Aerodynamic Load

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 15513 Experts worldwide ranked by ideXlab platform

Xiong Liu - One of the best experts on this subject based on the ideXlab platform.

  • vibration induced Aerodynamic Loads on large horizontal axis wind turbine blades
    Applied Energy, 2017
    Co-Authors: Xiong Liu, Shi Liang, Ajit R Godbole, Yan Chen
    Abstract:

    The blades of a large Horizontal Axis Wind Turbine (HAWT) are subjected to significant vibrations during operation. The vibrations affect the dynamic flow field around the blade and consequently alter the Aerodynamic forces on the blade. In order to better understand the influence of blade vibrations on the Aerodynamic Loads, the dynamic stall characteristics of an S809 airfoil undergoing translational motion as well as pitching motion were investigated using Computational Fluid Dynamics (CFD) techniques. Simulation results indicated that both the out-of-plane and in-plane translational motions of the airfoil affect the unsteady Aerodynamic forces significantly. In order to investigate the effects of blade vibration on the Aerodynamic Load on a large-scale HAWT blade during its operating lifetime, an Aerodynamic model based on the Blade Element-Momentum (BEM) theory and the Beddoes–Leishman (B–L) dynamic stall model was proposed. The BEM model was revised to account for the vibration-induced velocity components in the calculation of the effective angle of attack. Aerodynamic Load analysis of a 5MW wind turbine was then performed and the impact of blade vibration on the lifetime Aerodynamic fatigue Loads was analysed.

  • Influence of the vibration of large-scale wind turbine blade on the Aerodynamic Load
    Energy Procedia, 2015
    Co-Authors: Xiong Liu, Shi Liang, Ajit R Godbole, Yan Chen
    Abstract:

    Abstract The blades of a large wind turbine are subjected to significant vibrations during operation. The vibrations will impact the dynamic flow field around the blade and consequently alter the Aerodynamic forces. In order to better understand the influence of blade vibrations on the Aerodynamic Loads, the dynamic stall characteristics of an S809 airfoil undergoing various types of motion were investigated using Computational Fluid Dynamics (CFD) techniques. Simulation results indicated that the in-plane and out-of-plane translational motions of the airfoil affect the Aerodynamic forces significantly. Furthermore, the influence of vibrations on the Aerodynamic Loading on the blade of a 5 MW wind turbine was investigated using the Blade Element-Momentum (BEM) theory and the Beddoes-Leishman (B-L) dynamic stall model.

Yan Chen - One of the best experts on this subject based on the ideXlab platform.

  • vibration induced Aerodynamic Loads on large horizontal axis wind turbine blades
    Applied Energy, 2017
    Co-Authors: Xiong Liu, Shi Liang, Ajit R Godbole, Yan Chen
    Abstract:

    The blades of a large Horizontal Axis Wind Turbine (HAWT) are subjected to significant vibrations during operation. The vibrations affect the dynamic flow field around the blade and consequently alter the Aerodynamic forces on the blade. In order to better understand the influence of blade vibrations on the Aerodynamic Loads, the dynamic stall characteristics of an S809 airfoil undergoing translational motion as well as pitching motion were investigated using Computational Fluid Dynamics (CFD) techniques. Simulation results indicated that both the out-of-plane and in-plane translational motions of the airfoil affect the unsteady Aerodynamic forces significantly. In order to investigate the effects of blade vibration on the Aerodynamic Load on a large-scale HAWT blade during its operating lifetime, an Aerodynamic model based on the Blade Element-Momentum (BEM) theory and the Beddoes–Leishman (B–L) dynamic stall model was proposed. The BEM model was revised to account for the vibration-induced velocity components in the calculation of the effective angle of attack. Aerodynamic Load analysis of a 5MW wind turbine was then performed and the impact of blade vibration on the lifetime Aerodynamic fatigue Loads was analysed.

