Seeding Particles

For different flow applications proper seeding tracers are needed. Depending on the application LaVision is offering several solid particles and liquids to be used in suitable seeding devices.
The tracers are characterised by sufficient light scattering, perfect signal quality and very good traceabilty to the flow.

Applications:

  • air
  • flames/combustion
  • liquids

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Seeding in air

HFSB soap fluid
The soap fluid is a colourless fluid for generating soap bubbles at an extremely high rate. Soap fluid and the corresponding seeding device are used especially where a big amount of particles are needed e.g. in wind tunnels and/or large scale PIV measurements. A proper seeding device is needed.

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DEHS
DEHS is an odourless and colourless liquid. It´s insoluble in water and the droplets have a long lifetime. For generating particles a proper seeding device is needed.

  • small density of 0.91 g/cm³
  • particle mean size less than 1 µm by using a LaVision seeding device



Fog fluid
Fog fluid is an odourless fluid. For generating particles a proper seeding device is needed. Fog fluid and the corresponding seeding device are used especially where a big amount of particles are needed e.g. in wind tunnels.

  • small density of about 1.05 g/cm³
  • short lifetime
Product
Amount
HFSB Soap fluid 0.95 l
DEHS 0.5 l
DEHS 5 l
Fog fluid 5 l

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Seeding in flames/combustion

Aerosil
Due to its very porous structure of the agglomerated particles Aerosil is an ideal seeding material for PIV applications in combustion research:

  • primary particle size is 12 nm, agglomeration size in air several microns
  • very small density of 0.05 g/cm³ due to the “snow flake” structure of these particles
  • less velocity leak even in strongly accelerated flows
  • it can be used in hot gaseous environments with a temperature of up to 1800°C.

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Titanium dioxide
LaVision’s Titanium Dioxide is a surface treated, hydrophobic, highly insoluble and thermally stable material. Due to its submicron mean size and nanopowder form TiO2 is an ideal seeding material for PIV applications in combustion research:

  • the particles lead to a strong scatter of the laser light
  • particle size in clusters > 250 nm
  • density 3.9 – 4.2 g/cm³
  • highly insoluble and thermally stable up to 1800 °C
  • low agglomeration due to hydrophobic surface

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Graphite:
Due to its lubricating properties graphite particles offered by LaVision are an ideal seeding material for PIV applications in engines.

  • the particle size of several microns leads to a strong scatter of the laser light, particle mean size 3.5 µm
  • density 2.2 g/cm³
  • non-inflammable, only glowing
  • ignition temperature >450 °C
  • very good stability against pressure
Product
Amount
Aerosil 1 l
Titanium dioxide 0.5 kg
Graphite 0.5 kg

All these particles require a proper seeding device.

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Seeding in liquids

Polyamide particles
Due to its almost perfectly spherical particle shape the polyamide particles offered by LaVision are an ideal seeding material for PIV applications in liquids. A safe handling with these particles is guarenteed because of their non-toxic, non-water polluting nature.

  • the particle size of several microns leads to a strong scatter of the laser light
  • particle density close to water density
  • very good stability against e.g. water, fuel, oil
  • particle mean sizes, 20 µm, 55 µm, 100 µm
Product
Amount
Polyamide particles, 20 µm, 1.2g/cm³ 0.5 kg
Polyamide particles, 55 µm, 1.2g/cm³ 0.5 kg
Polyamide particles, 100 µm, 1.1 g/cm³ 0.5 kg
Polyamide particles HQ, 20 µm, 1.03g/cm³ 0.5 kg
Polyamide particles HQ, 60 µm, 1.03g/cm³ 0.5 kg

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Glass hollow spheres:
Glass hollow spheres are borosilicate glass particles with a spherical shape and smooth surface. Silver coated (SC) ceramic hollow spheres are available as well.

  • the particle size of several microns leads to a strong scatter of the laser light
  • very good stability against e.g. water, fuel, oil
Product
Amount
Glass hollow spheres, 9-13 µm, 1.1g/cm³ 0.5 kg
Glass hollow spheres SC, 10 µm, 1.7 g/cm³ 0.5 kg
Ceramic hollow spheres (SC), 100 µm, 1.1 g/cm³ 0.5 kg

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Fluorescent particles:
Fluorescent seeding particles are based on melamine resin, polystyrene or PMMA.
The fluorescent dye (Rhodamine B or Rhodamine 6G) is homogeneously distributed over the entire particle volume. Especially in PIV applications with a high background light level fluorescent seeding particles can enhance the signal to noise ratio. The optics of receiving devices must be equipped with a suitable filter centered on the corresponding wavelength. For µPIV applications the fluorescence is essential to separate the particle signal from the background scatter light. To separate the light emitted from the particles an epi-fluorescent microscope with filter cube is required.

  • Melamine resin density 1.51 g/cm³, temperature stability up to 300 °C
  • Polysterene (PS) density 1.05 g/cm³, temperature stability up to 100 °C
  • PMMA density 1.19 g/cm3, temperature stability up to 85 °C
Product
Amount
PS, Rhodamine 6G, 0.3 µm 15 ml
PS, Rhodamine 6G, 0.5 µm 15 ml
PS, Rhodamine 6G, 0.9 µm 15 ml
PS, Rhodamine 6G, 2.0 µm 10 ml
PS, Rhodamine B, 2.0 µm 10 ml
PS, Rhodamine B, 1 - 20 µm 1 g
Melamine, Rhodamine B, 10 µm 10 ml
PMMA, Rhodamine B, 1-20 µm 1 g
PMMA, Rhodamine B, 20-50 µm 1 g