Computation of unsteady viscous flow around a locally flexible airfoil at low Reynolds number

Effects of local oscillation of airfoil surface on lift enhancement at low Reynolds number

“…Such variation of the pressure is similar to the one for airfoil with locally flexible structure for elastic modulus E ¼ 5 Â 10 4 (see Fig. 15(i-l) in Kang et al, 2014).…”

“…The computational parameter for the oscillation is listed in Table 1, where the oscillating frequencies are mf ref ; m ¼ 0:3; …; 2. The computational mesh is chosen the same as the one in Kang et al (2014). Numerical results in Case I, Case II, and Case III are compared to highlight the effects of oscillating frequency, equilibrium and amplitude on aerodynamic performance and flow patterns, respectively.…”

“…The resulting equations are simple diffusion equations, which can be efficiently solved by standard finite element method. The detailed deduction of the algorithm can be referred to as Kang et al (2012Kang et al ( , 2014Kang et al ( , 2015. Herein only the split procedure of the algorithm is given: I.…”

Experimental Evaluation of the Critical Flutter Speed on Wings of Different Aspect Ratio

“…In contrast, HARWs have higher potential to flow induced vibration known as "flutter" and the associated instabilities (Tang and Dowell (2002)). This is due to the strong interaction between their wing oscillations and the surrounding unsteady flow that is a multi-physics phenomena (aerodynamic, elastic and inertia forces) and strongly nonlinear that can lead to wing failures (Baxevanou et al (2008); Romeo et al (2007); Kang et al (2014)). The aeroelastic computation of a locally flexible airfoil carried out by Kang et al (2014) to study the effect of the flexibility on the airfoil aerodynamic performance show that the coupling between the fluid and structure has important effects on the airfoil lift with different elastic stiffness.…”

“…(1) this interaction is a multi-physics phenomena and being strongly nonlinear, therefore the principle of their separation does not hold (Kang et al (2014), (2) The HARWs are designed to be very flexible, which creates a strong coupling between the wing oscillation and the unsteady separated flow that leads to complex instabilities as stall flutter (Rojratsirikul et al (2009)). (3) The unsteady characteristics of interaction between the flow and the wings have been confined very largely to cases before the flutter occurs using oscillating wings of low aspect ratio to quantify air loads (Soltani and Marzabadi (2009)), to characterize the near-field tip vortices (Birch and Lee (2005)) or to locate the laminar flow separation in space and time (Rudmin et al (2013)).…”