检索结果-南通市图书馆

Numerical Investigation of Flow Separation Control on a Highly Loaded Compressor Cascade by Plasma Aerodynamic Actuation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第3期25卷 349-360页

作者： ZHAO Xiaohu li yinghong WU Yun ZHU Tao li Yiwen Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038China

To discover the characteristic of separated flows and mechanism of plasma flow control on a highly loaded compressor cascade, numerical investigation is conducted. The simulation method is validated by oil flow visualization and pressure distribution. The loss coefficients, streamline patterns, and topology structure as well as vortex structure are analyzed. Results show that the numbers of singular points increase and three pairs of additional singular points of topology structure on solid surface generate with the increase of angle of attack, and the total pressure loss increases greatly. There are several principal vortices inside the cascade passage. The pressure side leg of horse-shoe vortex coexists within a specific region together with passage vortex, but finally merges into the latter. Corner vortex exists independently and does not evolve from the suction side leg of horse-shoe vortex. One pair of radial coupling-vortex exists near blade trailing edge and becomes the main part of backflow on the suction surface. Passage vortex interacts with the concentrated shedding vortex and they evolve into a large-scale vortex rotating in the direction opposite to passage vortex. The singular points and separation lines represent the basic separation feature of cascade passage. Plasma actuation has better effect at low freestream velocity, and the relative reductions of pitch-averaged total pressure loss coefficient with different actuation layouts of five and two pairs of electrodes are up to 30.8% and 26.7% while the angle of attack is 2~. Plasma actuation changes the local topology structure, but does not change the number relation of singular points. One pair of additional singular point of topology structure generates with plasma actuation and one more reattachment line appears, both of which break the separation line on the suction surface.

关键词： plasma aerodynamic actuation cascade oil flow visualization topology structure vortex singular point

Experimental investigation on a high subsonic compressor cascade flow

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第4期28卷 1034-1043页

作者： Zhang Haideng Wu Yun li yinghong Lu Huawei College of Aeronatutics and Aerospace Airforce Engineering University School of Energy and Power Beihang University Marine Engineering College Dalian Marinetime University

With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet *** the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient *** flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex *** vortex is the main corner separation *** its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting *** higher incidence, corner separation is further deteriorated, leading to higher flow ***, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of *** with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the *** obtained present details of high-speed compressor cascade flow,which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

关键词： Compressor Corner separation High speed Secondary flow Transition

Effects of dynamic recrystallization in extruded and compressed AZ31 magnesium alloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2010年第5期23卷 334-342页

作者： Xiaohui FAN Weiqin TANG Shaorui ZHANG Dayong li yinghong PENG School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

Commercial AZ31 billets were extruded to round rods at three extrusion velocities of 0.8 m/min, 1.4 m/min and 2.2 m/min, at 643 K, 673 K and 703 K, respectively. The microstructure and texture evolution at different conditions were investigated by optical microscopy （OM） and electron backscattered diffraction （EBSD） techniques. The average grain size is reduced significantly after the hot extrusion, and the microstructure is obviously inhomogeneous due to dynamic recrystallization, which is confirmed by uni-axial compression experiments at elevated temperatures with different strain rates. The uni-axial compression leads to a fibre texture, and {110}010 texture is the major texture in extruded rods due to non-basal slip. As the extrusion temperature is elevated, the main texture becomes weak and other texture components appear.

关键词： AZ31 Extrusion Dynamic recrystallization Microstructure Stress-strain Texture

Flight safety oriented ice shape modulation using distributed plasma actuator units

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第10期34卷 1-5页

作者： Yun WU Biao WEI Hua liANG like XIE Zhe li yinghong li Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038China

Ice accretion on the wings seriously threatens the flight safety of an *** the perspectives of ensuring flight safety and saving power consumption,the ice shape modulation method using distributed plasma is *** plasma actuator units are designed to modulate the spanwise continuous ice at the leading edge into periodically segmented ice pieces,forming a wavy leading *** airfoil and scaled aircraft model,with continuous and modulated ice,are experimentally investigated and *** with the continuous ice,ice shape modulation can significantly improve the aerodynamic performance,flight control characteristics and flight *** method can save about half electric power,which is very beneficial for application.

关键词： Anti-icing Flight safety Flow control Icing wind tunnel Plasma actuator

Flow separation control on swept wing with nanosecond pulse driven DBD plasma actuators

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第2期28卷 368-376页

作者： Zhao Guangyin li yinghong liang Hua Han Menghu Wu Yun Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University

A 15° swept wing with dielectric barrier discharge plasma actuator is designed. Experimental study of flow separation control with nanosecond pulsed plasma actuation is performed at flow velocity up to 40 m/s. The effects of the actuation frequency and voltage on the aerodynamic performance of the swept wing are evaluated by the balanced force and pressure measurements in the wind tunnel. At last, the performances on separation flow control of the three types of actuators with plane and saw-toothed exposed electrodes are compared. The optimal actua- tion frequency for the flow separation control on the swept wing is detected, namely the reduced frequency is 0.775, which is different from 2-D airfoil separation control. There exists a threshold voltage for the low swept wing flow control. Before the threshold voltage, as the actuation voltage increases, the control effects become better. The maximum lift is increased by 23.1% with the drag decreased by 22.4% at 14°, compared with the base line. However, the best effects are obtained on actuator with plane exposed electrode in the low-speed experiment and the abilities of saw-toothed actuators are expected to be verified under high-speed conditions.

