# Cold flow analysis on a AC generator

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 April 6, 2012, 05:49 Cold flow analysis on a AC generator #1 New Member   Sainath Join Date: Mar 2012 Posts: 27 Rep Power: 7 Sponsored Links I am trying to run a cold flow analysis on an A.C. Generator. The set up consists of both rotating and stationary bodies. There is a rotor and a fan on the same axis and the direction of rotation is the same. Surrounding the rotor is a stator. All these components are placed inside a box open at the top. On the top of the box is another box to represent a cooler, but for this case there are no tubes and just a dummy box on top. My aim is to determine the pressure drop inside the generator. The fan is a radial bi-directional fan rotating at a rpm of 1800. Both the rotor and fan are shaft mounted. I have meshed the problem(5 million elements) and set up the problem. Only input from my side is the rpm and i have set a SST model for turbulence. When i run it (in parallel), my solution diverges. Is there any suggestions or steps that i need to take in order to help my solution converge.

 April 6, 2012, 06:55 #2 New Member   Redddy Join Date: Sep 2010 Posts: 25 Rep Power: 8 Check your mesh quality ?

 April 6, 2012, 07:02 Re: #3 New Member   Sainath Join Date: Mar 2012 Posts: 27 Rep Power: 7 My mesh stats is as below. +--------------------------------------------------------------------+ | Mesh Statistics | +--------------------------------------------------------------------+ | Domain Name | Orthog. Angle | Exp. Factor | Aspect Ratio | +----------------------+---------------+--------------+--------------+ | | Minimum [deg] | Maximum | Maximum | +----------------------+---------------+--------------+--------------+ | Cooler | 81.6 OK | 1 OK | 1 OK | | Fan | 21.1 ok | 7 ok | 14 OK | | Frame | 15.2 ! | 36 ! | 26 OK | | Rotor | 7.7 ! | 106 ! | 32 OK | | Stator | 5.1 ! | 85 ! | 54 OK | | Global | 5.1 ! | 106 ! | 54 OK | +----------------------+---------------+--------------+--------------+ | | %! %ok %OK | %! %ok %OK | %! %ok %OK | +----------------------+---------------+--------------+--------------+ | Cooler | 0 0 100 | 0 0 100 | 0 0 100 | | Fan | 0 1 99 | 0 <1 100 | 0 0 100 | | Frame | <1 1 99 | <1 <1 100 | 0 0 100 | | Rotor | <1 3 97 | <1 1 99 | 0 0 100 | | Stator | <1 5 95 | <1 1 99 | 0 0 100 | | Global | <1 2 98 | <1 <1 100 | 0 0 100 | +----------------------+---------------+--------------+--------------+ Is there something wrong?

 April 6, 2012, 07:06 #4 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,331 Blog Entries: 6 Rep Power: 45 Angles are not good.

 April 6, 2012, 07:11 #5 New Member   Redddy Join Date: Sep 2010 Posts: 25 Rep Power: 8 Mesh quality check Orthog. Angle >20 deg Max Exp Factor < 20 Please go through the documentation to know the importance of above parameters on solution

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