| Abstract
| - Correlations were developed to model the performance of two types of multi-inlet aerosol samplingcyclones. The body of one cyclone had the Lappleconventional geometry and the other had a shorterdesign, which was one-half the length of the Lapplegeometry. Four cyclones of each type wereconstructed, with body diameters of 38.1, 57.2, 88.9,and 139.7 mm. Each cyclone was tested at severalflow rates, with the range of flow rates for the entiredata set being from 9.4 L/min to 1027 L/min.Aerodynamic particle cutpoint diameters,D0.5, weredetermined for several sets of test conditions,consisting of a given cyclone type and a fixed flowrate. The range of cutpoints determined in theexperiments was 3.9−17.1 μm aerodynamic diameter.Experimental data were correlated to a logarithmic-linear relationship: C0.51/2D0.5/dc= ln a + b lnRefwhere C0.5 is Cunningham's slip correction forthe cutpointsize; dc is the cyclone diameter; and,Ref is the flowReynolds number, which is characterized by the airinlet velocity and the width of the channel betweenthe cyclone body and the outlet tube. The correlationcoefficients, r 2, fordata of the long and short multi-inlet cyclones to the log-linear model were 0.984 and0.991, respectively. The log-linear relationshipbetween the size parameter and the flow Reynoldsnumbers was re-arranged to provide workingrelationships for designers. Fractional efficiencieswere measured for each cyclone, and sigmoid curveswere fitted to the data that provide a relationshipbetween fractional efficiency and dimensionless particlesize, (Da −D0.5)/D0.5, whereDa is the aerodynamicparticle diameter.
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