Aviation

COBEM-2017-0208 The Influence of the Reynolds Number on the Linear Instability of Laminar Separation Bubbles in the Absence of Environmental Disturbances

Gennaro, EM
Souza, BDP
Daniel Rodriguez
2017

The understanding and identification of the physical instability mechanisms responsible for the appearance of unsteadiness and three-dimensionality on laminar separation bubbles can provide a fundamental insight into the aerodynamic characteristics of airfoils at stall conditions, and guide the development of strategies for the control of separated flows. Separation bubbles have been demonstrated to have an intrinsic instability mechanism, which results in the appearance of spanwise-periodic three-dimensional structures. The instability mechanism responsible for three-dimensionality was...

COBEM-2017-0139 What Does Linear Instability Tell Us About Airfoil Tonal Noise?

Daniel Rodriguez
Gennaro, EM
Ramírez, WA
Wolf, WR
2017

Several studies spanning since the 1970s to the present, considering turbulent flows at realistic conditions for aircraft flight, have amassed evidence on the dominance of a far-field tonal noise, usually associated with vortex-shedding from the trailing edge. Furthermore, the appearance of multiple tones has been documented for increasing values of the angle of attack and Mach number, which exhibit a ladder-like pattern in terms of the variation of the frequencies with increasing free-stream velocity. Different explanations have been suggested for the origin of the (i) single tone, (ii)...

EPTT-2018-0047 Recirculating Large-Scale Structures Inside the Cove of a Sealed Slat

Himeno, FHT
Amaral, FR
Souza, DS
Daniel Rodriguez
Medeiros, MAF
2018

The development on Environmental Regulations related to aircraft noise propagated to the vicinity of airports forced the industry to investigate the noise sources and look for alternatives of noise reduction. The current aircraft noise has a large contribution provenient from the airframe, due to the turbofan engine development. One can identify the most relevant sources as the landing gear, flap and slat. Since slat is distributed in almost whole extension it becomes a distributed noise source. The presence of excrescences inside slat cove can changes significantly the recirculating flow...

The Potential Societal Barriers of Urban Air Mobility (UAM)

Susan Shaheen
Cohen, Adam
Farrar, Emily
2018

Urban Air Mobility (UAM) is an emerging concept of air transportation where small package delivery drones to passenger-carrying air taxis operate over populated areas, from small towns to the largest cities are being considered. This could revolutionize the way people move within and around cities by shortening commute times, bypassing ground congestion, and enabling point-to-point flights across cities. In recent years, several companies have designed and tested enabling elements of this concept, including; prototypes of Vertical Take-Off Landing (VTOL) capable vehicles, operational...

Wavepacket Models for Subsonic Twin Jets Using 3D Parabolized Stability Equations

Daniel Rodriguez
Jotkar, MR
Gennaro, EM
2018

An extension of the classical parabolized stability equations to flows strongly dependent on the two cross-stream spatial directions and weakly dependent on the streamwise one is applied to model the large-scale structures present in twin-jet configurations. The existence of these ...

Recirculating Coherent Structures Inside the Cove of a Bulb Sealed Slat

Himeno, FHT
Amaral, FR
Souza, DS
Daniel Rodriguez
Medeiros, MAF
2019

The current aircraft noise has a large contribution provenient from the airframe in which the most relevant sources are the landing gear, the flap and the slat. The leading edge slat is a distributed noise source since it spans almost the whole wing extension. The presence of excrescences inside the slat cove can change significantly the recirculating flow and the characteristics of noise generated. Previous experiments showed substantial increasing in the narrow band peaks for the MD30P30N high-lift model in which the slat geometry included a bulb seal attached at some positions of its...

The Effect of Compressibility on the Primary Global Instability of Unforced Laminar Separation Bubbles

Gennaro, EM
Souza, BDP
Daniel Rodriguez
2019

Laminar separation bubbles present a three-dimensional self-excited instability mechanism which leads to the appearance of spanwise-periodic structures. In incompressible flow, this mechanism was found to become active at conditions in which wave-like, two-dimensional perturbations are only convectively unstable. In the absence of continuous external excitation, the three-dimensional instability is expected to dominate the flow dynamics and initiate the laminar-turbulent transition. This work extends previous analyses by incorporating the effect of compressibility at subsonic...

Urban Air Mobility: History, Ecosystem, Market Potential, and Challenges

Cohen, Adam P.
Susan Shaheen
Farrar, Emily M.
2021

Since the early 20th century, inventors have conceptualized “plane cars” and other urban aerial transportation. Emerging innovations in electrification, automation, and other technologies are enabling new opportunities for on-demand air mobility, business models, and aircraft design. Urban air mobility (UAM) envisions a safe, sustainable, affordable, and accessible air transportation system for passenger mobility, goods delivery, and emergency services within or traversing metropolitan areas. This research employed a multi-method approach comprised of 106...

Future of Aviation: Advancing Aerial Mobility through Technology, Sustainability, and On-Demand Flight

Cohen, Adam
Susan Shaheen
2023

Advanced air mobility (AAM) is a broad concept enabling consumers access to air mobility, cargo and package delivery, healthcare applications, and emergency services through an integrated and connected multimodal transportation network. AAM includes local use cases of about a 50-mile radius in rural or urban areas and intraregional use cases of up to approximately 500 miles that occur within or between urban and rural areas. The Future of Aviation Conference: Advancing Aerial Mobility through Technology, Sustainability, and On-Demand Flight was held in person at the San Francisco...

On Instability Analysis of Realistic Intake Flows

González, L
Rodríguez, Daniel
Theofilis, V
2008

Instability analyses of incompressible ow through two intakes, both having realistic cross-sectional profiles have been performed. Without reference to concrete applications, representative duct geometries, inspired from motor racing and fighter jets has been selected. The projections on the plane normal to the streamwise ow direction normal to the plane of the intake, of two such duct geometries are depicted in figure 1; the parametric definition of these ducts is detailed in what follows. In order for the analysis to proceed two key assumptions are made. First, ow is taken to be...