Injectant mole-fraction imaging in compressible mixing flows using planar laser-induced iodine fluorescence

Area of Science:

• Fluid Dynamics
• Optical Measurement Techniques

Background:

• Compressible mixing flows are critical in various engineering applications.
• Accurate measurement of species distribution is essential for understanding mixing dynamics.
• Existing techniques often face challenges in thermodynamic dependency.

Purpose of the Study:

• To develop and demonstrate a novel technique for quantitative imaging of injectant mole-fraction distribution.
• To overcome thermodynamic dependencies in fluorescence-based measurements.
• To enable direct visualization and study of mixing in nonreacting compressible flows.

Main Methods:

• Utilizing planar laser-induced fluorescence of seeded iodine in air.
• Employing a broadband argon-ion laser for excitation.
• Using an intensified charge-injection-device (ICCD) array camera for image collection.
• Implementing a ratioing technique with two images under identical flow conditions but different seeding.

Main Results:

• Achieved the first quantitative planar measurements of mole-fraction distributions in nonreacting compressible flow fields.
• Successfully eliminated thermodynamic dependence of iodine fluorescence.
• Provided direct visualization of mixing processes.

Conclusions:

• The developed technique offers a robust method for quantitative mole-fraction measurements in compressible mixing flows.
• This advancement allows for direct and accurate study of mixing phenomena.
• The technique has significant implications for aerodynamic and propulsion research.