发动机高温自润滑配气阀座材料的技术攻关分析

高温自润滑配气阀座是某工程发动机的关键部件。文章对3种配气阀座的研制全过程进行了技术分析,并就三者的物理机械性能、马力试验考核、材料研制和测试条件及综合性能对比情况作了论述,最后还从与美国同类产品相比的角度提出了作者的看法。     

PIV EXPERIMENTAL STUDY ON THE HEMODYNAMICS OF AORTIC VALVE UNDER VARIED TILTED ANGLES 1)

瓣叶血栓是主动脉瓣置换术后典型的继发性瓣膜疾病,血流动力学特征异常在其发展过程中至关重要.本文利用粒子图像测速 (particle image velocimetry,PIV) 系统,实验研究了主动脉瓣开口纵向轴线与升主动脉纵向轴线之间倾斜角度 ($\alpha =0^\circ$, $\alpha=5^\circ$,$\alpha =10^\circ$ 和 $\alpha =15^\circ$) 对速度、涡度和黏性剪应力分布等血流动力学特性的影响.研究结果表明：当 $\alpha =0^\circ$ 时,主动脉根部跨瓣血液流动为中心对称流动,而 $\alpha =5^\circ$,$\alpha=10^\circ$ 和 $\alpha =15^\circ$ 时跨瓣血液流动向升主动脉的左冠状动脉一侧倾斜.随着倾斜角度增大,跨瓣血液流动方向倾斜程度增加,血液流动冲击升主动脉壁,损伤内皮细胞导致血栓形成.主动脉瓣倾斜时主动脉窦血液流动速度增大,涡旋也更向主动脉窦底部运动,不利于血液从冠状动脉口流出向心肌供血.同时,主动脉根部的高涡度和高黏性剪应力区域也向升主动脉的左冠状动脉一侧倾斜,主动脉窦的高涡度区域位于主动脉窦底部、高黏性剪应力区域分布于主动脉窦壁面处.主动脉瓣存在倾斜角度时,涡度和黏性剪应力较大,特别是 $\alpha =10^\circ$ 和 $\alpha=15^\circ$,为血栓形成提供了有利环境.研究结果可为临床主动脉瓣置换术参数选择以及继发性瓣膜疾病的避免提供理论依据和技术参考.     

簧片阀三种力学模型的建立及比较

一端固定一端自由的簧片阀片按其运动特征及不同的简化条件，可视为单质点力学系统，连续梁力学系统及平板振动力学系统，并分别给出其数学模型，建立相应的仿真软件系统。最后以管状直流阀为例比较了这三种力学模型的仿真结果，给出了它们的应用场合     

Primary pressure wave in a fluid after actuation of a pipeline valve

This paper considers the variation in the velocity, density, and pressure of an inviscid compressible fluid due to flow acceleration or deceleration after a change in the flow area of a valve installed on the pipeline with rigid walls. Expressions are given for the amplitude of the primary compression or rarefaction wave resulting form the change in flow area of the valve.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 78–84, January–February, 2005     

A COMPARATIVE STUDY OF THE OPENING AND CLOSING PROCESS OF TWO TYPES OF MECHANICAL HEART VALVES USING ALE FINITE ELEMENT METHOD

ＡＣＯＭＰＡＲＡＴＩＶＥＳＴＵＤＹＯＦＴＨＥＯＰＥＮＩＮＧＡＮＤＣＬＯＳＩＮＧＰＲＯＣＥＳＳＯＦＴＷＯＴＹＰＥＳＯＦＭＥＣＨＡＮＩＣＡＬＨＥＡＲＴＶＡＬＶＥＳＵＳＩＮＧＡＬＥＦＩＮＩＴＥＥＬＥＭＥＮＴＭＥＴＨＯＤＡＣＯＭＰＡＲＡＴＩＶＥＳＴＵＤＹＯＦ...     

Rupture-disk-less shock-tube with compression tube driven by free piston

A new technique is proposed for a shock tube driven by a freely moving piston. In a conventional free-piston-driven shock tube, a rupture disk is employed between the compression tube and the shock generation tube. In the present method, however, the conventional rupture disk is replaced by a newly developed fast action valve which is activated by the compressed gas generated in the compression tube. The present method enables us to generate high Mach number shock waves of arbitrary strength with good reproducibility. The performance of the new method is demonstrated experimentally. This also enables us to be carefree to scattering of fragments of the rupture disk. Received 6 June 1996 / Accepted 6 October 1996     

A Low Cost Gas Sampling Valve and Gc Set-Up for Analysis of Low Concentration Gas Mixtures

Abstract

A gas sampling valve suitable for on-line injection of low pressure (< 0.5 torr) gas mixtures is described. Its advantages over the commercially available valves are enumerated. An error of < 3 per cent due to non-reproducibility in sample injection was observed. A simple arrangement of column and hot wire detector together with this valve enabled quantitative separation of CO and O₂ with a lower limit of ～ 1 × 10^?7 moles for each component.     

A reliability-based manufacturing process planning method for the components of a complex mechatronic system

Uncertainties in the values of the parameters of a system can originate from the manufacturing tolerances of the system components, which can produce a degree of unreliability in the performance of the system. A systematic framework for realistic reliability assessment of an electro-hydraulic servo system has been presented in this paper with the objective of providing adequate information for the selection of the best manufacturing process for each of the servo valve components. Monte Carlo simulation has been employed to evaluate the effect of these uncertainties of the servo valve parameters on the statistical performance of the system. Possible manufacturing processes have been introduced for each component and the justifiability of using each one has been discussed based on the estimated reliability of the system.     

往复泵自动球阀的精确运动微分方程及其数值解

综合考虑了液体可压缩性与泵阀运动的魏氏效应对液缸内液体连续流条件的影响,并考虑泵阀运动的动力特性,建立了描述往复泵自动球阀运动规律的精确运动微分方程,它是关于液缸内液体压力、泵阀升程与泵阀运动速度的一阶常微分方程组,在泵阀的整个运动周期内都不存在奇点．本文应用数值积分方法求解了该微分方程组．     

Hydrodynamic gating valve for microfluidic fluorescence-activated cell sorting

Microfluidic cell sorter allows efficient separation of small number of cells, which is beneficial in handling cells, especially primary cells that cannot be expanded to large populations. Here, we demonstrate a microfluidic fluorescence-activated cell sorter (μFACS) with a novel sorting mechanism, in which automatic on-chip sorting is realized by turning on/off the hydrodynamic gating valve when a fluorescent target is detected. Formation of the hydrodynamic gating valve was investigated by both numerical simulation and flow visualization experiment. Separation of fluorescent polystyrene beads was then conducted to evaluate this sorting mechanism and to optimize the separation conditions. Isolation of fluorescent HeLa-DsRed cells was further demonstrated with high purity and recovery rate. Viability of the sorted cells was also examined, suggesting a survival rate of more than 90%. We expect this sorting approach to find widespread applications in bioanalysis.