Fluid–dynamic analysis of a multi–blade gravity damper

This paper addresses a computational fluid–dynamics study of a multi–blade inlet damper for gas turbine power plants. This device is used in the aspiration duct of the aforementioned plants with the aim to control the air mass flow rate, to dump flow turbulence and to guarantee the plant security. Nowadays the flat plate is the standard shape for damper blades. Clearly the device is rather simple but the operating conditions may prove burdensome. This is related to the vortex shedding developing behind the damper blades. If the shedding frequency of the vortices is close to the resonance frequency of the structure it generates a synchronism that involves the oscillation growth. This can lead to the structure damage. In this research work we have devised a new airfoil shaped blade for inlet dampers in order to suppress the vortex shedding phenomenon behind the damper blades. A proper numerical analysis of the damper blades pitching stability requires to solve a two-way fluid–rigid body interaction problem. Moreover the overset mesh method is strictly needed to investigate the blades motion due to aerodynamic interactions; as a matter of fact other techniques cannot be advocated for this problem since blades closure requirements produce the overlap of moving zones. For this reason we have developed a specific approach, based on the above mentioned techniques, to investigate the dynamic behaviour of the blades of a inlet damper. The obtained results show as the new blades have a very good pitching stability. © 2017 Elsevier Ltd