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A humidity resistant and high performance triboelectric nanogenerator enabled by vortex-induced vibration for scavenging wind energy

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Nano Research 2022年第4期15卷 3246-3253页

作者： Yan Wang Tianyu Chen Shuowen Sun Xiangyu Liu Zhiyuan Hu Zhenhui Lian Long Liu Qiongfeng Shi Hao Wang jianchun mi Tongming Zhou Chengkuo Lee minyi Xu Dalian Key Lab of Marine micro/Nano Energy and Self-powered System Marine Engineering CollegeDalian Maritime UniversityDalian 116026China Center for Intelligent Sensors and MEMS(CISM) National University of Singapore Engineering Drive 3 Singapore 117576Singapore3 College of EngineeringPeking UniversityBeijing 100871China School of Civil Environmental and Mining EngineeringThe University of Western AustraliaWA 6009Australia

Wind energy is a promising renewable energy source for a low-carbon society.This study is to develop a fully packaged vortexinduced vibration triboelectric nanogenerator(VIV-TENG)for scavenging wind energy.The VIV-TENG consists of a wind vane,internal power generation unit,an external frame,four springs,a square cylinder and a circular turntable.The internal power generation unit consists of polytetrafluoroethylene(PTFE)balls,a honeycomb frame and two copper electrodes.Different from most of the previous wind energy harvesting TENGs,the bouncing PTFE balls are fully packaged in the square cylinder.The distinct design separates the process of contact electrification from the external environment,and at the same time avoids the frictional wear of the ordinary wind energy harvesting TENGs.The corresponding VIV parameters are investigated to evaluate their influence on the vibration behaviors and the energy output.Resonant state of the VIV-TENG corresponds to the high output performance from the VIV-TENG.The distinct,robust structure ensures the full-packaged VIV-TENG can harvest wind energy from arbitrary directions and even in undesirable weather conditions.The study proposes a novel TENG configuration for harvesting wind energy and the VIV-TENG proves promising powering micro-electro-mechanical appliances.

关键词： vortex-induced vibration wind energy triboelectric nanogenerator self-powered

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On two distinct Reynolds number regimes of a turbulent square jet

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Theoretical & Applied Mechanics Letters 2015年第3期5卷 117-120页

作者： minyi Xu Jianpeng Zhang Pengfei Li jianchun mi Marine Engineering College Dalian Maritime University State Key Laboratory of Turbulence & Complex Systems College of EngineeringPeking University

The effects of Reynolds number on both large-scale and small-scale turbulence properties are investigated in a square jet issuing from a square pipe. The detailed velocity fields were measured at five different exit Reynolds numbers of 8 × 10^3 〈 Re 〈 5 × 10^4. It is found that both large-scale properties （e.g,, rates of mean velocity decay and spread） and small-scale properties （e.g., the dimensionless dissipation rate constant A = εL/（u^2）^3/2） are dependent on Re for Re ≤ 3 ×10^4 or Reλ ≤ 190, but virtually become Re-independent with increasing Re or Reλ. In addition, for Reλ 〉 190, the value ofA = εL/（u^2）^3/2 in the present square jet converges to 0.5, which is consistent with the observation in direct numerical simulations of box turbulence, but lower than that in circular jet, plate wake flows, and grid turbulence. The discrepancies in critical Reynolds number and A = εL/（u^2）^3/2 among different turbulent flows most likely result from the flow type and initial conditions.

关键词： Square jet Hot-wire Reynolds number Small-scale turbulence Mean energy dissipation rate

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Characteristics of Nitric-Oxide Emissions from Traditional Flame and miLD Combustion Operating in a Laboratory-Scale Furnace

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Journal of Thermal Science 2020年第4期29卷 868-883页

作者： SHU Ziyun WANG Feifei DAI Chong SI Jicang WANG Bo mi jianchun Department of Energy and Resource Engineering College of EngineeringPeking UniversityBeijing 100871China China Ship Development and Design Center Wuhan 430074China School of Environmental Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

This study investigated the formation and emission characteristics of nitric oxide(NO) from flameless miLD(moderate or intensive low-oxygen dilution) combustion(miLDC) versus traditional visible-flame combustion(TC) in a 30-k W furnace. Both combustion processes were experimentally operated successively in the same furnace, burning natural gas at a fixed rate of 19 k W and the equivalence ratio of 0.86. Numerical simulations of TC and miLDC were carried out to explain their distinction in the measured furnace temperature and exhaust NO emissions. Present measurements of the NO emission(XNO) versus a varying furnace wall temperature(Tw) have revealed, at the first time, that the relationship of XNO ~ Tw was exponential in both TC and miLDC. By analyzing the simulated results, the average temperature over the reaction zone was identified to be the common characteristic temperature for scaling NO emissions of both cases. Moreover, relative to TC, miLDC had a fairly uniform temperature distribution and low peak temperature, thus reducing the NO emission by over 90%. The thermal-NO formation was found to contribute more than 70%-80% to the total XNO from TC while the N2O-intermediate route dominated the NO emission from miLDC.

