Flow field in a gas turbine burner

Abstract: This report presents a numerical investigation of diesel fuel spray
combustion in SGT-800 gas turbines with ANSYS CFX 11.0. The gas turbine
SGT-800 has thirty burners and each burner has four fuel injectors. In this
thesis just a quarter of one burner is simulated. The main objective is to
get the diesel spray combustion simulation to work and set a frame work for
future investigation.

Spray consists of two fundamental and consecutive steps: the primary breakup
and the secondary breakup. The Blob method is used to model primary breakup
and secondary breakup is modeled by Cascade Atomization and Breakup model
(CAB). The trajectory and velocity of generated fuel droplets is determined
by Lagrangian Particle Tracking.

Fuel evaporation is modeled by simulating the mass and heat transfer of
generated fuel droplet. The mixing of evaporated fuel with air and combustion
of combustible mixture is modeled by multicomponent flow formulation.

Burning Velocity Model (BVM) is used to simulate combustion. Flamelet Library
for diesel fuel is generated by a special version of CFX-RIF. In order to
speed up simulations the reduced Flamelet Library is used.

At the end a parameter study is performed to find out important parameters on
the fuel concentration field. Studied parameters are working conditions (part
load and over load), injection direction (axial and angled injection),
injector diameter, fuel surface tension, secondary breakup models, turbulence
model and mesh.

Also, experiments and their corresponding simulation with ANSYS CFX are done
in order to predict droplet distribution size after injection. In this study
water is used instead of diesel.