Table of Content

28 April 2019, Volume 53 Issue 4 Previous Issue    Next Issue

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Triple-Level Opportunistic Maintenance Optimization Policy for Multi-Location Operation and Maintenance of Leasehold Service Network SI Guojin,XIA Tangbin,SONG Ya,XI Lifeng 2019, 53 (4):  387-395.  doi: 10.16183/j.cnki.jsjtu.2019.04.001 Abstract ( 1023 )   PDF (2420KB) ( 347 )   Save This study focuses on the multi-location operation and maintenance problem of the leasehold service network where original equipment manufacturers provide global maintenance services. We propose an opportunistic maintenance optimization policy with dynamic interactions between the machine level, the system level and the network level. According to individual health evolutions of leased machines, preventive maintenance intervals are scheduled at the machine level. At the system level, group maintenance schemes are arranged by using leasing profit optimization. By pulling the requirements of multi-location leased lines, the balancing of lease service demand and maintenance resource constraint is handled at the network level. Therefore, a triple-level opportunistic maintenance policy is developed and an alternating algorithm based on hierarchical progression is then designed. Through arithmetic analysis, this proposed policy is proved to be effective and feasible. References | Related Articles | Metrics

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Discrete Noise Control of Automobile Cooling Fan by Combining Rotor and Stator Phase Modulation Principle PENG Zhigang,OUYANG Hua,WU Yadong,TIAN Jie 2019, 53 (4):  396-404.  doi: 10.16183/j.cnki.jsjtu.2019.04.002 Abstract ( 995 )   PDF (1673KB) ( 346 )   Save With the development of automobile industry and the improvement of people’s requirements for driving comfort, it is increasingly important to control and improve the discrete noise level of the cooling fan module (CFM). In the early stage of CFM design, finding a fast method to predict discrete noise is helpful for designers to shorten design cycle and improve work efficiency. In this paper, a combined method of rotor-stator blade phase modulation is proposed to control the harmonic noise of CFM, i.e., to reduce the second and third harmonic in the CFM noise spectrum by controlling fan blade angle distribution parameter of CFM; Based on the “Venetian blind” theory of stator vanes, its angle distribution parameter is designed to further reduce the first harmonic component in CFM noise spectrum, aiming to improve the CFM discrete noise level. The method is verified by experiments in two combined cases of 7-blade fan, 6-vane and 8-vane respectively. And the experimental results are in good agreement with the theoretical prediction results. Related Articles | Metrics

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Robustness Analysis of Locating Scheme for 3D Workpieces and Its General Solution LIN Jia,YANG Fuyong,ZHENG Cheng,JIN Sun 2019, 53 (4):  405-412.  doi: 10.16183/j.cnki.jsjtu.2019.04.003 Abstract ( 1085 )   PDF (1280KB) ( 277 )   Save The locating error analysis model of 3D workpieces involves a large number of parameters and is complicated. To find robust locating scheme by this model, most of the existing researches adopt numerical method; however, only a specific solution can be achieved rather than a general solution, thus regularities or rules cannot be revealed explicitly. In this study, by introducing two additional assumptions according to common engineering conditions, the deterministic locating analysis model is simplified; based on the simplified model, the robustness of locating scheme is analyzed analytically, and general solution of the most robust locator layout is given. The solution and what it reveals, are validated by a commercial variation analysis software VisVSA, and by using the locating of a plate workpiece as an example. The result has applied to the locating scheme design of the mounting of a stamp exhaust pipe on the rear fuselage. References | Related Articles | Metrics

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Experimental and Numerical Research on the Aerodynamic Performance of Wide-Body Aircrafts Thrust Reverser Cascade WANG Peng,CUI Yuchao,CHEN Yingchun,ZHANG Xiaodong,DENG Zhi,LU Shaopeng,TENG Jinfang 2019, 53 (4):  413-422.  doi: 10.16183/j.cnki.jsjtu.2019.04.004 Abstract ( 1007 )   PDF (12328KB) ( 557 )   Save In this paper, experimental and numerical simulation methods were employed to investigate the aerodynamic performance and flow field characteristics of an independent design thrust reverser cascade of high bypass ratio turbofan engine for wide-body aircrafts. The numerical simulation was calibrated through experiments at three typical operating points of 0.18, 0.30 and 0.35 inlet Mach number. The results of the comparison between numerical simulation and experimental measurements show that the average total pressure recovery coefficient and the deviation angle of numerical simulation are in good agreement with the experimental results. References | Related Articles | Metrics

