Experimental investigation on acoustic effects of geometrical modifications of splitter attenuators for power generation systems

High end splitter-type silencers represent the object of the present paper, that summarizes the results obtained in an experimental campaign conducted in the framework of FlowAirS Project - ITN FP7, Marie Curie Actions. Sound measurements on several fully functional splitters scaled 1:3 with Mach and Reynolds number similarity to the typical conditions in gas turbine exhaust stack have been performed. Different trailing edge shapes including tapered and serrated extensions have been tested. Only moderate changes in the measured noise have been found, despite a reduction of the total pressure loss that can be achieved by appropriate design of the splitter trailing edges. Considerable effects due to the covering perforated plate have been found. The results are analyzed applying Nelson and Morfey's theory for obstacles in ducts, the scaling provides a good data collapsing, in particular for the frequencies above the cut-on.