in-situ measurement of high-temperature combustion flame in engine, the method based on radiation spectroscopy (RS) was presented. The system using optical fiber spectrometer was designed for on-line parameters measurements of flame in engine. The wavelength response of charge-coupled device (CCD) was calibrated by the blackbody furnace. Then, the radiation spectroscopy range of 200-1100nm wavelength of high temperature flame in rocket based combined cycle (RBCC) engine ground testing was obtained by using this system, and the temperature and radiance of flame were determined with Planck radiation law and the least square method. It can provide important reference for combustion diagnostics and optimization of engine.
Insulation design of aircraft pneumatic duct system based on air insulation
SHI Hong, JIANG Yan-long, CAI Yu-fei, PENG Yin, WANG He-xu
2015, 30(12): 2910-2918. doi: 10.13224/j.cnki.jasp.2015.12.014
Abstract PDF(1010KB) icon1105 icon502
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Based on the study of the performance of existing duct leakage detection system of commercial aircraft, an improved leakage detection system based on multilayer insulation design method was proposed. Also, the calculation method of multilayer insulation design was derived with engineering calculation method and the calculation of the insulation with different diameters was conducted. Meanwhile, in order to testify the accuracy of the method, the leakage detection experiment platform was built, and the outside surface temperature of air insulation in different air temperatures was obtained. Also, the influences of the number and the diameter of the diversion channel on the insulation calculation were investigated by numerical simulation. Finally, an optimized structure of the air detection system was proposed. The results show that the improved leakage detection system with quick diversion performance is superior to the traditional leakage detection system since the leakage signal can be detected in time and the alarm system can react quickly. Besides, the outside surface temperature of the insulation is averagely 23.08 percent larger than that of test, and decreases with the diameter and the number of the diversion channel. Also, as the number of the diversion channel increases, the influence of the diversion channel is more remarkable. This work could be helpful to domestic design of China's civil-aircraft ducting system.
Numerical simulation on the effect of misalignment on outlet flow field of double-swirler
JIANG Yao, HU Jian, HU Hao-sheng
2015, 30(12): 2919-2924. doi: 10.13224/j.cnki.jasp.2015.12.015
Abstract PDF(1044KB) icon976 icon454
Abstract:
Numerical simulation on outlet flow field of a double-swirler with misalignment of the first and second stages was performed by Fluent software, and standard k-ε model was chosen for the turbulence model.The numerical simulation was conducted on three configurations with different misaligned dimensions (0, 0.5, 1.7mm) and validated against the test data. The results show that misalignment has significant influence on the outlet flow field of a double-swirler, and distortion on the recirculation zone has already appeared since 0.5mm misalignment. Meanwhile, the zone with peak radial velocity is located at the region of X/D=0.5~1.0. Numerical simulations agree well with the test results for both axial and radial velocities.
Numerical study on the influences of tooth position in compressor stator well sealing
KONG Xiao-zhi, LIU Gao-wen, CHEN Kai
2015, 30(12): 2925-2933. doi: 10.13224/j.cnki.jasp.2015.12.016
Abstract PDF(952KB) icon1080 icon460
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Numerical simulations of the flow and temperature fields were carried out at different tooth positions in compressor stator well sealing. The sealing characteristics, swirl characteristics and windage heating characteristics of a labyrinth sealing with different tooth positions were studied. Influences of relative different positions of single, double and triple teeth on the discharge coefficient, outlet swirl ratio and windage heating were studied. The results show that the discharge coefficient is minimum, outlet swirl ratio and windage heating are maximum when the single tooth is placed at downstream position. Under the double teeth condition, when one is at upstream position and the other at downstream position, the discharge coefficient is minimum. Under the triple teeth condition, when upstream, downstream and middle positions are separately provided with a tooth, the discharge coefficient is minimum. With the decrease of discharge coefficient, the outlet swirl ratio and windage temperature increase.
Distribution of forces induced by rotation in rotating limited lamilloy
BAI Guo-qiang, CHANG Hai-ping
2015, 30(12): 2934-2941. doi: 10.13224/j.cnki.jasp.2015.12.017
Abstract PDF(937KB) icon918 icon476
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The distribution of forces induced by rotating limited lamilloy was researched by numerical simulation. It was emphasized that because the cool fluid was heated, the centrifugal force was reduced with the increase of the radius, and became lower near the wall, but higher far from the wall.The Coriolis force directed y was evident in the areas of inlet and outlet, but it could be ignored in the middle of lamilloy. The Coriolis force directed z was evident in the areas of inlet and outlet, and increased slowly with the increase of the rotation speed and radius. The buoyancy force caused by centrifugal force increased the velocity of fluid near impact zoo, but in the other zoo and near the wall, it decreased the velocity of fluid, and far from the wall, it also increased the velocity of fluid. In the middle lamilloy, centrifugal force and buoyancy force caused by centrifugal force played a leading role.
