High-repetition-rate interferometric Rayleigh scattering for flow-velocity measurements

Area of Science:

• Fluid mechanics
• Optical diagnostics
• Laser velocimetry

Background:

• Accurate high-speed flow velocity measurements are crucial for understanding complex fluid dynamics.
• Existing non-intrusive methods often face limitations in temporal resolution and data acquisition rates.
• Interferometric-Rayleigh-Scattering (IRS) velocimetry offers a promising avenue for advanced flow diagnostics.

Purpose of the Study:

• To implement and demonstrate a high-repetition-rate interferometric-Rayleigh-scattering (IRS) velocimetry system.
• To achieve non-intrusive, high-speed flow-velocity measurements with enhanced temporal resolution.
• To validate the IRS technique in a high-speed jet flow environment.

Main Methods:

• Utilized a quasi-continuous burst-mode laser delivering high pulse energy and repetition rates (10-100 kHz).
• Employed an etalon with an 8-GHz free spectral range for imaging the flow field.
• Captured Doppler shifts of Rayleigh-scattered light using a high-speed camera system.
• Ensured a narrow seed-laser linewidth (< 150 MHz) for precise measurements.

Main Results:

• Successfully implemented and demonstrated high-repetition-rate IRS velocimetry.
• Achieved high temporal resolution for non-intrusive flow velocity measurements.
• Acquired high-repetition-rate image sequences from a high-speed jet, showcasing the technique's capability.

Conclusions:

• High-repetition-rate IRS velocimetry is a viable technique for non-intrusive, high-speed flow measurements.
• The developed system provides high temporal resolution, enabling detailed analysis of dynamic flow phenomena.
• Further applications in various high-speed flow scenarios are anticipated.