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We need to do some basic geometry to find the rotating center. The blades are located 0.04m from the center of the turbine. The top blade is 120 degrees from the (positive) x-axis. So:
x=0.04*cos(120)=-0.02m
y=0.04*sin(120)=0.034641m
Go ahead and input that for X and Y of "Rotation-Axis Origin (Relative)".
FIGURE 12
Do the same for the right and bottom blades. Select "Frame Motion" and make it relative to the "inner" cell zone. The needed values for centroid and angular velocity are summarized below.
Zone name | Centroid (X,Y) | Angular velocity (RPM) |
---|---|---|
blade_top | (-0.02, 0.034641) | 0 |
blade_bot | (-0.02, -0.034641) | 0 |
blade_right | (0.04, 0) | 0 |
Don't forget to select the relative motion!
It would be good to go back and check each cell zone to avoid messy errors in the future!
We are now ready to set the other boundary conditions!
Boundary Conditions
Remember that we had already set some Boundary Conditions, before doing the Mesh Interfaces. However we still need to tell FLUENT what is wall, and specify some pressures and velocities.
Velocity at the inlet
First, specify the velocity at the inlet.
Locate and highlight "farfield1". Change its Type to "velocity-inlet".
FIGURE 13
Click "Edit...". In "Velocity Specification Method", change to "Components". Set "X-Velocity (m/s)" to 10.
Under "Turbulence", change the "Specification Method" to "Intensity and Length Scale". Set the "Turbulence Intensity (%)" to 5 and the "Turbulent Length Scale (m)" to 1.
FIGURE 14
Pressure at the outlet
Wall
MAYBE it's to big? Video...?
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To explain a little bit about the MFR method, see Numerical Results part, where I wrote something very short.
Cell zone conditions:
name zones, centroid, angular velocity. do for top blade
make table with values for other blades
Boundary Conditions:
-farfield 1: velocity inlet....
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