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The hydrothermal wave of large-Prandtl-number fluid in a shallow cavity

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Science China(Physics,Mechanics & Astronomy) 2007年第6期50卷 787-796页

作者： TANG ZeMei hu wenrui National Microgravity Laboratory Institute of MechanicsChinese Academy of SciencesBeijing 100080China

The hydrothermal wave was investigated numerically for large-Prandtl-number fluid (Pr = 105.6) in a shallow cavity with different heated sidewalls. The traveling wave appears and propagates in the direction opposite to the surface flow (upstream) in the case of zero gravity when the applied temperature difference grows and over the critical value. The phase relationships of the disturbed velocity,temperature and pressure demonstrate that the traveling wave is driven by the disturbed tem-perature,which is named hydrothermal wave. The hydrothermal wave is so weak that the oscillatory flow field and temperature distribution can hardly be observed in the liquid layer. The exciting mechanism of hydrothermal wave is analyzed and discussed in the present paper.

关键词： hydrothermal wave numerical simulation microgravity

Rheological flow from a die and painting on a moving solid wall

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Science China(Physics,Mechanics & Astronomy) 2004年第1期47卷 121-128页

作者： TANG Zemei hu wenrui National Microgravity Laboratory/CAS Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China National Microgravity Laboratory/CAS Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Die swell is an important phenomenon in polymer processing, and is explained usually by rheological properties of the fluid. Because of the nonuniform of temperature distribution on the free surface of the liquid jet, the thermocapillary convection driven by surface tension gradient exists. The rheological fluid flowing out of a die and painting on a moving solid wal is studied by the numerical finite element method of a two-dimensional and unsteady model in the present paper, and both the rheological effect of a non-Newtonian fluid and the thermocapillary effect are considered. The results show that both effects will enlarge the cross-section of the fluid jet, and the rheological effect of non-Newtonian fluid dominates the process in general.

关键词： die swell, thermocapillary flow, non-Newton flow, film jet.

Influence of the heating rate on the critical Marangoni number of oscillatory thermocapillary convection in the floating half zone

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Science China(Physics,Mechanics & Astronomy) 2012年第1期55卷 102-107页

作者： LI Kai TANG ZeMei hu wenrui National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

In the present study, numerical simulations were conducted on thermocapillary convection in floating half zones of 5 cSt silicone oil of different scales in comparison with the experimental studies in the microgravity conditions. The effect of heating rate on the marginal instability boundaries is indicated as a possible explanation for the significant quantitative discrepancies between the experimental results in the terrestrial conditions and in the microgravity conditions.

关键词： thermocapillary convection flow instability finite element methods

Instability of thermocapillary flow in liquid layers under microgravity

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Science China(Physics,Mechanics & Astronomy) 2012年第4期55卷 684-692页

作者： XUN Bo LI Kai hu wenrui Key Laboratory of Microgravity(National Microgravity Laboratory) Institute of MechanicsChinese Academy of SciencesBeijing 100190China

The instability of the thermocapillary flow in liquid layers is studied in the present paper using the linear stability *** on the two-dimensional steady flow state,the three-dimensional disturbance with a wave number in the spanwise direction is *** effects of the aspect ratio and free surface shape of the liquid layer on the flow instability are studied,and the results are compared with the case with the two-dimensional disturbance.

关键词： thermocapillary convection flow instability numerical simulations of chaotic systems

Numerical investigation of thermocapillary migration of the drop for large Marangoni numbers

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Science China(Technological Sciences) 2007年第5期50卷 694-696页

作者： GAO Peng YIN Zhaohua hu wenrui National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

An axisymmetric model is adopted to simulate the problem of unsteady drop thermocapillary motion for large Marangoni numbers. Front tracking methods are used in the investigation. It is found that the non-dimensional drop migration ve- locity will decrease with increasing Marangoni number. This agrees well with the experimental results obtained from the 4th Shen-Zhou space ship. In the meanwhile, this is also the first time for numerical simulations to verify the experimental phe- nomenon under large Marangoni numbers.

关键词： thermocapillary migration of drops, microgravity, front tracking methods

Space experimental investigation on thermocapillary migration of bubbles

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 894-904页

作者： CUI HaiLiang hu Liang DUAN Li KANG Qi hu wenrui National Microgravity Laboratory Institute of MechanicsChinese Academy of SciencesBeijing 100080China

Results from a space experiment on bubble thermocapillary migration conducted on board the Chinese 22nd recoverable satellite were presented. Considering the temperature field in the cell was disturbed by the accumulated bubbles, the temperature gradient was corrected firstly with the help of the temperature measurement data at six points and numerical simulation. Marangoni number (Ma) of single bubble migrating in the space experiment ranged from 98.04 to 9288, exceeding that in the previous experiment data. The experiment data including the track and the velocity of two bubble thermocapillary migration showed that a smaller bubble would move slower as it was passed by a larger one, and the smaller one would even rest in a short time when the size ratio was large enough.