Turbomachinery
Characteristic of controlling flow separation in divergent curved channels by pulsed jet
ZHU Jian-feng, HUANG Guo-ping, FU Xin, FU Yong
2015, 30(12): 2942-2948. doi: 10.13224/j.cnki.jasp.2015.12.018
Abstract PDF(948KB) icon981 icon465
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Combined with the pulsed jet overall control ruler of divergent curved channels, the steady and unsteady characteristics of flow fields in channel under different frequency states were analysed. Results show that the flow characteristics change amplitude is similar along the radial direction under steady control state, and the influence of steady jet suppresses the complex flow phenomenon and linearly changes the flow characteristic of the flow field. Under suitable pulsed jet control state, the influence of pulsed jet on the flow field is presented by changing the fluctuation time-space characteristic of separation vortex, so that the influence amplitude increases along the radial direction, and the decreased magnitude of total pressure loss in the mainstream region is more obvious; meanwhile, the periodic characteristic of the dominant separation vortex is improved significantly, and the flow coherent structure is more orderly.
Application of blended blade/endwall in turbines
TIAN Yong, JI Lu-cheng, SHAO Wei-wei, XIAO Yun-han
2015, 30(12): 2949-2959. doi: 10.13224/j.cnki.jasp.2015.12.019
Abstract PDF(1355KB) icon942 icon447
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Blended blade/endwall was applied into turbine for finding out its effectiveness of application. Taking the TTM-stage as example, seven kinds of blended blade/endwall models were designed and numerically simulated and compared. The results show that:the leading edge's blending surface can weaken the horseshoe vortex; the side blending surface can weaken the corner separation; the blending surface of the vane reduces the height of the boundary layer of total temperature at the inlet of the blade, and then the passage vortex moves the fluid of high total temperature away from the hub wall, reducing the adiabatic wall temperature of the hub evidently.
Stall mode of centrifugal compressor and mechanism of self-recirculating casing treatment
KANG Jian-xiong, HUANG Guo-ping, ZHU Jun-qiang, WEN Dian-zhong
2015, 30(12): 2960-2969. doi: 10.13224/j.cnki.jasp.2015.12.020
Abstract PDF(1603KB) icon1307 icon543
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In order to explore the variation of stall mode with changing speed and the mechanism transition of casing treatment under different stall modes, numerical simulation of a centrifugal compressor with solid wall casing and casing treatment under different speeds was performed. The results showed that the stall mode transited from diffuser stall at 100% design speed to inducer stall with the speed decrease. Inducer stall also experienced from end wall stall and blade leading edge stall at 80% design speed to wide-range full stall at 50% design speed. The effect of self-recirculating casing treatment on stall margin and efficiency of centrifugal compressor were closely related to the stall mode, its stability enhancement effect was only valid for the blade leading edge stall at 80% design speed. At about 80% design speed, casing treatment tended to bring about bigger flow rate operating point for the main flow efficiency, thus reducing the efficiency. When the speed was low enough to 50% design speed, with a wide recirculation region in main flow passage, the secondary reverse flow in casing treatment could reduce the load of the impeller to passage recirculation region, so as to improve the efficiency.
Effect of bowed stator blade on stability enhancement by tip injection
WANG Qian, HU Jun, LI Liang, TU Bao-feng, LI Bi-yu
2015, 30(12): 2970-2975. doi: 10.13224/j.cnki.jasp.2015.12.021
Abstract PDF(921KB) icon932 icon476
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In order to study the effect of bowed stator blade on stability enhancement by tip injection, the experimental research on a low-speed axial flow compressor was carried out. The effect of stability enhancement by tip injection and the compressor internal flow field information were comparative analyzed when the first stage stator blades were bowed and straight stator blades. Results show that,the first stage straight stator blades replaced by bowed blades, the effect of stability enhancement by tip injection is more significant, this is because in the process of compressor stall, the modal wave mainly concentrates in the tip region, and the tip injection can broaden stable working range of the compressor by improving the flow field in the tip region.
