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The measurement of internal surface characteristics of fuel nozzle orifices using the synchrotron X-ray micro CT technology

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Science China(Technological Sciences) 2018年第11期61卷 1621-1627页

作者： LI ZhiLong ZHAO WenBo WU ZhiJun GONG HuiFeng HU ZongJie DENG Jun LI LiGuang school of automotive studies Tongji University

The design of fuel nozzle orifices at micrometer scales is crucial for generating desired fuel spray patterns, and consequently optimizing fuel combustion and emission in internal combustion engines. Although there have been several recent advancements in the characterization of orifice internal geometries, quantitative studies on the orifice internal wall surface characteristics are still challeges due to the lack of effective measuring methods. A new method for quantifying the internal wall surface characteristics of fuel nozzle micro-orifices is presented in this study to achieve a better understanding and prediction of spray characteristics: Firstly, by using the synchrotron X-ray micro CT technology, a three-dimensional digital model of the fuel nozzle tip was constructed. Secondly, a data post-processing technique was then applied to unfold the orifice internal wall surface to a flat base plane. Finally, the conventional surface characteristic quantification techniques can be used to evaluate the wall surface characteristics. Two diesel nozzles with identical orifice geometry design but different hydraulic grinding time were measured using this method. One nozzle was hydro-ground for 2 s while the other was not. The internal wall surfaces of the two orifices were successfully unfolded to base planes and their surface characteristics were respectively analyzed. The surface fluctuation data were perfectly reproduced by a Gaussian distribution function. The standard deviations of the distribution demonstrate the fluctuation range and the distribution of the entire surface fluctuation profiles. As an effective parameter to evaluate the hydraulic grinding process and the spray behaviors, the standard deviation was considered feasible for the analysis of the orifice internal wall surface characteristics.

关键词： automotive fuel spray nozzle orifice wall surface characteristics synchrotron X-ray micro CT

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Deep reinforcement learning-based drift parking control of automated vehicles

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Science China(Technological Sciences) 2023年第4期66卷 1152-1165页

作者： LENG Bo YU YiZe LIU Ming CAO Lei YANG Xing XIONG Lu school of automotive studies Tongji University

Drift parking usually requires precise control of a vehicle by a professional driver,which can reflect the performance of the vehicle under critical *** obstacles to implementing this action include the high coupling between the longitudinal and lateral states,the high precision required for the vehicle initial state when the drift is triggered,and the difficulty in determining the reference state variables in the drift process.A two-segment drift parking control system is proposed in this *** the approaching control segment,the vehicle achieves the drift-triggered vehicle speed and pose,which relies on a pathtracking algorithm based on linear time-varying model predictive *** the drifting control segment,the deep reinforcement learning algorithm twin-delayed deep deterministic policy gradient is creatively introduced to the controller *** solves the precise vehicle motion control problem under the condition of the rear wheels having locked *** various simulations,the superiority and robustness to different initial conditions and abrupt changes in the parking space are *** effectiveness of the proposed control system is verified by a ground test.

关键词： automated vehicles deep reinforcement learning drifting control vehicle dynamics control

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Recursive Least Square Vehicle Mass Estimation Based on Acceleration Partition

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 448-459页

作者： FENG Yuan XIONG Lu YU Zhuoping QU Tong school of automotive studies Tongji University Clean Energy automotive Engineering Center Tongji University

Vehicle mass is an important parameter in vehicle dynamics control systems. Although many algorithms have been developed for the estimation of mass, none of them have yet taken into account the different types of resistance that occur under different conditions. This paper proposes a vehicle mass estimator. The estimator incorporates road gradient information in the longitudinal accelerometer signal, and it removes the road grade from the longitudinal dynamics of the vehicle. Then, two different recursive least square method （RLSM） schemes are proposed to estimate the driving resistance and the mass independently based on the acceleration partition under different conditions. A 6 DOF dynamic model of four In-wheel Motor Vehicle is built to assist in the design of the algorithm and in the setting of the parameters. The acceleration limits are determined to not only reduce the estimated error but also ensure enough data for the resistance estimation and mass estimation in some critical situations. The modification of the algorithm is also discussed to improve the result of the mass estimation. Experiment data on asphalt road, plastic runway, and gravel road and on sloping roads are used to validate the estimation algorithm. The adaptability of the algorithm is improved by using data collected under several critical operating conditions. The experimental results show the error of the estimation process to be within 2.6%, which indicates that the algorithm can estimate mass with great accuracy regardless of the road surface and gradient changes and that it may be valuable in engineering applications. This paper proposes a recursive least square vehicle mass estimation method based on acceleration partition.