关键词： bubble thermocapillary migration microgravity interaction

On large-signal modeling of GaN HEMTs: past, development and future

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Chip 2023年第3期2卷 20-31页

作者： Haorui Luo wenrui hu Yongxin Guo Department of Electrical and Computer Engineering National University of SingaporeSingapore 117576Singapore National University of Singapore(Suzhou)Research Institute Suzhou 215123China

In the past few decades,circuits based on gallium nitride high elec-tron mobility transistor(GaN HEMT)have demonstrated exceptional potential in a wide range of high-power and high-frequency applica-tions,such as the new generation mobile communications,object de-tection and consumer electronics,*** a critical intermediary be-tween GaN HEMT devices and circuit-level applications,GaN HEMT large-signal models play a pivotal role in the design,application and development of GaN HEMT devices and *** review pro-vides an in-depth examination of the advancements in GaN HEMT large-signal modeling in recent *** and comprehensive coverage of various aspects of GaN HEMT large-signal model was of-fered,including large-signal measurement setups,classical formula-tion methods,model classification and non-ideal effects,*** order to better serve follow-up researches,this review also explored poten-tial future directions for the development of GaN HEMT large-signal modeling.

关键词： Gallium nitride High electron mobility transistors Large-signal model

Science Research of Microgravity Satellite SJ-10

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空间科学学报 2018年第5期38卷 615-622页

作者： hu wenrui KANG Qi Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences

The program SJ-10, one of the scientific satellite programs in the Strategic Priority Research Program on Space Science, the Chinese Academy of Sciences, was launched on April 6, 2016. There are totally19 scientific payloads, a multi-function furnace for 8 material researches and three-dimensional cell cultures for the neural stem cell and the hematopoietic stem cell respectively. The recoverable satellite consists mainly of two capsules: a recoverable capsule was recovered on 18 April 2016, with all payloads of life science, the multi-function furnace and the payload for measurement of Soret Coefficients of Crude Oil(SCCO); and an un-recoverable capsule continued to work in additional 3 days with all other physics payloads. The experiments were operated via teleoperations, and all experimental data were received by the ground station in real *** data and recoverable samples are analyzed by the experiment teams of the program.

关键词：卫星节目科学研究神经干细胞中国科学院空间科学生命科学多功能载重

Interaction between the atmospheric boundary layer and a standalone wind turbine in Gansu—Part II： Numerical analysis

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Science China(Physics,Mechanics & Astronomy) 2018年第9期61卷 59-68页

作者： Zhi Zheng ZhiTeng Gao DeShun Li RenNian Li Ye Li QiuHao hu wenrui hu School of Energy and Power Engineering Lanzhou University of Technology Lanzhou 730050 China Gansu Provincial Technology Centre for Wind Turbines Lanzhou 730050 China Key Laboratory of Fluid Machinery and Systems Lanzhou 730050 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

To analyze the interaction between wind turbines and the atmospheric boundary layer, we integrated a large-eddy simulation with an actuator line model and examined the characteristics of wind-turbine loads and wakes with reference to a corresponding experiment in Gansu. In the simulation, we set the wind turbine to have a rotor diameter of 14.8 m and a tower height of 15.4 m in the center of an atmospheric boundary layer with a 10.6° yaw angle. The results reveal an obviously skewed wake structure behind the rotor due to the thrust component normal to the flow direction. The power spectra of the inflow fluctuation velocity exhibit a region of-5/3 slope, which confirms the ability of large-eddy simulations to reproduce the energy cascade from larger to smaller scales. We found there to be more energy in the power spectrum of the axial velocity, which shows that coherent turbulence structures have more energy in the horizontal direction. By the conjoint analysis of atmospheric turbulence and windturbine loads, we found that when the inflow wind direction changes rapidly, the turbulence kinetic energy and coherent turbulence kinetic energy in the atmospheric turbulence increase, which in turn causes fluctuations in the wind turbine ***, anisotropic atmospheric turbulence causes an asymmetric load cycle, which imposes a strike by the turbine blade on the shaft, thereby increasing the fatigue load on the shaft. Our main conclusion is that the atmospheric boundary layer has a strong effect on the evolution of the wake and the structural response of the turbine.

关键词： wind power atmospheric turbulence effects finite volume methods large-eddy simulations

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