I am simulating hydrodynamic journal bearing with ANSYS fluent. I want to calculate the load carrying capacity of the journal bearing. I have static pressure contour result with me. I have read that "The calculation of forces acting on the journal is performed with the integration of pressure in the area of the journal." I have exported the pressure forces on the journal as *.cdb file. How do I integrate these forces to get loads?
I have no idea on how to calculate resultant in ANSYS, however I think it would be much easier to export (pressure/angle) data to perform pressure integration with other programs (e.g. MatLab, Excel)
I would add a further comment. If you are using ANSYS to compute pressure distribution in oil film bearing, you must also include elastic deformations. In fact, the oil pressure strongly depends on the geometry of the lubrication gap. On the other hand, the oil pressures gives elastic deformation of both housing and shaft, hence it changes the lubrication gap. In summary, you have a "coupled analysis" between ANSYS fluent and structural.
We investigated this problem and we found that elastic deformation gives a reduction (about 50%) of the max. pressure (see attachments).
In conclusion, if you neglect the elastic deformation of the system, you can easily get the pressure distribution by solving (by finite difference scheme) the Reynolds equation (without using ANSYS fluent...).
Instead, if you use ANSYS fluent, you could also include the elastic deformation of the structure, but you need to solve a coupled analysis (by iterations).
Thanks for ur help. Can you guide me on how to perform pressure integration with other programs (e.g. MatLab, Excel)?
Dear Benas, u have said that if you consider elastic effects the max pressure reduces aprrox.50%. Then what happens to load carrying capacity? Does it increase? if yes how much % than plain bearing?
Also, I am using a shaft of 45mm dia. what value of clearance i should take if i want to use SAE50 oil and speed upto 10000 RPM. If possible plz provide reference for selection of clearance values for bearings with elastic deformation consideration.
Dear Dhande, i'm also studying on HJB performance nowadays.
I've found that Fluent can perfom this easily. The basic concept that i understand from the Load carrying Capacity is a multiplication of the average pressure on a surface by the surface area. This means also an integration of pressure distrubition on a surface. Fluent can calculate this as [Pa*m^2 -> N].
https://www.sharcnet.ca/Software/Fluent6/html/ug/node1199.htm
Try it from Fluent solver module; Report/Surface Integrals section.
https://www.sharcnet.ca/Software/Fluent6/html/ug/node1200.htm
Dear Mr. Dinesh, Did you know the way to calculate Load carrying capacity with integration in Excel, matlab from exported Data file? I am also needing the answer! Please share me! Thank you for all above comments!
Dear Dinesh,
The load carrying capacity of HD journal bearings you can receive after integration of the pressure.
At taking into account the elastic deformations effects you will receive reducing of the max pressure values and by result of this - reduction of load carrying capacity.
The effect of elastic deformations is not so high because in the case of journal bearings we don't have such high pressures as at point or line contact.
@ Juliana G. Javorova ,
Thank you very much madam, for your reply....
I indeed got the same results as you have mentioned in your reply.
Regards.
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