Gas flow mechanism and pressure analysis in plates in micro scale gas film
Gas flow mechanism and pressure analysis in plates in micro scale gas film
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DOI：
10.1108/ilt-01-2019-0009
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发表时间：
2019-08
影响因子：
1.6
通讯作者：
W. Long;Mimi Wu;Fasha Li;Jiyao Wang;W. Deng
中科院分区：
文献类型：
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作者：
W. Long;Mimi Wu;Fasha Li;Jiyao Wang;W. Deng
目的
本论文的目的是为微机电系统（MEMS）技术的发展为微流控技术的研究创造条件。在过去的十年中，微流体技术已经成为MEMS领域中的一个非常大的分支。对于气体静压推力轴承，两平行平板间小尺度气膜内的微流控气体流动是许多研究的主题。由于润滑油膜中存在稀薄的气体，在界面处会发生速度滑移，从而导致润滑油膜中气体流型发生变化。因此，弄清稀薄气体流动的机理和压力特性具有重要意义。
设计/方法/方式
首先，通过理论分析建立了新的流态假设和相应的流态模型。其次，利用大规模原子/分子大规模并行模拟器（LAMMPS）对压力分布和速度分布进行了数值模拟。第三，将LAMMPS模拟结果与直接模拟Monte Carlo计算结果进行了比较，验证了上述结果的可靠性。
结果
气体流动机制和相应的规律与传统的气动力学有显着不同，可以用Navier-Stokes方程准确描述。结合理论研究和计算结果，验证了气膜分层理论。研究表明，随着气体流量的增加，气膜压力减小，连续流层厚度增加，薄层厚度减小，气膜内分层压力消失。在这种情况下，速度滑移可以忽略不计。
独创性/价值
本文首先建立了气膜支撑的分析模型，提出了气膜分层理论。将气膜分为近壁层、薄层和连续层，并通过LAMMPS流动模拟计算进行了验证。速度滑移边界条件理论是可行的。其次，平板气膜尺寸在微米级，在其流动状态下无法观察到，只能通过计算和模拟确定。本文提出了一种分析气膜中气体流动的新模型和新工具。
Purpose
The purpose of this paper is to develop the micro-electro-mechanical systems (MEMS) technology has created the conditions for the study of microfluidic technology. Microfluidic technology has become a very large branch in the MEMS field over the past decade. For aerostatic thrust bearing, the micro-fluidic gas flow in a small-scale gas film between two parallel plates is the subject of many studies. Because of the thin gas in the film, velocity slip occurs at the interface, which causes the gas flow pattern to change in the lubricating film. So, it is important to clarify the mechanism and pressure characteristics in thin firm gas flow.
Design/methodology/approach
First, a new assumption and corresponding models for the flow regime were established by theoretical analysis. Second, computational simulations about pressure distribution and velocity were given by a large-scale atomic/molecular massively parallel simulator (LAMMPS). Third, comparison of the results of LAMMPS simulation and direct simulation Monte Carlo calculation were made to verify the reliability of above results.
Findings
The gas flow mechanism and corresponding regulations are significantly different from traditional pneumo dynamics, which can be described by Navier–Stokes equations accurately. Combining theatrical study and computational results, the stratification theory of the gas film was verified. The research shows that when the gas flow rate increased, the pressure of the gas film decreased, the thickness of the continuous flow layer increased, the thickness of the thin layer decreased and the layered pressure in the gas film disappeared. In this case, velocity slippage could be ignored.
Originality/value
First, this paper established an analytical model of the gas film support and proposed a film stratification theory. The gas film was divided into the near wall layer, the thin layer and the continuous layer, which was proved by the calculation of LAMMPS flow simulation. The velocity slip boundary conditions theory is feasible. Second, the gas film size of the flat plate is at the micron level, which cannot be observed in its flow regimen, only determined by calculation and simulation. This paper proposes a new model and a new tool to analyze gas flow in gas films.