New answers tagged engine-design
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From windmill physics we see that wind power is proportional to the cube of windspeed as:
Wind power = Density × Area × v$^3$/2
The exhaust gasses of a jet engine are of lower density from heating, slightly higher mass, but are going much faster than the inlet gasses
This explains why a smaller turbine can run a larger (more blade area compresser) with ...
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Your source about the flame temperature is valid for a stoichiometric mixture. This means all oxygen molecules will be matched by carbon and hydrogen such that theoretically a complete conversion into H₂O and CO₂ can take place.
Real gas turbines, however, operate with a fairly large amount of excess air, which is why they produce comparably large amounts of ...
5
There's the fact that the hot gases from combustion are actually cooled in the combustion chamber. The turbine cooling isn't sufficient enough to maintain the appropriate temperature for the turbine blade(~1700 C).
The above figure(shamelessly taken from Aircraft Propulsion) clearly depicts the cooling mechanism in the combustion chamber(CC). 12% of air ...
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The gas is not cooled prior to turbine inlet entry. Any attempt to cool down the gas, with decreasing efficiently of the engine. Most modern engines have turbine inlet temperatures of approximately 3600° F. This is far too hot for conventional alloys used to make the stator of rotor buckets to maintain acceptable yield strengths, so engineers have been ...
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I'm in aircraft engineering school right now, and i can tell you blisks are definitely in use.
For example the Rolls-Royce Trent 500 turbofan, or the Allison Model 250.
(The latter of which we have a cut-open version of, on a dolly here)
This is the turbine section as blisk (edit: corrected from fan)
And this is the compressor stages as blisk vvv
If you ...
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Because airflow will meet the leading edges at different velocities ( at the hub is slower and needs more AOA and at the external edge is faster and fine pitch is needed ). To benefit from the all available airflow and not get aerodynamic( for compressor) stalled air the twisting must be added to the blades. So to not have Stall of the blades is the answer.
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Why do jet engine fan blades have a twisted shape?
Your question is about fan blade twist, but actually the answer is valid for nearly all rotating blades. If a blade weren't twisted, the angle of attack would be very different from its root to its tip.
Twist equalizes the angle of attack along the length. I say equalize for simplification, the angle may ...
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There's been patent wars regarding this invention.
What you show is not just a twist, but also a varying sweep. According to Rolls-Royce's patent from 1996, which was the subject of one of the lawsuits, a basic summary is as follows:
This feature produces a distinct mid-height bias to the airflow distribution across the span of a blade, with the result that ...
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Listed under Benefits on the Wiki page link edited into your question:
The benefit of this setup is increased specific impulse over that of a rocket. For the same carried mass of propellant as a rocket motor, the overall output of the air turborocket is much higher.Emphasis added
Since most "jet fighters" use jet engines (or low-bypass turbo fans)...
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This is typical for the De Havilland Canada Dash-8, which is powered by Pratt & Whitney Canada PW100 engines. Other aircraft powered by that engine also seem to have their propellers feathered during shutdown. The propellers are only unfeathered after the engine has started (see e.g. this YouTube video of an ATR 72-600 starting its engines with the ...
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So first, both measurements are made by accelerometers, and accelerometers are by definition sensitive to acceleration. So the original units are either G or m/s^2. They are converted to different units for analysis and display.
So, what units are most convenient for analysis? It depends on the frequency range. If we have a sinusoidal vibration with ...
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Because the first sensor is measuring vibration levels on a bearing inside the engine (the #1 bearing) and the second sensor is measuring vibration at the turbine rear frame. The tolerances for vibration on those two are very different. A bearing's tolerance for vibration is extremely small, which is why it is measured in mils. The rear frame's tolerance for ...
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