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液体低流速测量热分布式微纳传感器制造与测试 被引量:1
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作者 车啸婷 王振宇 +2 位作者 管轶华 郜晚蕾 金庆辉 《传感器与微系统》 CSCD 北大核心 2022年第4期73-76,共4页
面向液体低流速测量应用需求,基于介质热传递工作原理,采用微电子机械系统(MEMS)加工技术制备了以玻璃为衬底的微纳热分布式流速传感器,加热和测温元件均采用铂电阻,传感器芯片尺寸仅为10 mm×10 mm,测温电阻与中心加热电阻的间距为... 面向液体低流速测量应用需求,基于介质热传递工作原理,采用微电子机械系统(MEMS)加工技术制备了以玻璃为衬底的微纳热分布式流速传感器,加热和测温元件均采用铂电阻,传感器芯片尺寸仅为10 mm×10 mm,测温电阻与中心加热电阻的间距为0.8 mm,完成了芯片的封装及测试。通过实验测试,在室温条件下,传感器加热电阻为108.8Ω,测温电阻为525.2Ω,且测温电阻具有良好的温度-阻值线性度(R^(2)≥0.9999),传感器适用量程为0~90 mm/s,在极低流速0~20 mm/s范围测试,有较好的输出曲线关系,最高灵敏度达到0.06mV/(mm·s^(-1)),且有较好的稳定性能。传感器具有尺寸小、成本低、可批量制造,将为液体流速测量领域提供核心传感器。 展开更多
关键词 低流速测量 热分布式 微纳传感器 铂电阻阵列
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Topological evolution of laminar juncture flows under different critical parameters 被引量:1
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作者 YOUNIS Muhammad Yamin ZHANG Hua +1 位作者 HU Bo MEHMOOD Saqib 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第7期1342-1351,共10页
Horseshoe vortex topological structure has been studied extensively in the past,traditional"saddle of separation"and new"attachment saddle point"topologies found in literature both have theoretical... Horseshoe vortex topological structure has been studied extensively in the past,traditional"saddle of separation"and new"attachment saddle point"topologies found in literature both have theoretical basis and experimental and computational evidences for support.The laminar incompressible juncture flows at low Reynolds numbers especially are observed to have new topology.Studies concerning the existence of the new topology though found in literature,the topological evolution and its dependency on various critical flow parameters require further investigation.A Particle Image Velocimetry based analysis is carried out to observe the effect of aspect ratio,?*/D and shape of the obstacle on laminar horseshoe vortex topology for small obstacles.Rise in aspect ratio evolves the topology from the traditional to new for all the cases observed.The circular cross section obstacles are found more apt to having the new topology compared to square cross sections.It is noted that the sweeping effect of the fluid above the vortex system in which horseshoe vortex is immersed plays a critical role in this evolution.Topological evolution is observed not only in the most upstream singular point region of horseshoe vortex system but also in the corner region.The corner vortex topology evolves from the traditional type to new one before the topological evolution of the most upstream singular point,resulting in a new topological pattern of the laminar juncture flows"separation-attachment combination".The study may help extend the understanding of the three-dimensional boundary layer separation phenomenon. 展开更多
关键词 horseshoe vortex saddle of attachment saddle of separation topological evolution sweeping effect
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Kutta-Joukowski force expression for viscous flow
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作者 LI Juan XU YiZhe WU ZiNiu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第2期90-94,共5页
The Kutta Joukowski(KJ) theorem, relating the lift of an airfoil to circulation, was widely accepted for predicting the lift of viscous high Reynolds number flow without separation. However, this theorem was only prov... The Kutta Joukowski(KJ) theorem, relating the lift of an airfoil to circulation, was widely accepted for predicting the lift of viscous high Reynolds number flow without separation. However, this theorem was only proved for inviscid flow and it is thus of academic importance to see whether there is a viscous equivalent of this theorem. For lower Reynolds number flow around objects of small size, it is difficult to measure the lift force directly and it is thus convenient to measure the velocity flow field solely and then, if possible, relate the lift to the circulation in a similar way as for the inviscid KJ theorem. The purpose of this paper is to discuss the relevant conditions under which a viscous equivalent of the KJ theorem exists that reduces to the inviscid KJ theorem for high Reynolds number viscous flow and remains correct for low Reynolds number steady flow. It has been shown that if the lift is expressed as a linear function of the circulation as in the classical KJ theorem, then the freestream velocity must be corrected by a component called mean deficit velocity resulting from the wake. This correction is small only when the Reynolds number is relatively large. Moreover, the circulation, defined along a loop containing the boundary layer and a part of the wake, is generally smaller than that based on inviscid flow assumption. For unsteady viscous flow, there is an inevitable additional correction due to unsteadiness. 展开更多
关键词 lift force Kutta Joukowski expression viscous flow
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