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Leading-edge flow separation control over an airfoil using a symmetrical dielectric barrier discharge plasma actuator

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Chinese Journal of Aeronautics 2019年第5期32卷 1190-1203页

作者： Xin ZHANG huaxing li Yong HUANG Kun TANG Wanbo WANG School of Aeronautics Northwestern Polytechnical University Low Speed Aerodynamics Institute China Aerodynamics Research and Development Center

In order to promote an in-depth understanding of the mechanism of leading-edge flow separation control over an airfoil using a symmetrical Dielectric Barrier Discharge(DBD) plasma actuator excited by a steady-mode excitation, an experimental investigation of an SC(2)-0714 supercritical airfoil with a symmetrical DBD plasma actuator was performed in a closed chamber and a low-speed wind tunnel. The plasma actuator was mounted at the leading edge of the ***-resolved Particle Image Velocimetry(PIV) results of the near-wall region in quiescent air suggested that the symmetrical DBD plasma actuator could induce some coherent structures in the separated shear layer, and these structures were linked to a dominant frequency of f0= 39 Hz when the peak-to-peak voltage of the plasma actuator was 9.8 kV. In addition, an analysis of flow structures without and with plasma actuation around the upper side of the airfoil at an angle of attack of18° for a wind speed of 3 m/s(Reynolds number Re = 20000) indicated that the dynamic process of leading-edge flow separation control over an airfoil could be divided into three stages. Initially, this plasma actuator could reinforce the shedding vortices in the separated shear layer. Then, these vortical structures could deflect the separated flow towards the wall by promoting the mixing between the outside flow with a high kinetic energy and the flow near the surface. After that, the plasma actuator induced a series of rolling vortices in the vicinity of the suction side of the airfoil, and these vortical structures could transfer momentum from the leading edge of the airfoil to the separated region, resulting in a reattachment of the separated flow around the airfoil.

关键词： Airfoil Dielectric Barrier Discharge(DBD) Flow control Particle Image Velocimetry(PIV) Plasma actuator

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习近平关于援藏精神重要论述的六重意蕴

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西藏发展论坛 2024年第3期 49-56页

作者：李华兴余志坤熊坤新中国农业大学马克思主义学院西藏农牧学院西藏大学中华民族共同体研究院中共大连市委党校中央民族大学

习近平关于援藏精神的重要论述,有着丰富的内涵意蕴,它阐明了:援藏精神的创造主体是中国共产党,援藏精神的本质属性是中国特色社会主义,援藏精神的核心要义是革命理想高于天,援藏精神的生成空间是雪域高原,援藏精神的传承发展是一代接... 详细信息

习近平关于援藏精神的重要论述,有着丰富的内涵意蕴,它阐明了:援藏精神的创造主体是中国共产党,援藏精神的本质属性是中国特色社会主义,援藏精神的核心要义是革命理想高于天,援藏精神的生成空间是雪域高原,援藏精神的传承发展是一代接一代干下去,援藏精神的实践价值是支援了西藏、锻炼了干部。文章以哲学向度为视角,探究了援藏精神的创造主体、本质属性、核心要义、生成空间、传承发展和实践价值等内容。

关键词：援藏精神哲学向度科学内涵

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Unmanned air vehicle flow separation control using dielectric barrier discharge plasma at high wind speed

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Science China(Physics,Mechanics & Astronomy) 2014年第6期57卷 1160-1168页

作者： ZHANG Xin HUANG Yong WANG WanBo WANG XunNian li huaxing College of Aviation Northwestern Polytechnical University China Aerodynamics Research and Development Center

