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Old 26th October 2006, 19:51   #1
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Default what is an afterburner??

hi
can anyone please tell me what an afterburner is and how does it work??
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Old 26th October 2006, 20:03   #2
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according to google
Quote:
  1. A device for augmenting the thrust of a jet engine by burning additional fuel with the uncombined oxygen in the exhaust gases.
  2. A device for burning or chemically altering unburned or partially burned carbon compounds in exhaust gases.
Is this what you were looking for ??
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Old 26th October 2006, 20:03   #3
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http://en.wikipedia.org/wiki/Afterburner

Peace.
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Old 26th October 2006, 20:12   #4
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Well basically its fuel thats injected directly into the hot gasses exiting a jet engine. The gasses being super hot ignite the fuel wich causes additional thrust in the process. Hence "After - Burning"
The entire process is extremely inefficient though and is used only in short bursts to avoid rapidly depleting fuel reserves.

hope that helps

Last edited by NikN : 26th October 2006 at 20:13.
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Old 26th October 2006, 20:17   #5
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thank you nikhil & aniguchisan... another question is it applicable to only jet engines or can it be mounted on a ic engine?
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Old 26th October 2006, 22:05   #6
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Quote:
Originally Posted by sanket12
hi
can anyone please tell me what an afterburner is and how does it work??
The term afterburner applies to jet-engines.

A jet engines is a gas turbine, that generates propulsion as a reaction to the high speed efflux of exhaust gases forcefully exiting out of the tailpipe.

To start the engine, it is spun by external means. The front stage turbine is a compressor that compresses intake air. This hot compressed air is ignited by injecting aviation kerosene as fuel. The fuel explodes creating a hot rush of gases. These gases spin a turbine which keeps the engine, compressor and all, alive and continuously spinning.

Finally the exhaust gases are accelerated (like a carburettor in reverse) by sending them through a constricted venturi.

Gas turbines and jet engines have excessively hot exhausts.

Injecting a little fuel into the exhaust stream would cause it to spontaneously explode creating an additional rush of gas, providing extra thrust.

Have you seen a blowtorch like flame coming out of the exhaust of a MiG-21 ?



This is of course wasteful of fuel, and is used nowadays only on military jets, whose goal is raw thrust unmindful of cost.

To give you a flavor, the Indian Air Force MiG-21 bis has a single Tumansky R-25 turbojet that produces
40.3 kiloNewtons of static thrust (dry) which increases to
68.5 kiloNewtons of static thrust with afterburner.
At max military power (dry) the MiG consumes 3.95 tons of fuel per hour
and with afterburner it consumes almost 157 tons of fuel per hour!

Ram
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Old 27th October 2006, 00:17   #7
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Quote:
Originally Posted by sanket12
thank you nikhil & aniguchisan... another question is it applicable to only jet engines or can it be mounted on a ic engine?
[FONT=Courier New]From a turbo-charging forum I followed; it makes the turbo spool up:[/FONT]
[FONT=Courier New][/FONT]
[FONT=Courier New]"... the current method is to inject an overly rich mix and fire it after TDC when the exhaust valve starts to open. Works great, can be set for staging and or for between shifts, it is very hard on exhaust manifolds/ turbine >wheels/ turbine housings/ ..."[/FONT]
[FONT=Courier New][/FONT]
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Old 27th October 2006, 04:23   #8
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@ram:ur post was like reading my course book man.....
@sanket12:no it cant be mounted to an ic engine because basic principle of operation of both the engines is different.
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Old 27th October 2006, 14:15   #9
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Default Gas Turbine power

In 1950, Rover of UK made the first gas-turbine powered car.
It reached 140 km/h, with the main turbine spinning at 50,000 rpm. It could burn petrol, kerosene or diesel fuel.

Two problems were excessive consumption of fuel and excessively hot exhaust temperatures. A prototype stands at the London Science Museum.

In the 1963 24-hr LeMans a Rover gas-turbine coupe touched 229 km/hr with an avg. speed of 173 km/h.

Chrysler built several gas turbine-powered prototype cars in the 'fifties, 'sixties and 'seventies.
Here is a 1963 Chrysler Turbine.


Gas turbine tech lets you keep the engine very small and light yet producing very high-power output. But gas-turbine engines need to operate at very high temperatures and maintain very high rpms.
Challenges:
  • to have a high-tech gearbox. Imagine the reduction gearing needed to cope with an engine spinning at 50,000 rpm!
  • advanced materials and material-working techniques to cope with the high centrifugal forces and stresses viciously tugging at the turbine blades.
  • designing synthetic lube fluids to handle the elevated temperatures and rpms.
  • special bearings required. (foil bearings)
  • ...
The Russian T-80 and US M1 Abrams battle-tanks use gas turbine engines. There was a Discovery Channel feature on this recently.

I have seen a jet engine powered drag racer at the Seattle-International Raceway in Kent, Washington State. Was extremely noisy (you had to wear ear-plugs), gave off sheets of flame and clouds of smoke as it sprinted across the quarter-mile.

Ram
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Old 27th October 2006, 16:10   #10
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Quote:
Originally Posted by hellspawn
... @sanket12:no it cant be mounted to an ic engine because basic principle of operation of both the engines is different.
Encourage people to think outside the box -- the spooling method for turbos is closely related. There are also flame producing devices that inject fuel into the exhaust tip of an automobile exhaust which is then ignited by a sparkplug. That is for show (and usually illegal) but does generate a small amount of forward thrust if the pipe is pointed backwards.
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Old 27th October 2006, 16:52   #11
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Quote:
Originally Posted by ram
In 1950, Rover of UK made the first gas-turbine powered car.
It reached 140 km/h, with the main turbine spinning at 50,000 rpm. It could burn petrol, kerosene or diesel fuel.

Two problems were excessive consumption of fuel and excessively hot exhaust temperatures. A prototype stands at the London Science Museum.

In the 1963 24-hr LeMans a Rover gas-turbine coupe touched 229 km/hr with an avg. speed of 173 km/h.

Chrysler built several gas turbine-powered prototype cars in the 'fifties, 'sixties and 'seventies.
Here is a 1963 Chrysler Turbine.


Gas turbine tech lets you keep the engine very small and light yet producing very high-power output. But gas-turbine engines need to operate at very high temperatures and maintain very high rpms.
Challenges:
  • to have a high-tech gearbox. Imagine the reduction gearing needed to cope with an engine spinning at 50,000 rpm!
  • advanced materials and material-working techniques to cope with the high centrifugal forces and stresses viciously tugging at the turbine blades.
  • designing synthetic lube fluids to handle the elevated temperatures and rpms.
  • special bearings required. (foil bearings)
  • ...
The Russian T-80 and US M1 Abrams battle-tanks use gas turbine engines. There was a Discovery Channel feature on this recently.

I have seen a jet engine powered drag racer at the Seattle-International Raceway in Kent, Washington State. Was extremely noisy (you had to wear ear-plugs), gave off sheets of flame and clouds of smoke as it sprinted across the quarter-mile.

Ram
Any reasons they didn't make it into sustainable production cars?! I can see they have more advantages than disadv. - aprt from the high rpm.
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Old 27th October 2006, 17:22   #12
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Quote:
Originally Posted by Kevin Johnson
Encourage people to think outside the box -- the spooling method for turbos is closely related.
Well thanks to the rally boys this technique has become widely accepted... but seriously help somebody who does it on a wrong kind of a manifold

Last edited by Psycho : 27th October 2006 at 17:26.
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