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Numerical Simulation of Oblique-Towing Test for a Fully Appended Ship Model Based on Two Propeller Modelling Methods LIU Yi,ZOU Zaojian,GUO Haipeng 2019, 53 (4):  423-430.  doi: 10.16183/j.cnki.jsjtu.2019.04.005 Abstract ( 1166 )   PDF (8684KB) ( 373 )   Save It is an effective method to establish the mathematical model of ship maneuvering motion by using CFD (computational fluid dynamics) method to simulate the captive model tests to obtain the hydrodynamic derivatives. When the captive model tests of a fully appended ship are numerically simulated, the key issue is to select a suitable propeller modeling method to compute the hydrodynamic force on the ship efficiently and accurately. Using CFD method, the oblique-towing tests of a fully appended KCS ship model are numerically simulated by solving the Reynolds-averaged Navier-Stokes (RANS) equations. Both the body force method and the sliding mesh method based on real propeller are used to deal with the rotating propeller. By comparing the computed hydrodynamic forces with the benchmark data, the numerical method is verified. The results of the two methods for dealing with the propeller are compared, and it shows that considering the computation efficiency and accuracy, the body force method can replace the real propeller method to simulate the oblique-towing test of fully appended ships. References | Related Articles | Metrics

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Evaluation of Flange Wrinkling Prediction Methods of Conventional Spinning for Thin-Walled Spherical Components DU Chenyang,KONG Qingshuai,ZHAO Yixi,YU Zhongqi 2019, 53 (4):  431-437.  doi: 10.16183/j.cnki.jsjtu.2019.04.006 Abstract ( 838 )   PDF (5820KB) ( 302 )   Save In order to explore the accuracy of the existing wrinkle evaluation method for the prediction of the wrinkling of the thin-walled spherical members, the first-pass conventional spinning of the 2024-O aluminum alloy spherical thin-walled member is taken as the research object, and the test method is used to determine the occurrence of the 2024-O aluminum alloy spinning flange wrinkle, combined with the numerical simulation method, which obtains the results of the wrinkling occurrence of the 2024-O aluminum alloy spinning flange based on the existing wrinkle evaluation methods. The results show that the flange geometry wave method and the model based on plastic instability theory can correctly predict the moment when the flange wrinkles occur, and the former method’s prediction error is 12.5% and the latter is 7.7%. The spin pressure method can predict the moment of serious wrinkles, but cannot quantitatively predict the occurrence time of wrinkles. The elastic strain energy oscillation method cannot predict the above two wrinkling problems. References | Related Articles | Metrics

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Task Scheduling Period Selection Based on Stability Analysis of Automatic Clutches CHENG Xiaoxuan,CHEN Li 2019, 53 (4):  438-446.  doi: 10.16183/j.cnki.jsjtu.2019.04.007 Abstract ( 669 )   PDF (2297KB) ( 301 )   Save Clutch engagement process consists of three sequential phases, i.e., open, slipping and stick (locked). The task scheduling period of the clutch control task should be selected carefully in case that the improper discretization leads to instability and deteriorates the engagement quality. An integrated approach which considers both control performance and real-time scheduling aspects is applied to allocate task scheduling periods. Firstly, the model of a closed-loop control system for a powertrain with a clutch element is developed and discretized by z-transformation. The stability criterion of the discretized system during slipping phase is derived, thus, the critical task scheduling period can be determined. The engagement quality in terms of vehicle jerk and clutch frictional losses is evaluated by simulation data, further, the dynamic response is also tested on transmission dynamometers. The results show that, the clutch engagement quality is insensitive to the task period which is less than the critical value, however, is deteriorated seriously when the task period exceeds the critical value. References | Related Articles | Metrics

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Application of Combined Dummy Modeling in Two-Wheel Electric Vehicle Traffic Accident Simulation QIN Chuang，FU Shuangzhi，JIN Xianlong，HOU Xinyi，QIU Zhong 2019, 53 (4):  447-453.  doi: 10.16183/j.cnki.jsjtu.2019.04.008 Abstract ( 1069 )   PDF (9042KB) ( 360 )   Save By combining the standard multi-rigid body dummy model and the finite element human model, the multi-rigid-finite element combined dummy model was established based on the real body characteristic parameters of the victim, and it was applied to a real two-wheel electric vehicle traffic accident. Using the photogrammetric method to reconstruct the scene, we studied the dynamic response of the vehicle after the collision and the damage of the electric vehicle cyclist. The movement of persons and cars after collision is basically consistent with the real situation. The head injury criterion (HIC) value of the dummy, the maximum bending moment of the calf and the von Mises of the skull were obtained through the simulation. The results show that human injury in the simulation are consistent with those of forensic identification. Our study effectively validates the correctness and accuracy of the combined dummy model in accident simulation. References | Related Articles | Metrics

