A Modified Dynamic Stall Model for Low Mach Numbers

Sheng, Wanan; Galbraith, R.A.McD.; Coton, F. N.

doi:10.1115/1.2931509

Cited by 106 publications

(57 citation statements)

References 17 publications

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“…4(e)), the separation moves to the leading edge and the flow is fully separated (the process by which the separation propagates from the trailing edge to the leading edge will be discussed in detail in Figs. [6][7][8][9]. It is noteworthy that the transition appears to occur at a slightly higher angle of attack for the higher reduced frequency case (Fig.…”

Section: B Mid-plane Dynamic Stall Evolutionmentioning

confidence: 82%

“…7 Early research into dynamic stall suggested that this increase in lift could be attributed to the formation and shedding of a large-scale vortex from the leading edge of the pitching airfoil, 4,8 which was eventually taken to be an expected component of dynamic stall. 9 If several dynamic cycles are observed and phase averaged, there is a distinct, large-scale structure that is apparent in the phase averaged flow field. The classic picture of dynamic stall is the formation of a leading edge vortical structure, which convects downstream, temporarily increasing lift as it convects downstream.…”

Section: Introductionmentioning

confidence: 98%

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Dynamic stall process on a finite span model and its control via synthetic jet actuators

Taylor

Amitay

2015

Physics of Fluids

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An experimental study of the process by which dynamic stall occurs on a finite span S809 airfoil was conducted at the Center for Flow Physics and Control at Rensselaer Polytechnic Institute. Understanding the flow field around a dynamically pitching airfoil helped in controlling the dynamic stall process through active flow control via synthetic jet actuators. The three component, two dimensional flow fields were measured with a stereoscopic particle image velocimetry system. This study demonstrated that, through the introduction of periodic momentum near the leading edge of this model, the evolution of the dynamic stall vortex, which forms and convects downstream under dynamic conditions, could be delayed or suppressed in favor of the preservation of a trailing edge vortex that arises due to trailing edge separation and recirculation in the time averaged sense. This process seems to be the result of changing how the flow field transitions from trailing edge separation to a fully separated flow. In a phase-averaged sense, absent of flow control, this process is defined by the creation of a phase averaged leading edge recirculation region, which interacts with the trailing edge separation. Through the introduction of momentum near the leading edge, this process can be altered, such that the phase averaged trailing edge separation region is the dominant structure present in the flow. Additionally, a cursory investigation into the instantaneous flow fields was conducted, and a comparison between the phase averaged flow field and instantaneous fields demonstrated that while similar effects can be observed, there is a significant difference in the flow field observed in the instantaneous fields versus the phase averaged sense. This would imply that a different method of analyzing dynamic stall from PIV measurements may be necessary.

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Section: B Mid-plane Dynamic Stall Evolutionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 98%

Dynamic stall process on a finite span model and its control via synthetic jet actuators

Taylor

Amitay

2015

Physics of Fluids

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“…Leishman [28] gave a good review of dynamic stall models for horizontal-axis wind turbines in 2002 including the popular BeddoesLeishman [29] model. Work by Sheng et al [30][31][32] has improved upon the Beddoes-Leishman model at low Mach numbers and provided data for certain airfoils. Their oscillatory airfoil testing was closer to the apparent motion of the blades of the turbine being researched at the University of Plymouth (UoP), although the results also showed sensitivity of the coefficients to chord length as well as profile, which further hinders its use as a predictive tool for untested, novel profiles.…”

Section: Unsteady Hydrodynamics and Dynamic Stallmentioning

confidence: 97%

Hydrodynamic analysis models for the design of Darrieus-type vertical-axis marine current turbines

Dai

Gardiner

Sutton

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part M:

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This work reviews hydrodynamic analysis models developed for the design of Darrieus-type vertical axis marine current turbines, with particular emphasis on the prediction of hydrodynamic rotor performance, as well as their suitability for aiding the optimization process, either directly, or as a fast filter of potential blade profiles.In order to improve the performance of a marine current turbine it is necessary accurately to model the flow passing the turbine's blades. Several types of models exist for Darrieus-type turbines, from momentum-based streamtube models to complex computational fluids dynamics (CFD) simulations. With continuously varying large angles of attack on the blades, the main issue is accurate prediction of the flow field around the rotor and thus its loads and torque. This is further complicated by the significant inherent unsteady hydrodynamic characteristics and potential for dynamic stall. Comparisons of the analytical results with experimental data are presented to compare these different models and thus illustrate their areas of suitability in this context. In conclusion, vertical axis machines have the potential of high power capture compared with that of their horizontal counterparts but this will depend on blade profile and design configuration, solidity, and tip speed ratio. None of the existing theoretical methods really captures the actual performance of the machines except for detailed CFD simulations, which are inevitably computational time intensive.

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“…Owing to the wind turbines operating at low Mach numbers, the 2D stall-onset criterion presented by Sheng et al [9] is used,…”

Section: Stall-onset Indicationmentioning

confidence: 99%

Modeling three-dimensional dynamic stall

Lü

Wang

2011

Appl. Math. Mech.-Engl. Ed.

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The dynamic stall process in three-dimensional (3D) cases on a rectangular wing undergoing a constant rate ramp-up motion is introduced to provide a qualitative analysis about the onset and development of the stall phenomenon. Based on the enhanced understanding of the mechanism of dynamic stalls, a 3D dynamic stall model is constructed with the emphasis of the onset, the growth, and the convection of the dynamic stall vortex on the 3D wing surface. The results show that this engineering dynamic stall model can simulate the 3D unsteady aerodynamic performance appropriately.

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A Modified Dynamic Stall Model for Low Mach Numbers

Cited by 106 publications

References 17 publications

Dynamic stall process on a finite span model and its control via synthetic jet actuators

Dynamic stall process on a finite span model and its control via synthetic jet actuators

Hydrodynamic analysis models for the design of Darrieus-type vertical-axis marine current turbines

Modeling three-dimensional dynamic stall

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