Boron carbide combustion in solid‐fuel ramjets using bypass air. Part I : Experimental investigation

Abstract The effects of bypass air on the combustion of highly loaded boron carbide/HTPB fuel grains in a solid‐fuel ramjet motor were investigated experimentally. It was found that combustion efficiency can be significantly increased by employing high bypass rations with low dump momentum. The results indicated that high bypass dump momentum causes the particles to collide with the wall and extinguish. Increasing pressure increased efficiency, apparently through the resulting increased residence time. Increased overall equivalence ratio (grain length) also was found to be beneficial, the result of a smaller percentage of larger particles which are generated in the recirculation zone. Some of the reduction in combustion efficiency was determined to be due to incomplete combustion of the HTPB rather than just to the incomplete burning of the boron carbide particles.