wake states

Wake states

Table of Contents

• 1. Turbulent Wake
• 2. turbulent wake of a circular cylinder
• 3. Reference
  • 3.1. Dissertation
  • 3.2. Others

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

Author: kemin

Created: 2019-03-28 四 18:26

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