High-speed (20  kHz) digital in-line holography for transient particle tracking and sizing in multiphase flows

Area of Science:

• Fluid Dynamics
• Combustion Science
• Optical Metrology

Background:

• Digital in-line holography (DIH) is a powerful technique for 3D particle sizing and velocimetry.
• Traditional DIH faces challenges with depth-of-focus, limiting accuracy for dynamic events.
• Quantifying transient phenomena like fragment formation and combustion particle dynamics requires high-speed, accurate measurement methods.

Purpose of the Study:

• To apply high-speed (20 kHz) DIH for 3D quantification of fragment size and velocity.
• To address the depth-of-focus issue in DIH using a novel multiframe tracking algorithm.
• To evaluate the method's effectiveness for measuring particle mass flow rates in combustion.

Main Methods:

• Implemented high-speed (20 kHz) digital in-line holography (DIH).
• Employed a regression-based multiframe tracking algorithm to overcome depth-of-focus limitations.
• Applied the technique to analyze water drop impact fragments and burning aluminum particles.

Main Results:

• Achieved an order-of-magnitude improvement in out-of-plane displacement accuracy.
• Demonstrated superior positional accuracy and detailed resolution of transient dynamics compared to low-speed DIH.
• Successfully quantified particle mass flow rates within 8% of expected values for investigated fields.

Conclusions:

• High-speed DIH with multiframe tracking offers significant advancements in 3D dynamic particle analysis.
• The method provides accurate quantification of transient phenomena and particle mass flow rates.
• This technique is highly advantageous for studying high-speed events in fluid dynamics and combustion.