Performance Assessment of a Prototype Trapped Vortex Combustor Concept for Gas Turbine Application

Abstract

GE Aircraft Engines and the Air Force Research Laboratory have been jointly developing a novel combustor technology concept for potential application in gas turbine engines. This novel combustor concept is known as the Trapped Vortex Combustor (TVC). The GE and AFRL team began work on the design of a prototypical TVC test rig in 1996. This effort represents the extension of earlier AFRL research with the TVC [1,2]. This work led to the fabrication of a 30.5 cm wide rectangular sector test rig capable of operation at inlet pressures up to 20.5 atmospheres, inlet temperatures up to 900 K, and to stoichiometric discharge conditions. Testing of the rectangular sector rig was initiated in mid year 1998. The performance evaluation performed on the test rig covered all aspects of gas turbine combustor performance and operability including ground start ignition, lean blowout, altitude re-light, emissions, combustion efficiency, exit gas temperature profile, and structural metal temperatures. Test rig operating conditions provided simulations of current commercial and military aircraft gas turbine engine cycles as well as some advanced engine cycles, with JP-8 type fuel. Data was also obtained at selected operating conditions for the LM2500 marine Navy duty cycle using DL-1 type fuel. The prototype rig has been operated for a total of approximately 300 run hours. 60 hours of run time at pressures exceeding 13.6 atmospheres and temperatures exceeding 675 K. 12 hours of run time at pressures exceeding 15.3 atmospheres, temperatures exceeding 780 K. Over 700 data points were obtained. The assessment of the demonstrated performance revealed the prototype TVC test rig had exceeded all initial expectations. Demonstrated ignition, blow out, and altitude re-light were up to 50% improved over current technology conventional swirl stabilized combustors. NOx emissions were in the range from 40% to 60% of the 1996 ICAO standard. Combustion efficiency at or above 99% was maintained over a 40% wider operating range than a conventional combustor. The performance and operability achieved with this prototype test rig has clearly demonstrated the validity and potential performance payoffs of the TVC concept. This paper will summarize the TVC rectangular sector test rig configurations evaluated as part of this test program, and the performance and operability achieved.