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Laser-Induced Thermal Acoustics (LITA)

  • Nonintrusive flow diagnostic

  • Two Versions:

    Resonant
    (absorption, followed by instantaneous gas heating)

    Nonresonant
    (electrostriction
    instantaneous formation of sound waves) - no seeding required

 

Summary of LITA:

What is LITA ?

  • Nonintrusive laser-based flow diagnostic
  • Close cousin of degenerate four-wave mixing (DFWM)
  • Measurements based on Doppler shifts and laser beam absorption

What does LITA do?

  • Measures flow velocity, sound speed, static pressure, & translational temperature -simultaneously from same sample volume
  • ~ 1-cm spatial resolution
  • ~ 1-μsec time resolution


Characteristics of LITA

We are pursuing non-resonant LITA (i.e. purely electrostrictive). It will work in any gas, but requires powerful lasers

LITA can make high-precision, high accuracy, 1-μsec duration measurements without seeding or inserting traditional probes

 

LITA Thermometry Results

LITA Thermometry Results

 

Schematic of Typical Wind Tunnel Setup

Schematic of Typical Wind Tunnel Setup

 

Wind Tunnel Results from Two Facilities

  • Subsonic: Basic Aerodynamic Research Tunnel (BART)
  • Supersonic: Unitary Plan Wind Tunnel (UPWT)

Wind Tunnel Results from Two Facilities

 

Wind Tunnel Results from Two Facilities

 

 

   
 
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NASA Official: Lisa Le Vie
Page Curator: Lisa Le Vie
Last Updated: March 2022
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