LES analisys for forces frequencies evaluation on a diverter

The work is a numerical evaluation of time-dependent phenomena on a regulation valve exerting dynamic actions periodically variable. This is caused by vortices formation and detachment. Forces periodically variable causesdangerous oscillations if frequencies are closed to one of the natural frequencies of the system or probably entails fatigue phenpmena. This situation is typical of combined heat and power plants , where exhaust from gas turbine can be sent to an heat recovery steam generator (HRSG) or by-passed toward a stack, by means of a system called diverter, installed at gas turbine outlet. Numerical simulations have been done for some valve positions and flue gas velocities on a simplified geometric model using LES turbulence model, aiming to gain some guidelines about vortex shedding from a bluff-body (the valve) in a confined flow