Navigating unsteady airwakes: Wake dynamics and sideslip in strong gust encounters
Abstract
The objective of the proposed work is to evaluate when it may be possible to decompose the effects of a complex airwake to approxima,te the unsteady forcing that results from a wing-wake interaction. The airwake of a naval ship and other common infrastructure is ma,de up of a many of flow structures of many spatial and temporal scales. For example, an aircraft operating in a ship airwake must co,ntend with strong shear layers, vortices, and wind gusts, all of which are spatially nonuniform and evolve over time. Previous work,has focused on a single two-dimensional canonical transverse gust encounter and the resulting flow structure and force response is n,ow known. Motivated by a desire to apply existing and readily modified unsteady aerodynamics models to more complex and practical gu,sts and airwakes, the proposed work aims to extend prior knowledge to a broader base of gust flows and include the effects of veloci,ty profile, gust exit, sideslip, and three-dimensionality.Air vehicle operation in wakes is particularly challenging as each of cons,tituent flow structures (e.g., vortices, shear layers) may impact force production differently on different vehicles. In a strong wa,ke or at low flight speeds, flow disturbances may be large relative to the flight speed of the vehicle and thus result in large-scal,e flow separation. In these nonlinear flows, the classical approach of superposition of potential flow solutions is no longer approp,riate. This is especially true for smaller, slower vehicles, and is thus of increasing importance as the Navy pushes towards greater, use of unmanned systems. For these small vehicles, it is likely necessary to implement some form of flight control assistance in st,rong gusts and airwakes.The proposed work focuses on the effect of parameters that affect the wake dynamics and three-dimensionality, of flow over the wing, namely the gust velocity profile, gust gradient distance, the process of gust exit, and sideslip angle. Time,-resolved force/moment, pressure, and velocity field measurements will provide a complete picture of flow separation and force produ,ction. The focus on gust velocity profile is motivated by a desire to generalize previous findings beyond canonical laboratory gusts,. Similarly, gust exit has largely been ignored to date, but is a critical part of the gust mitigation and recovery process, especia,lly in more complex unsteady environments where gusts may be encountered in rapid succession. Finally, the effect of sideslip angle,on flow separation and stall in a transverse gust encounter will be evaluated for the first time. Results from these experiments wil,l shed light on the role sideslip plays in the three-dimensional evolution of the wake, flow recovery, and the aerodynamic forces an,d moments that arise in wake interactions, as well as how different types of canonical gusts can be combined to more closely approxi,mate natural airwakes. The long-term impact of this work is to inform new aerodynamic models ofgust encounters for flight control, a,s well as sensor and actuator placement for gust response mitigation and assisted flight operations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 14, 2022
- Source ID
- N000142212009
Entities
People
- Anya Jones
Organizations
- Office of Naval Research
- United States Navy
- University of Maryland