Date: August 14, 2015

 

1. PURPOSE / DESCRIPTION

• To give an outline of basic setup of body and propeller MRF simulation.
  • It is assumed that you have some experience in ANSYS, but the paper is still quite detailed.
  • If help is needed, go to EP-701 for resources to learn ANSYS.
• You need the CAD of the body and propeller.
• MRF simulation is computationally less expensive, but is not able to capture accurately the interactions between the propellers and the propellers with themselves (research more on ANSYS website). Transient simulations are much more computationally expensive, but are able to accurately show interactions happening within the flow.
  • So doing a transient simulation to check the accuracy of the MRF simulation may be ideal.
  • You can convert MRF into transient easily through Fluent as well! Search in the internet.

2. Design Modeler

• Drag either a Geometry Cell or a Fluent Analysis System onto Workbench.
• DCLK on Geometry to open Design Modeler.
• File > Import External Geometry File… > Choose the CAD of the drone body (with or without legs)
  • Make sure that the CAD is clean, and if not ask for help from the CAD maker.
  • You can also use the tools within Design Modeler to merge faces, delete faces, delete bodies, repair holes, repair edges, etc. as shown below.
  • Delete bodies that are not desired, such as motors or inaccurate propellers already in that file

• (Do 2 times) File > Import External Geometry File… > Choose the CAD of the desired propeller
• Create > Delete > Face Delete
  • Select the faces of the holes in the hubs. You can hide one or the other prop to select faces more easily.
• (If needed) Create > Body Transformation > Mirror
  • Select one of the props
  • Select the correct plane (YZPlane in this case)
  • This step was necessary to flip the front prop to have counterclockwise rotation as in the real drone.
• Create > Body Transformation > Rotate
  • One for front prop 45 degrees
  • Another for back prop 45 degrees
• (For each propeller) Create > New Plane
  • Type = From Centroid
  • Base Entities = select the top face of the hub (hide the other prop while doing so)
• (For each propeller) Create > New Plane
  • Choose desired coordinates. (Parameterize these points by clicking the small boxes next to the parameter)
  • These planes will be used to move the props to desired positions.
• (For each propeller) Create > Body Transformation > Move

• (FOR EACH PROPELLER) Tools > Enclosure
  • Make sure to choose the right Cylinder Alignment axis.
• Create > Delete > Body Delete
  • Select the prop bodies (NOT the enclosures)
• Create > Body Transformation > Mirror

• Select the enclosures of the props.
• Choose the appropriate planes.

 

• Tools > Enclosure
  • Shape = Box or Cylinder –>
  • Just make sure that the domain is large enough.

• Create > Delete > Body Delete
  • Select the drone body and the 4 props that were created from the enclosure created above.
    
• Select all bodies in the outline tree, RCLK, and Form New Part.
  • This step ensures that the mesh will be conformal between the zones.
  • You can skip this if you want to use non-conformal mesh to work with interfaces.
• Hide the outer enclosure and then edit the names each propeller enclosures as appropriate (NOT NAMED SELECTIONS):

• Name the outer enclosure body as MainZone. (NOT NAMED SELECTIONS)

• File > Save Project
• Close the window

(EXAMPLE OF Parameters)