Characterization and wall compatibility testing of a 40K pound thrust class swirl-coaxial injector and calorimeter combustion chamber

Subscale injector-combustor tests under the NASA Space Transportation Engine Thrust Chamber Technology program measured characteristic velocity (c-asterisk) efficiencies and wall heat fluxes for the pressure range 1710 psia to 2360 psia and for the overall O2/H2 mixture ratio range 5.5 to 6.4. Tests involving radially-uniform mixture ratio profiles produced c-asterisk efficiencies above 99 percent; nonuniform profiles associated with wall durability-enhancement schemes resulted in lower efficiencies. Though all three wall protection methods proved successful at reducing wall heat flux, scarfing of the outer-row, swirl-coaxial injection elements was the technique which resulted in the least debit in c-asterisk per unit reduction in heat flux.