Advanced Demonstration of Fuel Injector/Flameholder for High Speed Ramburners.

Abstract : The combustion efficiency of ramburner technology is mixing-limited. Therefore, significant gains are possible if the fuel-air mixing can be increased without a significant increase in pressure loss or a decrease in flame stability. Several design concepts were explored in this report that increase the fuel-air mixing by generating large axial vortices downstream of the flameholder. The baseline flameholder for this project was the Integral Fuel Injector/Flameholder (1FF) used in previous studies by United Technologies Research Center (UTRC). CFD solutions were completed on the baseline design and 28 advanced configurations. Most designs did improve fuel-air mixing, but also increased the cold pressure loss by several fold. The most promising designs used the momentum of the fuel to contribute to the axial thrust, thereby reducing the pressure loss. Isothermal experimental tests were conducted at Wright laboratory in parallel with CFD analysis. A complete data set was taken for one baseline model, while several advanced models were screened for pressure loss. The baseline tests showed that a regular pattern of alternating vortices were shed from the base of the flameholder.