A high pressure, high volume Laskin seeder for PIV and Flow Visualisation.
The seeding generator works by injecting air into a fluid (normally oil) at near sonic velocity via a number of Laskin nozzles. Each nozzle produces micro-bubbles with micro-droplets (typically 1 micron) inside. These bubbles reach the free oil surface and burst, releasing the micro-droplets. Internal baffles are used to remove unwanted large droplets that can be produced by the splash when a bubble bursts.
The density of micro-droplets is determined by the air flow rate through the nozzles and the number of nozzles. It is important to have a large free surface where the bubbles burst to avoid foaming. This sets the upper limit to the micro-droplet production rate.
Control of the micro-droplet production rate is provided by turning nozzles on and off and by adjusting the air flow rate/pressure. This level of control tends to produce a fixed seed density at a variable flow rate. In order to provide control of the seed density and avoid the need for a mixing plenum in the experiment, dilution air can be admitted to the generator so that lower seed densities can be produced when required.
The VisiSeeder works with a number of fluids. Most work is done with corn oil as it produces drpolets around 1 micron diameter and is readily available at low cost. Olive oil is often used where elevated temperatures are expected (e.g. combustion studies) as it has a higher flash point and decomposition temperature. For very high temperatures or low pressure studies, silicone vacuum oils may be used.
Operating principle Laskin atomizer nozzles
Fully adjustable through control of individual seeding nozzles
Typical particle size 1 µm (peak in PDF of size distribution)
Seed materials include:corn oil, olive oil, silicone fluids (e.g. Dow Corning), water
One way valves on gas feeds
Operates up to 12 bar overpressure,
20 bar option
safety valve set to maximum working pressure
Supply pressure 20 bar max, uses regulator
Dilution air inlet from main air supply
Visible level indicator
Stainless steel pressure vessel
Pressure vessel meets appropriate Pressure Vessel standards
CE marked
Solenoid valves for remote operation
High pressure (to 20 bar) rating
Outlet pressure gauge
Flow meter
Air compressor
Particle Image Velocimetry (PIV)
Laser Doppler Velocimetry (LDA)
Mie Scattering combustion studies
Global Doppler Velocimetry (GDV)
Aerosol research
Controlled oil mist for lubrication
Laser Lightsheet Visualization
Stainless steel construction
12 bar rated (20 bar option)
Large liquid surface (300 cm^2) for high seeding density
Single unit construction
Pulsed pressure rated
Meets Pressure Vessel regulations