The present paper described an experimental investigation of separation control of an Unmanned Aerial Vehicle(UAV)at high wind *** plasma actuator was based on Dielectric Barrier Discharge(DBD)and operated in a steady *** flow over a wing of UAV was performed with smoke flow visualization in theΦ0.75 m low speed wind tunnel to reveal the flow structure over the wing so that the locations of plasma actuators could be optimized.A full model of the UAV was experimentally investigated in theΦ3.2 m low speed wind tunnel using a six-component internal strain gauge *** effects of the key parameters,including the locations of the plasma actuators,the applied voltage amplitude and the operating frequency,were *** whole test model was made of aluminium and acted as a cathode of the *** results showed that the plasma acting on the surface of UAV could obviously suppress the boundary layer separation and reduce the model vibration at the high wind *** was found that the maximum lift coefficient of the UAV was increased by 2.5%and the lift/drag ratio was increased by about 80%at the wind speed of 100 m/*** control mechanism of the plasma actuator at the test configuration was also analyzed.

关键词： plasma actuator flow control dielectric barrier discharge unmanned air vehicle

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Turbulent boundary layer separation control using plasma actuator at Reynolds number 2000000

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Chinese Journal of Aeronautics 2016年第5期29卷 1237-1246页

作者： Zhang Xin Huang Yong Wang Xunnian Wang Wanbo Tang Kun li huaxing School of Aeronautics Northwestern Polytechnical University Xi'an 710072 China China Aerodynamics Research and Development Center Mianyang 621000 China

An experimental investigation was conducted to evaluate the effect of symmetrical plasma actuators on turbulent boundary layer separation control at high Reynolds number. Compared with the traditional control method of plasma actuator, the whole test model was made of aluminum and acted as a covered electrode of the symmetrical plasma actuator. The experimental study of plasma actuators＇ effect on surrounding air, a canonical zero-pressure gradient turbulent boundary, was carried out using particle image velocimetry （PIV） and laser Doppler velocimetry （LDV） in the 0.75 m × 0.75 m low speed wind tunnel to reveal the symmetrical plasma actuator characterization in an external flow. A half model of wing-body configuration was experimentally investigated in the 3.2 m low speed wind tunnel with a six-component strain gauge balance and PIV. The results show that the turbulent boundary layer separation of wing can be obviously suppressed and the maximum lift coefficient is improved at high Reynolds number with the symmetrical plasma actuator. It turns out that the maximum lift coefficient increased by approximately 8.98% and the stall angle of attack was delayed by approximately 2° at Reynolds number 2 ×10……6. The effective mechanism for the turbulent separation control by the symmetrical plasma actuators is to induce the vortex near the wing surface which could create the relatively large- scale disturbance and promote momentum mixing between low speed flow and main flow regions.

关键词： Dielectric barrier discharge Flow control Plasma actuator Turbulent boundary layer Wing-body configuration

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Photodimerization of azaanthracene derivatives mediated by cucurbit[10]uril

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Chinese Chemical Letters 2022年第12期33卷 5124-5127页

作者： huaxing li Xianchen Hu Fengbo liu Dongdong Sun Yong Wu Simin liu School of Chemistry and Chemical Engineering Wuhan University of Science and TechnologyWuhan 430081China The State Key Laboratory of Refractories and Metallurgy Institute of Advanced Materials and NanotechnologyWuhan University of Science and TechnologyWuhan 430081China

Challenges of achieving efficient photodimerization of azaanthracene derivatives remain due to the low selectivity and slow reaction *** this paper,cucurbit[10]uril(CB[10]),with the largest rigid and hydrophobic cavity among CB[n]s,was used to affect the photodimerization reaction of four water-soluble 1-(2-)substituted azaanthracene derivatives(1-4).It revealed that 1-4 could form 1:2 host-guest complexes with CB[10]in aqueous *** of 1 in the presence of 0.5 *** CB[10]selectively produced a head-to-tail(anti-HT)photodimer *** for 2-4,CB[10]acted as a nanoreactor accelerating their photodimerization reaction in *** results suggest that photodimerization of azaanthracene derivatives could be promoted by the CB[10]-based host-guest strategy with high efficiency and selectivity.

