On the temporal response of active load control devices

Abstract

Flow around airfoils with deploying microtabs and microfl aps (or dynamic Gurney fl ap) have been numerically simulated by solving the unsteady turbulent compressible 2-D Navier-Stokes equations with the OVERFLOW 2 solver. Microtabs and microfl aps on the order of 1%c were installed in the trailing edge region of the symmetric NACA 0012 airfoil using a Chimera or overset grid topology. The devices were deployed on the order of one characteristic time unit, and the unsteady aerodynamic responses of both devices were compared. The two devices appear to affect the fl ow similarly by creating a low pressure region aft of the device and changing the Kutta condition. While initial transients varied, the post-deployment aerodynamic response showed a very similar temporal evolution towards a mean asymptotic solution. Both devices reached 90% of mean steady-state lift values by approximately nine characteristic time units from the onset of deployment. Drag and pitching moments evolved signifi cantly faster. The temporal development of these devices is not governed by near-body effects, and instead is an advection driven process. Microfl ap deployment times of 0.25, 0.50 and 1.00 characteristic time units were also examined. The corresponding mean aerodynamic coeffi cients for the three deployment times were comparable by one characteristic time unit after deployment. Validation studies with experimental results comparing shedding frequencies and Strouhal numbers for static, deployed microtabs and microfl aps were also performed to ensure accurate temporal resolution and convergence of the numerical simulations.

Iterative learning control with applications in energy generation, lasers and health care

“…As shown below, the latter can be addressed within the ILC framework by the addition of a proportional term to the basic ILC law. Examples of smart actuators are trailing edge flaps [16][17][18], microtabs [19,20] and active vortex generators.…”

Microtab Design and Implementation on a 5 MW Wind Turbine

“…In the last decades, many different flow control devices have been designed and developed (see Chow et al [8]). Most of them were intended for aeronautical applications (Taylor [9]), but also frequently used in turbo machinery (see Liu et al [10] and Xu et al [11]).…”

On synthetic jet actuation for aerodynamic load control

“…The initial reverse lift peak induced by the the micro-tab has also been observed by Chow & Van Dam [45]. They show that a micro-flap, which is a Gurney flap located at the trailing edge that can be deployed by rotation rather than translation, is a better option since it does not feature this behavior.…”