Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [inlet]

Also known as intake, is an opening that feeds air to an engine, air conditioning system, oil cooler, etc.

0
votes
2answers
103 views

How do engines cope with various intake airflow speeds?

On a recent trip out of Washington Dulles to San Francisco, our B777 met with 200+ mph headwinds (as per the passenger entertainment system) at 35,000 ft for the first half of the route, before ...
4
votes
1answer
124 views

Do ramjets use variable geometry supersonic inlets?

Ramjets are very often portrayed as super simple, I've read on few occasions that the only moving parts in a ramjet are the fuel pumps. However, turbojets operating at similiar speeds (mach 2 - mach 3)...
1
vote
0answers
51 views

How much lift can be generated by the intake lip of a duct?

How to calculate the extra lift gained by the intake lip of a duct? Aside from improving efficiency by preventing tip vortices, if a duct has a bell-shaped intake, this lip around the edge creates ...
3
votes
4answers
525 views

What drives the shape of an engine's intake on a fighter jet?

Rectangular intakes have more corners which might increase subsonic pressure losses and would weigh larger than a pitot (Semi-circular) type intake. Are the designer drivers solely based on supersonic ...
25
votes
5answers
4k views

What is this F-18 Hornet “air intake” for?

I think I read once that they served to cool the on-board computer systems, but I'm not sure.
4
votes
0answers
97 views

How come diverterless supersonic inlets haven't been discovered much earlier?

DSI's seem like such an absolutely elegant solution to a problem that has, so far, been solved in a truly overly complicated way. So, if I'm not missing out on some important small speck of knowledge ...
21
votes
3answers
5k views

Why are turboprop intakes placed below the propeller?

On many turboprop aircraft, such as the A400M and the ATR 72, it seems that the air intake tends to be placed below the propeller (images: Wikipedia): source source Given that mounting the intake ...
5
votes
2answers
538 views

How does a subsonic jet engine intake design ensure correct air intake?

I think I understand that inlets are there to slow down the airflow and increase the pressure to stop the compressors stalling?. If this is the case, I don't understand how the nacelle or intake ...
0
votes
1answer
364 views

What technical problems stopped scramjets from being used on hypersonic aircraft?

I have been researching hypersonic aircraft and scramjet engines after running a few calculations looking at ramjet/rocket hybrids for making single stage to orbit vehicles. After doing the analysis ...
3
votes
0answers
131 views

What different intake designs are there, and what are their pros and cons?

I noticed that over the years (on fighter jets specifically) there have been many different methods of directing air into the engines. Primarily, the nose-intake, side intake, and underbody intakes ...
6
votes
1answer
564 views

How is the jet engine inlet danger area affected when airborne?

Boeing published engine hazard areas as shown below: I am curious as to how the danger area is affected when the aircraft is in flight as the jet engine is still vulnerable to foreign object damage. ...
12
votes
1answer
707 views

What is the difference between side-by-side vs under-cockpit engine intakes?

What is the main difference between these two engine configurations? What are the differences between planes that have the intakes below the cockpit as compared to those who have them on the sides? ...
10
votes
2answers
697 views

What is the function of the holes in splitter plates?

Do the holes in splitter plates reduce the boundary layer, or do they serve a different function such as acoustic/vibration damping? Many splitter plates have a series of holes drilled into the ...
16
votes
1answer
3k views

Why are the intakes of some fighters not attached to the fuselage?

Look at the photo below. As you can see the intake isn't attached to the fuselage. Why? Other examples include the F-16, F-22, and F/A-18 Hornet. (F/A-18E Super Hornet Walk Around)
1
vote
0answers
75 views

Why does intake of turbofan engine have angle of attack? [duplicate]

As you can see the title of the question, intake of turbofan engine has an angle of attack. why? see:
9
votes
1answer
2k views

Is the nose cone of the MiG-21 adjustable in-flight?

In some of the photos I saw of the MiG-21, the nose cone was extended and in others it was shortened. So, is the nose cone of the MiG-21 adjustable in-flight to allow for increased/decreased air flow? ...
3
votes
1answer
152 views

Does intake mass-flow rate vary linear proportional with turbine fan speed?

