SPRAY CHARACTERISTICS MEASURED IN A NEW FLOX BASED LOW EMISSION COMBUSTOR FOR LIQUID FUELS USING LASER AND OPTICAL DIAGNOSTICS

摘要

A liquid fuel combustor based on the FLOX burner concept has been developed for application in a Micro Gas Turbine (MGT) Range Extender (REX) for next generation cars. The characterization of this combustor was performed at the High Pressure Optical Test rig (HIPOT) at DLR Stuttgart. The operability limits of the burner were mapped out for full load conditions at 3.5 bars by varying global lambda (λ_G) from 1.25 - 2.00 and bulk jet velocity (V_(Bulk)) from 80 - 140 m/s. Exhaust gas measurements show NO_x and CO levels below 5 and 10 ppm respectively (corrected for reference 15% O_2) at λ_G = 1.89. Optical and laser diagnostic measurement techniques have been employed to characterize the spray flames. The flames at stable burner operation points (BOPs) show a predominantly jet like flame shape irrespective of λ_G and V_(Bulk). Droplets in the size range 2-40 μm have been measured close to the nozzle exit plane. Velocities conditioned on the droplet size show large droplets d > 15 μm transitioning from negative slip velocity at the exit plane to positive slip velocity at downstream location. The positive slip velocities and slow evaporation of large droplets lead to droplets travelling further into the combustion chamber and hence resulting in long flames. A comprehensive data set for the spray characteristic of the new liquid FLOX burner is made available.