A Modified Dynamic Stall Model for Low Mach Numbers

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
W. Sheng ◽  
R. A. McD. Galbraith ◽  
F. N. Coton
Keyword(s):  
Mach Number ◽  
Wind Turbine ◽  
Experimental Results ◽  
Dynamic Stall ◽  
Modified Model ◽  
Wind Turbine Aerodynamics ◽  
Mach Numbers ◽  
The University

The Leishman–Beddoes dynamic stall model is a popular model that has been widely applied in both helicopter and wind turbine aerodynamics. This model has been specially refined and tuned for helicopter applications, where the Mach number is usually above 0.3. However, experimental results and analyses at the University of Glasgow have suggested that the original Leishman–Beddoes model reconstructs the unsteady airloads at low Mach numbers less well than at higher Mach numbers. This is particularly so for stall onset and the return from the fully stalled state. In this paper, a modified dynamic stall model that adapts the Leishman–Beddoes dynamic stall model for lower Mach numbers is proposed. The main modifications include a new stall-onset indication, a new return modeling from stalled state, a revised chordwise force, and dynamic vortex modeling. The comparisons to the Glasgow University dynamic stall database showed that the modified model is capable of giving improved reconstructions of unsteady aerofoil data in low Mach numbers.

Applications of Low-Speed Dynamic-Stall Model to the NREL Airfoils

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Wanan Sheng ◽  
Roderick A. McD. Galbraith ◽  
Frank N. Coton
Keyword(s):  
Wind Turbine ◽  
Power Level ◽  
Leading Edge ◽  
Dynamic Stall ◽  
State University ◽  
Low Speed ◽  
Helicopter Blades ◽  
Mach Numbers ◽  
The Ohio State University ◽  
Low Sensitivity

National Renewable Energy Laboratory, USA (NREL) airfoils have been specially developed for wind turbine applications, and projected to yield more annual energy without increasing the maximum power level. These airfoils are designed to have a limited maximum lift and relatively low sensitivity to leading-edge roughness. As a result, these airfoils have quite different leading-edge profiles from airfoils applied to helicopter blades, and thus, quite different dynamic-stall characteristics. Unfortunately for wind turbine aerodynamics, the dynamic-stall models in use are still those specially developed and refined for helicopter applications. A good example is the Leishman–Beddoes dynamic-stall model, which is one of the most popular models in wind turbine applications. The consequence is that the application of such dynamic-stall model to low-speed cases can be problematic. Recently, some specific dynamic-stall models have been proposed or tuned for the cases of low Mach numbers, but their universality needs further validation. This paper considers the application of the modified dynamic low-speed stall model of Sheng et al. (“A Modified Dynamic Stall Model for Low Mach Numbers,” 2008, ASME J. Sol. Energy Eng., 130(3), pp. 031013) to the NREL airfoils. The predictions are compared with the data of the NREL airfoils tested at the Ohio State University. The current research has two objectives: to justify the suitability of the low-speed dynamic-stall model, and to provide the relevant parameters for the NREL airfoils.

Aerodynamic Design and Testing of Three Low Solidity Steam Turbine Nozzle Cascades

2004 ◽  
Author(s):  
Bo Song ◽  
Wing F. Ng ◽  
Joseph A. Cotroneo ◽  
Douglas C. Hofer ◽  
Gunnar Siden
Keyword(s):  
Mach Number ◽  
Steam Turbine ◽  
Boundary Layer Transition ◽  
Experimental Results ◽  
Blade Surface ◽  
Layer Transition ◽  
Number Range ◽  
Baseline Design ◽  
Wide Range ◽  
Mach Numbers

Three sets of low solidity steam turbine nozzle cascades were designed and tested. The objective was to reduce cost through a reduction in parts count while maintaining or improving performance. The primary application is for steam turbine high pressure sections where Mach numbers are subsonic and high levels of unguided turning can be tolerated. The baseline Design A has a ratio of pitch to axial chord of 1.2. This is the pitch diameter section of a 50% reaction stage that has been verified by multistage testing on steam to have a high level of efficiency. Designs B and C have ratios of pitch to axial chord of 1.5 and 1.8 respectively. All three designs satisfy the same inlet and exit vector diagrams. Analytical surface Mach number distributions and boundary layer transition predictions are presented. Extensive cascade test measurements were carried out for a broad incidence range from −60 to +35 degrees. At each incidence, four outlet Mach numbers were tested, ranging from 0.2 to 0.8, with the corresponding Reynolds number variation from 1.8×105 to 9.0×105. Experimental results of loss coefficient and blade surface Mach number are presented and compared for the three cascades. The experimental results have demonstrated low losses over the tested Mach number range for a wide range of incidence from −45 to 15 degrees. Designs B and C have lower profile losses than Design A. The associated flow physics is interpreted using the results of wake profile, blade surface Mach number distribution and blade surface oil flow visualization, with the emphasis placed on the loss mechanisms for different flow conditions and the loss reduction mechanism with lower solidity. The effect of the higher profile loading of the lower solidity designs on increased end wall losses induced by increased secondary flow, especially on low aspect ratio designs, is the subject of ongoing studies.

