Simultaneous two-plane flame front detection using PIV based on defocusing.

Area of Science:

• Combustion science
• Optical diagnostics
• Fluid dynamics

Background:

• Accurate flame front detection is crucial for understanding combustion processes.
• Existing methods often lack the ability to capture multi-plane flame dynamics simultaneously.
• Particle Image Velocimetry (PIV) is a standard technique for flow visualization.

Purpose of the Study:

• To develop a simultaneous two-plane flame front detection method.
• To enhance the capabilities of standard single-camera PIV systems.
• To enable detailed analysis of turbulent flame structures in three dimensions.

Main Methods:

• Utilized a standard single-camera PIV system.
• Incorporated an inexpensive, compact image splitting device to capture two depth-offset planes.
• Employed a shallow depth of field to ensure focus on distinct planes.
• Developed a novel two-step filtering process to remove out-of-focus images.

Main Results:

• Successfully detected turbulent flame fronts on two separate planes simultaneously.
• Effectively removed out-of-focus particle images using the developed filtering technique.
• Maintained high in-plane spatial resolution comparable to single-plane measurements.

Conclusions:

• The proposed method enables simultaneous multi-plane flame front detection.
• This technique is suitable for practical combustion devices with limited optical access.
• It can be combined with polarization/wavelength discrimination for advanced flame reconstruction.