Influence of Different Inlet Conditions on Micromixer

Wei Xu,Xiuhua He,Lingfeng Gao,Tian Xia,Zhengying Yu 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.2

This paper presents the influence of different inlet conditions on the performance of micromixer. On the purpose of obtaining the internal flow fields and mixing characteristics, there are 28 micromixers with different structural parameters have been studied by numerical simulations. The influence of different inlet conditions on the mixing performance of micromixers with periodic triangle baffles and rectangle baffles was examined by experiments. The results of experiment and numerical simulation were completely discussed and analyzed. The consistency between results of experiment and numerical simulation proves the reliability of research method and the accuracy of numerical simulation. It also indicates that different numbers of inlets have significant effects on the mixing performance of micromixers. The optimum inclination angles of inlets for each kind of micromixer were obtained under different conditions. For optimizing or designing passive micromixers, it is an effective way to improve the performance of micromixers by increasing the number of inlets or changing the angle of the inlets.

Impurity Behaviors under Wall Conditioning in HL-2A

Zhengying Cui,Chenghe Cui,Mingxu Wang,Ping Sun,Quanming Wang,Wei Li,Yudong Pan,Zeng Cao 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

Impurities are one of the key issues of tokamak plasma research, as they are directly related to plasma quality and steady-state operation. The HL-2A device with two close divertor is the first divertor tokamak in China. It was successfully constructed in 2002 and has been operated for three 3 years up to now. In the 2004 campaign, siliconization as a wall conditioning was first done on the HL-2A tokamak by using glow discharge cleaning (GDC) with a gas mixture of SiH4 + He. The effects of siliconization on impurities and recycling are investigated, as well as the lifetime of siliconization, in this paper. The intensity of oxygen line is remarkably decreased after siliconization. Radiation of silicon line rapidly decreases shot by shot just after siliconization, but the effect of siliconization on the plasma properties is present all along and decreases gradually for a large amount of discharges. The effect of the siliconization can be maintained to about 180 discharges with similar discharge parameters.

Experimental analysis of component morphology by fused coating process

Guangxi Zhao,Zhengying Wei,Jun Du,Yunfei Yao,Wei Liu,Xin Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

Fused coating process is a novel method for additive manufacturing technology, which has greatly reduced the cost and improved the efficiency. A series of experiments were carried out with the orthogonal method using pass width and height to evaluate. The order of factors influence degree on width and height were figured out, and it’s found that the air pressure at the top of the nozzle is the most influential. The morphologies of single passes at different temperatures were measured and fitted separately with parabola, circular arc and cosine function, and the goodness of fit was compared and analyzed, based on which the overlapping models were investigated. Four kinds of overlapping patterns were mentioned for the single-layer multi-pass model. The relationship between central distance of adjacent layers and overlapping patterns was calculated out. Furthermore, experimental pieces with suspended structure were processed without supporting material. It is found that when the tilt angle is smaller than 40° the inclined thin wall will collapse.

Comparison of the mechanical performance between two-stage and flat-face cutter head for the rock tunnel boring machine (TBM)

Geng Qi,Wei Zhengying,He Fei,Meng Hao 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

To overcome the drawbacks of the large flat-face TBM cutter head (for example, enormous rock cutting forces and eccentric forcescause excessive deformation of the cutter head and damage to the main bearing), a two-stage cutter head is introduced. The two-stagecutter head was designed using grey relational analysis method according to the flat-face cutter head applied in the West Qinling Tunnel,China. The mechanical performance analysis models of the two cutter heads in the layered-banded rock (LBR) mixed ground were builtto calculate the cutter heads’ rock cutting thrust and torque, eccentric forces and overturning moments. The two cutter heads’ deformationand stress distribution were also compared. We concluded that with the same penetration, the thrust, torque, eccentric force, overturningmoment, deformation and maximum stress of the two-stage cutter head were smaller than those of the flat-face cutter head.

Numerical and experimental research on the rock-breaking process of tunnel boring machine normal disc cutters

Geng Qi,Wei Zhengying,Meng Hao,Chen Qiao 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

A common drawback presented by several numerical rock-breaking studies was that the rocks beneath disc cutters were cut off excessively while the rocks between disc cutters remained, which usually resulted in a smaller cutter spacing than the proper value. To overcome this limitation, the constitutive equations of different rock parts were defined separately using VUMAT, an ABAQUS-based material subroutine. The constitutive model of rock was an application of the Drucker-Prager yield criterion coupled with the Lemaitre damage model. Full-scale rock-breaking tests on a rotary cutting machine were conducted, and 25 groups of orthogonal numerical simulations were carried out. By comparing the normal force, rolling force, and specific energy of numerical results with those of experimental results, the optimal values of the defined parameters D c1 , k, and B were determined to be 9 ☓ 10 -4 , 0.1 and 0.8, respectively. With the presented numerical method and the determined parameters, the influences of cutter spacing on normal force, rolling force, and specific energy were studied. Both the normal and rolling forces of the first cutting generally remained constant, whereas the forces of the second cutting generally increased linearly with the cutter spacing. The optimal cutter spacing for the studied rock type (Hard sand rock collected from West Qinling tunnel) was approximately 72 mm, which was in accordance with the cutter spacing of the tunnel boring machine applied in this tunnel project.

