100-kHz Interferometric Rayleigh Scattering for multi-parameter flow measurements.

Area of Science:

• Fluid Dynamics
• Optical Measurement Techniques
• Aerodynamics

Background:

• Accurate flow characterization is crucial for understanding complex aerodynamic phenomena.
• High-speed, multi-parameter flow measurement techniques are essential for studying unsteady and turbulent flows.
• Existing methods often lack the spatial and temporal resolution required for detailed analysis.

Purpose of the Study:

• To demonstrate simultaneous multi-point, multi-parameter flow measurement using Interferometric Rayleigh scattering (IRS).
• To achieve high temporal resolution (100 kHz) for capturing rapid flow dynamics.
• To validate the technique's applicability in studying challenging flow conditions like choked jets.

Main Methods:

• Utilized a burst-mode laser and an un-intensified high-speed camera to capture interferograms.
• Developed and described methods for analyzing interferograms to extract spatial, temporal, and scattered light frequency information.
• Applied the Interferometric Rayleigh scattering (IRS) technique to a choked, under-expanded jet flow from a convergent nozzle.

Main Results:

• Successfully demonstrated simultaneous multi-point flow velocity and temperature measurements at a 100-kHz repetition rate.
• Obtained detailed interferograms containing rich spatial, temporal, and frequency information.
• Presented measurement results and discussed associated uncertainties for the studied jet flow.

Conclusions:

• The 100-kHz Interferometric Rayleigh scattering (IRS) technique with un-intensified imaging is a viable method for flow diagnostics.
• This technique is applicable to large-scale wind tunnels for the investigation of unsteady and turbulent flows.
• Enables high-resolution characterization of complex aerodynamic phenomena.