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框架结构对薄膜体声波谐振器性能提升的研究
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作者 吴永乐 吴昊鹏 +5 位作者 赖志国 蔡洵 唐滨 杨清华 杨雨豪 王卫民 《电子学报》 EI CAS CSCD 北大核心 2024年第2期407-413,共7页
本文研究了框架结构(Frame)对薄膜体声波谐振器(Film Bulk Acoustic Resonator,FBAR)提升性能的作用,从两种Frame结构对体声波能量的反射匹配基础理论出发,针对其功能特点,以实验的方式确定了低频和高频多组框架微结构的组合,对多组FBA... 本文研究了框架结构(Frame)对薄膜体声波谐振器(Film Bulk Acoustic Resonator,FBAR)提升性能的作用,从两种Frame结构对体声波能量的反射匹配基础理论出发,针对其功能特点,以实验的方式确定了低频和高频多组框架微结构的组合,对多组FBAR进行了版图绘制以及光刻流片,最终通过片上测试得到了所有分组的谐振器性能.对测试得到的性能进行了分组统计筛选,从测试结果来看,经过优选之后的Frame结构分组无论是对低频还是高频FBAR谐振器都具有提升性能的作用.对低频(1.7 GHz附近)FBAR来说,并联谐振品质因数可以提升1000以上.对高频(5.5 GHz附近)FBAR来说,并联谐振品质因数可以提升300以上.对横向寄生模式较强的高频FBAR,优选的Frame结构可以提升谐振器的横向寄生模式抑制,使串联谐振频率之下的阻抗相位波动减少5°以上. 展开更多
关键词 薄膜体声波谐振器 框架结构 流片实验 阻抗相位波动
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模拟集成电路课程群教学与实训体系的研究 被引量:5
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作者 胡远奇 王昭昊 《工业和信息化教育》 2021年第12期74-76,81,共4页
模拟集成电路及其相关前序课程是集成电路专业本科生的必修课程,课程链条较长,横跨4个学期,教学内容的合理设计至关重要。由于模拟电路具有较多抽象概念,因此单纯的理论讲授无法使学生直观地理解这些概念。以北京航空航天大学集成电路... 模拟集成电路及其相关前序课程是集成电路专业本科生的必修课程,课程链条较长,横跨4个学期,教学内容的合理设计至关重要。由于模拟电路具有较多抽象概念,因此单纯的理论讲授无法使学生直观地理解这些概念。以北京航空航天大学集成电路科学与工程学院模拟集成电路教研组课程改革方案为例,通过调整课程链上每门课程的内容,设计了基于产教融合思路的仿真案例,最终提出了教学与实训有机结合及按需拔尖的建设方案,初步达到了培养学生全局规划能力和工程思维方式的效果。 展开更多
关键词 集成电路 实训课程 教学设计 流片实验 全过程
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Influence of a Deflector or a Wall on Savonius Rotor Efficiency 被引量:1
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作者 A.H. Chauvin N. Belouaggadia B. Kamoun 《Journal of Environmental Science and Engineering》 2011年第10期1294-1296,共3页
The Savonius rotor is a vertical axis-wind machine composed of two half cylindrical blades presenting a central gap. It is a slow velocity machine compared with horizontal wind machines. Its efficiency is about twenty... The Savonius rotor is a vertical axis-wind machine composed of two half cylindrical blades presenting a central gap. It is a slow velocity machine compared with horizontal wind machines. Its efficiency is about twenty per cent. In this work experimental tests are presented using two kind of deflectors placed in front of the resistive blade. Such disposition allows to hide the resistant blade and to guide the flow toward the motrice blade. Two deflectors have been used: a short one and a long one. The results obtained in wind tunnel have shown that the long deflector is the more efficient, essentially for high values of the tip speed ratio. One has been interested, using a numerical approach, in the study of the influence of a wall on the aerodynamical field near the rotor. 展开更多
关键词 Wind energy vertical axis wind machine power coefficient.
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Experimental Investigation of the Internal Flow Field of Rotating Impeller Passage with Inlet Box 被引量:1
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作者 WuKeqi HuShengli 《Journal of Thermal Science》 SCIE EI CAS CSCD 1995年第1期1-9,共9页
Using PDA and its measurement system, the flow fields at the different peripheral locations of rotating impeller passage of a diagonal fan with inlet box are measured. The results are compared with the flow field of t... Using PDA and its measurement system, the flow fields at the different peripheral locations of rotating impeller passage of a diagonal fan with inlet box are measured. The results are compared with the flow field of the rotating impeller passage of the same fan without inlet box. The differences of the flow characteristics of the rotating passage at the different peripheral locations are revealed. The effects of the complex flow in the inlet box on the internal flow of the rotating impell passage are investigated. 展开更多
关键词 rotating impeller inlet box internal flow measurement.
