Large Eddy Simulation of Aeroacoustic Coupling in a Confined Wind-Concentrating Turbine: Modulating Tip Clearance Flows via Trailing-Edge Interventions

This study investigates trailing-edge serrations (TES) to attenuate noise in shrouded wind-concentrating turbines. Using Large Eddy Simulation (LES) and the FW-H analogy, we analyse flow-acoustic mechanisms under strong Venturi acceleration. Results reveal that TES significantly attenuates noise not only by disrupting spanwise wake coherence but also through a specific ‘spanwise pumping effect’ observed in this highly confined geometry. Driven by local pressure-gradient redistribution, this mechanism generates a noticeable spanwise mass flux that suppresses intense Tip Leakage Vortices (TLV) before they strongly interact with the inner shroud wall. For the optimal TES-W2H4 configuration, despite a marginal 0.28% decrease in the lift-to-drag ratio, the overall power coefficient remains approximately unchanged within the present numerical resolution (with a negligible variance of +0.22%). This design achieves a 2.29 dB overall noise reduction and reduces core broadband noise (300–1000 Hz) by 2.14 dB. Ultimately, TES balances aerodynamic efficiency and aeroacoustic performance.