How to calculate size of blower for forced calculation?
Answers
Answer:
If I understand the advert correctly the aim of the fan is to simulate the force the bicycle rider feels from aerodynamic drag. Aerodynamic drag increases with the square of the speed, so if you plot drag against speed squared you get a straight line. In the graph they show:
Drag
and the x axis is speed squared i.e. (m/sec)2 not m/(sec2). Also this isn't the wind speed through the fan, it's the speed of the cyclist (squared) so 160 means the cyclists speed is 160−−−√≈12.6 m/sec.
Actually 40N seems a very low drag - is the drag at 12.6 m/sec (≈28 mph) really only 4 kg?
Anyhow, I don't think their article is at all concerned with the wind speed through the fan. The fan is just a convenient way to generate a load that varies as speed squared and therefore gives a realistic impression of drag.