共查询到20条相似文献,搜索用时 15 毫秒
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参考文献(1,2)利用紊流整体流动理论,考虑了惯性项的影响,对短密封的动特生系数等进行了详细地推导,并研制出计算程序,对短密封动特性系数进行精确计算。 相似文献
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毛细管电渗流微泵的流体动力学的数值仿真 总被引:3,自引:2,他引:1
利用电渗流(EOF:Electroosmotic flow)机理制作出的微泵,以其体积小、噪声低、易于控制和结构简单等优点,在药物输送、生化合成及微机电系统(MEMS)中得到了广泛的应用。以实现CPU的温度控制为目标,对电渗流泵的控制及速度、压力间的关系进行了分析。应用无网格法(Meshless/meshfree)对Laplace方程、Poisson-Boltzmann方程、Navier-Stokes方程进行数值求解。数学模型不仅可以仿真几何形状简单的直管内微流体的驱动过程,也可以仿真几何形状复杂、ζ电势较大条件下的微流体的流动情况,为电渗流泵的设计提供了仿真模型。主要讨论通过改变外加垂直电势和ζ电势,实现对电渗流泵的控制以及电渗流泵所能承受的背压问题。 相似文献
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RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE 总被引:1,自引:0,他引:1
Quan LongMa JianWang YongjinInstitute of Mechatronics Taiyuan University of Technology Taiyuan China 《机械工程学报(英文版)》2003,16(3):281-284
A new closed loop flow controlling principle through correcting the valve's opening area while load pressure is changing is carried out. Further more a principle using only one proportional valve to compound control pressure and flow is suggested. By using very simple proportional throttle valve in structure, the functions that five kinds of proportional valves or any two of them combined possess can be complimented. After analyzing, comparing, and testing the dynamic and static characteristics of valve with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved. 相似文献
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Zhu Huangqiu School of Electrical Informational Engineering Jiangsu University Zhenjiang China 《机械工程学报(英文版)》2005,18(2):237-240
A state equation for radical 4-degree-of-freedom active magnetic bearings is built, and the approach on how to use linear quadratic method of optical control theory to design a centralized and decentralized parameters control system is introduced, and also Matlab language is used to simulate and analyze. The simulation results have proved that the differences are small between centralized parameters and decentralized parameters control system. The conclusions of experiments have shown that decentralized controllers designed from optimal state feedback theory meet the requirements of active magnetic bearing system. The vibration amplitude of the rotor is about 20 μm when the speed of the rotor runs between 0 to 60 000 r/min. This method may be used in the study and design of controllers of magnetic bearings. 相似文献
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多供气孔气垫平台气垫场压力的理论研究 总被引:2,自引:0,他引:2
应用流体的复势函数理论及缝隙流动理论 ,对具有多供气孔的矩形荷载的气垫场进行了理论分析。用大量的源和汇排列的方法找出了满足边界条件的势函数。从而建立了均匀分布的、任意布孔方式的、多供气孔矩形荷载的气垫压力场压力计算方法和公式 ,编制了计算气垫场任意一点的压力、气垫承载能力 ,压力中心和流量的计算程序 ,并用试验验证了理论分析的正确性。 相似文献
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This paper describes the development of a variable flow stress predictive machining theory for aluminium alloys. This theory is based on the Oxley's machining theory which allows for the high strain-rate/high temperature flow stress and thermal properties of the work materials and has so far been applied and tested for plain carbon steels.
