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Validity Analysis of Spray Model by Comparing Simulated with Measured Spray Liquid and Vapor Phase
( Zhe Sun ),( Xue Dong ),( Peng Yin ),( Tianyun Li ),( David L. S. Hung ),( Min Xu ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
Gasoline direct injection (GDI) Engine is proved to be a key technology to save energy and reduce emissions, which improves the overall engine performance. Spray injection affect the fuel-air mixing directly and computational fluid dynamics(CFD)software is utilized to model the macroscopic shape of the spray and the vapor mass. In this paper, the liquid and vapor phase of the spray of a one-hole injector was studied both experimentally and numerically. The structure and concentration distribution of the vapor phase of the spray, vapor mass and spray penetration were measured using laser induced exciplex fluorescence (LIEF) technique in a constant volume chamber. The simulations were performed by the CONVERGE software. Both the spray penetration and Sauter Mean Diameter (SMD) employed in the simulation were calibrated with the in-chamber measurements. The comparison of vapor concentration between the simulated results and the measured results acquired from the chamber suggest that the evaporation model of the single component fuel has significant influence on the simulated results. In addition, an analysis based on the present evaporation model has been made in this study. The results show that the 2-D plane and local line distributions of vapor concentration in simulation do not best match those from the experiments. It is found to get higher vapor concentration in the simulation model, suggesting that the relationship between vapor concentration and evaporation rate should be considered and further verified.
Zhe Chen,Junqing Zhu,Jiantao Peng,Xingxiang Zhang,Jianyue Ren 한국광학회 2016 Current Optics and Photonics Vol.20 No.1
A novel optical design for high resolution, large field of view (FOV) and multispectral remote sensingis presented. An f/7.3 Korsch and two f/17.9 Cook three-mirror optical systems are integrated by sharingthe primary and secondary mirrors, bias of the FOV, decentering of the apertures and reasonable structurearrangement. The aperture stop of the Korsch system is located on the primary mirror, while those ofthe Cook systems are on the exit pupils. High resolution image with spectral coverage from visible tonear-infrared (NIR) can be acquired through the Korsch system with a focal length of 14 m, whilewide-field imaging is accomplished by the two Cook systems whose focal lengths are both 13.24 m. The full FOV is 4°×0.13°, a coverage width of 34.9 km at the altitude of 500 km can then be acquiredby push-broom imaging. To facilitate controlling the stray light, the intermediate images and the real exitpupils are spatially available. After optimization, a near diffraction-limited performance and a compactoptical package are achieved. The sharing of the on-axis primary and secondary mirrors reduces the costof fabrication, test, and manufacture effectively. Besides, the two tertiary mirrors of the Cook systemspossess the same parameters, further cutting down the cost.
Nan Wang,Zhe Yuan,Peng Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
The current predominant contact loading device has several defects (such as friction, wear, vibration, and noise) which seriously affect the accuracy of test results of waterlubricated bearings. In this study, a non-contact electromagnetic loading device was designed, and the dynamic electromagnetic force variation mechanism and energy loss were examined. First, the structures of the test-rig of a water-lubricated bearing and electromagnetic loading device were described, and mathematical models of the dynamic electromagnetic force, reluctance torque, and energy loss were constructed. Then, finite element analysis was conducted, and the variation rules of magnetic induction intensity, reluctance torque, gap flux density, and energy loss were analyzed. Finally, the test results of numerical calculation and simulation were compared. The dynamic electromagnetic force is revealed to be closely related to the speed and eccentricity of the shaft and the coil current of the electromagnet. Increasing the coil current and shaft speed nonlinearly increases the energy loss of the electromagnetic loading device.
Zheng Gong,Peng Dai,Xiaojie Wu,Fujin Deng,Dong Liu,Zhe Chen 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1
In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) strategy is not practical for multilevel converters due to their substantial calculation requirements, especially under high number of voltage levels. To solve this problem, a hierarchical model predictive voltage control (HMPVC) strategy with referring to the implementation of g-h coordinate space vector modulation (SVM) is proposed. By the hierarchical structure of different cost functions, load currents can be controlled well and common mode voltage can be maintained at low values. The proposed strategy could be easily expanded to the systems with high number of voltage levels while the amount of required calculation is significantly reduced and the advantages of the conventional FCS-MPC strategy are reserved. In addition, a HMPVC-based field oriented control scheme is applied to a drive system with the NPC/H-Bridge converter. Both steady-state and transient performances are evaluated by simulations and experiments with a down-scaled NPC/H-Bridge converter prototype under various conditions, which validate the proposed HMPVC strategy.
