I am reading a SUBTOPIC----performance of similar geometric wind machines
MAIN TOPIC ----General theory of wind machines
BOOK NAME-----power generation
BRANCH ------- MECHANICAL
I have given a screenshot and I am confused with a the red line marked "a given wind speed". which type of wind speed?
Upstream wind speed , downstream wind speed , wind speed through rotor , tangential speed of rotor
![](https://www.physicsoverflow.org/?qa=blob&qa_blobid=8884966313121972118)