关键词： mass estimation recursive least square method acceleration partition

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Effect of catalyzed diesel particulate filter and its catalyst loading on emission characteristics of a non-road diesel engine

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Journal of Environmental Sciences 2023年第4期126卷 794-805页

作者： Yunhua Zhang Diming Lou Piqiang Tan Zhiyuan Hu Liang Fang school of automotive studies Tongji UniversityShanghai 201804China

In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel *** reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.

关键词： Catalyzed diesel particulate filter Catalyst loading Emissions Particle size distribution Geometric mean diameter

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Effect of catalyst diesel particulate filter aging and catalyst loadings on particulate emission characteristics from a diesel vehicle

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Journal of Environmental Sciences 2024年第2期136卷 35-44页

作者： Yunhua Zhang Diming Lou Piqiang Tan Zhiyuan Hu Liang Fang school of automotive studies Tongji UniversityShanghai 201804China

In this study,the effect of new and used catalyzed diesel particulate filter(CDPF)with different catalyst loadings on the particulate emissions including the particle mass(PM),particle number(PN),particle size distribution(PSD)and geometric mean diameter(GMD)from a diesel vehicle were investigated based on a heavy chassis *** showed that more than 97.9%of the PN and 95.4%of the PM were reduced by the CDPF,and the reduction efficiency was enhanced by the catalyst *** using the CDPF,the PSD transformed from bimodal to trimodal with the peak shifting towards smaller particle size,more nucleation mode particles were reduced compared with accumulation mode ones,but the reduction effect on the accumulation mode particles was more significantly influenced by the catalyst ***,the CDPF increased the accumulation mode particles proportion,producing a larger *** the used CDPF,its reduction effect on the particulate emissions enhanced,especially for the PM in accumulation *** PSD returned to bimodal,but the peak at accumulation mode began to be higher than that at nucleation mode,illustrating that more nucleation mode particles was *** aging of the CDPF resulted in greater effect on the PN-based PSD than that of PM-based PSD,but the effect of catalyst loading on the PN and PM emission factors was *** used CDPF further increased the GMD,and the effect of catalyst loading on the GMD was strengthened,a higher catalyst loading led to a reduction in the GMD.

关键词： Catalyzed diesel particulate filter (CDPF) Catalyst loading Aging Particle Particle size distribution Geometric mean diameter

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Numerical Investigation of the Centrifugal Compressor Stability Improvement by Half Vaned Low Solidity Diffusers

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Journal of Thermal Science 2021年第2期30卷 696-706页

作者： CHEN Siyue ZUO Shuguang WEI Kaijun school of automotive studies Tongji UniversityShanghai 201804China

Centrifugal compressors for the fuel cell vehicles often operate near the surge line compared with the turbocharger *** solidity and half vaned diffusers are recognized as good ways to improve the stability of the centrifugal *** presented work investigated four diffuser configurations (i.e.,the vaneless diffuser (VLD),full-height low solidity vaned diffuser (LSVD),hub-side half vaned diffuser (HVD) and shroud-side half vaned diffuser (SVD)) through steady-state and unsteady numerical *** results show that the best performance is achieved by the LSVD,HVD and SVD at the design,surge and choke *** flow rate at the surge operating point of the HVD has decreased by 15.53% compared with the LSVD,and 9.21% compared with the *** near surge operating point,a longitudinal suction side passage vortex is formed on the hub of the LSVD and rotates as circumferential stall cells.A hairpin vortex is formed along the leading edge and is dragged by the main flow along the suction side as a local vortex *** mechanism of the stability improvement by half vaned diffusers is that the tip leakage vortex migrates from the clearance side to the vane mounting side and replenishes the low-momentum zone on the mounting *** best position where the half vaned diffuser should be mounted is based on the impeller outlet flow conditions,namely,the location of the wake region,where the meridional velocity and relative stagnation pressure is low.

