Variable measurement range viscous flow sensor based on double-layer rotating boundary

Xufeng Shen

doi:10.1063/5.0252795

Variable measurement range viscous flow sensor based on double-layer rotating boundary

2025-03-04

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DOI：10.1063/5.0252795

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The characteristic curve of viscous flow resistance (i.e., the relationship between flow rate and pressure drop, commonly referred to as the Delta p-Q curve) depends on several inherent variables, such as structural dimensions, fluid viscosity, density, and temperature. In most cases, altering the characteristic curve of viscous flow resistance requires changing these inherent variables. In previous studies [X. Shen and X. Li, Variable viscous flow resistance based on rotational inertia, Phys. Fluids 35, 073612 (2023); X. Shen, J. Xu, X. Yu, and X. Li, A design based on centrifugal inertia of rotational oil film for reducing pressure at shaft hole, Proc. Inst. Mech. Eng. Part C-J. Eng. Mech. Eng. Sci. 238, 1295 (2024)], we proposed a novel design approach for variable flow resistance, which modifies the Delta p-Q curve by incorporating fluid inertia. The new variable flow resistance utilizes two coaxial disks that are relatively close to each other to construct a slit channel, using air as the fluid medium. When the air passes through the slit channel, it is constrained by the wall to generate viscous resistance. At the same time, the rotation of the lower disk drives the air in the slit flow field to rotate, thereby generating rotational inertia. Consequently, both viscous pressure drop and rotational inertial pressure drop act on the air in the slit. By adjusting the rotation speed, the Delta p-Q characteristic curve can be translated. Previous studies were based on the rotation of a single disk. Based on this, we propose the concept of double-layer rotating disks, aiming at enabling the air in the disks to rotate more fully. This approach significantly shifts the Delta p-Q curve and improves the linearity of the curve. Based on the similarity principle and von K & aacute;rm & aacute;n's hypothesis, a theoretical pressure distribution model for the slit flow field of double-layer rotating disks is derived. The variation of the velocity field in the slit flow path caused by the rotating double-layer rotating disks was investigated. Furthermore, the influences of flow rate and disk rotation speed on the components of the pressure drop are analyzed. Experimental measurements of the Delta p-Q curves for the double-layer rotating disks slit flow field at various rotation speeds are conducted to validate the theoretical model. Finally, the theoretical Delta p-Q drop characteristic curve is revised to reduce errors. As the rotation speed increases, the Delta p-Q curve shifts significantly to the right and demonstrates excellent linearity, with the slope remaining nearly constant. Therefore, this approach can expand the measurement range of flow sensors when applied to flow sensing devices.

Keywords:

LASER-DOPPLER FLOWMETER

PRESSURE-DROP

AIR-FLOW

METER

Variable measurement range viscous flow sensor based on double-layer rotating boundary

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