Influence of cross-flow on particle collection characteristics of multi-nozzle impactors

Abstract Studies of the flow fields and particle impaction characteristics are more complicated in multi-nozzle impactors than in single-nozzle impactors, since the jets of air must penetrate cross-flowing air to impinge on the impaction plate. Results of heat and mass transfer analysis are employed to describe the cross-flow pattern in multi-nozzle impactors. A cross-flow parameter has been derived to predict the deflection of the air jet by the cross-flow. This parameter is expressed as a function of the geometric parameters for the multi-nozzle impactor, D n N 4D c , where N is the number of nozzles, Dn the nozzle diameter and Dc the nozzle cluster diameter. Empirical particle collection data show that multi-nozzle impactors operate satisfactorily, if the cross-flow parameter is less than a critical value of 1.2. Impactors operating with a cross-flow parameter larger than this critical value are shown to possess poor particle collection characteristics.

[1]  Richard J Goldstein,et al.  Visualization of heat transfer from arrays of impinging jets , 1982 .

[2]  K. T. Whitby,et al.  Fluid mechanics of the laminar flow aerosol impactor , 1974 .

[3]  R. J. Goldstein,et al.  Impingement cooling from a circular jet in a cross flow , 1975 .

[4]  Robert S. Ruggeri,et al.  Investigation of the Penetration on an Air Jet Directed Perpendicularly to an Air Stream , 1948 .

[5]  Benjamin Y. H. Liu,et al.  A submicron aerosol standard and the primary, absolute calibration of the condensation nuclei counter , 1974 .

[6]  R. J. Margason,et al.  The path of a jet directed at large angles to a subsonic free stream , 1968 .

[7]  A. Nugent,et al.  Calibrating particulate air samplers with moniodisperse aerosols: application to the andersen cascade impactor. , 1967, American Industrial Hygiene Association journal.

[8]  Ephraim M Sparrow,et al.  EFFECT OF NOZZLE - SURFACE SEPARATION DISTANCE ON IMPINGEMENT HEAT TRANSFER FOR A JET IN A CROSSFLOW. , 1975 .

[9]  K. T. Whitby,et al.  On the Flow Fields of Inertial Impactors , 1974 .

[10]  David Y. H. Pui,et al.  Equilibrium bipolar charge distribution of aerosols , 1974 .

[11]  K. R. May.  CALIBRATION OF A MODIFIED ANDERSEN BACTERIAL AEROSOL SAMPLER. , 1964, Applied microbiology.

[12]  Daniel J. Rader,et al.  Effect of Ultra-Stokesian Drag and Particle Interception on Impaction Characteristics , 1985 .

[13]  Kenneth L. Rubow,et al.  A Microorifice Uniform Deposit Impactor (MOUDI): Description, Calibration, and Use , 1991 .