Development of a Premixed Combustion Capability for Dual-Mode Scramjet Experiments.

Area of Science:

• Aerospace Engineering
• Combustion Science
• Fluid Dynamics

Background:

• Hypersonic air-breathing engines utilize scramjet combustion, characterized by high-speed, turbulent, reacting flows.
• Simulating and studying these complex combustion environments in labs is challenging, with wind-tunnel tests often prioritizing engine development over fundamental physics.
• Existing research faces difficulties in isolating chemical kinetics and turbulence-chemistry interactions from fuel-air mixing effects.

Purpose of the Study:

• To isolate chemical kinetic effects and turbulence-chemistry interactions in a dual-mode scramjet.
• To investigate the underlying physics of combustion in hypersonic air-breathing engines.
• To establish a controlled experimental environment for studying premixed combustion in scramjets.

Main Methods:

• A novel fuel injection strategy was employed to create a uniform fuel-air mixture at the combustor entrance, enabling premixed combustion.
• A precombustion shock train was utilized to enhance mixing upstream of the combustor.
• A stable flame was successfully anchored on a cavity flameholder within the scramjet combustor.

Main Results:

• Achieved stable premixed combustion in a dual-mode scramjet combustor for the first time.
• The experimental setup successfully isolated chemical kinetic effects and turbulence-chemistry interactions.
• Enabled advanced diagnostic studies using CARS, PIV, and PLIF.

Conclusions:

• The developed experimental capability allows for fundamental studies of scramjet combustion physics.
• This research provides a foundation for understanding and improving hypersonic air-breathing engine performance.
• The successful demonstration of stable premixed combustion opens new avenues for scramjet research.