Journal ArticleDOI
Compressible dynamic stall vorticity flux control using a dynamic camber airfoil
TLDR
In this article, a variable droop leading edge (VDLE) airfoil was used to control compressible dynamic stall through management of its unsteady vorticity.Abstract:
This study reports control of compressible dynamic stall through management of its unsteady vorticity using a variable droop leading edge (VDLE) airfoil. Through dynamic adaptation of the airfoil edge incidence, the formation of a dynamic stall vortex was virtually eliminated for Mach numbers of up to 0.4. Consequently, the leading edge vorticity flux was redistributed enabling retention of the dynamic lift. Of even greater importance was the fact that the drag and pitching moment coefficients were reduced by nearly 50%. The camber variations introduced when the leading edge was drooped are explained to be the source of this benefit. Analysis of the peak vorticity flux levels allowed the determination of minimum necessary airfoil adaptation schedule.read more
Citations
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Journal ArticleDOI
Analysis of the onset and evolution of a dynamic stall vortex on a periodic plunging aerofoil
TL;DR: In this article , the onset and evolution of the dynamic stall vortex (DSV) were analyzed by means of large eddy simulations of an SD7003 aerofoil undergoing periodic plunging motion in a transitional Reynolds number flow.
Journal ArticleDOI
A vorticity-based criterion to characterise leading edge dynamic stall onset
TL;DR: In this paper , the boundary enstrophy flux (BEF) was used to characterise leading-edge-type dynamic stall onset in incompressible flows, and it was shown that the dominant contribution arises from the laminar leading edge region, due to the combined effect of large clockwise vorticity and favorable pressure gradient.
Journal ArticleDOI
Vorticity Analysis of a Cavitating Two-Phase Flow in Rotating
TL;DR: In this article, an expression of moment acting on blades is established via applying boundary vortex flux (BVF) to diagnose the cavitation of the two-phase flow in a rotating reference frame for hydraulic turbomachinery.
Book ChapterDOI
Smart Actuation for Helicopter Rotorblades
TL;DR: In this paper, the authors proposed a smart rotor blades system to adapt the aerodynamic characteristics of the blade during its revolution and to improve the overall performance of the rotorcraft by deploying flaps, by using flow control devices or by morphing the full shape of the profile at specific places during the blade revolution.
Proceedings ArticleDOI
Evaluating Dynamic Stall Onset Criteria for Mixed and Trailing-Edge Stall
TL;DR: In this article , the authors evaluate two leading-edge-based dynamic stall-onset criteria (namely, the maximum magnitudes of the leading edge suction parameter and the boundary enstrophy flux) for mixed and trailing-edge stall.
References
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Journal ArticleDOI
Progress in analysis and prediction of dynamic stall
TL;DR: In this paper, the authors defined the pitch-moment coefficient as the ratio of pitch moment to pitch moment, and used it to measure the pitch moment of a chord chord.
Journal ArticleDOI
Compressible Dynamic Stall Control Using a Variable Droop Leading Edge Airfoil
TL;DR: In this article, the leading 25% of a VR-12 airfoil is drooped as it executes sinusoidal pitch oscillations such that the leading portion is always at a low effective incidence to the flow.
Journal ArticleDOI
Competing Mechanisms of Compressible Dynamic Stall
TL;DR: In this paper, a newly discovered mechanism of dynamic stall onset was proposed, in which the supersonic flow and the bubble dynamics compete with each other, and the consequent complex interactions lead to a new mechanism.