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Investigation of a Technique for Clearing and/or Modifying a Military Smoke Cloud

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Contractor rept. Jul 1981-Sep 1983

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A numerical model is applied to assess the smoke particle 0.1 R sub p 5.0 micrometers scavenging by an oblate spheroid in the range of Reynolds numbers 0.1 Re sub c 50. The calculated collision efficiency is between 0.3 and 4.0. The collision efficiency of a charged thin spheroid Q sub c 2 e.s.u.sq. cm colliding with smoke particles of R sub p 0.3 micrometers is 14 for Re sub c 50. Experimental study of the smoke particle deposition on disks in the range of 80 Re sub C 320 in an aerodynamic wind tunnel leads to the following conclusion Collection efficiencies of stationary or steady settling disks are between 0.5 and 2.0. For disks oscillating at a frequency simulating the falling disk in the atmosphere, the collection efficiency is 20 higher. Collection efficiency of electrically charged disks 0.57 Q sub c 2.86 e.s.u.sq. cm is between 3 and 14. Deposition of particulates with R sub p 0.35 micrometer is higher on the disks back side than on the front side. Charged cylinders are featured by a collection efficiency between 0.3 to 5.0 for 3.5 Re sub c 26 and potential differences from 1 kV to 8 kV. High collection efficiencies are found on charged grid several percent for 1 kV and more than 5 for 5 kV. The effect of falling scavenger zone is considered to be more important for the scavengers fall velocity and its collection efficiency than for scavenger dispersion.

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  • Civil Engineering

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