Is jet turbine intake mass-flow rate linear proportional with its fan speed (N1)?
0
votes
1answer
184 views

How do I estimate how much air flows through the intake due to engine suction?

I read that the intake mass flow ratio (not sure its translated to correct lingo) can be expressed as: $C_A = \frac{\textrm{airflow through air intake}}{\textrm{air density } \times \textrm{ speed of ...
11
votes
2answers
1k views

If the intake of a running jet engine is blocked for some short duration what would be the sequence of events following it?

If the intake of a running jet engine is blocked for some short duration what would be the sequence of events following it? Will it cause any damage to the engine parts?
3
votes
3answers
5k views

What is the function of variable inlet guide vanes in terms of pressure change?

Nowadays in the turbofan Variable Inlet Guide Vanes are more and more used. My question is: which is their function in terms of pressure change? The question is very specific: I know that they allow ...
9
votes
2answers
662 views

How does a long inlet affect a jet engine's performance?

How, for example, would the long inlet of the tail-engine on an MD-11 or an L-1011 affect its thrust production/performance, if at all? (Source) I am not well versed in fluid dynamics, so any ...
6
votes
1answer
946 views

How does inlet spillage drag produce a lip suction effect?

From this page: Spillage drag, as the name implies, occurs when an inlet "spills" air around the outside instead of conducting the air to the compressor face. The amount of air that goes through ...
4
votes
1answer
527 views

What type of flow is preferable for jet engines?

I would like to know how laminar/turbulent flow affects engine performance. Any additional thoughts on the topic, even if not strictly related to the main question, are welcomed.
7
votes
2answers
581 views

Why does the MiG 21 use anti surge shutters?

Does the MiG-21 use anti surge shutters at high speed? What is the adverse effect on the airflow at such high speeds (despite using a conical spike ahead) which warrants the use of antisurge shutters? ...
6
votes
1answer
203 views

What is the temperature of intake air at several speed of sound intervals from 1x to 10x?

I watched a YouTube movie about Reaction Engines development of the Sabre engine which main feature is cooling intake air. However, I cannot find an overview of the temperature of intake air at ...
6
votes
2answers
2k views

Which supersonic airplanes use Pitot Air intakes?

Which supersonic (fighter) airplanes use the simple Pitot Air Intakes / Normal Shock Inlets? Two examples already seen here on Aviation.SE (one and two) are Dassasult Rafale ($Ma \leq 1.8$) Image ...
6
votes
2answers
1k views

What type of supersonic intake does the Dassault Rafale fighter jet have?

What type of supersonic intake does the Dassault Rafale use? Is it a Pitot Intake? It cannot be a Ramp Intake, nor can it be a Spike Intake / Cone Intake, and it does not seem as a Diverterless ...
2
votes
1answer
375 views

Is it possible to control the inlet Mach no. of the engine during flight? [duplicate]

While calculating the off design conditions of the engine, we need to know the off design characteristics, such as inlet additive drag. In the book Mechanics of Flight, by Warren F. Phillips, its ...
2
votes
2answers
1k views

Why are turbofan inlets circular- or oval-shaped instead of square-shaped?

Source: materialsengineeringconsultant.com and initious.blogspot.com. Most of the engines are circular except for some that are oval. The oval shape provides a better ground clearance. Why aren't ...
18
votes
2answers
2k views

What is the working principle of gravel kits?

In this answer gravel kits are mentioned. I then looked at the wikipedia page and I noticed that they are quite different from what I was expecting: I was expecting some kind of "shield", plate or ...
23
votes
2answers
1k views

Why are turbofan inlets leaned/angled forward?

(Image Source: Wikipedia) Seeing that everything is radially symmetric (apart from the nacelle mount, naturally), I wonder why the inlet (the front part of the nacelle) is usually skewed?
14
votes
1answer
4k views

What are the merits of an inlet cone/spike/centerbody vs. a 2D inlet?

And which is better for a scramjet? Is a 2D inlet basically a "2D cone"? Similar to how an aerospike engine is made "2D" in the linear aerospike? What's inside the cone/spike? Or is it just hollow?