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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Dynamics of buoyancy-driven microflow in a narrow annular space

Abstract: This paper aims to investigate the dynamics of buoyancy-driven microflow in a narrow annular space inside a liquid floated gyroscope (LFG). Several theoretical models with a non-uniform thermal boundary for fluid flow in annular channels are given to analyze the effects of various parameters, such as the clearance size h, roughness height re, and rough density ε, on the flow and temperature profiles as well as on the fluid-drag torque. In the narrow annular regime, the relationship between the temperature and the angular displacement of the outer wall is defined as a cosine function, and the surface roughness of the inner wall is structured as a series of surface protrusions with a circular shape. With the increase of clearance size h, the flow velocity gradually increases to a stable level, and the drag torque increases initially and then decreases to a stable level. Furthermore, the increase of roughness height re and roughness density ε intensifies the frictional effect of fluid on the inner-wall surface. However, these two parameters have no significant effect on the flow velocity. This study can provide theoretical references for precision manufacturing and precision improvement of gyro instruments.

Key words: Liquid floated gyroscope (LFG); Annular channel; Roughness feature; Fluid drag

Chinese Summary  <6> 狭窄环形空间内浮力驱动微对流的动力学特性

作者:王延忠1,张亚萍1,杨凯2,鲁博佶1,高浩3
机构:1北京航空航天大学,机械工程及自动化学院,中国北京,100191;2北京卫星制造厂,中国北京,100094;3三明学院,机电工程学院,中国三明,365001
目的:液浮陀螺仪环形流道的宏微观特征影响内部浮油的动力学特性,与仪表精度水平密切相关。本文旨在探讨狭窄环形流道的间隙尺寸、粗糙高度、粗糙密度等因素对浮油流场、温度场、粘滞力矩的影响,为陀螺仪表的设计优化和精度提升提供理论参考。
创新点:1.抽取液浮陀螺仪内部环形流道的结构特征,建立流体域的流热耦合模型;2.提出一种表征壁面粗糙特征的方法,获取粗糙特征对浮油流热特性的影响规律。
方法:1.通过分析液浮陀螺仪的结构和工况,建立简化的理论分析模型(图2);2.采用几何微圆构造粗糙特征,并定义壁面粗糙参数(图3);3.建立陀螺仪环形流体域的流热耦合模型;4.通过耦合模型的求解计算,分析壁面宏微观尺寸对浮油动力学特性的影响规律。
结论:1.间隙效应对粘滞力矩的影响大于粘温效应,且力矩随着间隙尺寸的增加先增大后减小,最后趋于稳定;2.流道壁面粗糙度对浮油动力学特性有显著影响,粗糙度高度对粘滞力矩的影响大于粗糙度密度对粘滞力矩的影响。

关键词组:液浮陀螺仪;环形通道;粗糙特征;流体阻力


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DOI:

10.1631/jzus.A2200617

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On-line Access:

2023-12-29

Received:

2023-01-03

Revision Accepted:

2023-06-08

Crosschecked:

2024-01-04

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