Pitch Variations Study on Helically Coiled Pipe in Turbulent Flow Region Using CFD

Abstract

A computational fluid dynamics (CFD) study was conducted to analyse the flow structure and the effect of varying the coil pitch on the coil friction factor and wall shear stress, through utilising different models’ configurations. Three coils were tested, all of them having the same diameter and coil diameter: 0.005m and 0.04m respectively. Pitch variations began with 0.01, 0.05, 0.25 m for the first, second and third model respectively. Two turbulence models, STD(k-ϵ) and STD(k-w), were utilised in this simulation in order to determine the turbulence model which could capture most of the flow characteristics. A comparison was made between the STD(k-ϵ) and STD(k-w) models in order to analyse the pros and cons of each model. The results were validated with Ito’s equation for turbulent flow and compared with Filonenko’s equation for a straight pipe. The governing equations were discretized using finite volumes method and the SIMPLE algorithm was used to solve the equations iteratively. All the models were simulated using the ANSYS Fluent solver CFD commercial code. The results showed that in turbulent flows, Dean number had a stronger effect on reducing coil friction factor than the increment in pitch dimension.