A Numerical Analysis of Flat-Fan Spray Injection into Coflow of Air

The online water washing technology refers to the injection of water spray into the intake air in land-based gas turbine engines to clean the compressor blades fouled due to air-borne dirt deposition. In such a case, typically, a series of flat-fan nozzles are employed at the engine bell mouth. The present research work focuses on the multi-phase simulation of the spray injected from a single flat-fan atomizer into coflowing air within a wind tunnel configuration. The simulations are carried out using Ansys Fluent based on a coupled Eulerian–Lagrangian framework. The discrete phase model (DPM) is adopted to track droplets, whilst the primary breakup, secondary atomization, droplet drag, evaporation and collision are suitably modelled. The numerical results are validated against in-house experimental data. The simulations are carried out for a wide range of coflow air velocity (0–70 m/s) for the same injected liquid volume flow rate. The preheated liquid injection is also considered. The spray tends to be narrower and the cone angle decreases with an increase in coflow air velocity. The axial evolution of spray characteristics (including characteristic droplet size, velocity and temperature) downstream of the injector exit is studied for different operating flow conditions mentioned above.