Difference between a propeller and a fan

[D.B.SriHridai]

Good evening to all...I am troubling with a doubt that how a propeller differs from a fan regarding jet engines..

 

[anorlunda]

In some respects, there isn't much difference, in other respects there are big differences.

If you want a better answer, you'll have to ask a more specific question.

 

[D.B.SriHridai]

Thank you

 

[D.B.SriHridai]

How a turbofan jet engine differs from turbo prop jet engine?

 

[anorlunda]

https://en.wikipedia.org/wiki/Turbojet
https://en.wikipedia.org/wiki/Turbofan

You know, you could do better looking up these questions on Wikipedia yourself.

 

[Work Hard Play Hard]

I'm just making an observation here which may or may not be the answer. A fan is stationary and displacing or moving a medium within its environment. A propeller isn't stationary. Its used to create movement by using a medium to displace itself. Putting the funky designs aside, both work by using rotational force on a wing design to create pressure differentials. Again I could be wrong but I think when the medium is the source of the applied force fans and propellers become turbines and impellers. An electric wind generator is a wind turbine, not a wind propeller.

 

[Nidum]

https://www.rolls-royce.com/~/media.../civil-aerospace/Trent1000-Cutaway-2048px.jpg

 

[jack action]

These quotes from Wikipedia probably answer best your questions about propeller, turbofan and turbojet:

Thus, whereas all the air taken in by a turbojet passes through the turbine (through the combustion chamber), in a turbofan some of that air bypasses the turbine. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of those contributing to the thrust.

Since the efficiency of propulsion is a function of the relative airspeed of the exhaust to the surrounding air, propellers are most efficient for low speed, pure jets for high speeds, and ducted fans in the middle.

 

[D.B.SriHridai]

I'm just making an observation here which may or may not be the answer. A fan is stationary and displacing or moving a medium within its environment. A propeller isn't stationary. Its used to create movement by using a medium to displace itself. Putting the funky designs aside, both work by using rotational force on a wing design to create pressure differentials. Again I could be wrong but I think when the medium is the source of the applied force fans and propellers become turbines and impellers. An electric wind generator is a wind turbine, not a wind propeller.

Thank yoh

 

[rcgldr]

I'm wondering why household fans use fans instead of something like a propeller from a large radio control model. Perhaps there's an efficiency trade off depending on the goal (fan moves air, rotor generates thrust), and/or the desired output flow speed. One observation is that the propeller needs to rotate fast enough that air doesn't flow backwards between the propeller blades, while a fan blocks off most of any potential back flow between fan blades, allowing the fan to operate at a lower speed.

 

[Jack Barker]

Please don't forget that a regular propeller on either a piston engine or a turbine creates its motive force (moving the plane forward/upward) by virtue of its cross-sectional shape, which in fact, is that of an airfoil; yes, just like the wings. The forward surface is slightly convex, while the rear surface is slightly concave. When the propeller spins, the air passing over its front surface is in negative pressure, and, thus creates lift to climb, or 'pull' when the aircraft is horizontal; either rolling down the runway or in flight. When the prop 'pull' is great enough, the plane will move forward, until there is sufficient air movement over the wings to cause flight.

 

[JBA]

In response to your #4 post: A turbo prop drive is one in which a turbine is used to power an external propeller that provides the driving thrust. In this arrangement the turbine does not contribute any direct driving thrust by its own gas discharge. Both a turbofan and turbojet directly provide the driving thrust and vary in the manner described by Wikipedia as referenced above.