  • Influence of the vibration of large-scale wind turbine blade on the Aerodynamic Load
    Energy Procedia, 2015
    Co-Authors: Xiong Liu, Shi Liang, Ajit R Godbole, Yan Chen
    Abstract:

    Abstract The blades of a large wind turbine are subjected to significant vibrations during operation. The vibrations will impact the dynamic flow field around the blade and consequently alter the Aerodynamic forces. In order to better understand the influence of blade vibrations on the Aerodynamic Loads, the dynamic stall characteristics of an S809 airfoil undergoing various types of motion were investigated using Computational Fluid Dynamics (CFD) techniques. Simulation results indicated that the in-plane and out-of-plane translational motions of the airfoil affect the Aerodynamic forces significantly. Furthermore, the influence of vibrations on the Aerodynamic Loading on the blade of a 5 MW wind turbine was investigated using the Blade Element-Momentum (BEM) theory and the Beddoes-Leishman (B-L) dynamic stall model.

L Guan - One of the best experts on this subject based on the ideXlab platform.

  • CSCWD - Multidisciplinary analysis transient flow effects on the impeller in a semi-open centrifugal impeller stage
    2017 IEEE 21st International Conference on Computer Supported Cooperative Work in Design (CSCWD), 2017
    Co-Authors: L Guan
    Abstract:

    Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady Aerodynamic Load on blades surface may be related to the blade fracture. This issue involves Aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open impeller stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and Aerodynamic Load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high Aerodynamic Load on the impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open impeller stage of a centrifugal compressor.

  • a simplified model of semi open impeller stage and analysis of its effects on the transient flow
    Applied Mechanics and Materials, 2014
    Co-Authors: L Guan, Zi Fu Lu
    Abstract:

    The centrifugal compressor is one type of vital energy conversion equipment and its unsteady characteristics are extremely complex in actual operation. A semi-open impeller stage with inlet guide vanes, an impeller and a diffuser in a centrifugal compressor was concerned. For simulation of unsteady flow, the full-passage model of the integrate stage requires much more simulating time and memory space, higher computer configuration. Therefore, a single-passage simplified model was established for unsteady analysis. The internal flow characteristics and Aerodynamic Load on the blade obtained by the simplified model were also compared with that by the full-passage model. The result shows that the precision of the simplified model can meet the engineering requirement. Compared with the full-passage model, the simplified model can give a relatively true reflection of the local flow characteristics and the Aerodynamic Load on blade surfaces, but it ignores the unevenness resulted from unsteadiness along circumferential direction. Only high-frequency information is retained in Aerodynamic Load analysis while low-frequency one is diluted. However, as far as the local flow pattern or high-frequency information resulted from unsteady effects is concerned, the simplified model provides the advantages of higher computational efficiency and lower hardware requirements.

C. P. Van Dam - One of the best experts on this subject based on the ideXlab platform.

  • An Innovative Design of a Microtab Deployment Mechanism for Active Aerodynamic Load Control
    Energies, 2015
    Co-Authors: Kuo-chang Tsai, Cheng-tang Pan, Aubryn Cooperman, Scott J. Johnson, C. P. Van Dam
    Abstract:

    This study presents an innovative design of a microtab system for Aerodynamic Load control on horizontal-axis wind-turbine rotors. Microtabs are small devices located near the trailing edge of the rotor blades and enable a rapid increase or decrease of the lift force through deployment of the tabs on the pressure or suction side of the airfoil, respectively. The new system has been designed to replace an earlier linearly-actuated microtab mechanism whose performance was limited by space restrictions and stiction. The newly-designed microtab system is based on a four-bar linkage that overcomes the two drawbacks. Its improved kinematics allows for the tab height to increase from 1.0% to 1.7% of the airfoil chord when fully deployed, thereby making it more effective in terms of Aerodynamic Load control. Furthermore, the modified four-bar link mechanism provides a more robust and reliable mechanical structure.

