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Why does a turbine engine compressor ratio affect stagnation pressure?

This might just be a misunderstanding on my part, but in an ideal Brayton cycle, the flow through the compressor and turbine is isentropic, meaning $\Delta s = 0$. However, usually you are given the ...
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2answers
82 views

How can I determine specific heats of gases for turbojet engine calculations?

I'm in a combustion lab and we are performing experiments on a turbojet engine. However, I am having some trouble calculating the exit velocity and compressor/turbine powers of the engine. Consider ...
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2answers
255 views

Can a turbojet jet or turbofan powered aircraft land and take off from water?

Can a turbojet jet or turbofan powered aircraft land and take off from water? How much clearence from the water surface would it need for its engines so that it does not suck up water?
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2answers
252 views

What exactly does the MB-326's 'relight' button do?

The following picture shows the engine throttle of an Aermacchi MB-326, which is powered by the Rolls-Royce Viper turbojet: (source - all photos © Drive&Fly Model Club) I wonder what exactly the ...
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2answers
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Fans of tubofan jet engines

Does the thrust of the fan in a turbofan jet engine decrease proportionally with decrease in the diameter of the fan? As the fan in a jet engine is responsible for over 70% of the total thrust can a ...
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1answer
3k views

Which jet engines have the highest thermal efficiency?

Some automakers (Mercedes-Benz, Toyota) have recently been making news about the improved thermal efficiency of their engines, stating that they reached the 50% mark. I was wondering if it was the ...
2
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1answer
564 views

Are there any differences between turbofan and turbojet engines besides bypass air?

I think I understand both engine types, but I am just wondering am I right in saying that the only difference between the two types of engines is the bypass air (i.e. a turbofan is just a turbojet ...
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2answers
480 views

Why were turbojets the first kind of turbo-engines, instead of turboprops?

During WW2, the first jet engines appeared en mass in combat aircraft. Britain and Germany made the first ones. But why were turbojets first? Why not turboprops, which are easier since the turbo-...
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2answers
390 views

Are there turbofan/turbojet analogues to a centrifugal-compressing jet engine?

Axial-compressor jet engines fall into two categories (and only two as far as I'm aware): turbofan and turbojet. I'm wondering if centrifugal-compressor jets also have such a distinction or something ...
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1answer
535 views

How small can turbojet engines be made whilst remaining fuel efficient, light, cheap, and producing enough thrust to carry a human, gas, and casing? [closed]

I've seen many videos of small turbojet engines (small enough to hold in your hands) that produce 30-40 pounds of force. If you mounted a couple of these on a small craft, that wouldn't even support ...
6
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1answer
172 views

Why is a turbofan engine less efficient when air leaks over fan blade tips?

Image source I understand part of the reasoning for minimal clearance between the casing and the fan blades, is to have the larger fan blade possible, which generates a larger low pressure area to ...
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2answers
142 views

What structural design methods were used for early turbojets?

I have had this question for long time. Can anyone please give me some references on early turbojet engine design methodologies? For example P&W J57 which was designed in early 1950's: How were ...
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2answers
111 views

Is there a way to calculate thrust without running experiments?

Is there any way to calculate the thrust generated without conducting experiments? In my case I need to figure out thrust generated by electric duct fans and/or turbojets.
4
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1answer
307 views

What is the actual exhaust velocity of the exhaust from the J58 engines at cruise (Mach 3.2)?

The SR-71 ran on two J58 turbojet engines and cruised at Mach 3.2. What I want to know is, what is the actual exhaust velocity (relative to the airplane itself) of the jet exhaust at those conditions?...
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1answer
218 views

Are there cases of a thrust reverser used on a turbojet engine?

In the case of a turbojet (with no "cold" bypass flow), the airflow being directed forward by an hypothetical thrust reverser can be really hot. Depending on the location of the engine, this flow may ...