Turbulence Intensity in Water Flow for Hydrokinetic Turbine Application

Abstract

A water tunnel is used to investigate a hydrodynamic behavior of an immersed body in the fluid dynamics study. The operational principle of water tunnel is identical to a wind tunnel but with a different working fluid and higher flow-pumping capacity. Tests such as flow visualization in wind tunnel are more challenging, as turbulent flows in wind dissipate quickly whilst water tunnel is more suitable for such purpose due to its higher fluid viscosity. However, the turbulence in the water tunnel test section must be low in order to produce a valid result. The present work focuses to improve the previous water tunnel performance to mimic a river flow that has been developed for micro hydrokinetic application particularly to reduce the turbulence intensity and improve its flow uniformity. To achieve this objective, several primary components of the water tunnel were modified, fabricated and assembled. Quantitative measurement on the velocity profiles and uniformity of the water flow at the test section were analyzed with small increments of 2 cm between the measured points. This was performed by collecting the data of the velocity at every point in the cross-section with increment of 1 cm. The results obtained were then used to plot a uniformity graph and analyze the turbulence intensity in the water tunnel test section. The turbulence intensity in the water tunnel test section after modification produced a minimum result of 6.8% in comparison to the previous version around 9.7%. Thus, the turbulence intensity in the water tunnel was reduced by 29.9%