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Questions tagged [jet-engine]

Engines which propel aircraft via "jet propulsion", i.e. by expelling high-velocity gasses (usually primarily air) through propelling nozzles.

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How does fuel flow and altitude affect the compression ratio of jets?

Does the compression ratio of jet engines change with altitude and/or with the rate of fuel flow?
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136 views

Increase to Flight idle during start-up?

Ground idle takes about 5% of the total rpm, flight idle takes about 85% of the total rpm. Why is so much of the engine power wasted before it gets to flight idle?
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138 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 ...
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138 views

Is there any mechanism in engine mount to prevent it from shock load while landing?

how engine is mounted in wing restricting motion in any direction but it is still resistant to shock loads, or is there any mechanism inside engine associated to bearings that ll absorb shock loads ...
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46 views

Acoustic analysis from an aircraft engine?

I have found it surprisingly easy to find information on jet engines; however, I've been unable to find acoustic information so I can make a noise spectrum model. I'm looking for oscillations from ...
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45 views

How are compressor maps drawn?

I've always thought they are empirically derived: once you have your axial compressor phisically in a bench, you set both a rotational speed and a mass flow throught the turbomachine then you measure ...
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100 views

How does a partially covered air intake affect the thrust of a propeller ?

does a partially covered air intake of a ducted propeller significantly affect its thrust? If so, will it be like 10 or rather 90 percent less thrust ? Thanks for your answers! Simon
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Do plug nozzles improve efficiency on lower throttle settings?

Plug nozzles are used to adjust for the overexpansion/underexpansion of the exhaust with altitude. Do they also adjust for overexpansion/underexpansion of the exhaust caused by lowered mass flow ...
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110 views

What could cause an engine shutdown on a Q400 with CDS codes 732, 907, 915 and 938?

A Bombardier Q400 displays error code 938 on the Central Diagnostics System(CDS), which is attributed to turbomachinery chip detector. An examination shows debris in the detector hitch which is ...
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137 views

Why is EGT decreasing on a jet engine when the generators cut in?

Is the EGT decrease related to the generators cutting on or is it related to the fact that the fan is now providing enough ventilation air for the engine?
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87 views

What are the differences between the proportional flow control FCU and pressure control FCU?

what are the basic differences between the proportional flow control FCU and pressure control FCU? ( FCU : fuel control unit )
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199 views

What is the order of Reynolds number inside the Compressor at cruise conditions?

I am doing a CFD study on a probe that will be installed inside a compressor of a civil aircraft for my final year project. I need to know the Reynolds number inside a compressor at cruise conditions. ...
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57 views

What is the minimum size of a ramjet?

Having recently learned that 155 mm ramjet artillery shells are now a thing, I wonder how much ramjet engines can be miniaturized. Could we see ramjet tank shells? Man-portable recoilless guns? ...
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35 views

Adjusting nozzle shape for reduced flow rate

Suppose i have a ramjet engine, but in the combustion area i make an opening along the whole cirumference (a slit) feeding a channel, in which the pressure is the same as in the combustion chamber. ...
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63 views

Does the stator blade angle changes? Why?

I have read that when jets are on the ground their compression ratio changes. With this change the stator compressor's blade angle changes. Is this true?
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118 views

What happened with the Boeing PETA Pulse Jet Engines

The boeing engines created a buzz when they were announced back in 2011, and were said to be proprietary technology. It created a buzz about easing VTOL concepts and more, but where does the project ...
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59 views

what is the impingement location of Streamwise vortices?

When I was reading an article about scalloped and lobed mixers in turbofan engines nozzle, I faced with this sentence that was comparing lobed and scalloped cases: "impingement location for the ...
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73 views

What‘s the diameter of the engines of the Airbus E-Fan?

does somebody know the diameter of the E-Fan‘s engines ? To me the look like around 80cm or what do you think ? Also, with more and wider blades and 60 kW motors instead of 30 couldn‘t they get much ...
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120 views

What are the air mass flow rate and fan pressure ratio of the Trent XWB?

I have some basic questions regarding the Trent XWB: What's the air mass flow rate (or its range) of the Trent XWB engine? Is all of the air mass flow of the engine produced only by the 118" diameter ...
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61 views

How does a mixer reduce noise in a turbofan engine?

I want to know how does a mixer reduce noise in a turbofan engine? How does its shape influence the flow and the acoustics of the output air generally?
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100 views

What is the inner diameter of the nozzle cone on the Trent 1000 engine?

Since the nozzle diameter shown is 63 inches, so what is the diameter of the one inside that circle? Need it for my project to find the actual size of nozzle
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212 views

Does the safe taxi distance vary behind jet types for light aircraft?

It would seem a light aircraft taxiing behind a business jet could be closer than a B747. Perhaps there is a law (country or international) regulating power setting of a jet taxiing. One authors ...
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63 views

At what operating temperatures would the Trent 900 need to operate, to equate to the efficiency of current geared turbofans?

What is the minimum optimum operating temperature (in degrees Celsius) that would be required for the Trent 900 to operate at, for it to attain the level of fuel efficiency of current geared turbo ...
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79 views

Are there any performance details available for the D8 Double Bubble engines?

For the D8 Double Bubble, what are the thrust requirements for the engines? Has it been stated what the estimated max thrust will be for each engine? Source: sputniknews.com
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How does supercruise thrust compare with static thrust ASL?

As I understand it, turbojet thrust decreases both with altitude due to rarefied air reducing massflow, and airspeed due to a smaller speed increase between intake and exhaust relative to the airframe....
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324 views

What are the specifications for the CFE738-1-1B?

I'm designing an aircraft for fun, and I've selected a CFE738-1-1B as the engine. It's never going to fly outside of X Plane, but it's still fun, so I'd like to make the X Plane version as realistic ...