The developed predictive theory for aluminium has been applied in predicting cutting forces, chip thicknesses, etc., for a wide range of cutting conditions (cutting speeds ranging from 100 to 1000 m/min) when machining two alloys: one with 97.64%Al and the other with 93.89%Al (a free machining aluminium alloy). The flow stress properties required in applying the predictive method were obtained from bar turning test results and by applying the machining theory in reverse. For the above mentioned aluminium alloys, a comparison between predicted and experimental cutting force results shows good agreement. 相似文献
The developed predictive theory for aluminium has been applied in predicting cutting forces, chip thicknesses, etc., for a wide range of cutting conditions (cutting speeds ranging from 100 to 1000 m/min) when machining two alloys: one with 97.64%Al and the other with 93.89%Al (a free machining aluminium alloy). The flow stress properties required in applying the predictive method were obtained from bar turning test results and by applying the machining theory in reverse. For the above mentioned aluminium alloys, a comparison between predicted and experimental cutting force results shows good agreement. 相似文献
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光滑及沟槽密封的转子动力学分析及计算 总被引:1,自引:1,他引:0
参考文献(1),将Hirs紊流整体流动理论进行扩展,在Childs环形密封有限长解的基础上,引入平均槽深,并研制出计算程序,对光滑密封和沟槽密封动特性系数及泄漏流量进行了分析计算,对沟槽密封的复数常微分方程组进行求解。 相似文献
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锥形流量计的锥角参数是影响锥形流量计性能的重要参数,锥体前锥角和后锥角均有较大的取值范围,这造成供选择的锥角组合无限多。通过实验和传统的CFD仿真优化锥形流量计锥角工作量大,效率低。研究证明了锥角的变化引起的下游取压位置处的压力波动会导致锥形流量计流出系数的改变。根据流体力学本构方程理论定义了评价黏性应力对压力波动影响的黏性应力比例因子k1和k2,并得到结论:任一锥角组合锥形流量计下游取压位置处黏性比例因子k1和k2越大,锥形流量计的压力信号受到的干扰越大,对应的流出系数重复性和线性度误差越差,在低入口雷诺数状态下这种干扰尤为明显。基于黏性比例因子的具有不同锥角组合锥形流量计的性能预测结论是:β值在0.45~0.75的锥形流量计,前锥角为27.5°±2.5°,后锥角为65°±5°时锥形流量计的流出系数重复性和线性度误差好于其他的锥角组合。实验测试DN100口径,β值分别为0.45,0.5和0.65的9个不同锥角组合的锥形流量计,实验结论证明了基于黏性应力比例因子的锥形流量计锥角组合预测的准确性。 相似文献
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This study is concerned with the development of a novel, high-precision, steady-flow instrument applicable to common unsaturated soils such as clay, silt, sand, gravel soil, and soft soil. The instrument consists of three parts: a high-precision water pressure control system, a high-precision air pressure control system, and a high-precision measurement system. A stepping motor was chosen as the source of water pressure power because it had a high divided driver, reliable operation, simple structure, low cost, and easy maintenance. An electro-pneumatic pressure regulator was used to produce the demanded air pressure. High-precision measurement was archived by a high-resolution grating interferometer, a high-precision balance, and a high-speed 16-bit A/D converter. The device can fully meet the precision requirement of the water pressure, air pressure, and the measurement during the steady flow test for unsaturated soils, which is a very automatic instrument (automatic testing and recording). In this study, volumes of inlet water and outlet water, which are usually difficult to gauge in traditional modes, were gauged by a high-resolution grating interferometer (0.001 mm) and a high-precision balance (0.001 g), and the related experimental study was successfully accomplished. 相似文献
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为了提高气相色谱仪气路控制自动化水平,研制了电子流量/压力控制模块.该模块在基于闭环控制的方式上,通过小流量比例电磁阀、小流量和压力传感器、微型可调限流装置、颗粒过滤网、集成流路块体的优化设计,以放大基准电路、A/D转换、单片机控制系统PID、D/A转换、功率驱动电路来达到控制气体流量/压力的目的.再以单气路控制为最小... 相似文献
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Cylinder pressure fluctuation during combustion process of internal combustion engine is closely related to combustion noise and knock.The current studies are based on cylinder pressure test to obtain ... 相似文献
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减压阀流量压力特性的分析与探讨 总被引:3,自引:0,他引:3
分析了减压阀的流量、压力、压力差和阀门开工的关系。通过设计一些典型的工况实例,从实际运用的角度对减压阀工作过程进行了分析研究。 相似文献
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"V"型内锥式流量计的应用前景 总被引:4,自引:0,他引:4
长期以来,标准孔板由于其发展技术成熟、标准化程度高、结构简单等特点在过热蒸汽流量计量中得到非常广泛的应用.然而,孔板流量计存在着一些固有的缺陷,如流出系数不稳定、线形差、重复性不高、准确度受客观因素制约而无法达到设计要求、量程比小、压损大等.本文介绍"V"型内锥式差压流量计的工作原理,分析了如何解决孔板流量计的这些缺陷,并通过计算实例介绍"V"型内锥式流量计在节能方面的优点,最后介绍在恶劣条件下"V"型内锥式流量计是如何提供准确计量的. 相似文献