1. Impact OF A380s on guidance signs
IES ALC 2015
Impact OF A380s on guidance signs
October 21, 2015
COMPREHENSIVE REPORT OF CFD ANALYSIS

2. Evaluation of Wind-Loading on Airport Signs
FAA Technical Note published in June 2000 investigated the forces exerted on airport signs caused by jet blast and wake turbulence
Key findings & conclusions led to incorporating changes to FAA AC 150/ F, with specific emphasis on third mode of signs designed to withstand wind loads > 300 mph with a 2.0 psi load factor
Recommended for use of Mode 3 sign where airports have history of sign failures, especially with heavier transport like B s
Aircraft Type
Engine Trust ER
PW 63,300 lbf (282 kN) GE 62,100 lbf (276 kN) RR 59,500/60,600 lbf (265/270 kN) ER: GE 62,100 lbf (276 kN)
Source: DOT/FAA/AR-TN00/32, June 2000 and Boeing

3. Dawn of Super Jumbo Entered services in October 2007
171 A380s have entered the fleets of 13 operators and 146 in orders
The A380 fleet operates more than 100 routes to 48 global destinations, taking off or landing every four minutes on average
Providing relief to dense, high-yield traffic flowing and severely capacity constrained airports or Hubs
Introduced “super-heavy” wake vortex category, relatively high runway occupancy time as well as line-up times
Increasing A380 operations at major hubs show more operational challenges for legacy airport infrastructure
Airport
Weekly Operations
Dubai Intl (DXB)
297
London Heathrow (LHR)
104
Singapore Changi (SIN)
Paris (CDG) 94
Frankfurt (FRA) 76
Seoul (ICN) 75
Los Angeles Intl (LAX) 70
Sydney (SYD) 47
Source: Airbus, Aviation Week & Space Technology

4. A380 & Airport Infrastructure Geometry
On Runway
On Taxiway
19.8m
30.2m

5. A380 Engine Diameter and Positions
GP 7200
Outboard engine distance to edge – 19.3m (63.3 ft)
Inboard engine distance to edge – 30.2m (99.1 ft)

6. A380 – Rolls Royce Trent 900 Engines
Source: Airbus

7. A380 – GP Alliance GP7200 Engines
Source: Airbus

8. Typical Guidance Sign Size

9. Geometry Created in CFD
Top-down view
Guidance Sign
Front looking back
The 3D-CAD tool in Star-CCM+ was used to create geometry
Screenshots of the engine and sign geometry are shown below
Engine

10. Effects of Increasing Wind Velocity Simulated
CFD simulations for 100, 200, 300, and 400 mph head wind were performed
Engines and wing tip vortices were not included
According to the standards, the sign will break when the pressure on the sign reaches 1.3 psig
Using this assumption, the sign will break for a wind velocity of 296 mph
These wind velocities are associated with the strongest category of tornadoes and are very unlikely to occur under normal circumstances
At this velocity, the force on the sign is 3830 lb
Wind Velocity
(mph)
Max Pressure on Sign
(psig)
Force on Sign (lb)
100
0.14
420
200
0.58
1710
300
1.34
3960
400
2.36
7290

11. Velocity Contours for 300 mph Wind
Significant wake region exists behind the sign
Sign expected to break for this case

12. Engines Alone Do Not Produce Breaking Force
Engine blast was simulated in two locations
Per Geometry described earlier
Maximum force on sign due to engines alone approximated by aligning the outboard engine with the sign
Plume does not strike the sign for standard conditions (see next slide)
When outboard engine is lined up with the sign, the force is much smaller than needed to break the sign
The plume is therefore not the sole cause of the sign damage
Because of this, secondary effects, such as wing tip vortices, must be considered
Engine
Location
Max Pressure on Sign
(psig)
Force on Sign (lb)
Default 2
Aligned
0.26
710

13. CFD Image of Velocity Contours
Narrow plume – essentially no impact on the runway sign for normal conditions

14. Tip Vortices can Cause Significant Damage
Force on Sign
Time history of force on the sign shown below
Cases where engines are 144 and 240 ft away from sign
First 2 seconds not shown – solution still stabilizing
Average force and peak pressure calculated for each case
Instantaneous maximum force and peak pressure also extracted
Strong buffeting is evident – force can vary by over 2000 lbs for 144 ft case
Force and Pressure on Sign
Results for the four tip vortex cases are shown below
Force on sign reaches a maximum when engine about 150 ft from sign
Peak force is near 3000 lb – this is relatively close to the breaking point
If other factors are included, such as wind or other random effects, this could cause the sign to break
Jet rotation could also increase the forces on the sign – this was not simulated for the present report
Buffeting could also increase impact of these forces
Variation of force on the sign is small when vortex is generated closer to the sign
Beyond wind and jet blast, it was theorized that the cause of damage could be buffeting from wing tip vortices for a heavy lift aircraft
A circular disc will be added to introduce tip vortices
The tip vortex will be introduced at the tip of the wing, as shown below
The vortex will be represented by a circular disc of radius 5.8 m
The vortex core has a radius of 2 m, so the vortex boundary includes tip vortex effects beyond the vortex core
Engines, along with tip vortex inlet, were positioned at four axial distances from the sign 240 ft – approximate length of an A380
144 ft – 60% of A380 length
72 ft – 30% of A380 length
36 ft – 15% of A380 length
Time (s)
Time (s)

15. Streamlines from Airplane – Case of 144 ft
Guidance Sign

16. Visual of Aircraft Wing Tip Vortices
Image shows that vortices can be strong and affect the runway guidance signs
Source: Airline.net

17. Exhaust/Ground Interaction at Rotation
Side view
Top view
These images show velocity contours (top) and a velocity isosurface (bottom) for an airplane during rotation
When exhaust plume strikes the ground, it spreads more quickly, expanding the influence of the exhaust

18. Conclusions
A wind of 296 mph is required to reach the breaking pressure of 1.3 psi on the guidance sign, current Mode 3 sign as per AC 150/ K up to 300 mph
The plume of an A380 engine is not strong enough to cause sign damage
Two major causes contributing to sign damage due to A380 operations are:
Wing tip vortices cause strong buffeting forces on the signs and can be responsible for breaking them
Jet rotation could also increase the pressure on the signs due to exhaust interaction with the ground
Need for fresh look at Lighted Sign Wind and Frangibility requirements to meet A380 operations
Picture: AirTeamImages.com