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-   -   [ICEM] Quarter O-grid topology for propeller blade (http://www.cfd-online.com/Forums/ansys-meshing/104737-quarter-o-grid-topology-propeller-blade.html)

venkat_aero2007 July 14, 2012 05:55

Quarter O-grid topology for propeller blade
 
4 Attachment(s)
Hi,

I am trying to mesh a propeller blade using ICEM CFD. I tried O block topology to mesh my geometry but the quality was not good. So I was recommended to try Quarter O-grid (aka Y block). The periodic angle is 32.72727 (11 blades). The flow is along X direction. I drawn Quarter O-grid using four faces. I have attached few pic, Figure1 represents the geomentry, Figure2 - initial block round the peopeller domain. Figure3- quater O-grid by using four faces (inlet face, outlet face, left side periodic face, bottem face), Figure4-after asssociation of vertex with points. face, two periodic faces and outlet face). I don't known how to fix the quarter O-grid to capture the propeller blade geometry. I have seen some post about Meshing wind turbine but I didn't get an idea to mesh my geometry. It will be great if will be great if someone help me to fix my problem. I have attached my geometry and blk file in the following link.

Geometry file
http://jyraphe.isae.fr/file.php?h=R5...44f48e5c361015

Block file
http://jyraphe.isae.fr/file.php?h=R7...9c816d30ae511e

project file
http://jyraphe.isae.fr/file.php?h=R0...6e5ea47498ce4d

Thanks in advance for your information. please help me to mesh this geometry. I am trying for the past 1month to mesh this geometry.

Far July 14, 2012 06:47

do you need meshing like this? http://www.cfse.ch/cfse/site/openfoam.php

venkat_aero2007 July 14, 2012 07:04

yes, I need a similar mesh. But I was told to use ICEM CFD for meshing. Could you please explain me how to use quarter O-grid for my geometry. I have gone through wind turbine meshing and dough meshing but i could get an idea how to start with quarter O-grid.

Far July 14, 2012 07:55

Here is my first try. I think it is successful. Also sharp trailing is handled in nice way as you can see and this is already discussed in thread structured hexa mesh on wing. Still I am associating the intermediate edges to curves on the constant span locations to capture the blade shape properly. Edges, curves and points are already created.

Also some working is needed in the tip region. This time I did not extended the o-grid into far field, because it will not suit the cylindrical far field (some one correct me, if it is wrong). Attaching the files for my intial try so that you can understand the way I am working.

Also I expect more sophisticated topologies to come latter in this discussion.


https://dl.dropbox.com/u/68746918/propeller_blade.zip


http://img35.imageshack.us/img35/1725/48393663.png

Far July 14, 2012 09:14

This is my idea, I will use this blocking as building block and then adopt the blocking given in previous post. This post will explain the use of Quarter O-grid http://www.cfd-online.com/Forums/ans...ic-trough.html

https://dl.dropbox.com/u/68746918/pr...rter-ogrid.zip

http://img209.imageshack.us/img209/6519/23984784.png

http://img24.imageshack.us/img24/6081/91571257.png

http://img820.imageshack.us/img820/7919/79825390.png

Far July 14, 2012 14:00

Change the shape of periodic boundaries in the region of blade. We shall follow the meshing strategy as discussed above and also some features from following Fig.

http://img801.imageshack.us/img801/2...olumesmall.png


http://img856.imageshack.us/img856/2...olumesmall.png

Far July 15, 2012 02:37

Quarter O-grid and periodic surfaces
 
Here is method for selection of faces to create the quarter o-grid...

http://img715.imageshack.us/img715/5729/84637680.png

http://img802.imageshack.us/img802/3879/27607197.png

Change periodic boundaries shape.

http://img43.imageshack.us/img43/8987/87460780.png

venkat_aero2007 July 15, 2012 07:21

Hi Far,
Thanks a lot for your kind help. I am trying to understand that you did. I am going to explain you that I understood from your meshing topology (post number 4). Please correct if it there is any mistake.

Initially, you created a block around the domain and made the vertex periodic then associated Edges to curves. Then you made two horizontal (at suction and pressure side) and two vertical split (at LE and TE side) Then you made Two horizontal split ( suction and pressure side) at each section of the airfoil. then associated point to vertex then edges to curves. then you created a O-grid around the blade. then you made a split (horizontal) across the blade such that it cuts the small Lading edge bock and Trailing edge block. then two more split perpendicular to the blade (Vertical split). Till now it is clear for me because I learnt this from your video tutorial.

Actually you said that you associated the intermediate edges to curves on the constant span locations to capture the blade shape properly. With my little knowledge in ICEM, I could not understand the point clearly. Could please tell me, Why cant we associate all the curves to edges as you did for the two airfoil near the hub section and finish the blocking?.

In the post number 6, you said "we are going to change the shape of periodic boundaries in the region of blade and follow the mesh strategy as we discussed". I couldn't understand how to change the shape of periodic boundaries in the region of the blade. does it mean allingment of edges properly.

In the post number 7, you told me to change the periodic boundary shape.
do you want me to change the entire shape of the domain as you proposed.

I am trying to understand the adaption of Quarter O-grid with the above discussed statergy (like Meshing of a parabolic trough).

Once again thanks your information and help. It is really great.

