Abstract
Gas turbines require filtered air to preserve operability, availability, and efficiency. Fouling, corrosion, and erosion severely affect the performance of the axial compressor and it can be in part prevented by filtering the air intake. For this reason, it is possible to use multiple filter stages in series to obtain a high level of capture efficiency. Traditionally, separation is achieved using porous material cartridges, which guarantee a high level of filtration but with an increasing pressure drop over time. Another common type of filter is the inertial one, whose operating principle is based on the inertial force acting on the solid particles to separate them from the mainstream. The capturing efficiency of the inertial filter is not comparable with that of the porous one, so it is used upstream as a pre-filter. In recent years, another technique has been developed to filter air flows thanks to an electrostatic field induced inside the flow. In the present work, numerical investigations are carried out to simulate the effect of the electrostatic force on gas turbine filtering systems. The CFD tool used is OpenFOAM, whose official release does not contain a library able to simulate the electrostatic force acting on the discrete phase. A new library was developed to calculate: the electric field, the electric potential, and the charge density of the continuous phase. Simulation results show how the calculation of these quantities allows us to predict the electrostatic force acting on particle flows in the presence of electrostatic fields