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Numerical and Experimental Study on Aerodynamic Performance of Small Axial Flow Fan with Splitter Blades 被引量:5
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作者 Zhu Lifu Jin Yingzi +3 位作者 Li Yi Jin Yuzhen Wang Yanping Zhang Li 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第4期333-339,共7页
To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-e turbulence model and SIMPLE algorithm were applied to the... To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-e turbulence model and SIMPLE algorithm were applied to the steady simulation calculation of the flow field, and its result was used as the initial field of the large eddy simulation to calculate the unsteady pressure field. The FW-H noise model was adopted to predict aerodynamic noise in the six monitoring points. Fast Fourier transform algorithm was applied to process the pressure signal. Experiment of noise testing was done to further investigate the aerodynamic noise of fans. And then the results obtained from the numerical simulation and experiment were described and analyzed. The results show that the static characteristics of small axial fan with splitter blades are similar with the prototype fan, and the static characteristics are improved within a certain range of flux. The power spectral density at the six monitoring points of small axial flow fan with splitter blades have decreased to some extent. The experimental results show sound pressure level of new fan has reduced in most frequency bands by comparing with prototype fan. The research results will provide a proof for parameter optimization and noise prediction of small axial flow fans with high performance. 展开更多
关键词 small axial flow fan splitter blades noise FREQUENCY
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Corner Separations around a NACA65 Blade in a Decelerating Flow (Experimental Investigations by Five-Hole Probe and PIV) 被引量:1
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作者 Yoichi Kinoue Ryutaro Ohhira +1 位作者 Norimasa Shiomi Toshiaki Setoguchi 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第1期23-28,共6页
In order to examine the fundamental characteristics of corner separation in a decelerating cascade flow,the experimental apparatus was made and separations around a NACA65 blade in a decelerating channel flow were exa... In order to examine the fundamental characteristics of corner separation in a decelerating cascade flow,the experimental apparatus was made and separations around a NACA65 blade in a decelerating channel flow were examined.Two-dimensional calculations show that the NACA65 cascade flow that has 45 deg.of turning,1.24 of solidity and 17 deg.of stagger angle is equivalent to the channel flow that has 14 deg.of stagger angle in terms of pitchwise blade force.Experimental investigation by five-hole probe shows that the accumulations of low energy fluid can be seen around the corner part and the overturning flow due to the secondary flow exists.And,as the periodicity of the blade wake in a pitchwise direction is comparably good,the wake of this channel flow is similar to the wake of the cascade flow for two pitch portion.PIV measurement results shows that a vortex pattern can be seen in the momentary streamline on the suction surface of the blade and in the averaged streamline on the perpendicular to both the suction surface and the endwall. 展开更多
关键词 corner separation NACA65 blade decelerating channel flow five-hole probe PIV
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Experimental study of the effect of blade tip clearance and blade angle error on the performance of mixed-flow pump 被引量:13
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作者 BING Hao CAO ShuLiang +1 位作者 HE ChengLian LU Li 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第2期293-298,共6页
The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors.The ratio of the mixed-flow pump efficiency reduction and the ... The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors.The ratio of the mixed-flow pump efficiency reduction and the blade tip clearance variation(η/δ) varies with the flow rate coefficient revealing a parabolic trend.An empirical equation has been developed for the mixed-flow pump model by parabolic fitting.For the same blade tip clearance variation δ,the mixed-flow pump efficiency reduction η increases rapidly as the flow rate rises.For any given flow rate,the efficiency,the head and the shaft power of the mixed-flow pump all decrease with the increase of the blade tip clearance.Among them,the efficiency reduction η varies approximately linearly with the blade tip clearance variation δ.When the angle of an individual blade of the mixed-flow pump has a deviation,the performance curves will move and change.These curves have consistent change directions with the performance curves under the condition of all the blades rotated at the same time,but have smaller offset and lower range of variation.When an individual blade angle error changes to ±2°,the optimal efficiency of the mixed-flow pump will have no significant difference.When the individual blade angle error increases to ±4°,the optimal efficiency will decrease by 1%. 展开更多
关键词 mixed-flow pump model test hydraulic performance blade tip clearance blade angle
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Numerical and Experimental Investigation on Aerodynamic Performance of Small Axial Flow Fan with Hollow Blade Root 被引量:4
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作者 Zhang Li Jin Yingzi1 +1 位作者 Dou Huashu Jin Yuzhen 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第5期424-432,共9页
To reduce the influence of adverse flow conditions at the fan hub and improve fan aerodynamic performance, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Ho... To reduce the influence of adverse flow conditions at the fan hub and improve fan aerodynamic performance, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Hollow blade root is manufactured near the hub. The numerical and experimental results show that hollow blade root has some effect on the static performance. Static pressure of the modified fan is generally the same with that of the datum fan, while, the efficiency curve of the modified fan has a different trend with that of the datum fan. The highest efficiency of the modified fan is 10% greater than that of the datum fan. The orthogonal experimental re- suits of fan noise show that hollow blade root is a feasible method of reducing fan noise, and the maximum value of noise reduction is about 2 dB. The factors affecting the noise reduction of hollow blade root are in the order of importance as follows: hollow blade margin, hollow blade height and hollow blade width. The much smoother pressure distribution of the modified fan than that of the datum fan is the main mechanism of noise reduction of hollow blade root. The research results will provide the proof of the parameter optimization and the structure de- sign for high performance and low noise small axial fans. 展开更多
