Turbojet combustor performance with natural gas fuel

Natural gas fuel f o r advanced turbojet combustor applications was investigated with two swirl-can modular-combustors.In t e s t s at a combustor inlet p r e s s u r e of 45 p s i a (31 N/cm ), inlet t e m p e r a t u r e s of 540' and 1140' F (556 and 889 K) and reference velocities up to 190 f t / s e c (57.9 m/sec).The efficiency of both combustors was n e a r 100 percent f o r inlet a i r t e m p e r a t u r e s of 1140' F (889 K).However, at inlet a i r temp e r a t u r e s of 540' F (556 K), the efficiency of one design decreased rapidly with d e c r e a sing fuel-air ratio.Acoustical instabilities, encountered with both combustors a s initiall: designed, disappeared when t h e blockage a t the module exit plane was sufficiently increased.Altitude blowout and ignition performance was p o o r e r than that of a JP-fueled combustor of s i m i l a r design.Vitiated preheat inlet a i r had a n important a d v e r s e effect on combustion efficiency. 2 18.