Aerodynamic Separability in Tip Speed Ratio and Separability in Wind Speed- a Comparison

M L Gala Santos,P Jamieson,W E Leithead

doi:10.1088/1742-6596/555/1/012039

M L Gala Santos, P Jamieson + Show 1 more

Open Access

https://doi.org/10.1088/1742-6596/555/1/012039

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Abstract

From extensive application over a number of years, it has been established that the nonlinear rotor aerodynamics of typical medium and large wind turbines exhibit an effectively global separability property, in other words the aerodynamic torque of the machine can be defined by two independent additive functions. Two versions of the separability of aerodynamic torque for variable speed wind turbines are investigated here; the separated function, related to wind speed, in the first version is only dependent on that variable and not rotor speed and in the second version is only dependent on tip speed ratio. Both provide very good approximations to the aerodynamic torque over extensive neighbourhoods of T0, at least from 0 to 2T0.

Highlights

The aerodynamic torque, T, for a wind turbine is dependent on the wind speed, V, the blade pitch angle, and rotor speed, ; that is, T ARV ; R /V (1)where is the density of air, A is the rotor area, CQ is the torque coefficient and the tip speed ratio
From extensive application over a number of years, it has been established that the nonlinear rotor aerodynamics of typical medium and large wind turbines exhibit an effectively global separability property, in other words the aerodynamic torque of the machine can be defined by two independent additive functions
Two versions of the separability of aerodynamic torque for variable speed wind turbines are investigated here; the separated function, related to wind speed, in the first version is only dependent on that variable and not rotor speed and in the second version is only dependent on tip speed ratio

Summary

Introduction

The aerodynamic torque, T, for a wind turbine is dependent on the wind speed, V, the blade pitch angle, , and rotor speed, ; that is, T. The separation of aerodynamics into two additive components, the first independent of wind speed and the second independent of pitch angle, is discussed in Jamieson et al [1], Leithead et al [2], [3],. Two different forms of separability of the aerodynamics for variable speed wind turbines are compared. The first form is purely empiric in derivation and is a direct extension of separability for a constant speed wind turbine.

Constant speed wind turbines

Separability in tip speed ratio

Conclusion