关键词 small axial flow fan hollow blade root performance noise reduction mechanism
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Experimental investigation of the unsteady flow in a double-blade centrifugal pump impeller 被引量:8
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作者 LIU HouLin WANG Kai +1 位作者 KIM Hyoung-Bum TAN MingGao 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第4期812-817,共6页
Particle Image Velocimetry (PIV) technology was used to study the unsteady internal flow in a double-blade centrifugal pump (DBCP) impeller at the design flow rate.Relative velocity distributions and turbulence intens... Particle Image Velocimetry (PIV) technology was used to study the unsteady internal flow in a double-blade centrifugal pump (DBCP) impeller at the design flow rate.Relative velocity distributions and turbulence intensity distributions in the DBCP impeller at six phase conditions were obtained.And mean dimensionless relative velocity,turbulence intensity,mean absolute flow angle,mean relative flow angle,mean dynamic pressure and mean angular momentum distributions at the different radii of impeller were calculated.Results show that from impeller inlet to impeller outlet,turbulence intensities gradually decrease.With the increase of radius r,mean dimensionless relative velocity first decreases and then increases,while variation tendencies of mean absolute flow angle and mean dynamic pressure are the opposite.With the increase of radius r,turbulence intensity and mean relative flow angle first decrease,then increase,and then decrease,while mean angular momentum gradually increases. 展开更多
关键词 double-blade centrifugal pump IMPELLER unsteady flow Particle Image Velocimetry (PIV)
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Turbine Blade Boundary Layer Separation Suppression via Synthetic Jet: an Experimental and Numerical Study 被引量:1
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作者 Bernardini C. +9 位作者 Carnevale M. Manna M. Martelli F. Simoni D. Zunino P. 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第5期404-412,共9页
The present paper focuses on the analysis of a synthetic jet device (with a zero net massflow rate) on a separated boundary layer. Separation has been obtained on a flat plate installed within a converging-diverging t... The present paper focuses on the analysis of a synthetic jet device (with a zero net massflow rate) on a separated boundary layer. Separation has been obtained on a flat plate installed within a converging-diverging test section specifically designed to attain a local velocity distribution typical of a high-lift LPT blade. Both experimental and numerical investigations have been carried out. Unsteady RANS results have been compared with experiments in terms of time-averaged velocity and turbulence intensity distributions. Two different Reynolds number cases have been investigated, namely Re = 200,000 and Re = 70,000, which characterize low-pressure turbine operating conditions during take-off/landing and cruise. A range of synthetic jet aerodynamic parameters (Strouhal number and blowing ratio) has been tested in order to analyze the features of control-separated boundary layer interaction for the aforementioned Reynolds numbers. 展开更多
关键词 Synthetic Jet Separated Flow Active Flow Control Unsteady Flow Ultra High Lift LPT.
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Effects of submerged sheet pile vanes on mobile river beds
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作者 Maria Antonietta BONIFORTI Roberto GUERCIO Roberto MAGINI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2015年第3期182-193,共12页
Submerged vanes are low-height flow-training structures emerging from the riverbed with a suitable angle of attack to the incoming flow. These structures redirect the stream flow and modify erosion and depositional ra... Submerged vanes are low-height flow-training structures emerging from the riverbed with a suitable angle of attack to the incoming flow. These structures redirect the stream flow and modify erosion and depositional rates in the bottom and in the banks of a river as a result of the secondary currents generated by their installation. For this reason they have many applica- tions in river hydraulics for controlling river bed morphology. An experimental investigation is carried out to compare the effi- ciency of sheet-piling vanes versus thin plane ones in controlling sediment redistribution in the channel bed. In particular, exper- imental tests were carried out within a straight water channel, in conditions of bed load motion. The morphology of the river bed both in the area close to the structure and in the far field was examined at different angles of attack of the vane to the incoming flow and at different values of the submergence parameter, which is the ratio between the height of the water above the structure and the water level. The experimental results show that both the shape of the vanes as well as the angle of attack affect their per- formance in terms of the effects on the bed morphology, especially for greater submergence parameters. Specifically, plane and sheet-piling vanes produce comparable remodelings of the channel bed in the downstream region, but when the attack angle is increased, the thin plane vane causes deeper scour holes close to the structure. This last effect is probably due to the increased erosive capacity of the horseshoe vortex associated with the plane vane, while the uneven surface of the sheet-piling vane miti- gates the erosive strength of that vortex. 展开更多
关键词 Vanes SEDIMENT SCOUR River hydraulics Experimental hydraulics
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