Session: 10.4.2 - Vortex Dynamics II

Paper Number: 157976

157976 - Spectral Proper Orthogonal Decomposition Flow Analysis of Gust Mitigation With the Morphing Airfoil Technology at Low Reynolds Number 

Abstract: 

Wind gust interaction with small- and mid-sized uncrewed aerial vehicles (UAVs) is known to cause flight instability which can severely limit the applicability of UAVs in complex flight environments. Although certain flow mechanisms pertinent to the gust-vehicle interaction have been explained with reasonable details, it is still far away from being sufficient to support the creation of reliable and energy-efficient gust mitigation strategies. In our previous studies, rigid-body pitch motion has been demonstrated as a very effective way to mitigate the effects of gusts on a flying wing. However, the entire wing needs to be pitched for gust mitigation with considerable energy consumption, even when the pitch rate and amplitude can be made small. Wing morphing technology, which only locally modifies the wing shape and/or deforms part of the wing, such as its leading and trailing edges, provides an alternative, more energy-efficient means of gust mitigation. In our recent work, we have performed a series of gust mitigation studies based on morphing wing technology with 2D high-order computational fluid dynamics (CFD) simulations. The morphing action of an airfoil in a developing, long-duration gust which will be studied includes: (1) sinusoidally oscillating trailing edge; (2) deforming trailing edge in the gust direction; (3) deforming leading edge against the gust direction; and (4) in-concert leading-trailing edge deformation. Those flow control methods show varying levels of gust mitigation effectiveness. In this study, we use the spectral proper orthogonal decomposition (SPOD) method to analyze flow physics from the high-fidelity simulation results with the aim of identifying fundamental mechanisms behind the different gust mitigation morphing wing technologies.
To obtain the baseline flow dynamics, we performed 2-D simulations on a NACA 0012 airfoil at Reynolds number 12,000 subjected to a vertical wind gust in addition to the incoming wind. The subsequent simulations were performed by gradually changing the airfoil configuration for each case to observe the flow response. The following configurations were tested: trailing edge sinusoidal oscillation with Strouhal (St) numbers from 0.01 to 0.05 and reduced frequency (k) of 0.1 to 0.5; trailing edge continuous deformation with a maximum amplitude of 0.2 chord length (c); Leading edge continuous deformation with a maximum amplitude of 0.05c; combined leading-trailing edge deformation: leading edge amplitude of 0.05c and trailing edge amplitude of 0.1c. SPOD analyses were performed on the vertical gust exit, leading-edge flow over the suction surface of the airfoil, and airfoil wake. Results show intrinsic connections between flow dynamics within those regions.

Presenting Author: Cindy Zozimo Aranda De Almeida University of Maryland Baltimore County (UMBC)

Presenting Author Biography: