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Rayleigh Scattering rayleigh scattering

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  molecular based flow diagnostics subheading   relevant links

Rayleigh Example 1:
Scattering measurements in supersonic facilities
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Rayleigh Example 2:
Planar Rayleigh scattering results in helium-air mixing experiments in a Mach-6 wind tunnel

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Rayleigh Example 3:
Flow Visualization by Elastic Light Scattering in the Boundary Layer of a Supersonic Flow

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Rayleigh Example 4:
Flow Visualization of Density in a Cryogenic Wind Tunnel Using Planar Rayleigh and Raman

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Research Interests: Dr. Paul Danehy
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Publication List: Dr. Herring
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Rayleigh Scattering

Single point or planar measurements of gas velocity and/or density in non-seeded, high speed flows.

Rayleigh Graphic


Rayleigh Scattering Measurement Technique


Rayleigh-Based Flow Density Visualization: Four Examples

Rayleigh Scattering Measurement Technique

Example 1: Hypersonic

  1. Hypersonic airflow at Langley’s High-Temperature, Mach-6 Tunnel
  2. ArF-excimer laser at 193 nm
  3. No seeding required
  4. Comparison of stream-wise CFD image & 5-sec-average Rayleigh measurements in flow over right-circular cylinder


Example 2: Scramjet

  1. Hypersonic airflow at Langley’s High-Reynolds Number, Mach-6 Tunnel
  2. ArF-excimer laser at 193 nm
  3. Fuel injection simulated with He
  4. Instantaneous visualization of He-air mixing with 10-nsec laser light sheets (transverse to stream-wise direction)


Example 3: Supersonic

  1. Supersonic airflow at Langley’s Unitary Plan Wind Tunnel (Mach-2.5)
  2. Nd:YAG laser at 532 nm
  3. No seeding required
  4. Instantaneous visualization of upper region (~ 1-2 cm off surface) of turbulent boundary layer
    with 10-nsec pulses


Example 4: Subsonic

  1. Subsonic pure N2 flow at Langley’s 0.3-Meter Transonic Cryogenic Tunnel (5 amagat, 100 K)
  2. Nd:YAG laser at 532 n
  3. Executed with and w/o CO2 seeding
  4. Instantaneous visualization of uniform-density free-stream with 10-nsec pulses suggests that the laser light sheet is randomly perturbed by turbulent boundary layer of sidewall



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