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Impedance eduction method based on multiple measurements with different incident modes in cylindrical ducts with
Haoyu Kuai1, Kang Gao1, Weikang Jiang1
1State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China.
The Journal of the Acoustical Society of America
|July 15, 2026
Summary
This study extends the impedance eduction method for acoustic liners to cylindrical ducts. The new method accurately measures acoustic impedance in real engines, considering higher-order modes.
Area of Science:
- Acoustics
- Fluid Dynamics
- Mechanical Engineering
Background:
- Traditional impedance eduction methods are limited to rectangular ducts.
- Accurate acoustic impedance measurement in engine environments requires adaptation to cylindrical geometries.
- Higher-order modes in circular ducts necessitate accounting for termination impedance.
Purpose of the Study:
- To extend the impedance eduction method for accurate acoustic impedance measurement in cylindrical ducts.
- To incorporate termination impedance of higher-order cut-on modes for multimodal acoustic propagation.
- To validate the extended method through numerical simulations and experiments.
Main Methods:
- Development of an extended impedance eduction method for cylindrical ducts.
- Inclusion of termination impedance for higher-order modes.
- Utilization of multiple measurements with different incident modes for comprehensive variable searching.
- Validation via numerical simulations and experimental tests.
- Application of the Monte Carlo Method for uncertainty evaluation.
Main Results:
- Successful extension of the impedance eduction method to cylindrical ducts.
- Accurate measurement of acoustic impedance in multimodal propagation scenarios.
- Validation of the proposed method's efficacy through simulations and experiments.
- Quantification of uncertainty in impedance measurements due to nonlinear sound pressure propagation.
Conclusions:
- The extended impedance eduction method provides accurate acoustic impedance measurements in cylindrical ducts.
- The method effectively handles multimodal acoustic propagation and higher-order modes.
- This advancement is crucial for precise acoustic liner characterization in real-world engine applications.
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