Particle-free velocity and temperature field imaging using krypton laser-induced fluorescence.

Area of Science:

• Fluid dynamics
• Laser-based diagnostics
• Spectroscopy

Background:

• Accurate measurement of temperature and velocity in gaseous flows is crucial for understanding fluid dynamics.
• Traditional methods often require seeding particles, which can interfere with flow characteristics.
• Developing particle-free diagnostic techniques is essential for non-intrusive flow analysis.

Purpose of the Study:

• To demonstrate simultaneous, particle-free velocimetry and thermometry in a gaseous flow.
• To utilize krypton (Kr) planar laser-induced fluorescence (PLIF) for non-intrusive flow field measurements.
• To validate the accuracy of the developed Kr-PLIF technique against computational results.

Main Methods:

• Employed krypton (Kr) planar laser-induced fluorescence (PLIF) for flow diagnostics.
• Leveraged spectral properties of Kr absorption profiles to determine temperature.
• Utilized Doppler shift and temperature data to calculate velocity fields.
• Fitted synthetic asymmetric Voigt profiles to measured Kr absorption profiles.

Main Results:

• Achieved time-averaged 2D temperature and velocity fields in a Mach 0.74 turbulent jet.
• Mapped local temperatures by correlating collisional widths from fitted profiles.
• Obtained velocity fields using Doppler shift and temperature data.
• Measured mean temperature fields showed <7% deviation from computed fields.
• Measured velocity fields showed <12% deviation from computed fields.

Conclusions:

• Kr-PLIF is a viable technique for simultaneous, particle-free velocimetry and thermometry.
• The method provides accurate measurements of temperature and velocity in turbulent gaseous flows.
• This non-intrusive approach offers a valuable tool for fluid dynamics research.