Transonic Combustion is pioneering the concept of supercritical fuel injection for the internal combustion engine. Application of this technology requires detailed understanding of the fuel injection dynamics, air-fuel mixing processes and combustion characteristics. Experimentation using a pressure vessel with optical access is utilized to provide data for correlating with Computational Fluid Dynamic (CFD) modeling. Once validated, CFD models are powerful tools that support the development of the fuel injection and combustion processes.

Supercritical fuel injection

Injection development necessitates information regarding plume dynamics. High speed images of injection events were thus acquired using optical techniques developed in-house. The left hand image is a shadowgraph of supercritical fuel injected into the high pressure and temperature conditions representative of engine operations. The right hand image has been processed to show only the fuel plume. The white bar tracks the leading edge of the plume to characterize the plume tip velocity for correlation with CFD modeling. This provides information regarding mixture formation which is necessary for combustion development.

CFD supercritical injection model

CFD is a powerful tool for designing and developing combustion systems. Although CFD is a powerful tool, validation of CFD results against experimental data is a necessary step. This video shows the correlation of experimental data (far left) with CFD simulations of supercritical fuel-air mixing. Right three panels show contours of mass fraction of fuel, equivalence ratio, and temperature of the plume. This work has contributed to Transonic’s detailed understanding of the supercritical fuel injection process.

CFD model of ignition delay & combustion

Adding a combustion model to the mixing model is yet another key step. These videos show correlation of CFD simulations with laboratory experiments performed in an optically accessible pressure vessel. The correlation demonstrates good understanding of physical and chemical processes in engine combustion systems involving supercritical fuel injection.

Comparison of fuel plumes at 100C & 300C

This video compares liquid (100C left) to supercritical (300C right) fuel injection with a Transonic injector into a pressurized chamber at 30 bar. Principal differences can be seen in the injection dynamics and the rate of vaporization which lead to better mixture preparation. This creates new opportunities for combustion system optimization.

About the videos

Our videos are produced in-house using a high speed color camera and special optics to photograph activity within a combustion chamber.