微型阀门的空气泄漏:压力衰减测量和 Knudsen 流体的扩展连续模型。

IF 3 3区 工程技术 Q2 CHEMISTRY, ANALYTICAL
Micromachines Pub Date : 2024-10-16 DOI:10.3390/mi15101263
Daniel Anheuer, Johannes Schwarz, Patrick Debera, Klaus Heinrich, Christoph Kutter, Martin Richter
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引用次数: 0

摘要

为了提高阀门在泄漏率方面的性能,必须全面评估阀门的特性和在压力暴露期间的行为。传统的流量传感器通常无法精确测量 0.1 cm3/min 以下的低气体流量。本文介绍了一种小型、低成本的测试设备,可利用压力衰减法精确测量气体泄漏率,甚至远低于 0.1 cm3/min。我们用一个流量模型证实了这些泄漏流量,证明了用扩展的纳维-斯托克斯框架对这些气体流量进行建模的可行性,从而获得更准确的理论预测。正如预期的那样,与实验结果的对比证明,经典的纳维-斯托克斯系统不适合模拟努森气流。因此,以一种物理上显而易见的方式引入了气体自扩散、壁面滑动边界条件和有效平均自由路径模型。就计算的质量流而言,虽然自扩散和滑移边界条件可以解释在克努森数小于 1 时与经典纳维-斯托克斯方程的偏差,但有效平均自由路径模型会产生影响,尤其是当 Kn > 1 时。在简化条件下,提出了一个分析解决方案,并将其与 OpenFOAM CFD 求解器的结果进行了比较,以确定通过翻板阀更复杂的间隙-流动几何形状的流速。由此观察到的可接受偏差在 10% 到 20% 之间。与测量结果进行了比较。通过将一个硅微阀样品的多次测量结果与最先进的流量传感器进行比较,验证了测量方法的可重复性。测量了三个几何形状相似的无源硅微阀,空气超压从 15 kPa 相对于大气压逐渐减小。观察到阻塞方向的最大气体流量为 1-26 µL/min,重现性很高,噪声很小。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Air Leakages at Microvalves: Pressure Decay Measurements and Extended Continuum Modelling of Knudsen Flows.

To improve the performance of valves in relation to the leakage rate, a comprehensive evaluation of the valve characteristics and behavior during pressure exposure is important. Often, these low gas flow rates below 0.1 cm3/min cannot be accurately measured with conventional flow sensors. This paper presents a small and low-cost test rig for measuring gas leakage rates accurately, even far below 0.1 cm3/min, with the pressure decay method. These leakage flows are substantiated with a flow model, where we demonstrate the feasibility of modeling those gas flows with an extended Navier-Stokes framework to obtain more accurate theoretical predictions. As expected, the comparison to the experimental results proves that the classical Navier-Stokes system is unsuitable for modeling Knudsen flows. Hence, self-diffusion of gas, a wall-slip boundary condition, and an effective mean free path model were introduced in a physically evident manner. In terms of the calculated mass flow, while self-diffusion and slip boundary conditions explain deviations from the classical Navier-Stokes equation for Knudsen numbers already smaller than 1, the effective mean free path model has an effect, especially when Kn > 1. For simplified conditions, an analytical solution was presented and compared to the results of an OpenFOAM CFD-solver for flow rates through more complex gap-flow geometries of the flap valve. Hereby, acceptable deviations between 10% and 20% were observed. A comparison with measurement results was carried out. The reproducibility of the measurement method was verified by comparing multiple measurements of one silicon microvalve sample to a state-of-the-art flow sensor. Three geometrically similar passive silicon microvalves were measured with air overpressure decreasing from 15 kPa relative to atmospheric pressure. Maximum gas volume flowing in a blocking direction of 1-26 µL/min with high reproducibility and marginal noise were observed.

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来源期刊
Micromachines
Micromachines NANOSCIENCE & NANOTECHNOLOGY-INSTRUMENTS & INSTRUMENTATION
CiteScore
5.20
自引率
14.70%
发文量
1862
审稿时长
16.31 days
期刊介绍: Micromachines (ISSN 2072-666X) is an international, peer-reviewed open access journal which provides an advanced forum for studies related to micro-scaled machines and micromachinery. It publishes reviews, regular research papers and short communications. Our aim is to encourage scientists to publish their experimental and theoretical results in as much detail as possible. There is no restriction on the length of the papers. The full experimental details must be provided so that the results can be reproduced.
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