Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance

Tongchitpakdee, Chanin; Benjanirat, Sarun; Sankar, Lakshmi N.

doi:10.1115/1.2346704

Cited by 45 publications

(31 citation statements)

References 39 publications

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“…The jet can cause the boundary layer to remain attached along the curved surface due to the Coanda effect 12 (a balance of the pressure and centrifugal forces) and turn smoothly without separation, resulting in a larger lift generation. The numerical study performed by Tongchitpakdee et al 10 indicates that for attached flow conditions, trailing-edge blowing and the Gurney flap both can produce a net increase in power generation compared to the baseline turbine rotor. However, the result also indicates that at high-wind speed condition where the flow is separated, the trailing-edge blowing and the Gurney flap both become ineffective in increasing the power output.…”

Section: Introductionmentioning

confidence: 98%

Numerical study of the S809 airfoil aerodynamic performance using a co-flow jet active control concept

Xing

2015

Journal of Renewable and Sustainable Energy

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A Co-Flow Jet (CFJ) active flow control concept is implemented on the S809 airfoil and numerically investigated by using an in-house code based on Reynoldsaveraged Navier-Stokes equations and the Spalart-Allmaras turbulence model, aiming to systematically study the jet effect on the airfoil aerodynamic performance. The solver is validated by comparing the computed results with the baseline experiment measurement. The calculated aerodynamic force and moment coefficients agree fairly well with the experimental data, demonstrating the present solver can predict the attached as well as separated flows around the S809 airfoil with an acceptable precision. The CFJ jet-off geometry of S809 airfoil is simulated to study the jet channel effect on the baseline aerodynamic characteristic, showing that the jet channel could reduce the lift, increase the drag and cause an earlier abrupt stall at angle of attack (AoA) 16.24 . The CFJ jet-on geometry is elaborately studied at three jet momentum coefficient levels, showing that co-flow jet has a significantly positive effect in increasing lift, stall margin, and drag reduction. For the cases with jet momentum coefficients 0.12 and 0.18, the total drag even becomes negative. It is found that the drag from pressure and shear stress of CFJ airfoil is larger than that of baseline, and it is the negative mass-flow-produced drag that significantly reduces the total drag to be below zero. For cases in which AoA are below a critical value (e.g., 20.15 for the case with jet momentum coefficient 0.18), the power required to drive the jet flow decreases when AoA increases, demonstrating that the CFJ concept has an attractive advantage of minimum energy consuming. The present CFJ concept is proved to be a promising and effective active flow control method in the wind turbine application. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 98%

Numerical study of the S809 airfoil aerodynamic performance using a co-flow jet active control concept

Xing

2015

Journal of Renewable and Sustainable Energy

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“…The drawback of this method was its inability to capture transient flow physics inside the rotor blade. A RANS-based N-S solver was used to solve for external airflow over a CC wind turbine blade [10] and estimates of aerodynamic performance were made. Watkins et al [11,12] developed a numerical formulation of the unsteady internal flow and correlated the results with experiments conducted on a reduced scale, nonrotating CC rotor blade.…”

Section: Introductionmentioning

confidence: 99%

Modeling Internal Flow Through a Rotating Duct Using Quasi 1-D Euler Equations

Karpatne

Sirohi

2016

AIAA Journal

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A numerical model of the internal flow in a duct rotating about one end is described. One-dimensional Euler equations are solved inside the duct using a finite volume formulation in which the advective fluxes are calculated using the advection upwind splitting method. The model was developed as a fast design tool for helicopter rotor blades with internal spanwise flow. To this end, centrifugal as well as Coriolis effects, frictional losses, duct sweep, and timedependent duct boundary conditions are modeled, and a spanwise flow control valve can be included. The model is used to explore the behavior of a 2-m-long duct with a circular cross section, rotating at tip speeds of up to 260 m∕s. The effects of centrifugal pumping, duct friction, duct sweep, and a flow control valve on the spanwise pressure and velocity distribution, mass flow rate of air through the duct, and torque required to spin the duct are discussed. Nomenclature a rel = relative acceleration of the rotating reference frame with respect to inertial frame= flux vector (y direction) across face "j" K = thermal conductivity of the medium, W∕m · K M = Mach number P = local static pressure, Pa P 1∕2 = local static pressure at a face denoted by (1∕2), Pa Q = vector of forcing/source terms q = duct torque due to internal flow, N · m R = length of the rotating duct, m r x = distance of any point from the axis of rotation in the x direction, m r y = distance of any point from the axis of rotation in the y direction, m T = local static temperature, K u = velocity of fluid in the x direction, m∕s v = velocity of the fluid in the y direction, m∕s w = velocity of a fluid element in the rotating reference frame x = coordinate along duct axis, m y = coordinate perpendicular to duct axis, m Δt = computational time step, s ΔV = volume of a unit cell, m 3 Δx = spanwise length of each grid cell, m Ω = rotational rate of the duct, rad∕s ρ = density of air, kg∕m 3

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“…In 2006 the aerodynamic performance of a circulation controlled horizontal axis wind turbine (HAWT) rotor was investigated numerically and showed an augmentation in the net power production at low wind speeds (7 m/s) with moderate blowing momentum coefficients (C μ ≤ 0.075) [19]. WVU also performed preliminary numerical studies on a CC H-type VAWT in 2009, predicting that overall power output performance could be increased by 24% at a blowing coefficient of C μ = 0.1 [20].…”

Section: Circulation Controlmentioning

confidence: 99%

“…This research considers the technical feasibility of utilizing active CC technology for improving VAWT aerodynamic efficiency, particularly at low wind speeds when performance is compromised relative to HAWTs. Although CC technology has previously been considered for wind turbine applications [19][20][21][22][23][24][25][26][27][28][29] few researchers consider the system requirements essential to determine if the technology is feasible for deployment on medium to large VAWTs.…”

Section: Introductionmentioning

confidence: 99%

Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

Shires

Kourkoulis

2013

Energies

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Abstract:The blades of a vertical axis wind turbine (VAWT) rotor see an inconsistent angle of attack through its rotation. Consequently, VAWT blades generally use symmetrical aerofoils with a lower lift-to-drag ratio than cambered aerofoils tailored to maximise horizontal axis wind turbine rotor performance. This paper considers the feasibility of circulation controlled (CC) VAWT blades, using a tangential air jet to provide lift and therefore power augmentation. However CC blade sections require a higher trailing-edge thickness than conventional sections giving rise to additional base drag. The choice of design parameters is a compromise between lift augmentation, additional base drag as well as the power required to pump the air jet. Although CC technology has been investigated for many years, particularly for aerospace applications, few researchers have considered VAWT applications. This paper considers the feasibility of the technology, using Computational Fluid Dynamics to evaluate a baseline CC aerofoil with different trailing-edge ellipse shapes. Lift and drag increments due to CC are considered within a momentum based turbine model to determine net power production. The study found that for modest momentum coefficients significant net power augmentation can be achieved with a relatively simple aerofoil geometry if blowing is controlled through the blades rotation.

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Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance

Cited by 45 publications

References 39 publications

Numerical study of the S809 airfoil aerodynamic performance using a co-flow jet active control concept

Numerical study of the S809 airfoil aerodynamic performance using a co-flow jet active control concept

Modeling Internal Flow Through a Rotating Duct Using Quasi 1-D Euler Equations

Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

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