Numerical Simulation of Flow Between Two Parallel Co-Rotating Discs


Book Description

The study of fluid flow between two rotating discs aims to predict flow characteristics. In this paper numerical simulation is used to investigate axisymmetric swirling flow between two parallel co-rotating discs. Methodology entails, firstly, inputing parameters from CFD software are into previos study developed dimensionless radial velocity model for flow between two discs to obtain dimensional radial velocity of the model. Secondly, previous study parameters are used to perform numerical simulation on laminar and turbulent flows between two parallel co-rotating discs. The numerical simulation results are compared to previous study results. Then comparative numerical simulations was carried out on laminar and turbulent flows using CFD software.Results obtained showed that for the this study dimensional radial velocity and previous study dimensionless radial velocity, radial velocity distribution increase proportionately from the disc surface at 0m/s to 2208.00m/s and 0 to 0.0002396 respectively, at the domain centre. And both results satisfy initial inlet and boundary conditions with resultant parabolic profiles. In the study, it is shown that turbulent flow radial velocity profile is smoother than for laminar flow. The radial velocity increases from 0 at the walls to 0.15m/s before decreasing to - 0.2m/s at the mid-centre for laminar flow while for turbulent flow the radial velocity intitially increases from 0 at the walls to 0.15m/s before decreasing to -0.06m/s at the discs centre; while for laminar flow, swirl velocity decrease from approximately 2.55m/s to 0.55m/s and for turbulent flow the swirl velocity decrease from approximately 2.84m/s to 1.62m/s. The turbulent flow swirl velocity profile seen to be smoother than for laminar flow around the discs centre. The study further showed that for fluid near the discs surfaces radial velocity net momentum is radially towards the outlet with flow laminar in the boundary layer region and the velocity turbulent towards the domain centre. For static pressure, laminar flow maximum and minimum static pressure 2.48pa and -0.033pa respectively, while for turbulent flow maximum and minimum static pressure were 0.00 and -0.0024pa. The developed previous study model can therefore be used to predict radial velocity distribution between steady axisymmetric flow between two parallel co-rotating discs.




Laminar Flow Between Two Parallel Rotating Disks


Book Description

The viscous flow between two parallel disks rotating in the same direction with the same velocity is investigated. The fluid enters the space between the disks at a certain in radius in the radial direction. Because of the shear forces, it assumes a rotating motion with about the velocity of the disks. The centrifugal forces then build up a pressure increase in the radial direction. The arrangement corresponds to a centrifugal fluid pump, which may be advantageous if cavitation is a problem. The general equations of viscous flow are simplified by the assumption that the pressure difference normal to the disks is negligible (boundary layer assumptions). One obtains a system of parabolic partial differential equations. For large radii the deviation from rigid body rotation (with the angular velocity of the disks) is small. The linearized equations which then result are solved analytically. The velocity profiles depend upon a parameter containing e kinematic viscosity, the angular velocity and the distance of the disks, but not he radius. The non-linearized parabolic differential equations are approximated by a difference scheme and solved numerically. The results are given in non-dimensional form with the entrance velocity and the distance of the disks as parameters. Furthermore, the efficiency of the pump is computed from the gain of the total pressure and the torque at the shaft of the rotating disks.













The Theory of Rotating Fluids


Book Description




Turbulent Fluid Friction of Rotating Disks


Book Description

The incompressible flow field between two infinite parallel disks, one of them rotating and the other stationary, is analyzed and solved for situations where the radial Reynolds number is large enough to produce turbulent flow. An effective viscosity method is used, the effective viscosity being regarded as a scalar. The validity of the approach is demonstrated for the case of boundary layer development on a rotating disk in an infinite fluid otherwise at rest. An implicit finite-difference method is used to obtain a numerical solution of the boundary layer flow from the axis out to a radius corresponding to R sub e = 10 to the 7th power. For an assumed transition from laminar to turbulent flow at the experimentally observed value of R sub e = 300,000, the resulting skewed velocity profiles and disk friction drag agree with measurements. The case of the surrounding fluid rotating at one-half the disk speed is also solved. The resulting values of drag moment approximate experimental data for enclosed rotating disks, and the results provide insight and data for computing the flow between the parrallel disks mentioned. Applicability of the results to the disk friction drag of centrifugal pump impeller shrouds is claimed.




Smart Flow Control Processes in Micro Scale Volume 2


Book Description

In recent years, microfluidic devices with a large surface-to-volume ratio have witnessed rapid development, allowing them to be successfully utilized in many engineering applications. A smart control process has been proposed for many years, while many new innovations and enabling technologies have been developed for smart flow control, especially concerning “smart flow control” at the microscale. This Special Issue aims to highlight the current research trends related to this topic, presenting a collection of 33 papers from leading scholars in this field. Among these include studies and demonstrations of flow characteristics in pumps or valves as well as dynamic performance in roiling mill systems or jet systems to the optimal design of special components in smart control systems.