# The difference between the current fixed and mobile blade row in CFX

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 January 19, 2016, 13:55 The difference between the current fixed and mobile blade row in CFX #1 New Member   Aleksandr Join Date: Dec 2015 Location: Kharkov, Ukraine Posts: 21 Rep Power: 2 Dear users CFX tell me, what's the difference between the calculations turbo machines with rotating and stationary blade row but with the feed stream at an angle? Will the results be different? ??????????.png https://www.youtube.com/watch?v=PCM2_UKG6Mw

 January 19, 2016, 18:12 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 11,571 Rep Power: 90 If the blades are just translating then there is no difference. If the blades are rotating then rotational effects occur - centripetal and coriolis accelerations. These accelerations will make cases 1 and 2 different.

January 20, 2016, 03:25
#3
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Aleksandr
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Quote:
 Originally Posted by ghorrocks If the blades are just translating then there is no difference. If the blades are rotating then rotational effects occur - centripetal and coriolis accelerations. These accelerations will make cases 1 and 2 different.
Ok, I can solve the first task, but i never do the second. Does it doing with profile BC in CFX. I means that velocity can set from file with components of velocity, but domain is set stationary?

 January 23, 2016, 01:24 #4 Member   Join Date: Jun 2009 Posts: 37 Rep Power: 8 Your case 1 = Rotating frame of reference rotor blade row, but case 2 = Stationary frame of reference stator blade row. Case 2 will have an inlet flow angle based on the inlet velocity triangle from U and C1, but will be a non-rotating cascade flow without the additional effects of Coriolis terms.

January 28, 2016, 14:35
#5
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Aleksandr
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Quote:
 Originally Posted by turbo Your case 1 = Rotating frame of reference rotor blade row, but case 2 = Stationary frame of reference stator blade row. Case 2 will have an inlet flow angle based on the inlet velocity triangle from U and C1, but will be a non-rotating cascade flow without the additional effects of Coriolis terms.
Hello again, I am now occupied by this experiment. I had a Problem at the import stage Profile BC, as I said earlier, from rotating frame of reference rotor blade row (case 1) to the new case. In process of transportation, I`ve set centrifugal velocity (x) to 0. After this one Profile BC was loaded in the preprocessor. After solving the problem, the current lines were derived which revealed that the direction of the velocity has not changed, but it has become the axis direction.

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Thanks for help!

 January 28, 2016, 16:06 #6 Member   Join Date: Jun 2009 Posts: 37 Rep Power: 8 Your question is unclear to me, but I guess your model is R1 of rotating frame, but the inlet flow is axial leading to a flow separation. If the flow vector is on the relative streamline, it means your inlet relative velocity (W1) is purely axial. Two possible reasons : (1) the blade velocity (U1 = r1*omega) is zero (2) the inlet absolute velocity vector has a big angle, so that W1 becomes axial. I do not understand what you meant by "I've set centrifugal velocity (x) to 0". I guess it could be (1).

 January 28, 2016, 18:02 #7 Senior Member   Join Date: Jun 2009 Posts: 400 Rep Power: 11 I think your images do not illustrate your setup completely. Please add the image for the Domain panel the inlet is attached to, and the image of the Basic Settings tab on the boundary as well. So far, the only we can tell is that you specified the inlet velocity in Cartesian Components and the flow is subsonic. It is impossible to tell w/o the other two images, if you specify this velocity in the rotating frame, or the stationary frame. Hope the above helps,

January 30, 2016, 09:39
#8
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Aleksandr
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Quote:
 Originally Posted by turbo Your question is unclear to me, but I guess your model is R1 of rotating frame, but the inlet flow is axial leading to a flow separation. If the flow vector is on the relative streamline, it means your inlet relative velocity (W1) is purely axial. Two possible reasons : (1) the blade velocity (U1 = r1*omega) is zero (2) the inlet absolute velocity vector has a big angle, so that W1 becomes axial. I do not understand what you meant by "I've set centrifugal velocity (x) to 0". I guess it could be (1).
507483035.png
this screen my cordinate, from BC file. i think than U in is velocity to X cordinate.
At first I solve with rotating domaine, in post CFX I get BC file, than set stationary in setup of domaine. Install BC profile without centrifugal velocity U (if i think right).

January 30, 2016, 09:43
#9
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Aleksandr
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Quote:
 Originally Posted by Opaque I think your images do not illustrate your setup completely. Please add the image for the Domain panel the inlet is attached to, and the image of the Basic Settings tab on the boundary as well. So far, the only we can tell is that you specified the inlet velocity in Cartesian Components and the flow is subsonic. It is impossible to tell w/o the other two images, if you specify this velocity in the rotating frame, or the stationary frame. Hope the above helps,
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507483632.png
I can not instal velocity in Cartesian Components because I want to have different angle vectors of velosity on radius of blade

 January 31, 2016, 09:56 #10 Member   Join Date: Jun 2009 Posts: 37 Rep Power: 8 Sorry, still why you are doing this is unclear to me due to imperfect communication. Your domain turned out to be stationary under the name of "R1" though. From your posted inlet velocity profile, the inlet flow is almost axial because u1=0 and v1 << w1 (= z direction velocity = axial velocity). You solved a staggered stator vane row with an axial inlet flow, resulting in of course the large stall. I think you look confused between (u,v,w) absolute 3D velocity components and (U,V or C,W) turbomachinery velocity triangle notations. They are totally different.

February 5, 2016, 04:44
#11
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Aleksandr
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Quote:
 Originally Posted by turbo Sorry, still why you are doing this is unclear to me due to imperfect communication. Your domain turned out to be stationary under the name of "R1" though. From your posted inlet velocity profile, the inlet flow is almost axial because u1=0 and v1 << w1 (= z direction velocity = axial velocity). You solved a staggered stator vane row with an axial inlet flow, resulting in of course the large stall. I think you look confused between (u,v,w) absolute 3D velocity components and (U,V or C,W) turbomachinery velocity triangle notations. They are totally different.
Ok, I undertood, how can get rotating components of velosity if I take BC profile from Inlet (none rotating boundary). Inlet can not to be setting how rotating, does not it?

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