Question

An airplane with a hot-wire anemometer mounted on its wing tip is to fly through the turbulent boundary layer of the atmosphere at a speed of 50 m/sec. The velocity fluctuations in the atmosphere are of order 0.5 m/sec, the length scale of the large eddies is about 100 m. The hot-wire anemometer is to be designed so that it will register the motion of the smallest eddies.What is the highest frequency the anemometer will encounter

Answer 1

Answer:

0.55 hz

Explanation:

Given that the plane fly through the turbulent boundary layer of the atmosphere at a speed of 50 m/sec. And the velocity fluctuations in the atmosphere are of order 0.5 m/sec, the length scale of the large eddies is about 100 m.

The maximum speed attained will be

Maximum speed = 50 + 0.5 = 5.5 m/s

The Length = 100m

Speed = FL

Where F = frequency

Substitute speed and distance length into the formula

55 = 100F

F = 55/100

F = 0.55 Hz

Therefore, the highest frequency the anemometer will encounter will be 0.55 Hz