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Research and Performance Optimization of Refrigerant Flow Noise in Automotive Air Conditioning System ZHANG Zhenyu，WANG Linan，CHEN Jiangping 2019, 53 (4):  454-460.  doi: 10.16183/j.cnki.jsjtu.2019.04.009 Abstract ( 1112 )   PDF (15528KB) ( 276 )   Save During the initial operation phase of the automobile refrigeration system, there is a two-phase flow in the pipeline from the condenser to the expansion valve, generating bubble groups accompanied by high-frequency abnormal sound. This paper designs and verifies three different muffling schemes from the perspectives of reducing two-phase flow and dissipating sound energy. They are the installation of silencer, valve ball opening to increase the valve action value and the installation of orifice muffler. The outdoor/interior temperatures were controlled at 35/27℃. The experimental results show that the orifice muffler eliminates the high-frequency abnormal noise above 9kHz. The valve ball has the best perforating effect, basically eliminating above 8kHz, eliminating the first half of 6-8kHz and reducing the decibel value of the second half, which is acceptable to the human body. Expansion muffler can eliminate high frequency abnormal noise, and the subjective feeling is better than the original state. References | Related Articles | Metrics

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Structure Optimization of Chip Cooling Radiator Based on Numerical Simulation LI Jian,LU Fanli,DONG Wei,CAI Yifan,XU Mengmei 2019, 53 (4):  461-467.  doi: 10.16183/j.cnki.jsjtu.2019.04.010 Abstract ( 1310 )   PDF (13706KB) ( 403 )   Save Three-dimensional numerical simulation of chip cooling radiator was carried out and the performance of four different radiators and influence of fin thickness were contrastively analyzed. Radiator model and fin thickness with better performance were also obtained. The results indicated that the heat transfer effect in both sides of radiator was better than that in the symmetrical central region, which meant that the heat transfer enhancement in the symmetrical central region should be mainly taken into account in the radiator structural design. The heat transfer coefficient of C-type and D-type radiators was obviously improved compared with A-type and B-type radiators. The temperature of substrate heating surface of C-type was much lower and the performance was better. When the fin thickness was 2mm, the cooling effect of A-type, B-type and C-type radiators was better, while the optimum value of D-type radiator was 2.5mm. 20 kinds of radiators with different structural dimensions were comprehensively analyzed in the study and the characteristics of flow and heat transfer were stated, which provided a theoretical basis and engineering guidance for the structural optimization design of chip cooling radiators. References | Related Articles | Metrics

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Experimental Research on Waste-Heat Recovery Heat Pump System in Electric Vehicles LI Ping,GU Bo,MIAO Menghua 2019, 53 (4):  468-472.  doi: 10.16183/j.cnki.jsjtu.2019.04.011 Abstract ( 1145 )   PDF (2054KB) ( 325 )   Save A set of waste-heat recovery heat pump system is designed for electric vehicles, which includes two parts absorbing the waste heat from battery and motor. The generation rule of waste heat from battery and motor is analyzed and the waste heat recovery heat pump system is tested. The results showed that with the speed change of electric vehicle, battery cooling is increasing rapidly, which increases the waste heat; when waste-heat recovery heat pump system operates at 2℃, maximum heat transfer can be increased to 3797W, the range of coefficient of performance (COP) is 1.82-2.43, and the increase of waste heat can meet the heating requirements; when the temperature drops to -7℃, maximum heat transfer can be increased to 2407W, the range of COP is 1.56-2.63, and the air temperature is 13.2℃, but the system still needs to provide additional heat source to meet the heating requirements. References | Related Articles | Metrics

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The Process of Mass Transport for a Buoyant Plume in Linearly Stratified Environment ZHAO Liang,ZHANG Wei,HE Zhiguo,TAN Liming,JIANG Houshuo 2019, 53 (4):  473-479.  doi: 10.16183/j.cnki.jsjtu.2019.04.012 Abstract ( 1141 )   PDF (1884KB) ( 338 )   Save Eighteen experimental cases for the buoyant plume were conducted in linearly stratified saltwater. The particle image velocimetry (PIV) technique was used to acquire flow fields of plumes in high spatial and temporal resolutions. A new formula for maximum transported mass of buoyant plumes in stratified fluids was proposed. The process for entrainment and mass transport of plumes were analyzed quantitatively. Results show that the entrainment coefficient αe increases gradually along the jetting direction from the source, fluctuates at 0.11 from 0.3Zmax to 0.5Zmax (Zmax is the maximum penetration distance) and then decreases gradually to negative. The buoyant plume which entrains ambient fluids from the plume stem is transported to －Zmax along the jetting direction and its vertical mass flux reaches the maximum at about －0.65Zmax. The mixed plume finally spreads to surroundings at the neutral buoyancy layer. The maximum transported mass is determined by the buoyancy flux, the buoyancy frequency and the environment density at the same level. The calculation error due to pseudo turbulence caused by variations of the refractive index within the stratified fluid is about 3%, so the influence of refractive index is negligible. References | Related Articles | Metrics