关键词： miLD(moderate or intensive low-oxygen dilution)combustion traditional combustion NO emission

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PIV measurements of turbulent jets issuing from triangular and circular orifice plates

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Science China(Physics,Mechanics & Astronomy) 2013年第6期56卷 1176-1186页

作者： XU minYi ZHANG JianPeng mi jianchun NATHAN G J KALT P A M Marine Engineering College Dalian Maritime University State Key Laboratory of Turbulence & Complex Systems College of EngineeringPeking University Centre for Energy Technology and School of Mechanical Engineering University of AdelaideSA 5005Australia

The present study experimentally investigated the near-field flow mixing characteristics of two turbulent jets issuing from equilateral triangular and circular orifice plates into effectively unbounded surroundings,respectively.Planar particle image velocimetry(PIV) was applied to measure the velocity field at the same Reynolds number of Re=50,000,where Re = UeDe /with Ue being the exit bulk velocity and the kinematic viscosity of fluid,D e the equivalent diameters.The instantaneous velocity,mean velocity,Reynolds stresses were obtained.From the mean velocity field,the centreline velocity decay rate and half-velocity width were derived.Comparing the mixing characteristics of the two jets,it is found that the triangular jet has a faster mixing rate than the circular counterpart.The triangular jet entrainments with the ambient fluid at a higher rate in the near field.This is evidenced by a shorter unmixed core,faster Reynolds stress and centreline turbulence intensity growth.The primary coherent structures in the near field are found to break down more rapidly in the triangular jet as compared to the circular jet.Over the entire measurement region,the triangular jet maintained a higher rate of decay and spread.Moreover,all components of Reynolds stress of the triangular jet appear to reach their peaks earlier,and then decay more rapidly than those of the circular jet.In addition,the axis-switching phenomenon is observed in the triangular jet.

关键词：等边三角形 PIV测量湍流射流圆形发行孔板混合特性粒子图像测速

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基于“肺朝百脉”理论探讨新冠病毒感染转阴后下肢深静脉血栓形成的治疗思路

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中医药学报 2024年第2期52卷 1-4页

作者：王唱曹建春牛少辉程亚清常金霞宓宝来杨俏丽方毅娜卜雯钰崔艺箫北京中医药大学北京100029 北京中医药大学东方医院北京100078

下肢深静脉血栓形成是周围血管科常见病,可引起血栓形成后综合征,严重影响患者生活质量,亦可导致肺栓塞,甚者危及生命。有关数据显示,新冠病者感染后患者深静脉血栓形成的发病率较前有明显升高,可见肺部受损在下肢深静脉血栓形成的发病... 详细信息

下肢深静脉血栓形成是周围血管科常见病,可引起血栓形成后综合征,严重影响患者生活质量,亦可导致肺栓塞,甚者危及生命。有关数据显示,新冠病者感染后患者深静脉血栓形成的发病率较前有明显升高,可见肺部受损在下肢深静脉血栓形成的发病机制中具有一定影响。中医药防治下肢深静脉血栓形成具有长期的实践性及有效性,本文基于“肺朝百脉”理论论述新冠病毒感染转阴后下肢深静脉血栓形成的发病机制,归纳其从肺论治的中医治疗原则,探讨新的辨证思路,为进一步提高临床疗效提供理论依据。

关键词：静脉血栓形成下肢深静脉血栓形成肺朝百脉新冠病毒感染理论探讨

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Progress and recent trend in miLD combustion

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Science China(Technological Sciences) 2011年第2期54卷 255-269页

作者： LI PengFei mi jianchun DALLY B B WANG FeiFei WANG Lin LIU ZhaoHui CHEN Sheng ZHENG ChuGuang State Key Laboratory of Turbulence and Complex Systems Peking University Beijing 100871 China School of Mechanical Engineering University of Adelaide South Australia 5005 Australia State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 China

Moderate or intense low oxygen dilution(miLD)combustion plays a significant role in the mitigation of combustion-generated pollutants and greenhouse gases whilst meeting thermal efficiency needs.However,due to the lack of the fundamental knowledge on this combustion,there is a misconception that miLD combustion should be established by high preheating of the air,which has limited its application.Our research and development on this combustion has been performed for several years. We have found that the requirements for establishing the miLD combustion are more relaxed than previously.It is also revealed that this combustion of different type,i.e.,non-premixed,partially premixed and fully premixed,can be achieved by firing various fuels(i.e.,gaseous,liquid and solid fuels).It is suggested that the application of the miLD combustion can be expanded significantly.The present review summarizes the progress and recent trend made in the R&D of this combustion and recommends further fundamental studies for improving our knowledge and widening its applications.