关键词： Dielectric barrier discharge Flow control Flow separation Nanosecond pulse Plasma Swept wing

Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第1期28卷 66-76页

作者： Jin Di Cui Wei li yinghong li Fanyu Jia Min Sun Quan Zhang Bailing Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University School of Aerospace Engineering Tsinghua University

The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 · 1012W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

关键词： supersonic heating shockwave authority actuator details currently pulsed numerically remarkable

Characteristic of rich-mixture ignition kernel driven by nanosecond repetitive pulsed discharge

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第1期59卷 109-116页

作者： liN BingXuan WU Yun li YiWen JIA Min ZONG HaoHua DING Jian li yinghong College of Aeronautical and Astronautical Engineering Air Force Engineering University School of Electrical Engineering Xi'an Jiaotong University

Plasma-assisted ignition is a promising technology to improve engine performance. Nanosecond repetitive pulsed discharge is widely used in plasma-assisted ignition owing to its chemical activations and thermal and hydrodynamic expansions. However, the influence of ultrafast heating and hydrodynamic effects on the development of the rich-mixture ignition kernel is largely unknown. The present study aims to illustrate these effects using electrical and schlieren measurement. The number and the frequency of discharge pulses are exactly controlled to establish the relationship among the discharge energy, frequency, and rich-mixture ignition-kernel characteristics. The evolution of the ignition kernel in the early stage is mainly dominated by the discharge energy and frequency, i.e., a greater energy and a higher frequency yield a larger ignition kernel. Moreover, the influence of both the energy and frequency on the ignition kernel gradually disappears as the ignition kernel develops. According to the experimental data and theoretical analysis, the calculated laminar burning velocity is 0.319 m/s with a Markstein length of 13.43±0.11 cm when the voltage is 5.9 k V, the frequency is 3 k Hz, and the equivalence ratio is 1.3. This result indicates that the rich-mixture flame is stable in the early stage of ignition.

关键词： plasma-assisted ignition NRP discharge rich-mixture ignition kernel laminar burning velocity markstein length

Shock wave-boundary layer interactions control by plasma aerodynamic actuation

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第7期57卷 1335-1341页

作者： SUN Quan li yinghong CUI Wei CHENG BangQin li Jun DAI Hui Science and Technology on Plasma Dynamics Laboratory School of Aeronautics and Astronautics Engineering Air Force Engineering University

This study demonstrates the potential for shock wave-boundary layer interaction control in air by plasma aerodynamic *** investigations on shock wave-boundary layer interactions control by plasma aerodynamic actuation are conducted in a Mach 3 in-draft air *** imaging shows that the discharges cause the oblique shock to move *** imaging and static pressure probes also show that separation phenomenon shifts backward and the size of separation is enlarged when plasma aerodynamic actuation is *** intensity of shock wave is weakened through wall pressure ***,numerical investigations on shock wave-boundary layer interactions control are conducted with plasma aerodynamic *** discharge is modeled as a steady volumetric heat source which is integrated into the energy *** input energy level is about 7 kW through discharge *** show that the separation phenomenon shifts backward and the intensity of shock is reduced with plasma *** numerical results are consistent with the experimental results.

关键词： shock wave boundary layer plasma separation flow control

Gene expression in rat mesenchymal stem cells following treatment with natural cerebrolysin-containing serum Validation of a whole genome microarray technique

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2010年第6期5卷 424-432页

作者： yinghong li Zhengzhi Wu Ming li Xiuqin Jia Min Yang Manyin Chen First Affiliated Hospital of Shenzhen University Shenzhen Institute of Integrated Chinese and Western Medicine Shenzhen 518035Guangdong Province China

BACKGROUND： Natural cerebrolysin （NC）, a Chinese herbal drug for the treatment of Alzheimer＇s disease （AD）, induces mesenchymal stem cell （MSC） differentiation into neuron-like cells, with low toxicity. But the mechanisms involved in NC effects on MSCs remain poorly understood. OBJECTIVE： We used a whole genome microarray technique to further investigate the molecular, genetic, and pharmacodynamic mechanisms of NC on MSC gene expression profiles. DESIGN, TIME AND SETTING： A parallel, controlled, in vitro experiment was performed at the First Affiliated Hospital of Shenzhen University, Shenzhen Institute of Integrated Chinese and Western Medicine, China, between September 2006 and October 2008. MATERIALS： NC was provided by Shenzhen Institute of Integrated Chinese and Western Medicine China. It was predominantly composed of Renshen （Radix Ginseng）, Tianma （Rhizoma Gastrodiae） and Yinxingye （Ginkgo Leaf） and prepared by conventional water extractJon technology. Twelve adult, male, New Zealand rabbits were included, six of which underwent intragastric administration of NC extract for 1 month to create NC-containing serum. METHODS： Bone marrow was collected from the tibia and femur of Sprague Dawley rats, aged 6 8 months old. Rat MSCs were isolated and purified by the whole bone marrow adherence method. After in vitro culture, MSCs from passage 4 were treated with NC-containing serum for 48 hours, and total RNA was extracted. Gene expression in MSCs was analyzed using Affymetrix whole genome microarray analysis. MAIN OUTCOME MEASURES： Differentially expressed genes in NC serum-treated MSCs. RESULTS： NC treated MSCs displayed 46 differentially expressed genes, 22 with upregulated expression （fold change 〉 2） and 24 with downregulated expression （fold change 〈 -2）. Differentially expressed genes participated in neuronal growth, differentiation, and function, cell growth, differentiation, proliferation, apoptosis, signal transduction, substance/energy metabolism, ion trans

关键词： natural cerebrolysin whole genome chip mesenchymal stem cells gene expression profile Alzheimer's disease neural regeneration neurodegenerative disease