Aerothermodynamics and Aeroengine Design
Application of the parabolized stability equation in curved surfaces boundary layers
LI Jia, LUO Ji-sheng
2015, 30(12): 2976-2982. doi: 10.13224/j.cnki.jasp.2015.12.022
Abstract PDF(755KB) icon879 icon513
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In order to research the application of the parabolized stability equation in curved surfaces boundary layers, three typical curved surface boundary layers of identical curvature circle pipelines, identical curvature plates and NACA0012 wing were calculated.Through calculation of the evolution of small amplitude disturbance waves, the results of the parabolized stability equation were compared with the linear stability theory and numerical simulation of disturbance equations.The consistency indicates the evolution and stability analysis of small amplitude disturbance waves could be studied by the parabolized stability equation in curved surfaces boundary layers. For the evolution of finite amplitude disturbance wave, the result by the parabolized stability equation is accordant with disturbance equations in linear stage.Using the parabolized stability equation, computational divergence will appear in the strong nonlinear stage and the divergence position can be used as the transition position.
Electromagnetic scattering characteristics for spherical converging flap nozzle
YANG Sheng-nan, SHANG Shou-tang, SHAO Wan-ren, DENG Hong-wei
2015, 30(12): 2983-2991. doi: 10.13224/j.cnki.jasp.2015.12.023
Abstract PDF(869KB) icon1186 icon462
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The electromagnetic scattering characteristics for spherical converging flap nozzle (SCFN) were studied using the methods of iterative physical optics and equivalent edge current. A study on the structure and scattering mechanism of electromagnetic scattering,spatial distribution characteristic of scattering field, and frequency characteristics of scattering for SCFN was presented. The scattering characteristics of electromagnetic wave for SCFN in middle state and maximum state on yaw plane and pitch plane were separately calculated and analyzed. Studies show that the edge diffraction field contributes to the whole scattering field in large angles under vertical polarization. The more frequently electromagnetic wave incidence enters, the more intense the nozzle backscatters, and the more sensitive the radar cross section distribution is to the attitude angle.
Prediction of civil aircraft emission in complete flight route
CAO Ming-dong, WANG Zhan-xue, LIU Zeng-wen, ZHANG Xiao-bo
2015, 30(12): 2992-3001. doi: 10.13224/j.cnki.jasp.2015.12.024
Abstract PDF(858KB) icon1348 icon484
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To predict the emission of civil aircrafts in complete flight routes, the aircraft lift-to-drag characteristic model, engine performance model and flight routes performance model were adopted to calculate the aircraft lift-to-drag characteristic and engine performance in complete flight routes.The above models were combined with the established emission calculation model based on T3-p3 method and Boeing method to calculate the emissions index of unburned hydrocarbons (UHC), carbon monoxide (CO), nitrogen oxides (NOx) and the total emissions in the aircraft flight routes.These models could improve the civil aviation engine emission prediction analysis system and provide a theoretical basis for the design and evaluation of the low pollution civil aviation engine.The results show that the emission index of NOx is high while the emission index of UHC and CO are low when the aircraft takes off and climbs, the emission index of NOx is low while the emission index of UHC and CO are high when the aircraft approaches and lands off,and the total mass of NOx is higher than the other two emission products.
Deceleration transition control law design for short take-off vertical landing unmanned aerial vehicle with thrust vector
CHEN Kun, SHI Zhi-wei, GONG Zheng
2015, 30(12): 3002-3009. doi: 10.13224/j.cnki.jasp.2015.12.025
Abstract PDF(763KB) icon1135 icon460
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In order to achieve the deceleration transition of short take-off vertical landing (STOVL) unmanned aerial vehicle (UAV) with thrust vector, a comprehensive control law design method for deceleration transition was studied.First, the deceleration transition thrust vectoring control schemes were evaluated based on the analysis of STOVL UAV deceleration transition performance.Then implicit dynamic inversion method was used to design guidance laws which provide guidance instructions for STOVL UAV deceleration transition mission.Finally, an improved eigen-structure assignment method was applied for the inner loop control laws design, enabling to track guidance instructions and maintain stable attitudes; the attitude nozzles were joined for the attitude control with the drop of dynamic pressure.Results from six degree of freedom (DOF) flight simulation platform show that, when the deceleration transition speed is lower than the minimum level flight speed, STOVL UAV still keeps favorable trajectory tracking and stable attitude.Deceleration transition integrated control laws fully adopt direct collocation methods, making it conducive to rapid assessment for control configuration of vehicle program.
