Influence of Tip Speed Ratio on Wake Flow Characteristics Utilizing Fully Resolved CFD Methodology

Abstract

Abstract. Dominant flow structures in the wake region behind the turbine employed in the Blind Test campaign [1], [2] is investigated numerically. The effect on the wake configuration at variable operating conditions are studied. The importance of the introduction of turbine tower inside the numerical framework is highlighted. High-fidelity simulations are performed with Multiple Reference Frame (MRF) numerical methodology. A thorough comparison among the cases is presented, and the wake evolution is analyzed at variable stations downstream of the turbine. Streamlines of flow field traveled towards ground adjacent to turbine tower and strongly dependent on the operating tip speed ratio. Wake is composed of tower shadow superimposed by rotor wake. Shadow of the tower varies from x/R=2 until x/R=4 and breaks down into small vortices with the interaction of rotor wake. This study also shows that the wake distribution consists of two zones; inner zone composed of disturbances generated by blade root, nacelle and the tower, and an outer zone consisting of tip vortices.

A review of commercial numerical modelling approaches for axial hydrokinetic turbine wake analysis in channel flow

“…The effects of a HK turbine on ambient inflow conditions has been studied in recent years as reviewed in [4]. These studies include the velocity deficit [32,81]; the complex three-dimensional flow structure (including hub and tip vortices) [84]; increase in turbulence intensity and anisotropy [26,40,85]; effects of ambient turbulence levels; unsteady loading; flow depth to turbine diameter; and turbine operating conditions affecting thrust (e.g., tip-speed-ratio) [86,87].…”

A particle image velocimetry study of dual-rotor counter-rotating wind turbine near wake

“…Alternatively, a rotor having too large K acts as more of a barrier effect to the incoming air. It is shown by Siddiqui et al (2017) that K greatly impacts properties of the wake, namely velocity, vorticity and flow streamline trend, rendering it a parameter that must remain constant throughout the experimentation. However, X required for K opt from the 50% auxiliary rotor was too high to be feasible, and for this reason, a slightly lower value of K ¼ 3:46 was chosen and was set to be the same for all the rotors.…”

Qualitative Investigation of Wake Composition in Offshore Wind Turbines: A Combined Computational and Statistical Analysis of Inner and Outer Blade Sections

“…Over the past decade, wind energy has experienced rapid growth due to the global demand for renewable energy resources [1].To maximize yields, wind turbines are typically placed in limited areas and clustered together to maximize gains [2,3]. While clustering improves and lowers the cost of energy, it also negatively impacts the aerodynamic efficiency of turbines.…”