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explaning about Passages per Mesh, Passages to Model and passages in 360

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Old   October 16, 2015, 10:02
Default explaning about Passages per Mesh, Passages to Model and passages in 360
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Aja
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Hi,

I have some questions:

Flow in an axial turbine stage is investigated. The stage contains 60 stator blades and 113 rotor blades.




The overall approach to solving this problem is to first define the Frozen Rotor simulation using the Turbomachinery wizard. The geometry to be modeled consists of a single stator blade passage and two rotor blade passages. In the stator blade passage a 6 section is being modeled (360/60 blades), while in the rotor blade passage, a 6.372 section is being modeled (2*360/113 blades). This produces a pitch
ratio at the interface between the stator and rotor of 0.942.

Here, what is your exact mea

It means area ratio between in interfaces1 and interfa Am i right?

In tutorial, the following statements are mentioned as follows:

You should always try to obtain a pitch ratio as close to 1 as possible in your model to minimize approximations, but this must be weighed against computational resources. A full machine analysis can be
performed (modeling all rotor and stator blades), which will always eliminate any pitch change, but will require significant computational time. For this geometry, a 1/4 machine section (28 rotor blades, 15 stator blades) would produce but this would require a model about 15 times larger than in this tutorial example.

Here, what is your exact meaning of




Analysis Type > Type>Steady State

In tutorial, it is performed the following step as follows:

6. Click Passages and Alignment> Edit.
7. Set Passages and Alignment> Passages/Mesh>
8. Ensure that Passages and Alignment>
9. Click Passages and Alignment> Done.
10. Click Next.

Values of 2 are set in "Passages per Mesh" and "Passages to Model". I think that it is logical. But value of passages in 360 is not mentioned in this example. why?!!? how much this value?



This tutorial uses an to illustrate the basic concepts of setting up, running, and monitoring a transient blade row calculation with blade motion in CFX. The full geometry consists of one rotor containing 36 blades as seen in the following Figure:



In this chapter, it is set as follows:

Passages per Mesh: 1

Passages to Model: 2

Passages in 360: 36


Why? What is different between second case and first case?

................

Now i explain about my work:

I am simulating an turbine, known , using CFX as a solver.

My
turbine have 8 blades((360/8)=45 deg=pitch angle). Due to the circumferential symmetry, only one eight of the annulus has been computed, imposing periodic boundary conditions (periodic rotational) in the tangential direction. The computational domain has been restricted in the axial direction to four chord lengths upstream and six chord lengths downstream of the blade.




values of Passages per Mesh, Passages to Model and passage0 degree are 1 , 1 and 8 respectively. Is these values correct?

I am grateful that guide and explain me more about "Passages per Mesh, that what are these.

Thanks.

Best.

Aja





Last edited by aja1345; October 19, 2015 at 06:39.
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