Velocity of gas from free fall type atomisers

The velocity of gas around the geometric point of atomisers of different fo cal lengths, apex angles, and number and diameter of nozzles was studied as a function of plenum pressure by measuring pitot pressure. The gas field a round the geometric point was found to consist of widely varying velocities . The velocity increases with increase in plenum pressure and diameter of n ozzle but with decrease in focal length. The change in velocity was found t o be insignificant with either change in apex angle or number of nozzles. E mpirical correlations were obtained to determine the velocity at and downst ream of the geometric point. The exponent value of the power function of th e downstream velocity was shown to decrease exponentially with increase in the ratio of gas density to surrounding air. The discharge coefficient was found to be independent of plenum pressure but decreased with increase in t otal cross-sectional area of atomiser nozzles.