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about kuta condition
Hi David
I would like to ask about the treatment of the Kutta condition for the blade trailing edge.
In my calculations, I am following the row of vortex filaments in the spreading direction of the blade lift line and the row of vortex filaments in the chordal direction from the boundary point to the trailing edge of the blade, treating them as bound vortices. But is the row of vortex filaments in the spreading direction at the trailing edge of the blade treated as shed vortices? If so, how do I ensure that the delta gamma is equal to 0?
Due to the circulation iterations and relaxation factors, it is only possible to ensure that the circulation value of the shed vortex at the trailing edge of the blade is as small as possible, but not zero, which is why shed vortex filaments are still present even in steafy wind. Is this reasonable if treated this way?
Thanks
BR,
Roby
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In addition ，Can I calculate the shed vortex at the trailing edge of the blade by calculating the bound circulation twice during initialization? It will be a very small value. If this is not done, the shed vorticity at the trailing edge of the blade will enter the flow field with the first calculated value of the bound vorticity.
Hello Roby,
when simulating in steady wind, there is initially some shed vorticity during the transient phase at the beginning of the simulation. This transient phase is related to the impulsive start of the blade rotation, which causes the starting vortex and the build-up of the wake. Over time, this transient behavior diminishes, leading to a steady-state operating condition. In this steady state, the shed vorticity becomes zero as the temporal derivative of the blade circulation vanishes.
In QBlade there is no shed vortex element located at the trailing edge as elements should cancel out at this position. the first shed vortex element is then found in the first wake row thats newly created by the blade. See the attached image below…
BR,
David
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