Ultra-Violet Iodine Planar Laser-Induced Fluorescence
(UV I2 PLIF)

Space Shuttle Return-to-Flight Project
Fundamental Supersonic/Hypersonic Cavity Flow Physics Study

Goals: Cavity Damage Risk Assessment CFD verification

Method: UV-excited Iodine PLIF

Measurements: gas temperature + density

Flow visualization of flow structures

Type: Off-body point + line

Spatial Resolution: < 0.1mm

Cavity model in Mach 6 tunnel with laser sheet

UV Iodine PLIF

• Iodine Cordes bands based Optical Diagnostic
• Quantitative Measurements
  - Density of any gas (Ex. N₂, Air, CF₄, SF₆, He)
  - Temperature (250-1000K)
• - Single laser pulse (20 ns) capability
  - Point or Line
  - 50 um resolution over 1 cm line
  - 1-30 Torr pressure range
  - Uncertainties (10% instantaneous, <5% average)
• Quantitative Flow Visualization
  - Any pressure range
• Trace iodine quantities (10¹² – 10¹⁴ molecules/cm³)

UV Iodine PLIF Based Flow Visualization Behind a Right
Circular Cylinder in the LaRC 15" Mach 6 Windtunnel