NACA RM E54H16 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS ALTITUDE PERFCRMANCE OF PENTABORANE- JP-4 FUEL BIJEPTDS

The combustion character is t ics of several pentaborane- JP-4 (MIL-F-5624A) f u e l blends in a turbo je t combustor were investigated at simulated f l i g h t conditions of 100-percent ra ted engine speed and a l t i-tudes of 44,000, 48,000, and 61,000 f ee t. The combustor consisted of a standard 547 combustor housing and l iner, and w a s f i t t e d with a dual-f u e l injector t ha t perqi t ted variation of the f u e l composition i n the combustor. The combustion performance of JP-4 f u e l and blends of 27 and 66.8 percent pentaborane by weight w a s examined. Combustion efficiency with the blends w a s from 6 percent higher t o 2 percent lower than for Jp-4 alone. Relat i re ly large quant i t ies of boron oxide were deposited on the These deposits did not combustor walls f o r the short test durations. appear t o have reached an equilibrium thickness. the deposits were removed by subsequent operation on JP-4 over periods of 30 minutes at combustor ou t le t temperatures of 1550 ' F. Only small amounts of Despite the performance deficiencies noted, the combustor appeared suitable fo r the purpose f o r which it was developed; namely, to- permit combustor Spec a short-duration tes t of ' a 547 engine employing this type and fuel of various pentaborane- JP-4 blends