Fiber-based high-speed 3D schlieren imaging.

Area of Science:

• Optical diagnostics
• Fluid dynamics
• Combustion science

Background:

• Traditional schlieren techniques often lack the speed and dimensionality to capture transient combustion phenomena.
• Understanding dynamic ignition processes requires high-resolution, time-resolved visualization methods.

Purpose of the Study:

• To demonstrate a novel high-speed three-dimensional (3D) schlieren technique.
• To apply this technique for visualizing turbulent flames and dynamic ignition processes.
• To enable time-resolved measurement of ignition kernel properties.

Main Methods:

• Integration of fiber imaging, Toepler's lens-type schlieren, and computed tomography (CT).
• Utilized a single high-speed camera, xenon lamps, and fiber bundles for multi-angle image acquisition.
• Achieved framerates exceeding tens of kHz for capturing rapid events.

Main Results:

• Successful demonstration and validation on turbulent premixed and stable laminar flames.
• Captured time-resolved 3D structures and edge speeds of ignition kernels.
• Showcased the technique's flexibility, high speed, and low cost compared to existing methods.

Conclusions:

• The developed high-speed 3D schlieren technique offers a powerful new tool for combustion research.
• Enables detailed analysis of transient phenomena like flame ignition.
• Provides fundamental insights into dynamic combustion processes with high temporal and spatial accuracy.