Help me on how to do the work. Just answer 1 question. One of the most important
ID: 1988599 • Letter: H
Question
Help me on how to do the work. Just answer 1 question.
One of the most important applications of fluid dynamics is in the design of airplane wings. In this SLP, we'll introduce some basic terminology and take a quick look at the relationship between angle of attack, airspeed, and lift.
Go to the NASA GRC (2010) link on the Background page, which is a simulation called FoilSimII, created and maintained by the NASA Glenn Research Center.
Basic terminology (click "Geometry" in the upper left-hand view.)
Airfoil: The wing.
Leading edge: The forward (rounded) part of the wing.
Trailing edge: The aft (thin) part of the wing.
Chord: The distance between the forward and aft edge of the wing.
Angle of attack, AOA (In the simulation, it's called Angle): The angle in degrees between the chord and direction of flight, relative to the air. At higher values of AOA, the wing is taking a bigger "bite" of the air.
Camber: The downward curvature of the airfoil, measured as a percent of chord.
Thickness: The maximum distance between the upper and lower surface of the airfoil, measured as a percent of chord.
Read all the instructions carefully. Set up the simulation as follows:
Student version: Stall model
Metric units
Input:
Size:
Chord = 2.00 m.
Span = 10.0 m (Distance from wingtip to wingtip.)
Area = 20 m^2
Aspect ratio (AR, defined as span / chord) = 5
AR correction = ON
Shape/Angle:
AOA (Angle) = 5 deg.
Camber = 5%
Thickness = 10%
Flight test:
Earth - Average day
Assume that the lift needed to maintain level flight is 20,000 N. On the "Flight test" page, adjust the speed (km/h) until lift is just over 20,000N (it won't be exact.) Record the speed.
Go back to the "Shape/Angle" input page, and change the AOA to 6 degrees. Go back to the "Flight test" page and find the airspeed necessary to maintain just over 20,000 N of lift. (It will be lower than it was at AOA = 5 deg.) Repeat for the following increments of AOA: 7, 8, 9, and 10 degrees. Notice that the wing stalls just before 10 degrees. At this point, the lift drops (the simulation is wrong) and the aircraft begins to lose altitude. Record your data in a table.
Repeat all of the above for camber = 20%. Record your data in a table. After you've collected all your data, plot speed (Y-axis) vs. AOA (X-axis) for camber = 5% and camber = 20%. Discuss the advantages of a high-camber wing when an airplane is operating near stall speed. (Note that the flaps that extend from the trailing edge of jetliner wings increase the effective camber.)
Some notes on the simulation:
For all of its apparent complexity, the simulation is actually too simple. The wing is rectangular, without sweep or taper. There's no aircraft fuselage interfering with lift. The calculations are based on air as an ideal fluid, with no viscosity; hence, no boundary layer and no loss of lift when the wing stalls. Just the same, the simulation is an excellent teaching tool. You should explore some of the many informative web pages that are linked to the simulation.
Explanation / Answer
AEROSPACE AMERICA/DECEMBER 2010 Fluid dynamics This year saw many exciting developments in fluid dynamics over a range of flow regimes and scales. Of particular interest were accomplishments in flow control, supersonic and hypersonic flow, roughness effects, low Reynolds-number flows, and wind turbines. Flow control research is becoming more integrated with flight control and applications involving unsteady flow and flexible wings. Investigators at the Air Force Academy are exploring ways to use closed-loop active flow control to modify the spanwise lift distribution on 3D flexible wings. Gust suppression and energy harvesting techniques for micro air vehicle (MAV) based modern closed-loop control algorithms are under joint development at the Illinois Institute of Technology and Caltech. These efforts have highlighted the importance of low-dimensional models for separated flow dynamics and unsteady aerodynamics. University of Florida researchers have highlighted the importance of 3D effects in flow control for applications related to cavity flows. The team has been able to reduce both broadband and tonal surface pressure components using open-loop strategies in supersonic flows, as well as closed-loop strategies in subsonic freestream conditions. The Computational Aerophysics Branch at AFRL has used ILES (implicit large-eddy simulations) to investigate the unsteady flowfield structure and forced generation of a rapidly pitching plate at low Reynolds numbers to model a prototypical perching maneuver for MAV applications, as well as deep dynamic stall phenomena induced by the large-amplitude plunging oscillations of an airfoil. Investigators at UCLA have used a vortex particle method to simulate the flow field and force generated by a rapidly pitching plate at low Reynolds numbers. They have also developed a reduced-order model for this flow. LES conducted at AFRL investigated a novel serpentine plasma-based actuation for control of a low-Reynolds-number airfoil representative of MAV applications.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.