Aerodynamic Design and Testing of Three Low Solidity Steam Turbine Nozzle Cascades

2004 ◽  
Vol 129 (1) ◽  
pp. 62-71 ◽  
Author(s):  
Bo Song ◽  
Wing F. Ng ◽  
Joseph A. Cotroneo ◽  
Douglas C. Hofer ◽  
Gunnar Siden
Keyword(s):  
Mach Number ◽  
Steam Turbine ◽  
Boundary Layer Transition ◽  
Experimental Results ◽  
Base Line ◽  
Blade Surface ◽  
Number Range ◽  
Wide Range ◽  
Mach Numbers ◽  
Line Design

Three sets of low solidity steam turbine nozzle cascades were designed and tested. The objective was to reduce cost through a reduction in parts count while maintaining or improving performance. The primary application is for steam turbine high pressure sections where Mach numbers are subsonic and high levels of unguided turning can be tolerated. The base line design A has a ratio of pitch to axial chord of 1.2. This is the pitch diameter section of a 50% reaction stage that has been verified by multistage testing on steam to have a high level of efficiency. Designs B and C have ratios of pitch to axial chord of 1.5 and 1.8, respectively. All three designs satisfy the same inlet and exit vector diagrams. Analytical surface Mach number distributions and boundary layer transition predictions are presented. Extensive cascade test measurements were carried out for a broad incidence range from −60to+35deg. At each incidence, four outlet Mach numbers were tested, ranging from 0.2 to 0.8, with the corresponding Reynolds number variation from 1.8×105 to 9.0×105. Experimental results of loss coefficient and blade surface Mach number are presented and compared for the three cascades. The experimental results have demonstrated low losses over the tested Mach number range for a wide range of incidence from −45to15deg. Designs B and C have lower profile losses than design A. The associated flow physics is interpreted using the results of wake profile, blade surface Mach number distribution, and blade surface oil flow visualization, with the emphasis placed on the loss mechanisms for different flow conditions and the loss reduction mechanism with lower solidity. The effect of the higher profile loading of the lower solidity designs on increased end wall losses induced by increased secondary flow, especially on low aspect ratio designs, is the subject of ongoing studies.

scholarly journals Controlling dynamic stall using vortex generators on a wind turbine airfoil

2021 ◽  
Author(s):  
D. De Tavernier ◽  
C. Ferreira ◽  
A. Viré ◽  
B. LeBlanc ◽  
S. Bernardy
Keyword(s):  
Wind Turbine ◽  
Vortex Generators ◽  
Dynamic Stall ◽  
Wind Turbine Airfoil

scholarly journals Identification of a Longitudinal Human Driving Model for Adaptive Cruise Control Performance Assessment

2002 ◽  
Author(s):  
Kangwon Lee ◽  
Huei Peng
Keyword(s):  
Adaptive Cruise Control ◽  
University Of Michigan ◽  
Cruise Control ◽  
Modified Model ◽  
Driving Model ◽  
Vehicle Motion ◽  
Transportation Research ◽  
The University ◽  
Traffic Behavior ◽  
Control Performance Assessment

The main purpose of this paper is to develop a longitudinal human driving model that is accurate enough for the performance evaluation of adaptive cruise control systems. Six driver models were evaluated based on selected data from two vehicle motion databases—the SAVME database and the ICCFOT database, both created at the University of Michigan Transportation Research Institute (UMTRI). Among the models we evaluated, the Gipps’ model was found to be the most promising and was further analyzed. A modified version of the model was suggested and evaluated. The modified model was implemented in a microscopic traffic simulator and was found to produce results that agree with macroscopic traffic behavior very well.

Dynamic Stall Control on a Vertical-Axis Wind Turbine Using Plasma Actuators

AIAA Journal ◽  
2014 ◽  
Vol 52 (2) ◽  
pp. 456-462 ◽  
Author(s):  
David Greenblatt ◽  
Amos Ben-Harav ◽  
Hanns Mueller-Vahl
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Plasma Actuators ◽  
Vertical Axis Wind Turbine ◽  
Stall Control

State of the art in wind turbine aerodynamics and aeroelasticity

2006 ◽  
Vol 42 (4) ◽  
pp. 285-330 ◽  
Author(s):  
M.O.L. Hansen ◽  
J.N. Sørensen ◽  
S. Voutsinas ◽  
N. Sørensen ◽  
H.Aa. Madsen
Keyword(s):  
Wind Turbine ◽  
State Of The Art ◽  
Wind Turbine Aerodynamics

Modeling dynamic stall of a straight blade vertical axis wind turbine

2015 ◽  
Vol 57 ◽  
pp. 144-158 ◽  
Author(s):  
K.M. Almohammadi ◽  
D.B. Ingham ◽  
L. Ma ◽  
M. Pourkashanian
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Vertical Axis Wind Turbine ◽  
Straight Blade
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