what engine is this ?

[garrya]

what engine is this ?
what is the purpose of the spiral part ?

Capture.PNG (616.37 KiB) Viewed 9702 times

[SpudmanWP]

Here you go:

ATA Engineering has demonstrated a novel aircraft drag management device in a series of ground tests performed on an FJ44-4A engine at the Williams International Outdoor Test Facility #2 on October 5–12, 2015. This successful full-scale engine test of a prototype version of ATA’s Engine Air Brake (EAB) demonstrates the technology’s potential to support the goals of NASA and the aircraft industry for next-generation quiet aircraft.

More at the JUMP
https://www.ata-plmsoftware.com/ata-eng ... echnology/

BONUS

[sferrin]

What is the purpose of this? What is it supposed to do?

[zhangmdev]

"Enables slower and/or steep approaches, thereby locating the noise source farther from affected communities below the flight path.

Reduces aircraft approach noise by creating “drag on demand,” without the associated unsteady flow structures of devices such as flaps, slats, and undercarriage.

Can be rapidly stowed in a go-around event"

https://ntrs.nasa.gov/archive/nasa/casi ... 005304.pdf

"The EAB is a deployable device for drag management in aircraft. Pressure drag is generated through swirling outflow from the engine's propulsion system by reducing thrust. The EAB is stowed during flight but deploys a swirl vane mechanism during landing, creating a swirling vortex from the jet engine exhaust flow. The constant flow of swirling air creates additional drag by reducing thrust and is sustained by the radial pressure gradient from the swirl vanes. The system enables a slower, steeper and acoustically cleaner approach/descent when engine thrust cannot be further reduced."

https://www.aerodefensetech.com/compone ... Itemid=686

My understanding is the air brake reduces thrust without spool down the engine.