Liquid Seeders

LS-10 Remote Operation Liquid Droplet Seeder

Dantec Dynamics are acting as agents for our liquid seeder.  For details and pricing please refer to the Dantec Dynamics web page, model number 10F02.

Applications

  • Droplet Seeding for Particle Image Velocimetry
  • Droplet Seeding for Laser Doppler Velocimetry
  • Oil mist for flow visualisation
  • Seeding for Mie Scattering combustion studies of flame shape
  • Aerosol research
  • Controlled oil mist for lubrication

Specification

  • Up to 10 bar working back-pressure.
  • Ten Laskin nozzles.
  • Approximate 108 particles/second. seed output per jet
  • Stainless steel pressure vessel construction.
  • Acrylic level indicator rated for 10bar max pressure.
  • Dilution air: Variable through central tube.
  • M6 tapped mounting holes compatible with NewportTM saddles.
  • Quick re-fill operation without the need to stop experiment.
  • Remote Panel: Pneumatically operate any number of nozzles (1-10) to control seed density remotely from the experiment.
  • Compatible with solenoid valves for PLC or computer control.
  • Push-fit pipe connectors and colour coded air tubes for easy installation and adjustment of remote cable length.
  • One way valves on all Laskin nozzles to avoid contamination of air supply pipes with seeding liquid.
  • Controllability of seeder can be customised to suit other user requirements.

Principle of Operation

The individual Laskin nozzles operate close to sonic conditions at typical air supply pressures. The high shear region between the emerging air and liquid atomises and entrains microscopic liquid droplets into bubbles which release the seed on bursting at the free surface. Bubble busting is a source of secondary atomisation that gives larger droplets, which are prevented from exiting the seeder by the horizontal baffle plate at the top of the device. In this device ten identical Laskin nozzles at the base of the device can be operated independently to give an easily controlled and repeatable seed density. Further dilution of the seed is made possible by means of an additional dilution jet that bypasses the liquid and mixes with the emerging mist.

Recommended Working Fluids

Typical seed materials include corn oil, olive oil, and silicone fluids (eg Dow Corning). Corn oil is frequently used in wind tunnel applications at atmospheric pressures and temperatures, as it is inexpensive and produces micron-sized droplets. Olive oil has a higher flash point or decomposition temperature, and is the liquid of choice for many internal combustion engine flows. Where operation at very high temperatures, and reduced pressures is required, silicone vacuum fluids are preferred. These liquids were developed for use in vacuum diffusion pumps and combine very low vapour pressure with high flash points and surface tension and kinematic viscosities similar to the vegetable oils. It is also possible to use this seeder to provide solid particle seeding by diluting powders with water or methanol.