Consider the flow of air through a wind turbine whose blades sweep an area of diameter D (in m). The average air velocity through the swept area is V (in m/s). On the bases of the units of the quantities involved, choose the correct equation for the mass flow rate of air.

Respuesta :

Answer:

M = ρ*[tex]\frac{\pi }{4}[/tex]*D²*V

Explanation:

The mass flow rate (M) is the mass (m) that is flowing by a determine period, thus is the mass divided by the time (t):

[tex]M = \frac{m}{t}[/tex]

The density (ρ) of a substance is its mass divided by its volume (Vol), thus:

ρ = [tex]\frac{m}{Vol}[/tex]

m = ρ*Vol

So, the mass flow rate is:

M = ρ*Vol/t

The volume of the substance is occupying is the area (A) multiplied by the legth of the turbine (l):

Vol = A*l

M = ρ*A*l/t

And, the division of the length by the time is the velocity (V) of the fluid in the turbine, so:

M = ρ*A*V

If the turbine is a circunfernce, the area is related to its diameter (D):

A = π*D²/4

So:

M = ρ*[tex]\frac{\pi }{4}[/tex]*D²*V