AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Experimental Determination of the Effective Vortex Length of Cyclones
HSIAO-YI HUNG, Chih-Wei Lin, Sheng-Hsiu Huang, Chih-Chieh Chen, National Taiwan University
Abstract Number: 145 Working Group: Control Technology
Abstract In a conventional cyclone, the outer vortex flow weakens and changes its direction at a certain axial distance from the vortex finder. This axial magnitude has been called the “natural vortex length” of the cyclone. Since the space below the vortex will not be used for particle collection, cyclone designs with a natural vortex length equal to or greater than the physical length of a cyclone is recommended. Although some studies have investigated this parameter and obtained its empirical formula, there are contradictions among these models. Therefore, the main purpose of the present study was to experimentally measure the effective vortex length, from the perspective of aerosol penetration and pressure drop across the cyclone.
To characterize the cyclone performance, an ultrasonic atomizing nozzle was used to generate micrometer-sized potassium sodium tartrate particles. An Am-241 radioactive source was employed to neutralize the particles to the Boltzmann charge equilibrium. Aerosol size distributions and number concentrations upstream and downstream of the cyclones were measured using an aerodynamic particle sizer. Each aerosol penetration measurement was repeated five times. The pressure drop across the cyclone was measured using an inclined manometer. All types of sampling cyclones developed in this work were based on the Very Sharp Cut Cyclone designed for PM2.5 sampling. The effective vortex length of a cyclone was analyzed by using both the aerosol penetration and the pressure drop across the cyclone. The results showed that the body diameter and the sampling flow rate are significant parameters affecting the effective vortex length of cyclone. However, inlet diameter, outlet diameter, and cyclone with or without a cone do not significantly influence the effective vortex length. Until now, the model for estimating the effective vortex length is yet to be developed.