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Numerical Simulation and Experimental Verification of Vortex-Induced Vibration for Risers After Considering Platform Heave Motion YUAN Yuchao,XUE Hongxiang,TANG Wenyong 2019, 53 (4):  480-487.  doi: 10.16183/j.cnki.jsjtu.2019.04.013 Abstract ( 1210 )   PDF (3019KB) ( 239 )   Save An alternative time domain numerical simulation approach is proposed to predict top-tensioned risers’ dynamic response under combined action of top-end platform heave motion and vortex-induced vibration (VIV). The VIV simulation is based on force-decomposed model, and hydrodynamic force coefficient database originates from forced vibration experimental data. The time-varying axial tension is adopted, and the platform heave motion effect on structural response is taken into account, and structural stiffness matrix is updated at each time step according to the variation of axial tension. A newly published 2.552m riser model test is utilized to validate the proposed numerical approach under constant and time-varying top-end tension situations, and the predicted results based on the numerical model show a good agreement with test observations. For the sub-harmonics response, asymmetrical vibration shape and Mathieu-type resonance phenomena captured in the comparisons between numerical and experimental results, further researches are carried out and the corresponding essential explanations are given as well. References | Related Articles | Metrics

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The Solution of Uneven Fillet Radius Defect in the Flanging Process of Window Trim Strip ZHAN Yang,ZHAO Yixi,ZHU Baohang 2019, 53 (4):  488-496.  doi: 10.16183/j.cnki.jsjtu.2019.04.014 Abstract ( 1315 )   PDF (11202KB) ( 271 )   Save The shape of the end of window trim strip is complex, the dimension is about 1000mm×30mm, the thickness is about 1mm, and the cross section in the width direction is narrow, which is a complex variable curvature convex section. The uneven fillet radius defect appeared at the end of window trim strip in the flanging process severely influenced its surface quality. Through simulations and tests, it is found that when the die radius is reduced, the defect of uneven fillet of the window trim strip is improved to some extent, but it has not reached the ideal index. Based on this conclusion, a die with variable fillet radius is designed to solve this problem and raised its design procedure. This die can solve this defect by reasonably arranging the die fillet radius. The fillet radius of the die is smaller in the center and gradually increases from center to corner. The simulation and test results showed that this method remarkably reduces the difference and variance of the fillet radius in different cross-sections of window trim strip. References | Related Articles | Metrics

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Catalytic Capacity of Titanium Phthalocyanine for Redox Reactions Complex Based on Lattice Kinetic Monte Carlo Method ZHOU Su,HU Zhe,GAO Yang,JIANG Zhen 2019, 53 (4):  497-503.  doi: 10.16183/j.cnki.jsjtu.2019.04.015 Abstract ( 911 )   PDF (3897KB) ( 318 )   Save The lattice kinetic Monte Carlo method is applied to investigate the catalytic activity of the titanium phthalocyanine complex (TiPc) at different temperatures and partial pressure ratios of H2 and O2, and TiPc is compared with platinum (Pt) catalyst. On one hand, the study results show that: the activity of TiPc increases with the temperature between 470-570K; the active range of TiPc is between 0.2 to 2 of H2/O2 partial pressure ratio; under same conditions, the activity of TiPc is higher than that of Pt. On the other hand, from the perspective of computational chemistry tools, the feasibility of kinetic Monte Carlo method is verified for the study of unknown potential catalysts’ catalytic activity. References | Related Articles | Metrics

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Thermal and Fluid Coupling Field Analysis of MR Damper for Gun Recoil ZHANG Guang,WANG Huixing,OUYANG Qing,WANG Jiong 2019, 53 (4):  504-512.  doi: 10.16183/j.cnki.jsjtu.2019.04.016 Abstract ( 948 )   PDF (2479KB) ( 366 )   Save In order to investigate the multi physics coupling characteristics in the recoil process of magnetorheological (MR) damper, an independent three-stage MR damper of double rod was designed. Magnetorheological gel (MRG) based on silicone was prepared and the steady-state shear test was carried out for obtaining the consistency coefficient and the non-Newtonian index of the Herschel-Bulkley model. MRG-70 was applied to the damper, and the motion analysis of recoil part was carried out by combining with the law of chancing of the bore resultant force for a certain type fixed artillery. The multiple physical fields of damper was analysed and calculated. The results show that Poiseuille pressure flow loss and Couette viscous flow loss are the main and controllable parts of the damper. The temperature of each pole corresponds to a different peak value at different times, and the temperature distribution was obviously nonlinear and time-variable. The pressure distribution and the pressure drop on the central axial surface of the damping channel are nonlinear and time-variable, the dynamic viscosity of the central axial surface of the effective damping channel is also obviously nonlinear and time-variable, and varies sharply at each pole, and the peak value fluctuates with the position. References | Related Articles | Metrics