Shear behavior of composite frame inner joints of SRRC column-steel beam subjected to cyclic loading
Hui Ma,Sanzhi Li,Zhe Li,Yunhe Liu,Jing Dong,Peng Zhang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.4
In this paper, cyclic loading tests on composite frame inner joints of steel-reinforced recycled concrete (SRRC) column.steel beam were conducted. The main objective of the test was to obtain the shear behavior and analyze the shear strength of the joints. The main design parameters in the test were recycled coarse aggregate (RCA) replacement percentage and axial compression ratio. The failure process, failure modes, hysteresis curves and strain characteristics of the joints were obtained, and the influences of design parameters on the shear strength of the joints have been also analysed in detail. Results show that the failure modes of the joints area are typical shear failure. The shear bearing capacity of the joints maximally decreased by 10.07% with the increase in the RCA replacement percentage, whereas the shear bearing capacity of the joints maximally increased by 16.6% with the increase in the axial compression ratio. A specific strain analysis suggests that the shear bearing capacity of the joints was mainly provided by the three shear elements of the recycled aggregate concrete (RAC) diagonal compression strut, steel webs and stirrups of the joint area. According to the shear mechanism and test results, the calculation formulas of the shear bearing capacity of the three main shear elements were deduced separately. Thus, the calculation model of the shear bearing capacity of the composite joints considering the adverse effects of the RCA replacement percentage was established through a superposition method. The calculated values of shear strength based on the calculation model were in good agreement with the test values. It indicates that the calculation method in this study can reasonably predict the shear bearing capacity of the composite frame inner joints of SRRC column–steel beam.
Xing‑Quan Liu,Zhe Li,Zhen‑Jia Peng,Rui‑Xun Wang,Zhi‑Quan Liu 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1
Electroplated copper is a key electronic interconnect material in integrated circuits and printed circuits and inevitablyexposed to corrosive media in manufacturing processes. The present work reports, for the first time, that corrosion resistanceof electroplated copper in 4 wt% NaOH is enhanced via nanotwinned microstructure engineering. Nucleation and growthof oxide/hydroxide on nanotwinned copper are inhibited, attributed to existence of highly (111)-preferred grain orientationand high-density parallelly-aligned coherent twin boundaries at surface. This study unveils a novel anti-corrosion strategyof nantowinned microstructure engineering against alkaline etchant, and exhibits great application values in industrial electroplatingof copper, silver, or their alloys.
Experimental studies on behaviour of bolted ball-cylinder joints under axial force
Xiaonong Guo,Zewei Huang,Zhe Xiong,Shangfei Yang,Li Peng 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.1
Due to excellent advantages such as better illuminative effects, considerable material savings and ease and rapidness of construction, the bolted ball-cylinder joint which is a new type joint system has been proposed in space truss structures. In order to reveal more information and understanding on the behaviour of bolted ball-cylinder joints, full-scale experiments on eight bolted ball-cylinder joint specimens were conducted. Five joint specimens were subjected to axial compressive force, while another three joint specimens were subjected to axial tensile force. The parameters investigated herein were the outside diameter of hollow cylinders, the height of hollow cylinders, the thickness of hollow cylinders, ribbed stiffener and axial force. These joint specimens were collapsed by excessive deformation of hollow cylinders, punching damage of hollow cylinders, evulsion of bolts, and weld cracking. The strain distributions on the hollow cylinder opening were mainly controlled by bending moments. To improve the ultimate bearing capacity and axial stiffness of bolted ball-cylinder joints, two effective measures were developed: (1) the thickness of the hollow cylinder needed to be thicker; (2) the ribbed stiffener should be adopted. In addition, the axial stiffness of bolted ball-cylinder joints exhibited significant non-linear characteristics.