Hello,
I wanted to measure the airflow of some computer fans I own, so I purchased an anemometer, this one:
https://www.ebay.com/itm/195382463171 . I understand that to get a really accurate figure, I'd need a large machine that has a chamber. I think an anemometer would be good enough for practical usage.
I held the top of my anemometer up to my fans output. I got an average reading of 2.4m/s. Out of curiosity, I held it right against the fan's motor such that the anemometer's tiny fan couldn't spin because there was no airflow. I got a reading of over 6 m/s. This seemed really strange to me, so I thought, "Maybe it's the vibration that is causing a reading." I pushed the anemometer against my fan and did not get a reading.
Puzzled, I then covered the anemometer with my hand so that both the small and large opening couldn't get much, if any, air through them. I held it up to the fan and got a reading of 5-6m/s. I removed my hand and got a reading of 1.7m/s from the same distance.
I'm totally lost here. How do anemometers work?
Why am I getting higher airflow while the anemometers fan is not turning?
Thanks!