Variable viscous flow resistance based on rotational inertia

Abstract

Viscous flow resistance is dominated by viscous friction between fluid and wall. The flow resistance characteristic curve (i.e., the relationship curve between pressure drop and flow rates, represented as the Δp–Q curve) depends on some inherent characteristic variables, such as structural size, fluid viscosity, density, and temperature. Usually, to change the Δp–Q curve, these inherent characteristic variables must be changed. This paper proposes a new design of variable viscous flow resistance. The new design uses two disks to construct a slit flow channel, and rotate one of the disks to drive the fluid in the slit flow channel to form a rotational inertia effect. Therefore, by changing the rotating speed of the disk, the rotational inertia effect can be changed, thereby achieving the purpose of changing the Δp–Q curve. This paper derives a theoretical model for the pressure distribution of the rotating slit flow field and conducted experimental verification. It was found that the rotational inertia gradient and viscous gradient terms play major roles in governing the radial pressure gradient. The sum of the other two inertial gradient terms accounts for a maximum of about 1.58% of the total pressure gradient. There is a coupling relationship between circumferential velocity, radial velocity, and flow rates. An increase in Q can increase the rotational inertial gradient term by up to 24.9%. The rotating disk causes additional radial velocity and thus weakens the viscous gradient term by at least 16.41%.