Rocket Engine
Forced start-up procedure of a staged combustion cycle engine
CHEN Hong-yu, LIU Hong-jun, CHEN Jian-hua
2015, 30(12): 3010-3016. doi: 10.13224/j.cnki.jasp.2015.12.026
Abstract PDF(710KB) icon1273 icon556
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Using the advanced staged combustion cycle LOX (liquid oxygen)/kerosene engine as an example, the engine start-up characteristics were investigated. The mathematical model of transient process of the engine was developed based on modular modeling means. The nonlinear hyperbolic partial differential equations governing the unsteady flow of propellant pipelines were solved by the Chebyshev pseudo-spectral method. Furthermore, an extensible simulation library for liquid propellant rocket engines has been elaborated by using the new object-oriented simulation language-Modelica. Simultaneously, by using the simulation library, a staged combustion cycle LOX/kerosene engine model is built on the platform MWorks and forced start-up characteristics of the engine calculated. Results from the numerical simulation agree well with the ground-test data, the relative errors of steady-state are less than 4%, and the dynamic simulation errors are less than 10%, which indicates that the model can accurately predict the transient behavior of the engine. Some rules relating to start-up were simulated. The results demonstrate that solid propellant starter working should be lasted up to the gas generator ignition, and gas generator head should be filled with liquid oxygen when gas generator igniting.
Internal ballistic simulation of multi-burning-rate solid rocket motor based on parameterized feature CAD model
CHEN Wei, LIANG Guo-zhu
2015, 30(12): 3017-3028. doi: 10.13224/j.cnki.jasp.2015.12.027
Abstract PDF(906KB) icon1576 icon451
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Internal ballistic simulation (IBS) method of multi-burning-rate solid rocket motor (SRM) was developed based on 3-D burning regression method by parameterized feature CAD model (PFCADM) and lumped parameter, in consideration of time-dependent, erosive-burning-effect from internal ballistic numerical algorithm. By driving multi-parameter CAD model based on PFCADM, the approach is capable of conducting the geometric regression simulation of various grain combinations of complex configurations with different burning rates. Through suitably simplifying the internal ballistic numerical algorithm, the problems of coupling geometric regression simulation of sub-grains of different burning rates and high computational consumption of internal ballistic calculation were solved. One tri-burning-rate grain motor, which had been firing-tested, was used as the validation case of simulation. The results show that, with the 3-D grain regression model and sufficient accurate internal ballistic algorithm, the method realizes IBS of the case in low computational-consumption prediction of its performance within the accuracy of 2% during 1h clock-time. The application of the method provides a practical approach to aid SRM design of multi-burning-rate grain.
Rapid optimization design of ascent rendezvous trajectory for launch vehicles based on hybrid particle swarm algorithm
LI Zhen-hua, XIAN Yong, LEI Gang, ZHANG Da-qiao, LIU Bing-qi
2015, 30(12): 3029-3034. doi: 10.13224/j.cnki.jasp.2015.12.028
Abstract PDF(620KB) icon921 icon423
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Based on efficiency of gradient search and randomness of particle swarm search, a hybrid particle swarm algorithm was proposed, and applied to research the rapid optimization design of ascent rendezvous trajectory for launch vehicles. Regarding the minimum distance between launch vehicles and target aircraft at intersection point as the objective function, the flight program of solid launch vehicles was designed and an optimization model of ascent rendezvous trajectory was established, and solved by the hybrid particle swarm algorithm, genetic algorithm and particle swarm algorithm. The simulation results indicat that:the algorithm can solve the optimization design problem effectively, the average error of rendezvous position is 4.137m, 17.940m less than genetic algorithm, and the average optimization time is 488.922s, 2342.125s shorter than particle swarm algorithm. The algorithm can be applied to the rapid optimization design of ascent rendezvous trajectory for launch vehicles because of its faster search speed and higher convergence accuracy.
Power Transimission
Rolling bearing fault diagnosis based on wavelet packet analysis and multi kernel learning
ZHENG Hong, ZHOU Lei, YANG Hao
2015, 30(12): 3035-3042. doi: 10.13224/j.cnki.jasp.2015.12.029
Abstract PDF(762KB) icon1654 icon468
Abstract:
To diagnose the rolling bearing fault more accurately, a method based on wavelet packet analysis and multi kernel learning was proposed for rolling bearing fault diagnosis. Firstly, the three-level wavelet packet decomposition algorithm was used to decompose the vibration signals into different frequency bands. The relative energies of each frequency band were computed to form the feature vector. Secondly, multi kernel learning was employed to learn a kernel function and classifier from the training samples. Finally, the trained classifier was used to identify the fault type of rolling bearing. To validate the proposed method, an experiment of fault diagnosis for the rolling bearings was carried out. The results show that the fault diagnosis accuracy rate of the proposed method reaches 98.25%, higher than the traditional rolling bearing fault diagnosis method based on the wavelet packet and support vector machine. Since the problem of kernel function selection is avoided, the proposed method is more convenient for practical application.