  • computational investigations of small deploying tabs and flaps for Aerodynamic Load control
    Journal of Physics: Conference Series, 2007
    Co-Authors: C. P. Van Dam, Raymond Chow, Jose R Zayas, Dale E Berg
    Abstract:

    The cost of wind-generated electricity can be reduced by mitigating fatigue Loads acting on the blades of wind turbine rotors. One way to accomplish this is with active Aerodynamic Load control devices that supplement the Load control obtainable with current full-span pitch control. Techniques to actively mitigate blade Loads that are being considered include individual blade pitch control, trailing-edge flaps, and other much smaller trailing-edge devices such as microtabs and microflaps. The focus of this paper is on the latter Aerodynamic devices, their time-dependent effect on sectional lift, drag, and pitching moment, and their effectiveness in mitigating high frequency Loads on the wind turbine. Although these small devices show promise for this application, significant challenges must be overcome before they can be demonstrated to be a viable, cost-effective technology.

  • active Aerodynamic Load control of wind turbine blades
    ASME JSME 2007 5th Joint Fluids Engineering Conference, 2007
    Co-Authors: Dale E Berg, Jose R Zayas, Raymond Chow, C. P. Van Dam, Don W Lobitz, Jonathon P Baker
    Abstract:

    The cost of wind-generated electricity can be reduced by mitigating fatigue Loads acting on the rotor blades of wind turbines. One way to accomplish this is with active Aerodynamic Load control devices that supplement the Load control obtainable with current full-span pitch control. Thin airfoil theory suggests that such devices will be more effective if they are located near the blade trailing edge. While considerable effort in Europe is concentrating on the capability of conventional trailing edge flaps to control these Loads, our effort is concentrating on very small devices, called microtabs, that produce similar effects. This paper discusses the work we have done on microtabs, including a recent simulation that illustrates the large impact these small devices can exert on a blade. Although microtabs show promise for this application, significant challenges must be overcome before they can be demonstrated to be a viable, cost-effective technology.© 2007 ASME

  • computational investigation of finite width microtabs for Aerodynamic Load control
    43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005
    Co-Authors: Edward A Mayda, C. P. Van Dam, D Nakafuji
    Abstract:

    The use of deployable microtabs on wind turbine blades has been proposed for the purpose of active Load control. A great deal of two-dimensional wind tunnel testing and CFD simulation has already been conducted to study the effects of tabs on the Aerodynamic performance characteristics of airfoil sections. This paper presents a literature survey of existing studies that have looked at the effects of introducing gaps and serrations to the tabs. Such treatments are found to allow modulation of the lift enhancing properties of the tab. Three-dimensional Reynolds-averaged Navier-Stokes calculations of various tabgap configurations applied to an airfoil are described, and results are presented. The relationship between tab solidity ratio and increments in lift is found to be highly linear. Such a relationship could be significant for the development of future microtab deployment systems.

David Cleaver - One of the best experts on this subject based on the ideXlab platform.

  • dynamic deployment of a minitab for Aerodynamic Load control
    Journal of Aircraft, 2020
    Co-Authors: Daniel Heathcote, Ismet Gursul, David Cleaver
    Abstract:

    Load control is the reduction of extreme Aerodynamic forces produced by gusts, maneuvers, and turbulence to enable lighter, more efficient aircraft. To design an effective control system, the actua...

  • Aerodynamic Load Alleviation Using Minitabs
    Journal of Aircraft, 2018
    Co-Authors: Daniel Heathcote, Ismet Gursul, David Cleaver
    Abstract:

    Increased Aerodynamic Loads during gusts, turbulence, and maneuvers define the outer envelope of aircraft structural design. Minitabs, which are small spanwise strips that protrude normal to the airfoil’s upper surface, have been studied to alleviate this requirement. To investigate the minitab’s steady-state effects, force and particle image velocimetry measurements were conducted at Re=6.6×105 on a NACA0012 airfoil. Minitabs with heights of h/c=0.02 and 0.04 were placed at a wide range of chordwise locations. In general, the optimum location for peak lift reduction moved toward the leading edge as the angle of attack increased, with significant effect on the lift curve gradient. Trailing-edge placement was effective at small angles. Placement close to the midchord provided a constant effect across the range of 0  deg≤α≤5  deg. For both locations, the baseline flow separation progressed ahead of the minitab with increasing α, which reduced effectiveness at stall. In comparison, placement close to the lea...

