+ Dr. Jeff Balla + Dr. Paul Danehy + Dr. Reggie Exton + Dr. Greg Herring
		Rayleigh Example 1: Scattering measurements in supersonic facilities + Download Rayleigh Example 2: Planar Rayleigh scattering results in helium-air mixing experiments in a Mach-6 wind tunnel + Download Rayleigh Example 3: Flow Visualization by Elastic Light Scattering in the Boundary Layer of a Supersonic Flow + Download Rayleigh Example 4: Flow Visualization of Density in a Cryogenic Wind Tunnel Using Planar Rayleigh and Raman Scattering + Download Research Interests: Dr. Paul Danehy + Download Publication List: Dr. Herring + Download

Rayleigh Scattering

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

Rayleigh-Based Flow Density Visualization: Four Examples

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