Far July 15, 2012 07:46

Quote:

Originally Posted by venkat_aero2007 (Post 371500)

Initially, you created a block around the domain and made the vertex periodic then associated Edges to curves. Then you made two horizontal (at suction and pressure side) and two vertical split (at LE and TE side) Then you made Two horizontal split ( suction and pressure side) at each section of the airfoil. then associated point to vertex then edges to curves. then you created a O-grid around the blade. then you made a split (horizontal) across the blade such that it cuts the small Lading edge bock and Trailing edge block. then two more split perpendicular to the blade (Vertical split). Till now it is clear for me because I learnt this from your video tutorial.

Thats right

Quote:

Actually you said that you associated the intermediate edges to curves on the constant span locations to capture the blade shape properly. With my little knowledge in ICEM, I could not understand the point clearly. Could please tell me, Why cant we associate all the curves to edges as you did for the two airfoil near the hub section and finish the blocking?.
First I associated edges at hub and tip section to corresponding curves. When generated premesh, I got a mess. I had two solutions:
1. Edit edge and either make them surface projected or associate them to some curve (for which i need vertical curves, which I dont have in this model) and then project them to curve with the help of automatic linear option OR
2. I create four to five curves and then make the splits for each curve and associate them.
Although I use to prefer first approach, but this time I thought 2nd approach would do the better work. Although I did not compare both for your model. So you can try both methods.


Quote:

In the post number 6, you said "we are going to change the shape of periodic boundaries in the region of blade and follow the mesh strategy as we discussed". I couldn't understand how to change the shape of periodic boundaries in the region of the blade. does it mean allingment of edges properly.
Either you change this in CAD software by cutting in such way that it approximately follow the average blade contour or do it in ICEM.

Quote:

In the post number 7, you told me to change the periodic boundary shape.
do you want me to change the entire shape of the domain as you proposed.
See above. I just want you to change to shape of periodic boundaries in region of blade. Say half chord upstream, region parallel to blade and region one chord downstream. (downstream = left of blade and upstream = right of blade according to my convention). May be after changing the periodic boundary shape we don't require quarter o-grid (just a guess, but we need to try).

I will work my self on this geometry tomorrow evening as tomorrow I have job interview.

venkat_aero2007 July 15, 2012 08:08

Thanks far. I will work on the model and post the doubts and results. Best wishes for your job interview.

venkat_aero2007 July 15, 2012 21:23

3 Attachment(s)
Hi Far,

Is this the periodic boundary you want me to change near the region of the blade (figure1). I thought there will be a periodicity problem if I don't change the periodic shape at top of the far field (figure2). But there are some problem to create surface at the top of the far field. I could not get a proper surface. The blade also interact with the domain (figure 3).

Or, should I just want to copy and translate the boundary surface near the blade to far field.

here is the tin file.
http://jyraphe.isae.fr/file.php?h=R1...dd05940808ec49

Far July 15, 2012 23:18

First concentrate on getting the mesh for the available model and then we modify it. I tell you that how to handle the annular models.

I am trying to say, we must the master the process and when applied to better geometry topology will produce the better results.

energy382 July 16, 2012 05:00

nice job far ;)

Far July 16, 2012 05:18

energy382 is back. :D

Far July 16, 2012 05:25

Since energy382 is here with us again. He will tell us how to block this model with shifted periodic and other things from his experience of mixed flow turbine. Ralen, diamondx and BrolY are also going to share their experiences. I hope we get the very nice mesh.

I am also waiting for ultimate topology and tips from Simon.

venkat_aero2007 July 16, 2012 21:46

5 Attachment(s)
I created quater O-grid and tried to adapt block as suggested in post 4. but could not get a fine mesh. I don't know where I am going wrong.

Firstly I made a horizontal and vertical split (Figure1) and then to create quarter O-grid, I selected 4 faces as shown in figure2. I thought of associating the edges parallel to the two curves (figure3). I made horizontal split at each section of the blade. then associated edges to curves. I tried to make a O-grid but ICEM should me an error message saying that O-grid not successful.

The mesh around the pressure side of the blade flows the profile of the blade (figure 4) but where as near the suction side, mesh does not follows the blade's profile (figure5). mesh near the trailing edge are clustered. The quality at the tip of the blade is also bad. should we want to do a special treatment
near the tip region.

Here are the files
https://www.dropbox.com/s/k28abvd4b3...quater%20O.prj
https://www.dropbox.com/s/indjfxjj4b...quater%20O.blk
https://www.dropbox.com/s/8vcbc6uod3...quater%20O.tin


waiting for your suggestions.

venkat_aero2007 July 17, 2012 16:38

Hi far,

Can you please help me to adapt the quater O-grid with the method that you described. I tried a lot but I am getting bad quality elements in the tip region.
Don't know how to proceed. please give me some suggestions.

Far July 23, 2012 13:47

Sorry. I was out of station for few days, just came back today. Lets start it again.

venkat_aero2007 July 23, 2012 18:38

3 Attachment(s)
Thanks for coming back. I have tried to mesh the geometry. Got a nice mesh on the blade. This time I created quater O-grid as you said and collapsed the trailling edge block. I inserted Y grid on the tip of the blade. I extend all the blocks till the far field. But there is cluster of mesh near the leading edge of the blade (Figure1) and Far Field (Figure2). Mesh in the the upstream of the blade follows the shape of blade. Waiting for your suggestions. website to upload files is not working in my lab so I am sending all the files to your mail.

venkat_aero2007 July 23, 2012 21:48

I forgot to mention one thing. I aligned vertex (XY direction) in the far field (domain top ) with reference to tip vertex of the blade.


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