BA97 From Canada, joined Apr 2004, 377 posts, RR: 0 Posted (10 years 2 months 2 weeks 3 days 18 hours ago) and read 2160 times:
I notice on pictures of Concorde that there is a gap along the front half of the engine where it meets the wing. I would have thought the surfaces would have to be smooth and joints sealed. I can't think of seeing similar spaces on other planes. Is there a purpose for this?
FredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 2, posted (10 years 2 months 2 weeks 3 days 12 hours ago) and read 2029 times:
Close to the surface of an aircraft is a layer where the air has been slowed down by friction. This is called the boundary layer. It is turbulent and not at all what you want to feed your engines. When it does get sucked into the engine intakes, it is called boundary layer ingestion, and is something you try to avoid. To avoid it, you make sure to have the lip of the engine intake some distance away from the skin of the aircraft. There’s a wedge shape in there to steer the air out to the sides.
Take a look at military aircraft, e g the Saab 39 Gripen or the F-16, and you will see similar features on the intakes.
I thought I was doing good trying to avoid those airport hotels... and look at me now.