INVESTIGATION OF ELECTRIFICATION OF POWDERS IN FLOW THROUGH TUBES AND NOZZLES. I. A CHARGE ANALYZER
Abstract
As a part of an investigation of the electrification of powders in flow through tubes and nozzles, a charge analyzer has been designed, constructed, and tested. The charge analyzer has two electrodes at + or - 1000 volts with respect to ground. At a stationary state, the current from each electrode is equal to the rate of deposition of charge. The two currents are recorded and integrated with a planimeter. The electrodes are weighed on a micro-balance for determination of the amount deposited. The nozzle is located at one end of the pair of electrodes. Experiments have been conducted with several airborne powders, in the range 1 to 30 micron of particle diameter, flowing through a hypodermic needle of 0.8 mm diameter and 3 ft length of flow rates between 50 and 500 cc/min. The average positive charge, the average negative charge, and the average absolute charge are proportional to the square of the flow rate. The charge is all acquired in friction between the powder particles and a deposit on the tube wall. Average charges up to 0.01 C/g have been measured. The charge is smaller the greater the extent of agglomeration of the powder. It depends as much upon agglomeration as upon the nature of the powder. It follows that literature data on aerosol charges determined with samples in slow rectified flow, e.g., by a capillary tube or a slit system, are misleading and may be too low by many orders of magnitude.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1963
- Accession Number
- AD0449189
Entities
People
- G. C. Fernish
- T. G. Owe Berg
- W. J. Flood
Organizations
- Aerojet Rocketdyne Holdings