Thermo-aero Dynamic Analysis of Wind Turbines P M V Subbarao Professor Mechanical Engineering Department Development of Characteristic Design Variables ….

Wind Flow Past A Locked Wind Turbine

Thermodynamic Description of Flow Past A Working Wind Turbine

Description of Flow Past A Working Wind Turbine The rotor disc acts as a resistance device slowing the wind speed V o from far upstream of the rotor to u at the rotor plane and to u 1 in the wake. The drag is obtained by a pressure drop over the rotor. Close upstream of the rotor there is a small pressure rise from the atmospheric level p o to p. A discontinuous pressure drop ∆p over the rotor. Downstream of the rotor the pressure recovers continuously to the atmospheric level. The Mach number is small and the air density is thus constant and the axial velocity must decrease continuously from V o to u 1.

Signatures of Wind Turbine on Wind & Recovery

Layout of An Offshore Wind Farm

Structure of Offshore Wind Farms Name of Wind FarmHorns Rev. 1NystedScorby Sands Egmond aan Zee Available site at harbour (km) Project Capacity 160 MW MW60 MW108 MW Turbine Capacity 2 MW 2.3 MW2 MW3 MW Number of Turbines Total Turbine Height 110 m 100 m115 m Hub Height 70 m 69 m60m70 m Rotor Diameter 80 m 82 m80 m90 m CO 2 reduced per year (tons)

For a frictionless wind turbine:  p WT : Utilized Pressure Deficit Thrust Generated at the rotor Plane: Momentum Theory for an Ideal Wind Turbine

Identification of Surroundings to Wind Turbine The axial momentum equation using the simplified assumptions of an ideal rotor applied on control volume Consider a Larger Control Volume covering the entire wind turbine fluid domain:

The conservation of mass for the inner CV gives a relationship between A and A 1 as: It is seen that the velocity in the rotor plane is the mean of the wind speed V o and the unused wind speed in the wake u 1. Momentum Theory for an Ideal Wind Turbine

The flow is assumed to be frictionless and incompressible. There is no heat transfer across the boundary of CV. Ideal Power Absorbed by an Wind turbine

The axial induction factor (of rotor) a is defined as: The available power in a cross-section equal to the swept area A by the rotor is: Characteristic Parameter of A Wind Turbine Rotor

The absorbed power is often non-dimensionalized with respect to P avail as a power coefficient C P : Similarly a thrust coefficient C T is defined as: the power and thrust coefficients for the ideal 1-D wind turbine may be written as: