A new stall delay algorithm for predicting the aerodynamics loads on wind turbine blades for axial and yawed conditions

Elgammi, Moutaz; Sant, Tonio

doi:10.1002/we.2115

Cited by 15 publications

(9 citation statements)

References 22 publications

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“…In this research, the airfoil aerodynamic database (Re=5×10 4 -3× 10 6 , α=-10°-18°) was firstly generated by the CFD solver, and then extended to a larger α range using the AERODAS model [48]. Meanwhile, the impact of the finite blade span on the airfoil aerodynamics was considered using the method proposed by Jacobs and Anderson [49], and the stall delay effect of the rotating blade was corrected using the method proposed by Elgammi [50].…”

Section: ) Airfoil Precalculationmentioning

confidence: 99%

Comprehensive Optimization of the Unmanned Tilt-Wing Cargo Aircraft With Distributed Propulsors

Chen

Jia

et al. 2020

IEEE Access

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The unmanned tilt-wing cargo aircraft using distributed propulsors is an emerging aircraft significantly different from traditional types. This paper proposes an aerodynamic, propulsion, noise, weight integrated optimization design method for this new aircraft. The method consists of several functional modules specially developed or adjusted targeting the aircraft's characteristics, such as the boundary state analysis, propeller/rotor oblique inflow analysis, waked wing analysis, propeller/rotor noise evaluation, multi-state wing mass analysis, multi-objective genetic algorithm optimization. It comprehensively considers the impact of various complex factors on the optimization results, such as the impact of distributed propulsors on the wing aerodynamics, the effect of wingtip propellers on the induced drag reduction, the coupling between wing aerodynamics and structure, the propeller/rotor aerodynamics optimization, and noise control. With the proposed method, it is possible to directly translate the top-level design requirements into the design scheme with the optimal specific system performance (such as the lowest delivery cost and highest delivery efficiency) at the very initial aircraft design stage, thereby greatly shortening the development cycle. A case study was presented. The results show that the introduction of distributed propulsors can increase the delivery efficiency by 28.2% and reduce the delivery cost by 15%; suppressing the wingtip vortices using propellers can increase the wing lift-drag ratio by 5.43%-6.65%; the slipstream generation efficiency and thrust efficiency are significantly different between different distributed propulsor schemes. To maximize the overall efficiency, it is necessary to balance between the slipstream generation efficiency and the overall thrust efficiency when optimizing the tilt-wing cargo aircraft. INDEX TERMS Convertiplane; Cargo aircraft; Unmanned aerial vehicle; Vertical takeoff and landing; Aircraft multidisciplinary optimization.

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Section: ) Airfoil Precalculationmentioning

confidence: 99%

Comprehensive Optimization of the Unmanned Tilt-Wing Cargo Aircraft With Distributed Propulsors

Chen

Jia

et al. 2020

IEEE Access

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“…In this study, the proposed new stall delay model (NSDM) by Elgammi and Sant 18 is used to correct the 2D airfoil lift and drag force coefficients for stall delay. Unlike the traditional stall delay models, which correct the 2D data accounting only for axial flow conditions, the NSDM is applicable for both axial and yawed flow conditions with a high resolution because it includes the advancing and retreating effects due to yawed flow.…”

Section: Overview Of the Unsteady Bem Modelsmentioning

confidence: 99%

“…Unlike the traditional stall delay models, which correct the 2D data accounting only for axial flow conditions, the NSDM is applicable for both axial and yawed flow conditions with a high resolution because it includes the advancing and retreating effects due to yawed flow. Further details can be found in Elgammi and Sant 18 . An example for 3D stall delay corrections by the NSDM model on the blade of NREL VI rotor is depicted in Figure 1 at various blade sections.…”

Section: Overview Of the Unsteady Bem Modelsmentioning

confidence: 99%

“…It becomes more complex and time consuming if a stall delay model is applied. This is due to the fact that correcting the 2D airfoil data for stall delay will generate various different C L,3D and C D,3D curves (see Figure 1), one for each radial location and also for each blade azimuth angle if the advancing and retreating effects under yawed flow are considered (see Elgammi and Sant 18 and Yu et al 24 ). The latter influence is presented in Figure 3, where it can be seen that the tangential aerodynamic load distributions along different blade azimuth angles are different along the radial locations.…”

Section: Overview Of the Unsteady Bem Modelsmentioning

confidence: 99%

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New vortex‐lift and tangential‐force models for HAWT aerodynamic load prediction