Numerical and experimental method to determine the boring diameters of a two-stage TBM cutterhead to prevent rock burst

Geng Qi,Wei Zhengying,Meng Hao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

A two-stage tunnel boring machine (TBM) cutterhead with a pilot-enlargement boring method was presented to reduce the risk of rockbursts resulting from boring with a TBM with a large flat-face cutterhead. A reduced scale similarity experiment was designed on rocktunnel boring to determine the boring diameters of the two stages, and numerical simulation models were built. A micron X-ray computerizedtomography system was adopted to examine the failure area of the excavated testing piece and validate the numerical models. Stress distribution and energy release rate (ERR) were used in the numerical simulations to evaluate the rock burst risk of the boringprocess. Experimental and numerical results show that rock burst is prone to occur in the upper, lower, and side areas of the surroundingrock around the tunnel, and risk increases with the lateral pressure coefficient and boring diameter. The optimal boring diameter ratio ofstages 1 to 2 was determined between 0.55 and 0.59. Meanwhile, the ERR of the designed two-stage cutterhead is approximately 60%smaller than that of the flat-face cutterhead.

Research on interlayer remelting process of multi-layer forming by metal fused-coating additive manufacturing

Wang Xin,Du Jun,Wei Zhengying,Zhang Shan,Zhao Guangxi,Ren Chuanqi,Bai Hao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

In order to achieve good interlayer metallurgical bonding in the metal fused-coating additive manufacturing, the finite element thermal analysis model was established and the influences of different heating temperatures of fused coating nozzle and substrate on the interlayer remelting was analyzed. The maximum remelting depth under different temperature conditions was obtained. The multi-layer forming experiments were performed under different temperature conditions, and the results showed that increasing the heating temperature of nozzle or substrate will effectively increase the remelting depth, that the surface forming quality is better when the remelting depth is in the range of 0.1~0.2 mm, and that the deviation between the remelting depth and the calculated value is less than 15 %. So, the model can predict the remelting depth of the intermetallic microstructure.

Correlation Between Different Antidiarrheal Treatments and Changes in Chemical Components of Allii Sativi Bulbus Before and After Steaming Treatment Based on Flora Sequencing and In Vitro Experiments

Yarong Li,Yaqian Zhou,Huanjin Liu,Chenxu Wei,Shuli Chen,Zhengying Hua,Yan Xu,Yu Wu,Weidong Li 한국식품영양과학회 2022 Journal of medicinal food Vol.25 No.10

We investigated the changes in the main active ingredients and pharmacodynamic differences in the therapeutic effect of garlic before and after steaming and the correlation between them. The main active ingredients in raw garlic products (RGPs) and steamed garlic products (SGPs) were determined by high-pressure liquid chromatography and ultraviolet spectroscopy. Acute rapid diarrhea (AD) and antibiotic-induced diarrhea (DD) models were established in rats, and each group was treated with RGP and SGP, respectively. The main chemical components of garlic changed before and after steaming. Garlicin and alliinase were only found in RGP, whereas only alliin was found in SGP. Both RGP and SGP contained garlic polysaccharides. For in vivo experiments on AD, the average rate of loose stools was 100.00 ± 0.00, 31.55 ± 11.76, and 19.14 ± 6.62 in the RGP high-dose and SGP high-dose treatment groups, respectively; in DD, the rates were 91.11 ± 14.40, 19.33 ± 3.63, and 30.56 ± 4.30, respectively (P < .01, treatment vs. model groups). In AD, the average grade of loose stools was 2.33 ± 0.52 and 1.83 ± 0.75 in the model and RGP high-dose treatment groups, respectively (P < .05); in DD, the values were 2.17 ± 0.41 in the model group and 1.67 ± 0.52 in the SGP high-dose treatment group (P < .05). RGP had a better therapeutic effect on AD, mainly related to the antibacterial effect of garlicin in RGP. SGP had a better therapeutic effect on DD, mainly related to the alliin and garlic polysaccharide in SGP. This study could provide evidence to support the clinical use of garlic.