Stats

More Content

Mesh configuration in Omnis/turbomachinery

sriluta

Hey, together in Omnis iam using the structured mesh for turbo machinery. I have two Problems, first iam investigating a blade with a wavy leading edge. In the geometry context the blade looks good. In the Mesh context the leading edge is unfortunately no longer wavy but very shape, as you can see in the Picture. 

Is the reason because I chose a structured mesh, if not how can I optimize the leading edge to make it wavy again. The 2nd point is my solution unfortunately does not converge, this is certainly because my max asp. ratio is 50,000 and is far from the recommended range as in the manual. My maximum spanwise angular deviation is also far from the recommended range at 57 degrees. Under which settings could I improve these parameters ?

thank you very much greetings Hussein

  • sriluta
    0

    The first problem with the sharp leading edge is solved.  In the mesh context click on row 1/ wizard and increase the flow paths number, mine was set too low 

  • Colinda
    +1 in reply to sriluta

    Hello Hussein,

    You may indeed even want to set the number of flow paths higher to really well capture the wavy shape at the leading edge. That will probably also improve the angular deviations. Did you have a look whether these spanwise angular deviations are highest?
    What is the y+ value at the blade, hub and shroud? Is it feasible to run with low Reynolds mesh or should an extended wall function be used? To decrease the aspect ratios often a mesh refinement is the only solution but then the cell count may get quite high and use of an extended wall function approximation may be better.

  • sriluta
    0 in reply to Colinda

    Hallo Colinda, exactly thank you. By increasing the flow paths number, the leading edge is now wavy. Unfortunately, since my mesh has changed, I can no longer see any results under result analysis and have to restart the  Simulation.

    I can then surely output the y+ values under result analysis ? And where could I display the largest span wise angular deviations? Regarding the term low Reynolds mesh, would it mean that in this case I work without a wall function and with a very fine mesh in comparison to the high Reynolds mesh, where I then apply the wall functions ? By the way, I use the k-omega-SSTmodel. The resolution of the boundary layer is not very important to me, but the whole flow field. I have a very high totalpressure at the inlet about 2.5 bar and a total temperature about 1800k as well a Mach Number of about 0.6. I also investigate only 15 stators without rotors

  • sriluta
    0 in reply to sriluta

    I was able to display the y+ values.  These are for the mentioned areas between 0.02 and 0.14. The leading edge has the highest value with 0.14.

  • domen
    0 in reply to sriluta

    Hi, if you change the mesh you need to rerun the simulation to update the results. 

    The values if y+ seem quite low even for a Low-Re turbulence model. Better be around y+=1. 

Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.