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| Experimental Investigation of Turbofan Engine Acoustic Liner Noise Reduction and Mode Scattering |
| Received:November 27, 2019 Revised:December 09, 2019 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2020.12.005 |
| KeyWord:liner noise scattering directivity |
| Author | Institution |
| WEI Kai |
Aircraft Strength Research Institute of China, Xi’an , China;Aviation Science and Technology Key Laboratory of Aircraft Noise and Vibration Engineering, Xi’an , China |
| CAO Qi |
Aircraft Strength Research Institute of China, Xi’an , China;Aviation Science and Technology Key Laboratory of Aircraft Noise and Vibration Engineering, Xi’an , China |
| PAN kai |
Aircraft Strength Research Institute of China, Xi’an , China;Aviation Science and Technology Key Laboratory of Aircraft Noise and Vibration Engineering, Xi’an , China |
| YAN Qun |
Aircraft Strength Research Institute of China, Xi’an , China;Aviation Science and Technology Key Laboratory of Aircraft Noise and Vibration Engineering, Xi’an , China |
| XUE Dong-wen |
Aircraft Strength Research Institute of China, Xi’an , China;Aviation Science and Technology Key Laboratory of Aircraft Noise and Vibration Engineering, Xi’an , China |
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| Abstract: |
| The work aims to study the sound absorption and acoustic model scattering phenomenon of acoustic liner. Noise experiment was conducted on the liner of nacelle inlet of an airplane. Based on the scaled test bench, the single stage axial fan was taken as the noise source. Through the far-field measuring points of 10 times the diameter of the inlet, acoustic modal and far-field directivity under the action of solid wall and liner were obtained to analyze the sound absorption effect of each far-field measuring point at different speeds under the action of liner. At three different rotating speeds, the acoustic modal distribution, far-field spectrum and directivity distribution of the pipeline upstream and downstream of the acoustic liner under the first three-order blade passing frequencies were obtained. And on this basis, the noise reduction effect of the acoustic liner at different rotating speeds, noise frequencies and flow rates were obtained. At 2973rpm, the sound power level of modal (1,0) was reduced to 24.3dB. Under modal (±3,0), the sound power level near the sound source increased unexpectedly. Under design frequency and modal, the liner has the best sound absorption effect. With the increase of the modal order, the noise reduction capacity of the liner decreased. When deviating from design frequency, acoustic model scattering occurs at the impedance interface. |
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