Seeding Generators

Liquid Seeding Generator (top left), Powder Seeding generator (top right), High Volume Liquid Seeding Generator (bottom left), Helium Filled Soap Bubble generator (bottom right).

Seeding particles are essential to all LDA and PIV measurements and in most applications, liquid or solid particles must be added to obtain high quality measurements.

We recommend Helium-Filled-Soap-Bubble (HFSB) generators for Planar or Tomographic PIV and PTV in large measurement volumes.

For LDA, PIV or tomographic PIV and PTV with smaller fields of view, liquid and powder seeding generators are suitable.

For LDA and flow visualization, fog generators are available.

Selecting the right type of seeding

Selecting a seeding generator requires finding a compromise between signal amplitude and the particles ability to follow the flow. Larger particles will increase signal quality and 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.

HFSB, Liquid and Powder Seeding Generators

ModelParticle DescriptionApplications
Helium-Filled Soap Bubble Generator
10F10
Helium filled soap bubbles 300-500 µmPlanar or Tomographic PIV and PTV in large area or volume.
Liquid Seeding Generator, 10 Bar back pressure
10F02
Oil droplets
~3 µm
PIV and LDA
High Volume Liquid Seeding Generator, 3 Bar back pressure
10F03
Oil droplets
~3 µm
PIV and LDA in large wind tunnels
Powder Seeding Generator, 10 Bar back pressure
10F01
Aluminum oxide or titanium dioxide particles ~0.3 µmPIV and LDA in high temperature applications, e.g. combustion

Fog Generators

Flow 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 on a common mount to form a fog rake. Different probe nozzles allows adaptation to various flow speeds.

Flow visualization using 8 fog probes in an automotive wind tunnel. Courtesy of China Automotive Engineering Research Institute Co., Ltd.
Flow visualization using eight fog probes in an automotive wind tunnel. Courtesy of China Automotive Engineering Research Institute Co., Ltd.

Fog Probe NS4

This is a fog-injection system for aerodynamic flow visualization in large wind tunnels. The fog quantity can be adjusted and adapted to the air-flow velocity. The fog probe NS4 is available for 220V 50 Hz line power only.

image of fog probe system

Accessories

A range of accessories are available for the Fog Probe System.

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.

image of fog generators

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.

Fog generator: 195 SG-D

The system for applications requiring fog in very large quantities.

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.

Data Sheets and Literature

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