Questions tagged [bypass-ratio]

This is the ratio of air (by mass) that bypasses the combustion chamber of a jet engine, and instead is pushed through the outer shell of the engine by the main fan in the same way that a propeller pushes air.

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5answers
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What is the bypass air in a turbofan engine actually for?

I'm planning on building a small model turbofan engine for a bit of fun but I thought I'd better get a better understanding of how they work first. I understand the majority of it at the moment but I'...
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2answers
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Why do military turbofan engines use a low bypass ratio?

I know that the most civilian engines use a high bypass ratio which is good for fuel economy and noise reduction. What prevents military engines from using the same technology instead of opting for ...
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1answer
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How was the high-bypass concept invented?

(Source) Wikipedia says: After [the Ryan XV-5 Vertifan demonstrated] that large amounts of air could be moved through a lift fan, an 80 in (2.0 m) tip drive fan turned through 90 degrees, driven ...
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3answers
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Is it possible to have an afterburner in a turbofan with bypass ratio greater than 1:1?

Is it possible to have an afterburner in a turbofan with a bypass ratio greater than 1:1? At 1.05:1, say, can it have an afterburner?
9
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3answers
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How does the bypass air provide thrust?

To my knowledge, bypass air produces 80% of total thrust. But I don't understand to how it does that. By accelerating the air, by increasing the speed or increasing the pressure of the air? Is it ...
4
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2answers
671 views

How do aircraft engine manufacturers achieve a higher bypass ratio while still meeting the thrust requirements for a given aircraft?

I understand that a higher bypass ratio leads to greater efficiency as less air moves through the core, and therefore less fuel is burned. However, how is the thrust requirement for the same aircraft ...
12
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2answers
3k views

Why is the bypass ratio of a turboprop higher than turbofan?

Whenever, I come across turboprop, the author always mentions that they have higher bypass ratio than turbofan but no one explains the reason for this. So, is the bypass ratio higher due to higher ...
17
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3answers
4k views

Can high-bypass turbofans cruise at high altitude?

They have talked for years about re-engining the B-52 with something more modern than its TF33-P-3/JT3D turbofans, which are fairly low-bypass (1.42:1 for the JT3D). Modern engines are much higher ...
8
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1answer
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Why does the CF6 have a lower bypass ratio than the TF39?

The General Electric TF39, which powered the original C-5 Galaxy, was the very first high-bypass turbofan brought into mass production, with a previously unheard-of 8:1 bypass ratio. Yet, when it ...