1. PURPOSE / DESCRIPTION
- To set a standard procedure for airfoil simulation in ANSYS Fluent
- The procedure follows the wind tunnel simulation that was run for the NX Drone
- Useful resources:
- “Workshop 07: Sliding Mesh” from ANSYS Fluent full course materials
- Full course videos on ANSYS website for Fluent.
- “Workshop 04: Airfoil” from ANSYS Fluent full course materials
- Airfoil Tools: http://airfoiltools.com/airfoil/details?airfoil=naca0015-il
- UIUC Airfoil Database: http://m-selig.ae.illinois.edu/ads/coord_database.html
- How to import/plot points: http://pjotr.ru/ansys_dm_01/
- General Tips: http://www.computationalfluiddynamics.com.au/category/tips-and-tricks/
- Air Properties Calculator: http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
- If you have no experience with ANSYS, it is recommended that you go through the ETP for Learning ANSYS.
2. Geometry & Meshing PROCEDURE (without explicit inflation layer definition)
NOTE: These instructions match the steps taken in SimCafe’s tutorial on airfoil ( https://goo.gl/OLIX5g) and the tutorial regarding importing points (http://pjotr.ru/ansys_dm_01/)
- Find online the coordinates for the desired airfoil.
- You need to write the points into a .txt file with the following format:
- Any lines beginning with #’s are simply comments and do not have to be included.
- There can be spaces and tabs between the numbers so do not worry too much about delimiting using only one space.
- The first number is the group number and the second is the order within the group. The remaining three numbers are the XYZ coordinates of each point. You only need 1 group, however, for this procedure.
- You need to write the points into a .txt file with the following format:
- Follow the first 5 steps in the tutorial about point importing. Because this is a 2D procedure, you will only have one surface (one group of points) to create.
- Before creating the surface of the Make sure to zoom into the trailing edge and connect the open points after creating the curve from the points.
- After
Use the same geometry made with the instructions from SimCafe but without the line projections. - Open Meshing and change the settings of Mesh to match the settings below (except for Statistics):
- SETTINGS (especially Min Size) SHOULD BE ALTERED, TESTED, AND EXPERIMENTED WITH DEPENDING ON THE GEOMETRY.
- The statistics should be checked, as mentioned, each time the mesh generated.
- For 2D mesh, an orthogonal quality above 0.4 is preferred, but using inflation will most likely result in lower OQ, which is acceptable.
- RCLK on Mesh > Insert > Sizing
Scoping | Scoping Method | Geometry Selection |
Geometry | Select the main edge of the airfoil. (excluding the trailing edge) | |
Definition | Type | Number of Divisions
You can also use Element Size. |
Number of Divisions | 900
Adjust number of divisions as needed. |
|
Behavior | Soft | |
Bias Type | _____ ___ _ ___ _____
This is to have smaller sizing near the trailing edge in order to improve orthogonal quality. Adjust according to the geometry. |
|
Bias Option | Bias Factor | |
Bias Factor | 35
Adjust bias factor as needed. |
- RCLK on Mesh > Insert > Sizing
Scoping | Scoping Method | Geometry Selection |
Geometry | Select the trailing edge of the airfoil. | |
Definition | Type | Number of Divisions
Or you can use Element Size and use a size that is about half the height of the trailing edge. |
Number of Divisions | 2 | |
Behavior | Hard | |
Bias Type | No Bias |
- RCLK on Mesh > Insert > Inflation
Scoping | Scoping Method | Geometry Selection |
Geometry | Select the main surface (do not select it as a body) | |
Definition | Boundary Scoping Method | Geometry Selection |
Boundary | Select the main edge (excluding the trailing edge) of the airfoil | |
Inflation Option | First Layer Thickness
Choose appropriate option depending on the situation. |
|
First Layer Height | .1 mm
This was the desired first cell height calculated for an Re of 3000000. Calculate and use an appropriate height, or use another method. |
|
Maximum Layers | 20 |
- (Optional)
- RCLK on Coordinate Systems > Insert > Coordinate System
Origin | Define By | Global Coordinates |
Origin X | 1500 mm
Select appropriate coordinates so that the sphere of influence is slightly to the right of the trailing edge. |
|
Origin Y | 0 | |
Origin Z | 0
|
- Mesh > Insert > Body Sizing
Scoping | Scoping Method | Geometry Selection |
Geometry | Select the main body (do not select it as a surface) | |
Definition | Type | Sphere of Influence |
Sphere Center | Coordinate System
Or select the coordinate system created in the step above. |
|
Sphere Radius | 2000 mm
This can be altered as needed. |
|
Element Size | 40 mm
This can be altered as needed. You can change this to do mesh independence study as well. |
- Creating Named Selections
- Select the edges that form the airfoil
- RCLK on the graphics window > Create Named Selections
- Name it “wing”
- Do the same for the edges for the inlet and outlet as shown:
- Select the edges that form the airfoil
Example of how it should look: