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Problems with positive and negative values of simulation results
Hello David!
I want to ask, when my fan was in the physical experiment, the data were all positive and the effect was better than the original design. Why is the power value negative after inputting into the horizontal wind simulation? In addition, there are negative values for me How can this situation be explained?
thanks
#Both experiments and simulations rotate counterclockwise.
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Hello,
it looks like you are using the “old” QBlade 0.96, which is not supported anymore. The reason why you could have negative CP is probably due to an incorrect blade definition for the counter-rotating blade.
In QBlade 2.x its also possible to simulate counter rotating turbines. To setup such a simulation the blade is defined as if it would be rotating in the “normal” clockwise direction. When “reversed” is then chosen as the direction of rotation the blade is automatically “mirrored” accordingly, so that the expected angles of attack are the same as for the “standard” direction of rotation.
BR,
David
