# turbomachinery coordinates m', theta vs m, r*theta

 Register Blogs Members List Search Today's Posts Mark Forums Read

 April 27, 2011, 16:34 turbomachinery coordinates m', theta vs m, r*theta #1 New Member   Join Date: May 2009 Posts: 24 Rep Power: 10 Sponsored Links Hi, I am currently writing a small tool which helps me to set up blade geometries in a turbomachine. In order to define the blade camberlines, I am using either a m' / theta (m' = m_prime) or a m/r*theta (m = meridional coordinate) coordinate system. I found both definitions in the handbook of Mises (Drela). Now, I am asking myself which coordinate system is more senseful. I know that some "comercial" tools prefer the m'/theta-definition because it shell be angle-preserving - but why is this not the case with m/r*theta? Can this be proven mathematically? Is the m'/theta coordinate-system senseful if the fluid is _not_ following a streamline (e.g. in a deswirler which turns the flow from radial to axial), as described in the mises manual? Thx for the help.

 September 1, 2013, 22:01 #2 Member   A. S. Join Date: Apr 2009 Location: Raipur (INDIA) Posts: 41 Rep Power: 10 Hi, My reply is very late, but may be helpful. Based on my mapping experience based on both m-rtheta and m'-theta. I found that m'-theta is indeed angle preserving and m-rtheta was more dimension preserving. Recently I can across a paper that mentions m-theta transform also. But for my purpose I have used m'-theta for mean-line and m-rtheta for adding thickness and preserving absolute dimensions of LE , max thickness and TE. Best Regards Apoorv

 April 20, 2015, 02:58 #3 New Member   Join Date: Apr 2015 Posts: 1 Rep Power: 0 Hi Apoorv, This post is a while ago but hopefully you could help me. I am intrested in that coordinate tranformation. After searching a lot in the internet I could not find any usefull decriptions. The most of them only provide the formula m'=dm/r. But all my tries doesent seem to reach any success. Could you help me we that mapping process. Maybe with an simple example. I am very greatfull for your help. Thanks Kam Hi, My reply is very late, but may be helpful. Based on my mapping experience based on both m-rtheta and m'-theta. I found that m'-theta is indeed angle preserving and m-rtheta was more dimension preserving. Recently I can across a paper that mentions m-theta transform also. But for my purpose I have used m'-theta for mean-line and m-rtheta for adding thickness and preserving absolute dimensions of LE , max thickness and TE. Best Regards Apoorv[/QUOTE]

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Randheer Yadav FLUENT 2 January 18, 2015 17:25 KB Main CFD Forum 2 March 24, 2008 00:18 hani OpenFOAM 0 March 21, 2008 03:33 tommy FLUENT 0 February 13, 2004 03:19 Franz Wingelhofer CFX 0 December 28, 1999 08:46