Single-phase aerodynamic flow field validation of novel airblast atomizer designs

Airblast atomizers are used extensively in aero gas turbine engines. In the pursuit of reducing emissions and increasing fuel efficiency a novel airblast atomizer design is being developed that is capable of variable fuel-placement. Such a design will create two independently fuelled zones, a pilot and a main that can be optimised for fuel efficiency, emissions and stability throughout the flight envelope. The airflow and spray structure of three designs have been investigated experimentally using Phase Doppler Anemometry (PDA) to determine the size and direction of their respective recirculation regions. The experiments were performed isothermally and under atmospheric conditions. Axial air velocity profiles were obtained at a number of radial and axial positions downstream of the injectors. Findings show that all three devices have two independently fuelled regions and two of the devices have very similar flow structures despite their geometrical differences. The three airblast atomizers were also modelled using the commercial Computational Fluid Dynamics package (CFD) CFX. The devices were modelled isothermally in order to validate the CFD models using the PDA data. Qualitatively the CFD captured the flow profiles for the three devices, and there was also good quantitative agreement especially in the downstream regions for two of the devices