Application of Fiber-Optical Microphone for Thermo-Acoustic Measurements

Konle, H. J.; Paschereit, Christian Oliver; Röhle, I.

doi:10.1115/1.4001983

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…If the thermo stability of microphones were good enough, the cool down period would be maintained. In 2011 a fiber-optical microphone for thermo-acoustic measurements was designed, and it proved to be high temperature resistant (Konle, Paschereit, Röhle, 2011). However, the application of this microphone to measuring acoustic loads with high frequency and intensity was limited.…”

Section: Introductionmentioning

confidence: 99%

Design of Acoustic Tubes Array and Application to Measuring Acoustic Loads in Supersonic Airflow

Long¹,

Li²,

Fu³

et al. 2015

Archives of Acoustics

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In the acoustic fatigue experiment for hypersonic vehicle in simulated harsh service environment on ground, acoustic loads on the surface of test pieces of the vehicle need to be measured. However, for the normal microphones without high temperature resistance ability, the near field sound measurement cannot be achieved. In this work, on the basis of previous researches, an acoustic tubes array is designed to achieve the near field measurement of acoustic loads on the surface of the test piece in the supersonic airflow with high temperature achieved by coherent jet oxygen lance. Firstly, the process of designing this acoustic tubes array is introduced. Secondly, the equality of phase differences at the front and at the end of the tubes is stated and proved using a phase differences test with an acoustic tubes array whose design is presented in this text; therefore, the phase differences of signals acquired by microphones can be directly applied to beamforming algorithm to determine the acoustic load source. Finally, using above mentioned acoustic tubes array, measurement of acoustic load, with and without a test piece in the supersonic airflow made by the coherent jet oxygen lance, is conducted respectively, and the measurements results are analyzed.

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Section: Introductionmentioning

confidence: 99%

Design of Acoustic Tubes Array and Application to Measuring Acoustic Loads in Supersonic Airflow

Long¹,

Li²,

Fu³

et al. 2015

Archives of Acoustics

View full text Add to dashboard Cite

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Measurement of the Local Sound Pressure on a Bias-Flow Liner Using High-Speed Holography and Tomographic Reconstruction

et al. 2019

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Bias-flow liners (BFL) are used as part of the cooling mechanism in airplane turbines and they also enable the reduction of noise emission. The attenuating principle is based on the interaction between sound waves and air flow. This turbulent aeroacoustic interaction occurs on a microscopic level and under harsh conditions. Therefore, in order to investigate local aeroacoustic phenomena, the distribution of the local sound field impedance, defined as sound pressure over acoustic particle velocity, is measured non-invasively. This work focuses on the non-invasive measurement of the local sound pressure. A fast camera-based holographic measurement system for the two dimensional tomographic measurement of the local sound pressure with high spatial resolution is presented. It features a spatial resolution of 52 µm with a simultaneous acquisition of up to 1600 measuring points. This enables the observation of sub-mm aeroacoustic effects, which are expected in the near field over the BFL's surface, while reducing the measurement duration by three orders of magnitude compared to single point measurement systems. An experimental validation of the camera-based tomographic system is carried out by reference measurements. The system was applied at an acoustical model and an aeroacoustic model. The measured local sound pressure variations are discussed for both models. This work seeks to enable the non-invasive investigation of sound pressure, in order to further understand aeroacoustic effects, their sound attenuating properties and increase the attenuation capability of a BFL without degrading the overall performance of turbines.

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Analysis of the effect of thermal environment on the natural frequency of fiber-optic microphone membrane

Zheng¹,

Liu²

2017

Advances in Energy Science and Equipment Engineering II

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Application of Fiber-Optical Microphone for Thermo-Acoustic Measurements

Cited by 3 publications

References 25 publications

Design of Acoustic Tubes Array and Application to Measuring Acoustic Loads in Supersonic Airflow

Design of Acoustic Tubes Array and Application to Measuring Acoustic Loads in Supersonic Airflow

Measurement of the Local Sound Pressure on a Bias-Flow Liner Using High-Speed Holography and Tomographic Reconstruction

Analysis of the effect of thermal environment on the natural frequency of fiber-optic microphone membrane

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