Pressure Ration Explanation

CFD_Newby · April 11, 2018, 10:00

Hi all,

you can see attached the total pressure ratio along the span of a rotor blade of an axial compressor. I am sure the calculation is right but I cannot explain why the ratio becomes bigger and bigger in the hub region and then it decreases suddenly more and more and gets a minimum in the tip region.

Is a possible explanation that I defined a no slip wall, so the static pressure (and the total pressure) has its maximum there. Ans along the span the work of the blade is smaller and smaller and thats why the total pressure as well?

Greetings

LuckyTran · April 11, 2018, 13:16

It is hard to say without actually seeing what the hardware looks like. For any blade, the tip and root move at different linear speeds so that the blade contour must be designed to achieve any particular distribution of flow parameters. Your absolute and relative blade angles (alpha's and beta's) determines what that looks like.

Also, if you modeled a real geometry, then there would be a gap between the blade tip and shroud and there would be tip leakages there.

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April 11, 2018, 13:16		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	It is hard to say without actually seeing what the hardware looks like. For any blade, the tip and root move at different linear speeds so that the blade contour must be designed to achieve any particular distribution of flow parameters. Your absolute and relative blade angles (alpha's and beta's) determines what that looks like. Also, if you modeled a real geometry, then there would be a gap between the blade tip and shroud and there would be tip leakages there.