Hello humans! I know you have missed me… so here I am with some new interesting news!
Following the lead of Lufthansa Today JetBlue has announced plans to retrofit all of its Airbus aircrafts with noice reducing vortex generators. All of the Airbus aircrafts delivered to JetBlue since 2015 already have them installed but now they have committed to add those devices to all of its remaining 138 A320s and 8 A321s by 2021. The small devices disrupt wind over ports on the wing which can produce a “whistling” tone during approach into an airport.
The most surprising thing I found about this news is that the cost of retrofitting all of their Airbus aircrafts is less than $1 million.
I know RWA is not a news reporting agency but I found this step very interesting and no I’m not planning on spamming the forum with any kind of unimportant news.
Now I’d like to know if you have ever been on an aircraft with these devices? are they effective? . Also let me know your thoughts on this down below.
The engine strakes are called ‘chines’ they are there, as above, to direct and smooth airflow over the wing and pylon.
Looks more like a device to prevent turbulent drag caused by the wing vent than a noise reduction device. The most noise on approach from an Airbus is usually when pulling the speedbrake. That’s when you get the very distinctive Airbus ‘whoosh/whine’ noise.
Noise dampeners are always good for the non-avgeeks on the ground below the aircraft, but are often sad for us avgeeks that love the roar and vibrations of the engine…
Basically that little piece of metal is going to make the wing flow turbulent around that port, which will allow more air to go over vs in it. Laminar flow has a tendency to “stick” to the surface more than a turbulent flow. Think of it similar to how the air behaves on a stalled wing.
Have you ever blown air across the top of an empty water bottle with no cap? It produces a humming noise. Now if you use something to deflect that air upwards away from the opening, the noise is pretty much gone. What this mechanism does is divert the air over the open port so the air moving over the port does not make that whistling sound.
A hole or vent in an aerodynamic surface potentially causes drag as the laminar flow will ‘curl’ into the void, disrupt the laminar flow and impact the other side setting up vibration, noise and friction (drag).
By deflecting the flow you sacrifice a very small amount of parasite drag (parts of the airframe sticking up into the airflow) for less friction drag. I would assume that the egg heads have calculated the trade off between the two as being beneficial toward the deflector!
