Effect of balanced edge cutting configurations on the aeroacoustics of high-speed turbomachinery

Abstract

Abstract Flow-noise corresponding to the balanced edge cutting configurations on the compressor wheel of a turbocharger is investigated in this study. The turbocharger is a type of high-speed turbomachinery that rotates at up to 2.0×105 RPM. Microscopic air bubbles are generated inside the compressor wheel due to inaccuracies in the cast introduced in the production process. These bubbles cause a mass-unbalance phenomenon when operated at high rotational speeds, which even leads to breakage in severe cases. To prevent theses problems, cutting configurations are utilized at various locations on the rear of the wheel. However, the cutting shapes rather produce severe vortices from a flow perspective, which has a significant effect on the flow noise. Therefore, after calculating the steady-state shear stress transport k-ω based on the Reynolds-averaged Navier-Stokes equation model, transient large eddy simulation was conducted from initial values using the commercial computational fluid dynamics software, ANSYS FLUENT V20.2. The flow-noise was calculated based on unsteady analysis data with the Ffowcs-Williams and Hawkings equation. The flow-noise of the balanced edge cutting configurations of turbocharger compressor wheels was calculated according to various receiver points, and rotational velocities. Results show that various noise characteristics occur depending on the rotational speeds and the receivers depending on the cutting configurations.