Fog, smoke & seeding generators

Seeding generator selection guide

Model	Type	Particle type	Characteristics
10F02	Liquid seeding Generator	Oil droplets ~3 µm	PIV and LDA, high signal amplitude, remote control
10F03	High volume Liquid seeding Generator	Oil droplets ~3 µm	PIV and LDA where large volumes must be seeded, high signal amplitude
10F01	Powder seeding Generator	Aluminum oxide or titanium dioxide particles ~0.3 µm	PIV and LDA, high signal amplitude, remote control, high temperature e.g. combustion
10D15-60	Fog Generators, fog probes	Water based droplets ~1 µm	Visualisation, PIV and LDA, water based droplets, fine positioning, multiple probes in rake etc., remote control (optional), portable

Particle size considerations
Selecting a seeding generator is the compromise between signal amplitude and the particles ability to follow the flow. Larger particles will increase signal quality, data rate or reduce demand for illumination, but will have a slip in accelerating flows, e.g. a high frequency turbulence.

Smaller particles will reduce signal amplitude and data rate or increase demand for illumination, but will follow the flow to higher frequencies.

Rough guidelines:

• 3 µm oil droplets in air will follow flow fluctuations up to 1 kHz.
• 1 µm oil droplets in air will follow flow fluctuations up to 10 kHz.
• 1 µm powder particles in air will follow flow fluctuations up to 1 kHz.
• 0.4 µm powder particles in air will follow flow fluctuations up to 10 kHz.

For supersonic flows particles should not exceed 1 µm.

For further considerations on the selection of seeding particles, please consult litterature. (Principles of Lased Doppler Anemometry, Durst, Melling and Whitelaw; Laser Doppler and Phase Doppler Measurement Techniques, Albrecht, Borys, Damaschke and Tropea )

Fog generators (10D15-60)

SAFEX fog generators are small, powerful devices that generate a dense white fog by evaporation and condensation of a water-based fog liquid. The fog is non-irritant and non-flammable.

The mean droplet size is around 1 µm and the fog's durability can be controlled through the choice of different fog liquids (Blitz, Standard, Super). The fog fluid type Extra Clean consists of ingredients with extremely high purity and is designed for applications in clean-room environments.

Fog generator: FOG 2010
This standard device satisfies the majority of applications. The fog quantity can be varied directly at the fog generator or by using an electronic remote control unit.
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Fog generator: 195 SG-D
The system for applications requiring fog in very large quantities.
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Fog fluids
The durability of the fog can be varied through the choice of different fog fluids, but also depends on the ambient temperature and relative humidity.
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Accessories
A range of accessories are available for both the Fog Generator units 
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Flow field visualization with the fog probe system

The fog probe system is especially developed and optimized for flow field visualization in wind tunnels. The flexible connection between the probe and the supply unit makes it very easy to use. Multiple fog probes can be combined in a common mount to form a fog rake. Different probe nozzles allows adaptation to various flow speeds.

Fog Probe 2
This is a fog-injection system for aerodynamic flow visualisation in large wind tunnels. The fog quantity can be adjusted and adapted to the air-flow velocity.
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Accessories
A range of accessories are available for the Fog Probe System.
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Seeding generators

Dantec Dynamics offers 3 new seeding generators for LDA and PIV in addition to the existing range of smoke and fog generators.

Liquid Seeding Generator (F02)
This seeding generator produces droplets ideal for PIV and LDA measurements. It is the preferred solution for small to medium size facilities, and where remote control is required.

High volume liquid seeding generator (10F03)

This seeding generator produces droplets ideal for PIV and LDA measurements. It is the preferred solut