Aviation

On Instability Analysis of Realistic Intake Flows

González, L
Rodriguez, D
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...

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
Rodriguez, D
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...

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

Himeno, FHT
Amaral, FR
Souza, DS
Rodriguez, D
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...

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

Rodriguez, D
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)...

Development of a Modeling Framework for Analyzing Improvements in Intermodal Connectivity at California Airports

Lu, Xiao-Yun
Gosling, Geoffrey D.
Shladover, Steven E.
Xiong, Jing
Ceder, Avi
2006

This report has been prepared as part of a research project developing a combined quantitative and qualitative approach to planning for improved intermodal connectivity at California airports. The quantitative approach involves the development of an Intermodal Airport Ground Access Planning Tool (IAPT) that combines an air passenger mode choice model, a model of transportation provider behavior and a traffic network analysis model. The qualitative approach will be used to enhance the quantitative analysis to account for those factors which are difficult to quantify and to provide...

Effect of an Excrescence in the Slat Cove: Flow-field, Acoustic Radiation and Coherent Structures

Souza, DS
Rodriguez, DA
Simões, LGC
Medeiros, MAF
2015

Slat noise during aircraft landing is already a barrier to the development of quieter commercial airplanes. Investigations have been made by several research groups to understand the mechanism of slat noise generation. Most of the published works related to slat noise consider clean idealized geometries, whereas real slats contain some imperfections to enable its operation. The influence of a protrusion on the slat...

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

Rodriguez, DA
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 ...

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

Gennaro, EM
Souza, BDP
Rodriguez, D
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...

A Combined Quantitative and Qualitative Approach to Planning for Improved Intermodal Connectivity at California Airports

Lu, Xiao-Yun
Gosling, Geoffrey D.
Ceder, Avi
Tung, Steven
Tso, Kristin
Shladover, Steven
Xiong, Jing
Yoon, Sangwon
2009

This report has been prepared as the final deliverable for a research project developing a combined quantitative and qualitative approach to planning for improved intermodal connectivity at California airports. The quantitative approach involves the development of an Intermodal Airport Ground Access Planning Tool (IAPT) that combines transportation system performance measurement, an air passenger mode choice model, and a model of transportation provider behavior, and is designed to interface with a traffic network analysis model. The qualitative approach is used to enhance the quantitative...

Opportunities for Improved Intermodal Connectvitiy at California Airports

Lu, Xiao-Yun
Gosling, Geoffrey D.
Xiong, Jing
2006

This working paper has been prepared as part of research to develop a combined quantitative and qualitative approach to planning for improved intermodal connectivity at California airports. The quantitative approach involves the development of an Intermodal Airport Ground Access Planning Tool that combines an air passenger model choice model, a model of transportation provider behavior and a traffic network analysis model. The qualitative approach will be used to enhance the quantitative analysis to account for those factors which are difficult to quantify and to provide recommended policy...