I’m a freshman in Aircraft maintenance and my prof in Powerplant 2 (Gas Turbine Engine) explained to us about the venturi duct within the compressor of the Turbine engine. I get that the compressor increases the pressure of the air but what I don’t get is his statement that according to Bernoulli’s principle once the air passes through the inlet duct and towards the compressor the air’s pressure decreases and the velocity increases as it passes through the venturi duct the pressure only increases after it reaches the divergent part of the venturi duct before it gets to the combustion chamber.
So what I want to know is why does the pressure decrease first before it enters the compressor?
In: 1
If you have a smaller section of pipe, then before and after this section (in the bigger pipe) the water is moving slower, but in the smaller section of pipe it has to move faster.
This is because the same amount of flow has to happen all throughout the pipe. All the water going into the large pipe must also go into the small pipe.
So it’s slower in the big pipe.
We know that the energy of movement scales with the square of its speed, so if the water is moving faster in the small pipe, it must have more kinetic energy. That energy has to come from somewhere.
That energy came from the pressure forcing the water through the small pipe. The pressure drops in the smaller pipe, since it resists the pressure by forcing water to flow faster.
At the end of the small pipe, that fast-moving water has to slow down again. The same process happens in reverse, with the fast-moving water ramming into the water in the larger pipe and causing a pressure increase there.
In an ideal constriction, the pressure before and after is the same. In the real world, it is not. And yes, this all applies to air too.
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