Two-dimensional visualization of liquid layers on transparent walls.

Area of Science:

• Optical diagnostics
• Combustion analysis
• Internal combustion engines

Background:

• Understanding liquid-fuel film dynamics is crucial for optimizing combustion efficiency and reducing emissions in engines.
• Previous visualization methods for fuel films in engines have limitations in resolution and applicability.

Purpose of the Study:

• To introduce and validate a new two-dimensional visualization technique for studying liquid-fuel films on transparent engine walls.
• To demonstrate the technique's capability in observing wall-film formation and behavior within an SI engine.

Main Methods:

• A novel visualization technique utilizing laser-induced fluorescence was developed.
• Optical access to the SI engine cylinder was achieved by replacing the upper part with a quartz ring.
• An UV laser beam was coupled into the quartz ring, utilizing total internal reflection.
• Laser light penetration into the liquid fuel was enabled by the similar refractive indices of quartz and fuel.
• Fluorescence signals were captured to visualize the presence and extent of fuel wall films.

Main Results:

• The technique successfully visualized two-dimensional liquid-fuel films on the transparent cylinder walls.
• The method demonstrated the ability to observe the development and distribution of fuel films during engine operation.
• The fluorescence signal accurately indicated areas where the fuel wall film was present.

Conclusions:

• The developed laser-induced fluorescence technique is an excellent tool for investigating liquid-fuel wall-film development in combustion engines.
• This visualization method provides valuable insights into fuel-wall interactions, aiding in engine design and performance optimization.