Elgammi

Schepers²,

Osta-Oma

2020

Wind Energy

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Horizontal axis wind turbines (HAWTs) experience three-dimensional rotational and unsteady aerodynamic phenomena at the rotor blades sections. These highly unsteady three-dimensional effects have a dramatic impact on the aerodynamic load distributions on the blades, in particular, when they occur at high angles of attack due to stall delay and dynamic stall. Unfortunately, there is no complete understanding of the flow physics yet at these unsteady 3D flow conditions, and hence, the existing published theoretical models are often incapable of modelling the impact on the turbine response realistically. The purpose of this paper is to provide an insight on the combined influence of the stall delay and dynamic stall on the blade load history of wind turbines in controlled and uncontrolled conditions. New dynamic stall vortex and nonlinear tangential force coefficient modules, which integrally take into account the three dimensional rotational effect, are also proposed in this paper. This module along with the unsteady influence of turbulent wind speed and tower shadow is implemented in a blade element momentum (BEM) model to estimate the aerodynamic loads on a rotating blade more accurately. This work presents an important step to help modelling the combined influence of the stall delay and dynamic stall on the load history of the rotating wind turbine blades which is vital to have lighter turbine blades and improved wind turbine design systems. K E Y W O R D Sblade element momentum (BEM) model, dynamic stall, stall delay, tower shadow, turbulent wind, unsteady aerodynamic loads | INTRODUCTIONThe prediction of wind turbine performance requires efficient aerodynamic models. This is, in particular, true for the extremely demanding calculation of a wind turbine design load spectrum which leads to more than a million time steps, each requiring a full aeroelastic calculation of inflow, rotor, and wake. This is explained in the work of Schepers, 1 where it is moreover mentioned that the main "workhorse" in wind turbine design is the so-called blade element momentum (BEM) theory. This model is basically 2D and steady and then engineering models (i.e., efficient and transparent models) are added amongst others to account for dynamic stall and 3D rotational effects. The combined effects of these phenomena and other unsteady sources yield to the blade exhibiting unsteady aerodynamic loads, which play an important role for the wind turbine aerodynamic performance and the fatigue life of its structure.

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“…Nevertheless, research of the pitch load has always been the focus of attention. Many methods, such as the blade element momentum theory [8][9][10], dynamic stall model [11,12], computational fluid dynamics [13][14][15] and wind tunnel experimental research [16,17], have been employed to investigate the aerodynamic characteristics of wind turbine blades, which is one of the main factors of the pitch load. For example, by combining the element momentum theory with the dynamic stalling model, a deep theoretical analysis of the pitch load characteristics of a megawatt-scale wind turbine was carried out.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Pitch Load of Large-Scale Wind Turbines Using Field SCADA Data

et al. 2019

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Variable pitch technology is an indispensable key technology of large-scale wind turbines. The reliable pitch mechanism is the basic guarantee for achieving variable pitch. At present, the main problem with the design and maintenance of the variable pitch mechanism is that the pitch load is not clearly known. This paper focuses on obtaining pitch load characteristics through extracting SCADA (Supervisory Control and Data Acquisition) data. Here, the pitch load refers to the resistance moment to be overcome when the wind turbine blade is rotated on its own axis. From the data collected by the SCADA system, although the edgewise moment and the flapwise moment cannot be obtained, the pitch torque (load) can be extracted indirectly. This provides data support for the research. Specifically, the pitch moment is obtained by indirect calculation of the pitch motor current. Then, the effects of the wind speed, rotor speed, hub angle and pitch angle on the pitch load are theoretically analyzed. To obtain more reliable results, data preprocessing algorithms are presented to consider the data filtering range, the elimination of abnormal values and data dispersity. Subsequently, the influence mechanisms of wind speed, rotor speed, hub angle and pitch angle on the pitch load are investigated in detail based on the SCADA data.

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A new stall delay algorithm for predicting the aerodynamics loads on wind turbine blades for axial and yawed conditions

Cited by 15 publications

References 22 publications

Comprehensive Optimization of the Unmanned Tilt-Wing Cargo Aircraft With Distributed Propulsors

Comprehensive Optimization of the Unmanned Tilt-Wing Cargo Aircraft With Distributed Propulsors

New vortex‐lift and tangential‐force models for HAWT aerodynamic load prediction

Investigation of the Pitch Load of Large-Scale Wind Turbines Using Field SCADA Data

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