关键词： Supramolecular nanoreactor Cucurbituril Azaanthracene Photodimerization Host-guest interaction

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Soil Components Affecting Phosphate Sorption Parameters of Acid Paddy Soils in Guangdong Province

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Pedosphere 2000年第4期10卷 317-321页

作者： li huaxing, ZHANG XINMING and liU YUANJIN (College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 China) 华南农业大学广东广州 510642

Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province. For each soil, seven 2.50 g subsamples were equilibrated with 50 mL 0.02 mol L-1 (pH=7.0) of KCI containing 0, 5, 10, 15, 25, 50 and 100 mg P kg-1, respectively, in order to derive P sorption parameters (P sorption maximum, P sorption intensity factor and maximum buffer capacity) by Langmuir isotherm equation. It was shown that the main soil components influencing phosphate sorption maximum (Xm) included soil clay, PH, amorphous iron oxide (Feo) and amorphous aluminum oxide (Alo), with their effects in the order of Alo > Feo > pH > clay. Among these components, pH had a negative effect, and the others had a positive effect. Organic matter (OM) was the only soil component influencing P sorption intensity factor (K). The main components influencing maximum phosphate buffer capacity (MBC) consisted of soil clay, OM,pH, Feo and Alo, with their effects in the order of Alo > OM > pH > Feo > clay. Path analysis indicated that among the components with positive effects on maximum phosphate buffer capacity (MBC), the effect was in the order of Alo > Feo > Clay, while among the components with negative effects, OM > pH. OM played an important role in mobilizing phosphate in acid paddy soils mainly through decreasing the sorption immensity of phosphate by soil particles.

关键词： Guangdong Province phosphate sorption parameters soil components

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等离子体对流动湍动能的控制

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航空学报 2015年第12期36卷 3809-3821页

作者：王斌李华星西北工业大学航空学院

在湍流流动中,雷诺应力是一个能够影响平均流动的重要动态量,它可以在很大程度上影响湍流中动能的传输,强烈影响表面摩擦力,对于摩擦阻力和流动的分离起着至关重要的作用。因此,本文的实验目的是：针对后台阶流动,特别设计了能够沿着45... 详细信息

在湍流流动中,雷诺应力是一个能够影响平均流动的重要动态量,它可以在很大程度上影响湍流中动能的传输,强烈影响表面摩擦力,对于摩擦阻力和流动的分离起着至关重要的作用。因此,本文的实验目的是：针对后台阶流动,特别设计了能够沿着45°方向形成射流的直角形状等离子体激励器对后台阶流动中的雷诺应力进行控制,同时实现对后台阶流动再附着位置的改变。实验过程中,按照台阶后流向位置0.5 H（H为台阶高度）的自然不稳定性频率对直角形状等离子体激励器的脉冲频率进行调制。使用PIV对台阶后0~2.5 H的区域以及再附着区域进行测量。实验结果表明：在直角形状等离子体激励器开启后,在台阶后0~2.5 H的区域,围绕剪切层及其附近区域的雷诺应力各分量在最大数值上分别增加了42%（流向雷诺正应力）,75%（垂向雷诺正应力）,46%（雷诺切应力）,湍动能产生项在最大数值上减小了35%。在再附着区域,后台阶流动的再附着位置也向台阶的上游发生了移动。

关键词：流动控制等离子体雷诺应力湍流能量 PIV

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等离子体激励器控制圆柱绕流的实验研究

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力学学报 2018年第6期50卷 1396-1405页

作者：张鑫黄勇李华星西北工业大学航空学院西安710072 中国空气动力研究与发展中心四川绵阳621000

为了发展新型移动附面层控制技术,提升流动控制效率,采用粒子图像测速技术,开展了基于对称布局等离子体气动激励的圆柱绕流控制研究,获得了静止空气下,对称布局激励器诱导流场的演化过程,评估了来流条件下等离子体控制效果,通过等离子... 详细信息