关键词： centrifugal compressor low solidity diffuser half vaned diffuser flow control numerical simulation

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Comparisons of nozzle orifice processing methods using synchrotron X-ray micro-tomography

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第3期13卷 182-188页

作者： Zhi-jun WU Zhi-long LI Wei-di HUANG Hui-feng GONG Ya GAO Jun DENG Zong-jie HU school of automotive studies Tongji University Shanghai 201019 China

Based on the high flux synchrotron X-ray of the Shanghai Synchrotron Radiation Facility (SSRF), high precision 3D digital models of diesel nozzle tips have been established by X-ray micro-tomography technology, which reveal the internal surfaces and structures of orifices. To analyze the machining precision and characteristics of orifice processing methods, an ap- proach is presented based on the parameters of the internal structures of nozzle orifices, including the nozzle diameter, the orifice inner surface waviness, the eccentricity distance and the angle between orifices. Using this approach, two kinds of nozzle orifice processing methods, computerized numerical control drilling and electric discharge machining, have been studied and compared. The results show that this approach enables a simple, direct, and comprehensive contrastive analysis of nozzle orifice processing methods. When processing a single orifice, the electric discharge machining method has obvious advantages. However, when there are multiple orifices, the error levels of the two methods are similar in relation to the symmetry of distribution of the orifices.

关键词： Diesel nozzle Internal structures Orifice processing methods Synchrotron X-ray micro-tomography

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Recent advances and future prospects on Ni_(3)S_(2)-Based electrocatalysts for efficient alkaline water electrolysis

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Green Energy & Environment 2024年第4期9卷 659-683页

作者： Shiwen Wang Zhen Geng Songhu Bi Yuwei Wang Zijian Gao Liming Jin Cunman Zhang Clean Energy automotive Engineering Center School of Automotive StudiesTongji UniversityShanghai201804China

Green hydrogen(H_(2))produced by renewable energy powered alkaline water electrolysis is a promising alternative to fossil fuels due to its high energy density with zero-carbon ***,efficient and economic H_(2) production by alkaline water electrolysis is hindered by the sluggish hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Therefore,it is imperative to design and fabricate high-active and low-cost non-precious metal catalysts to improve the HER and OER performance,which affects the energy efficiency of alkaline water ***_(3)S_(2) with the heazlewoodite structure is a potential electrocatalyst with near-metal conductivity due to the Ni–Ni metal ***,the review comprehensively presents the recent progress of Ni_(3)S_(2)-based electrocatalysts for alkaline water ***,the HER and OER mechanisms,performance evaluation criteria,preparation methods,and strategies for performance improvement of Ni_(3)S_(2)-based electrocatalysts are *** challenges and perspectives are also analyzed.

关键词： Alkaline water electrolysis Hydrogen Electrocatalysts Ni_(3)S_(2)

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Research on the Physical Property of Diesel-Gasoline Blend Fuel

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Journal of Shanghai Jiaotong university(Science) 2014年第6期19卷 721-727页

作者：包堂堂周波邓俊吴志军 school of automotive studies Tongji University

In this paper, physical property parameters including density, viscosity and surface tension of different contents of diesel-gasoline blend fuel were measured and analyzed. The experiments were performed on the diesel gasoline blend fuels with 4 different volume fractions of diesel(20%, 40%, 60% and 80%) at temperature from 5℃ to 65℃. The influence of temperature and diesel content on the blends' properties was summarized based on experimental data, formulas about the material parameters were established, and the accuracy of these formulas was verified. Besides, saturated vapor pressure, freezing point and flash point of the blend fuel have also been measured and analyzed, and a database of the material parameters of the blends was also established.

关键词： internal combustion engine diesel-gasoline blend fuel physical property

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Shock wave generation and its influencing parameters based on diesel injector

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Chinese Science Bulletin 2014年第27期59卷 3504-3510页

作者： Weidi Huang Zhijun Wu Ya Gao Zhilong Li Liguang Li school of automotive studies Tongji University

Based on schlieren imaging method the shock wave generated by diesel injector has been investigated,and the influences of ambient gas property, the progress of the spray, ambient gas density and ambient gas temperature on shock wave have been analyzed. The results show that:the images of spray shock wave are cleaner using sulfur hexafluoride(SF6) as ambient gas than using the nitrogen(N2); at the beginning of injection, shock wave phenomenon does not generate immediately as the fuel leave the nozzle because of the needle movement, and the hesitation is decided by the injection condition and characteristics of injector. The generation of shock wave in the spray tip and the detachment of shock wave from the spray tip show little effect on the spray macroscopic characteristics. The ambient gas density and temperature have a significant effect on the maximum of spray tip velocity, types of shock wave and the detachment timing of shock wave from the spray tip.

关键词：柴油机影响参数喷油器激波冲击波气体密度喷射器气体比

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