Imaging Aluminum Particles in Solid-Propellant Flames Using 5 kHz LIF of Al Atoms.

Area of Science:

• Combustion Science
• Materials Science
• Spectroscopy

Background:

• Aluminized solid propellants are crucial for rocket propulsion.
• Understanding the combustion behavior of aluminum particles is key to optimizing propellant performance.
• Spatio-temporal analysis of combustion products is essential for detailed flame studies.

Purpose of the Study:

• To investigate the spatio-temporal behavior of aluminum atoms during aluminized solid propellant combustion.
• To analyze the dynamics of aluminum particles and flame evolution using advanced imaging techniques.
• To quantify gaseous distribution and particle detachment phenomena.

Main Methods:

• Laser-induced fluorescence imaging of aluminum atoms (Al-PLIF) was employed.
• Alternating LIF and chemiluminescence images captured particle phases (gaseous and liquid).
• High-speed imaging (5 kHz) enabled droplet velocity measurements and detailed analysis.

Main Results:

• Al-PLIF successfully tracked flame dynamics near particles up to 1.5 MPa.
• Observed plume structures aligned with alumina formation predictions and shadowgraphy.
• The aluminum vapor phase extended 3-6.5 radii around molten particles.
• Particle detachment dynamics above the propellant surface were visualized.

Conclusions:

• Al-PLIF is a sensitive method for studying aluminized propellant combustion.
• The study provides detailed insights into aluminum particle behavior and flame structure.
• High-resolution imaging reveals crucial information about vapor phase distribution and particle dynamics.