Interaction of active flow control and global instability
Abstract
Interaction of active flow control and global instability When an aerodynamic body undergoes ight maneuvers in o -design conditions, ow sepa- ration can adversely impact its aerodynamic performance. Active ow control can play an important role in modifying the behavior of the surrounding ows to achieve improvement in terms of lift enhancement, drag reduction, fuel e ciency, and enhanced maneuverability of the ying vehicle. The challenges in modifying or controlling the behavior of uid ow stem from the rich dynamics that uid ows possess over a wide range of temporal and spatial scales, especially for high Reynolds number ows. While there has been tremendous development in the eld of nonlinear dynamics and control theory, the available theories are still limited to small and moderate sized problems. The high-dimensional (if not in nite- dimensional) uid ow systems pose a challenge in controlling the ows in a predictable and robust manner. Hence, the proposed project aims to extract the features of the ow that contribute to the dominant stability characteristics and understand how they interact with forcing inputs in altering the mean ow pro le. The objective of the proposed e ort is to uncover the interaction mechanism between active ow control input and the global instability modes in external ow over a canonical airfoil geometry. To achieve the goals of this study, we will examine the ow eld with global stability analysis and resolvent analysis, whose results will be examined in detail using a novel network theoretic approach to highlight the interactions and the causal relationship in the ow eld. The use of network analysis in this proposed project will reveal the missing links between the stability modes and how they interact with external forcing to modify the mean ow eld that predominantly determines the performance of aerodynamic bodies. The formulation proposed here is general in nature and can consider the interaction between hydrodynamic instability modes and ow control forcing inputs or perturbations in the ow, in the form of atmospheric uctuations or vortical disturbances. Such formulation at the moment is largely missing when analyzing large-scale uid ow data sets and can provide a broader impact on the uid mechanics community at large. The analytical toolsets developed from this study and the resulting physical insights into the uid ow will enhance our present capability of aerodynamic design and active ow control technologies. If successful, the output from the current investigation will enable engi- neers and scientists to understand how active ow control inputs and external perturbations can alter the mean ow which directly in uences the performance of aerodynamic bodies, such as wings. As we aim for our next-generation aircraft (and submarines) to achieve higher levels of maneuverability and agility in unsteady environments with large-scale disturbances, the use of ow control and the underlying ow physics become ever more important. The proposed investigation may o er critical insights into how uid ows are altered by external forcing and disturbance, providing pathways to tame unsteady uid ow over not only the vehicles employed by the US Navy but also those in service by the Department of Defense.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 23, 2016
- Source ID
- N000141612443
Entities
People
- Kunihiko Taira
Organizations
- Florida State University
- Office of Naval Research
- United States Navy