  • Aerodynamic Load Alleviation Using Minitabs
    Journal of Aircraft, 2018
    Co-Authors: Daniel Heathcote, Ismet Gursul, David Cleaver
    Abstract:

    Increased Aerodynamic Loads during gusts, turbulence, and maneuvers define the outer envelope of aircraft structural design. Minitabs, which are small spanwise strips that protrude normal to the ai...

  • an experimental study of mini tabs for Aerodynamic Load control
    54th AIAA Aerospace Sciences Meeting, 2016
    Co-Authors: Daniel Heathcote, Ismet Gursul, David Cleaver
    Abstract:

    Aircraft and wind turbines are exposed to increased Loads during gusts and turbulence, necessitating a stronger and stiffer structure. The field of Aerodynamic Load control aims to reduce this need, mitigating the extreme Loads at the fluid structure interface. Force, Particle Image Velocimetry and pressure measurements were conducted on a NACA0012 airfoil equipped with mini-tabs, small span-wise tabs that were to the airfoil’s upper surface, at a Reynolds number of 6.61 x 10. Mini-tabs of height h/c = 0.02 and 0.04 were employed across a range of chord-wise locations to investigate the effects of mini-tab height and chord-wise position. Overall, the mini-tab was found to have a lift reducing effect which increased with height. It was found that the effect of the chord-wise location was highly dependent on the angle of attack. Placement close to the trailing edge induced a large effect at zero degrees. Peak suction over the lower surface increased resulting in a reduction of ΔCL = -0.48. Approaching stall, effectiveness decreased as the mini-tab became immersed in the separated flow. Placement at xf/c = 0.60 produced an almost constant lift reduction between α = 0° and 5° of ΔCL ≈ -0.60, with a gradual reduction to stall. A mini-tab positioned close to the leading edge (xf/c = 0.08) was found to separate the flow effectively at low incidences but with no noticeable change in lift observed. It was found that the flow separation produced by the minitab effectively eliminated the suction peak on the upper surface. However, placement close to the leading edge has increasing effectiveness towards stall, as the shear layer induced by the separation was displaced further from airfoil surface. Peak lift reduction at stall was found to be ΔCL ≈ -0.67. The optimum chord-wise location for peak lift reduction is dependent on the airfoil angle of attack: the position of the mini-tab for maximum lift reduction moves towards the leading edge as the angle of attack increases.

  • Aerodynamic Load control through blowing
    54th AIAA Aerospace Sciences Meeting, 2016
    Co-Authors: Nader H Albattal, David Cleaver, Ismet Gursul
    Abstract:

    Aircraft are subject to extreme Loads during gust encounters. Amelioration of these Loads will allow for reduced structural weight and therefore greater efficiency. In this paper, two versions of blowing jet from suction surface, normal and upstream, are studied under steady state conditions to illustrate the effectiveness of these devices at mitigating extreme lift. Force, pressure and Particle Image Velocimetry measurements were performed at a Reynolds number of 660,000 for a NACA 0012 airfoil. A range of volumetric flow rate coefficients, below CQ = 0.44%, for a range of angles of attack 0° ≤ α ≤ 20°, are studied for five chordwise locations. It was observed that normal blowing at xJ/c = 0.95 induces a change in lift of ΔCL = -0.15 for the maximum momentum coefficient. Locations further forward produce a negligible change in lift coefficient. Whereas, upstream blowing was capable of reducing lift at all chordwise locations studied by up to ΔCL = -0.33. Upstream blowing encourages the shear layer to deflect upwards and inciting a greater adverse pressure gradient on the upper surface. Locations near the trailing edge are preferable for low angles of attack, as greater lift mitigation is obtained. Lift reduction can be augmented for higher angles of attack, with leading edge locations. As expected, increasing momentum coefficient increases the magnitude of the change in lift for all cases studied.