Computational fluid dynamics simulation of sound propagation through a blade row

Area of Science:

• Acoustics
• Fluid Dynamics
• Computational Science

Background:

• Understanding sound propagation in blade rows is crucial for noise reduction in turbomachinery.
• Existing numerical methods require validation for complex aeroacoustic interactions.

Purpose of the Study:

• To numerically investigate sound wave propagation through a blade row.
• To assess the accuracy of computational fluid dynamics (CFD) methods for aeroacoustic simulations.
• To analyze the influence of flow parameters and blade geometry on sound propagation.

Main Methods:

• A wave splitting method was developed for sound wave analysis in a 2D duct with mean flow.
• Unsteady Reynolds-averaged Navier-Stokes (URANS) equations were solved to simulate sound propagation through a flat plate blade row.
• CFD-derived transmission and reflection coefficients were compared with semi-analytical results.

Main Results:

• The study identified that low-order URANS schemes introduce significant errors at sound pressure levels below -100 dB.
• CFD simulations demonstrated sufficient precision for sound wave-blade row interactions when boundary reflections were minimal.
• The accuracy of CFD was validated against semi-analytical predictions for acoustic transmission and reflection.

Conclusions:

• Numerical simulations provide valuable insights into sound propagation through blade rows.
• CFD accuracy is sensitive to sound pressure levels and boundary conditions.
• Flow Mach number, blade thickness, and turning angle significantly affect sound wave propagation characteristics.