A cylindrical shear layer model applied to the semi-infinite jet pipe problem

Area of Science:

• Fluid dynamics
• Acoustics
• Aeroacoustics

Background:

• Acoustic wave propagation in jet pipes is crucial for aeroacoustic engineering.
• Existing models, like rectangular-coordinate or vortex sheet models, have limitations in describing the transitional flow region.

Purpose of the Study:

• To develop a cylindrical shear layer model for analyzing acoustic wave propagation at the exit of a semi-infinite circular jet pipe.
• To improve the accuracy of aeroacoustic predictions, particularly the reflection coefficient.

Main Methods:

• Formulation in cylindrical coordinates based on the Pridmore-Brown equation.
• Development of coupling conditions for the transitional flow region.
• Application to the semi-infinite jet pipe problem under low Mach number and small perturbation conditions.

Main Results:

• The cylindrical shear layer model shows improved agreement with experimental data for reflection coefficients.
• Numerical analysis demonstrates enhanced fidelity compared to previous models.
• The model accurately predicts behavior in configurations with nonzero diffuser angles.

Conclusions:

• The proposed cylindrical shear layer model offers enhanced fidelity for aeroacoustic analysis.
• This model represents a significant improvement over existing shear layer and vortex sheet models.
• The findings have potential applicability to a broad range of aeroacoustic engineering problems.