关键词：燃烧温室气体减排部分预混大肠杆菌应用程序热效率污染物燃料

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振荡射流研究进展

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实验流体力学 2023年第4期37卷 1-17页

作者：吴梦维徐敏义米建春北京大学工学院北京100871 大连海事大学轮机工程学院大连116026

振荡射流可有效增强喷射流体与周围流体的相互作用,在能源、化工、航空航天、精密制造等领域有着重要应用价值,受到国内外学者广泛关注。为更好地了解振荡射流发展现状及未来发展趋势,本文对微射流、机械式、反馈式、钝体–V形喷嘴、冲... 详细信息

振荡射流可有效增强喷射流体与周围流体的相互作用,在能源、化工、航空航天、精密制造等领域有着重要应用价值,受到国内外学者广泛关注。为更好地了解振荡射流发展现状及未来发展趋势,本文对微射流、机械式、反馈式、钝体–V形喷嘴、冲击V形板、腔体自激拍打、薄膜自激拍打等7种激励方式的振荡射流进行了全面归纳与分类,对比分析了不同激励方式的原理及其产生的振荡射流特性,指出了振荡射流技术存在的问题及工业应用的局限性,预测了其发展前景并给出了发展建议。

关键词：振荡射流流动控制射流混合自激振荡

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Numerical Simulation of Flameless Premixed Combustion with an Annular Nozzle in a Recuperative Furnace

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Chinese Journal of Chemical Engineering 2010年第1期18卷 10-17页

作者：米建春李鹏飞郑楚光 State Key Laboratory of Turbulence and Complex Systems Department of Energy-& Resources Engineering College of Engineering Peking University Beijing 100871 China State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 China

This paper reports an investigation of Computational Fluid Dynamics(CFD)on the influence of injection momentum rate of premixed air and fuel on the flameless Moderate or Intense Low oxygen Dilution(miLD) combustion in a recuperative furnace.Details of the furnace flow velocity,temperature,O2,CO2 and NOx concentrations are provided.Results obtained suggest that the flue gas recirculation plays a vital role in establishing the premixed miLD combustion.It is also revealed that there is a critical momentum rate of the fuel-air mixture below which miLD combustion does not occur.Moreover,the momentum rate appears to have less significant influence on conventional global combustion than on miLD combustion.

关键词：预混合燃烧燃烧炉数值模拟无火焰计算流体动力学回热管带环形

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大湍流度对超低雷诺数下翼型受力及绕流的影响

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航空学报 2011年第1期32卷 41-48页

作者：王庶米建春北京大学湍流与复杂系统研究国家重点实验室北京100871

实验测量了超低雷诺数(Re=5 300)下NACA 0012翼型在自由来流下的升力系数和阻力系数,重点研究来流的湍流度对升力系数和阻力系数的影响,并进一步通过对翼型流场的研究揭示湍流度对翼型受力产生影响的机理。结果显示,低湍流度下升力系数... 详细信息

实验测量了超低雷诺数(Re=5 300)下NACA 0012翼型在自由来流下的升力系数和阻力系数,重点研究来流的湍流度对升力系数和阻力系数的影响,并进一步通过对翼型流场的研究揭示湍流度对翼型受力产生影响的机理。结果显示,低湍流度下升力系数和阻力系数均无失速特征;当湍流度提高,升力系数和阻力系数在12°～15°迎角下表现出明显的失速特征。翼型流场的流动显示表明,自由来流的湍流度不仅对翼型边界层的流动有明显影响,而且对边界层分离后的剪切层流动状态有很大影响,使得翼型在相同雷诺数和相同迎角下表现出完全不同的特性,并得出湍流度的增大和雷诺数的提高在影响翼型绕流形态及受力特征方面起着相似作用的结论。

关键词：湍流度超低雷诺数升力流动显示失速

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煤粉miLD燃烧的数值模型优化

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中国电机工程学报 2016年第19期36卷 5245-5253,5406页

作者：梅振锋张健鹏米建春西安热工研究院有限公司苏州分公司江苏省苏州市215163 北京大学工学院北京市海淀区100871

采用用户自定义函数(UDF)对煤粉miLD燃烧的数值模型进行了优化,包括挥发分的多组分比拟、脱挥发分极限的温度依赖优化和煤粉颗粒燃烧过程的算法优化。通过与IFRF的煤粉miLD燃烧经典实验的对比,验证了模型优化所产生的效果。研究发现,挥... 详细信息

采用用户自定义函数(UDF)对煤粉miLD燃烧的数值模型进行了优化,包括挥发分的多组分比拟、脱挥发分极限的温度依赖优化和煤粉颗粒燃烧过程的算法优化。通过与IFRF的煤粉miLD燃烧经典实验的对比,验证了模型优化所产生的效果。研究发现,挥发分的多组分比拟能更准确地预测炉内O2浓度分布;脱挥发分极限的温度依赖优化,一方面能够使挥发分在低温区间开始脱附,改善模拟中着火延迟过长的问题,另一方面,能够使煤粉颗粒在高温区间脱附出更多的挥发分,使得温度分布的预测更为准确;煤粉颗粒燃烧过程的算法优化能够刻画挥发分脱附过程和焦炭反应过程在温度区间(780~1200K)上的重叠现象,能更准确地预测炉内CO分布,与真实的煤粉miLD燃烧过程更为相符。

关键词：煤粉 miLD燃烧数值模拟挥发分用户自定义函数

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