Linked Questions

0
votes
0answers
42 views

How is fuel ignited in jet engines? [duplicate]

From what I understand, in jet engines, air is compressed and fuel is not only injected but also ignited : how is this done ?
60
votes
4answers
32k views

Why can't jet engines operate with supersonic air and how do they slow it down?

Typically jets cannot operate when intake airflow is supersonic relative to the engine. Why is this so? Also, why are scramjets able to use supersonic air? To slow down the air to subsonic speeds, ...
36
votes
4answers
16k views

Why do gases in the combustion chamber only flow one direction to the gas turbine in a jet engine?

As far as I know from the working principle of jets engines, compressed air in the combustion chamber (or combustion canister) is mixed with fuel. The ignited mixture expands backwards to turn the ...
24
votes
6answers
7k views

In what way are the Concorde's engines considered efficient?

The Concorde is powered by a bunch of Rolls-Royce/Snecma Olympus 593 turbojet engines. Much has been said about how efficient they are at speed, and the fact that they allow long-range cruise at Mach ...
29
votes
2answers
6k views

Are the fastest moving pieces of a jet engine supersonic?

A jet engine is composed of fast moving pieces. Those pieces are moving into an airmass different form the ambient airmass the aircraft is flying into. The turbine pieces are spinning quite fast, ...
8
votes
4answers
3k views

Do modern jet engines need igniters?

I've read that modern aircraft don't need spark plugs like conventional aircraft do, as the jet fuel autoignites once it's mixed with the hot air exiting from the compressors. Then why do aircraft ...
5
votes
4answers
4k views

How is the correct air speed for fuel combustion obtained at the inlet of the combustor? [duplicate]

Many jet aircraft travel at speed of about Mach .8 which at an altitude of 11 km represents an airspeed of about 300 kt or 150 m/s. If fuel was injected into air at this speed, the mix would just ...
7
votes
1answer
1k views

How is flame stabilisation carried out?

How is flame stabilization done in a jet engine combustion chamber? What are the various ways of doing this? What are the challenges/ problems faced?
5
votes
1answer
241 views

Is a subsonic scram-jet reasonable?

By placing a de laval nozzle at the inlet, can the resulting supersonic airflow allow a scram jet to operate efficiently?
4
votes
1answer
1k 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.
2
votes
1answer
261 views

Why is the thrust-specific fuel consumption much worse for high bypass turbofans at cruise?

General Electric GE90 Takeoff: 0.278 lb/lbf/h (28.3 kg/kN/h) Cruise: 0.545 lb/lbf/h (55.6 kg/kN/h) Source: https://en.wikipedia.org/wiki/General_Electric_GE90#Specifications I assume this is typical ...