Session: 04-25 Atomization and Spray Combustion I
Paper Number: 123979
123979 - Effects of a 3D-Printed Atomizer Component on Fuel-Spray and Flame Characteristics of a Jet-Stabilized Compact Gas Turbine Combustor Fed With Liquid Fuels
Benefits of employing metal 3d-printing technique, especially laser powder bed fusion, for gas turbine components are significant. It can realize challenging geometries and is time and cost efficient. However, due to the powder-melting and layer-by-layer building process, it is often concerned about the surface quality of printed components. In order to understand effects of rough surface from 3d-printing on realistic applications, spray and flame characteristics using a 3d-printed atomizer component in a jet-stabilized compact gas turbine combustor have been studied. The 3d-printed component is called airblast, and it serves as a wall to collect fuel spray and to form a wall film. It has been recently reported, that the atomization concept using the airblast is very efficient for the jet-stabilized combustion. Therefore, manufacturing the component with 3d-printing has been our interest to further optimize the geometry and to reduce manufacturing time and cost.
Atomization of liquid fuels and combustion process were simultaneously investigated in a lab-scale single nozzle combustor under atmospheric pressure. Droplet distribution and velocity components were obtained by optical shadowgraphy with a double-pulse laser, where the field of view was scanned from the tip of the nozzle to downstream where flame exists. Flame characteristics, e.g., lift-off height and length, were analyzed by high-speed OH* chemiluminescence imaging. Recording at 14 kHz allowed tracing flame propagation from consecutive images. Exhaust gas compositions were measured by an emission probe installed at the exit of the combustor. Major chemical species of hydrocarbon combustion including NOx were probed, and NOx values served as an indicator for large flame temperature change between conditions.
A few parameters of flame conditions apart from the airblast have been consecutively changed: Air jet velocities of 120 and 160 m/s, equivalence ratio (ϕ) of 0.8 and 1.0, lengths of the wall film by changing the injector position from 1 to 2 times the nozzle diameter, and Jet A-1 and heating oil as a fuel. The largest difference between the flames was observed for the equivalence ratio variation. Not only the rapid increase of NOx value at ϕ=1.0 was detected, but it showed also the largest CO emission and shift of the flame position. The shift was about 10 percent of the flame length, defined by 80 percent of the peak chemiluminescence signal intensity. For the fuel variation, larger number of droplets were detected with heating oil than Jet A-1 for all cases.
In general, the 3d-printed airblast resulted in droplet size distributions that is slightly larger than with the machined airblast. In addition, the overall speed of the droplets was slower for the 3d-printed airblast, which is presumably corelated to the size distribution. However, no significant change of flame positions was observed, based on the peak intensities of the chemiluminescence signals. On the other hand, the shape of the flames tended to become compacter with the 3d-printed airblast by reducing the length of its trailing edge. Nevertheless, emission profiles did not exhibit meaningful differences between the airblasts, which indicates that flame temperatures stayed in the similar level regardless of the airblast type.
Presenting Author: Haisol Kim German Aerospace Center (DLR)
Presenting Author Biography: Haisol Kim received a Ph.D. degree of engineering at Combustion Physics of Lund University in Sweden. His Ph.D. work was focusing on developing laser techniques for combustion diagnostics. Investigating lab-scale laminar flames with improved Raman spectroscopy and turbulent flames with high-speed laser-induced fluorescence (LIF) are the main topics of his thesis.
Currently, Haisol Kim is working at the Institute of Combustion Technology of German Aerospace Center (DLR) as a researcher. His project is developing a jet-stabilized gas turbine combustor operating with liquid fuels, employing optical techniques for spray visualization and flame diagnostics.
Authors:
Haisol Kim German Aerospace Center (DLR)Jhon Pareja German Aerospace Center (DLR)
Oliver Lammel German Aerospace Center (DLR)
Effects of a 3D-Printed Atomizer Component on Fuel-Spray and Flame Characteristics of a Jet-Stabilized Compact Gas Turbine Combustor Fed With Liquid Fuels
Paper Type
Technical Paper Publication