Flow Control through Surface Suction for Small Wind Turbines

Jasvipul Singh Chawla
2017
This thesis seeks to arrive at estimates of improvement in blade aerodynamic efficiency and reduction in structural loads in small wind turbines through surface suction-based active flow control at low Reynolds numbers (Re). Improved aerodynamic efficiency and reduced fatigue loads help achieve lower Cost-of-Energy. Small wind turbines typically operate off-grid, providing power at the point of consumption. Consequently, such turbines often operate in locations with poor wind speed regimes. Low
more » ... wind speeds coupled with small chord length of the blades result in low operating Re that often lie between 104 and 105. It is well-known that such operating Re imposes significant challenges in realising good aerodynamic efficiency due to the propensity for flow separation to occur. It has been established that flow separation can be avoided or delayed using active flow control. However, much of such work on active flow control has focused on high Re applications. This thesis focuses on the application of surface suction, a popular active flow control methodology, in low Re regimes seen in small wind turbines. The approach adopted towards arriving at the aforementioned estimates of improvement in blade aerodynamic efficiency and reduction in structural loads in small wind turbines is as follows: 1. Experimental characterisation of the improvement in the aerodynamic characteristics of two aerofoil profiles, NACA0012 and S814, commonly used in small wind turbine applications, in low Re regimes is performed. Specifically, this characterisation captures both the steady-state characteristics as well as identification of the temporal dynamics between change in the coefficient of lift (ΔCL) and change in the coefficient of drag (ΔCD) with the non-dimensional parameter, Cμ (defined as the ratio of the momentum of air drawn through suction and the momentum of the air flowing over [...]
doi:10.4225/03/58d898d7ed5a2 fatcat:diowldvk4jazdakfql4elrsjzi