Roller bearing envelope analysis method based on local mean decomposition and kurtogram
ZHANG Kang, CHENG Jun-sheng
2015, 30(12): 3043-3050. doi: 10.13224/j.cnki.jasp.2015.12.030
Abstract PDF(840KB) icon1167 icon427
Abstract:
Roller bearing envelope analysis method based on local mean decomposition (LMD) and kurtogram was proposed. In this method, the original roller bearing fault vibration signal was decomposed into a set of frequency components and preliminary reduced noises adaptively by LMD, and the parameters of band-pass filter in envelope analysis were provided objectively by kurtogram, thus the envelope analysis accuracy for roller bearing can be enhanced. The analytical results from roller bearing simulation signals and experiment signals indicate that the natural vibration components of roller bearing can be separated by LMD adaptively and the parameters of band-pass filter in envelope analysis can be determined by kurtogram automatically in low signal-to-noise ratio. Compared with traditional envelope analysis, the proposed method can extract the fault features of roller bearing more clearly and accurately.
Fault diagnosis of rolling bearing based on tunable-Q wavelet reconstruction
ZHANG Ding-cheng, YU De-jie, LI Xing
2015, 30(12): 3051-3057. doi: 10.13224/j.cnki.jasp.2015.12.031
Abstract PDF(774KB) icon1098 icon421
Abstract:
To overcome the difficulty of early fault diagnosis for the rolling bearing, a method for the fault diagnosis of rolling bearings based on the resonance-based sparse signal decomposition and the tunable-Q wavelet reconstruction was proposed. In this method, the vibration signal of a rolling bearing was decomposed into the high-resonance component and the low-resonance component by the resonance-based sparse signal decomposition. Then, the low-resonance component was further decomposed into a set of sub-signals by the tunable-Q wavelet method and the proper signal was reconstructed from some selected sub-signals combined with kurtosis analysis. Finally, the proper signal was analyzed by the Hilbert demodulation method and the fault characteristics of the rolling bearing could be extracted. Simulation and application examples show that the proposed method is effective in extracting impulse signal from vibration signal of rolling bearing and making the fault characteristics more prominent.
Autocontrol
Pressure characterization of the pre-stage of jet pipe servo valve
YIN Yao-bao, WANG Yu
2015, 30(12): 3058-3064. doi: 10.13224/j.cnki.jasp.2015.12.032
Abstract PDF(734KB) icon961 icon452
Abstract:
In order to analyze the characteristic of high jet pressure of jet pipe nozzle in the jet pipe servo valve, a pre-stage jet pipe servo valve mathematical model was established to get the impact of the jet pipe deflection displacement, the radius of jet pipe nozzle and the radius of receiving hole on its internal fluid pressure, nozzle exiting velocity and recovery pressure in the left and the right holes of receiver. Flow field analysis found that vortex was prone to occur at high velocity jet exit, and there existed annular negative pressure effect. The results showed that:under high jet pressure, when the radius of jet pipe nozzle increased, the recovery pressure increased, and when the radius of receiving hole increased, the recovery pressure decreased. The best internal value of the ratio of the radius of receiving hole to the radius of the jet pipe nozzle was[1.3, 1.5]. When jet pipe deflection displacement increased, on the side of displacement increase, the effective recieving area between the jet pipe and the receiving hole increased, but the vortex between the jet pipe and the receiving hole expanded and the annular negative pressure effect of the internal flow field increased, and the recovery pressure of the receiving hole decreased.
Fuel injection control strategies based on LPV state-space model for small two-stroke aviation kerosene engine
CHEN Lin-lin, SUN Qun, WANG Chong
2015, 30(12): 3065-3072. doi: 10.13224/j.cnki.jasp.2015.12.033
Abstract PDF(795KB) icon981 icon454
Abstract:
To simplify the calculation of fuel injection control model based on the average model, a linear parameter varying (LPV) injection control state-space model was established based on the average model according to LPV state-space model principles. On this basis, the fuel injection pulse width control model under steady operating conditions and transient operating conditions was established, then simulated by Matlab/Simulink tool, and finally verified in an engine test bed. The simulation and test results show that:(1) the LPV state-space fuel injection control model meets the control requirements under steady and transient operating conditions. Although the accuracy of calculated fuel injection pulse width is slightly lower than that of the average model, the LPV state-space model calculation is simple, and can be directly used in the injection control algorithm design and easy to implement in engineering. (2) Compared with the interpolation algorithm, the control strategy based on the LPV state-space model leads to a lower engine power output, mainly owing to the simplified model that results in a reduced intake air flow rate.

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