Important dimensionless numbers Resistance coefficient = Euler number –Relates cyclone pressure drop to some characteristic velocity: Gives ratio to pressure forces to inertial forces Constant for given cyclone geometry, important for scaleup What characteristic velocity should we use? –One based on gas flow rate q/cross sectional area (D = cyclone diameter)

Stokes 50 number (Stk 50 ) Physical significance: Ratio of centrifugal force (less buoyancy) to the drag force acting on a particle of diameter x 50  - gas viscosity, density is particle density, D is cyclone body diam., char.velocity is same as previous. x 50 = Cut size… at this diameter, 50 percent of particles will be collected

Cool rule of thumb: For well-designed cyclones, there is a direct correlation between Eu and Stk 50 This is pretty neat because you could find x 50 by knowing specifics about cyclone

For hw problem 1, Rhodes 7.2 Info about size distribution given in dFc/dx and dF/dx format