Numerical Simulation of Flow between Two Parallel Co-Rotating Discs

Dr Smg Akele,Prof J.A Akpobi

doi:10.31033/ijemr.9.6.3

Abstract

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.

Highlights

Nikola Tesla’s 1913 turbine patent is popularly referred to as bladeless turbine because the turbine rators are a set of smooth closely-spaced discs connected parallel to each other along a shaft
The bladeless turbine operates by the fluid spiralling from the inlet at the discs periphery inward towards the centre of the disc where it exits through the small hole near the disc centre
Parameters from the Computational Fluid Dynamics (CFD) software are input into Akpobi and Akele (2016) developed radial velocity model for flow between two discs to obtain dimensional radial velocity of the model

Summary

Introduction

Nikola Tesla’s 1913 turbine patent is popularly referred to as bladeless turbine because the turbine rators are a set of smooth closely-spaced discs connected parallel to each other along a shaft. In the case of a Tesla pump, the flow direction is reversed with the fluid entering through the small holes near the discs centre from where it spirals outwards towards the disc peripheral. In this case centrifugal forces come into play. For both cases, as the fluid rotates within the rotating discs, it develops viscous drag in the boundary layer which in turns develops velocity gradient with gains in momentum (Schosser et al, 2016; Jose et al, 2016 )

Methods

Results

Conclusion