wake states
Wake states
Table of Contents
1** Wake States
1 Turbulent Wake
the wake behind the front rotor is far from turbulent (leishman, 2009) what is turbulent wake?
- when Turbulent intensity, I, is higher than 5% (Eldad)
Ct vs a [fig. 4.5 (hansen)] 0.5<a<1 at turbulent wake state
When does it happen? at high TSR
- for fixed rotational speed turbine, at low inflow speed
- for fixed inflow speed, at high rotational speed
Why does it happen?
- a velocity jump at the edge of the wake ( fig. 4.7 hansen)
baseline: 1D momentum theory,
when 0.5 <a<1 the velocity jump at wake is high and eddies are formed ( P33 fig. 4.6 hansen) 
( fig. 4.7 hansen)
Figure 1: Schematic view of the turbulent-wake state induced by the unstable shear flow at the edge of the wake
2 turbulent wake of a circular cylinder
- Cantwell and Coles 1983
3 Reference
3.1 Dissertation
refer to Johansson 2002 (PhD Dissertation) Johansson, Peter BV. axisymmetric turbulent wake behind a disk . Chalmers University of Technology, 2002.
3.2 Others
Steffen et al 2007 "3D-simulation of the turbulent wake behind a wind turbine." Journal of Physics: Conference Series. Vol. 75. No. 1. IOP Publishing,
B. Sanderse 2011 Review of computational fluid dynamics for wind turbine wake aerodynamics
N Sedaghatizadeh et al 2018 Ren. Energy, Modelling of wind turbine wake using large eddy simulation
Sørensen 2013 "Analysis of turbulent wake behind a wind turbine." International Conference on aerodynamics of Offshore Wind Energy Systems and wakes (ICOWES 2013). Technical University of Denmark (DTU), 2013. J.N. Sorensen 1998 analysis of wake steate oby a full field actuator disc model
