NATIOML ADWEDRY COMNITEB FOR AERONAUTICS INFLUENCE OF BORIC OXIDE DEPOSITIOR ON TLTIIBOJET EmGIKE OPERATIO1p

In aa e f fo r t t o provide a better understanding of the effect of oxide-depositing fuels on engine stazting, operatian, and performance, a modified production turbojet engine waa operated using a trimethyl borate azeatrope as a fuel. Trimethyl borate, a comparatively low-heating-value fuel that forms boric oxide during combustion, was used as a subst i tute f o r the more expensfve and l e ~ s available boron hydride fuels currently under consideration. Operation with trimethyl borate f o r 100.minutes produced a 2-percent de te r iora t ion in engine speed and only a 1-percent increase i n combustor total-pressure loss with the best engine configuration investigated. The deposits had no measurable effect on the turbine efficiency. Following the operation with trimethyl borate fuel, the engine was operated with a hydrocarbon fuel (Jp-4) t o dissfpate the boric oxide deposits. After 50 minutes of operation with JP-4 fuel, the deposits were substantially removed and the engine approached normal operation