Impinging air jets may be used to clean particles from surfaces. The kinetic energy per unit volume (J/m3) of an air jet at a surface, Er, may be written as:

E=1/2*(rho*v2)* k*d-1.3

Where:

rho = density of air (1.3 kg/m3),

v = air velocity

k = proportionality constant (0.4 mm 1.3)

d = distance from the jet nozzle (10 mm).

For a sphere (A4 = 1x10-19 J) adhered to a flat surface (A2 = 1x10-20 J), find:

1. What size of particle (diameter) could a hurricane force wind (v = 118 km/h) remove from a

surface?

2. What size of particle can be removed at v = 340 m/s (speed of sound)?

3. What air velocity would be required to remove a 1 mm particle and a 100 nm particle?