为了发展新型移动附面层控制技术,提升流动控制效率,采用粒子图像测速技术,开展了基于对称布局等离子体气动激励的圆柱绕流控制研究,获得了静止空气下,对称布局激励器诱导流场的演化过程,评估了来流条件下等离子体控制效果,通过等离子体诱导涡实现了虚拟移动附面层控制,分析了诱导涡随时间演化的过程,揭示了圆柱绕流等离子体控制机理.结果表明:(1)在静止空气下,对称布局激励器在刚启动瞬间,会在暴露电极两侧诱导产生一对旋转方向相反的启动涡;随着时间的推移,启动涡逐渐向远离壁面的方向运动;随后,激励器在暴露电极两侧产生了两股速度近似相等,方向相反的诱导射流,诱导射流在柯恩达效应的影响下,朝壁面方向发展.(2)当激励电压峰峰值为19.6 kV,激励频率3 kHz时,施加等离子体气动激励后,圆柱脱落涡得到了较好抑制,圆柱阻力系数减小了21.8%;(3)在来流作用下,对称布局激励器在靠近来流一侧,诱导产生了较为稳定的涡结构.诱导涡通过旋转、运动,促进了壁面附近低能气流与主流之间的掺混,抑制了圆柱绕流流场分离,实现了"虚拟移动附面层控制"效果.与传统移动附面层控制技术相比,基于等离子体气动激励的新型移动附面层控制技术不需要复杂、笨重的机构,不会带来额外的阻力,具有潜在的应用前景.

关键词：移动附面层控制流动控制等离子体介质阻挡放电风洞实验

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不同焊接方法下燃料元件包壳用ODS钢焊接接头界面演化规律

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电焊机 2024年第5期54卷 39-45页

作者：杨灿湘魏连峰郑勇王宇董宇王军健李华鑫杨建国张鸿羽侯霭麟中国核动力研究设计院反应堆材料及燃料重点实验室四川成都610041 浙江工业大学机械工程学院浙江杭州310023

ODS钢具有优异的高温力学性能、抗辐照性能和抗热蠕变性能等,是最有潜力的下一代核反应堆包壳候选材料之一。ODS钢的焊接技术主要包括熔焊、钎焊、压力焊等,根据核燃料元件包壳结构,选择电子束焊接、旋转摩擦焊及脉冲电流辅助扩散焊三... 详细信息

ODS钢具有优异的高温力学性能、抗辐照性能和抗热蠕变性能等,是最有潜力的下一代核反应堆包壳候选材料之一。ODS钢的焊接技术主要包括熔焊、钎焊、压力焊等,根据核燃料元件包壳结构,选择电子束焊接、旋转摩擦焊及脉冲电流辅助扩散焊三种焊接方法进行对比研究,并对ODS钢焊接接头微观形貌演化进行分析,揭示了最优焊接方法及界面形貌演化规律。结果表明,电子束焊接及旋转摩擦焊接工艺下,焊接接头的晶界处均有Y_(2)O_(3)析出,而采用脉冲电流辅助扩散焊无氧化物析出和团聚,对于Fe-Cr系ODS钢有突出优势。因此,脉冲电流辅助扩散焊在抑制ODS钢中纳米氧化物的析出、团聚和减少接头变形等方面具有显著优势,是一种适合ODS钢焊接的高质量焊接方法。

关键词： ODS钢核燃料元件焊接电子束焊接旋转摩擦焊接脉冲电流辅助扩散焊接

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NA样本均值的随机加权估计及应用

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西北工业大学学报 2008年第3期26卷 346-348页

作者：李华星高社生王海维西北工业大学陕西西安710072

研究了随机变量序列{Xn,n≥1}为NA相协样本条件下,均值X-n的随机加权逼近。用n(Hk(x)-X-n)的条件分布去模拟n(X-n-μ)的分布,证明了该分布的随机加权逼近及其收敛性,并对研究结果进行了仿真分析。

关键词：分位点过程 NA相协样本随机加权法

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