Measurement method of echo reduction/reflection coefficient of underwater acoustic passive materials based on time-reversal focusing
A technology of underwater acoustic passive material and reflection coefficient, which is applied to the analysis of solids using sonic/ultrasonic/infrasonic waves, which can solve the problems of large measurement error and low measurement accuracy.
Inactive Publication Date: 2014-10-22
ZHEJIANG UNIV +1
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[0003] In order to overcome the shortcomings of large measurement errors and low measurement accuracy in the middle and low frequency band testing of the existing underwater acoustic passive material acoustic performance measurement technology, the present invention provides a time-reversal focusing-based hydroacoustic Acoustic Passive Material Echo Reduction / Reflection Coefficient Measurement Method
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[0042] The present invention will be further described below in conjunction with the accompanying drawings.
[0043] refer to Figure 1 to Figure 6 , a method for measuring the echo reduction of underwater acoustic passive materials based on time defocusing, which is used for testing the sound absorption performance of underwater acoustic component materials. The technical scheme of the whole measurement method is as follows:
[0044] 1) When the back-launch signal is generated
[0045] First, depending on the frequency range to be measured, the measurement system generates a transmitted signal, such as a broadband chirp signal or a narrowband pulsed cosine signal. Then, the transmitting-receiving transducer and the sample to be tested are put into the testing environment (water pool / pressure vessel), and the two are as close as possible in distance, such as figure 1 As shown, the transmitting-receiving transducer can be used as a time-reversed PS, and can also be used as a...
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Abstract
The invention discloses a method for measuring an echo reduction / reflection coefficient of an underwater sound passive material based on time reversal focusing. The method comprises the following steps of: 1) generating a time reversal sending signal; 2) acquiring a focusing signal when a tested sample exists, namely sending the time reversal sending signal generated by the step 1) by a sending-receiving array (SRA), generating space and time focusing at a sending-receiving transducer near the tested sample by the sending signal according to a time reversal principle, wherein the focusing signal is in a time reversal form of the original sending signal, and recording the focusing signal pr+i+ri+rir when the tested sample exists by a transducer at the sending-receiving transducer, wherein the transducer is used as a hydrophone; 3) acquiring the focusing signal when the tested sample does not exist; 4) calculating the echo reduction / reflection coefficient, namely obtaining the required sample parameter calculation result by using a reflection coefficient / echo reduction calculation formula; and 5) correcting an echo reduction correction measurement result. The measurement errors of a low-mid-frequency echo reduction / reflection coefficient can be reduced effectively, and accuracy is improved, so the method is suitable for full-frequency-range measurement.
Description
technical field [0001] The invention relates to a method for measuring the echo reduction / reflection coefficient of an underwater acoustic material. Underwater acoustic material components are widely used and crucial underwater components in underwater acoustic engineering. In order to evaluate the sound absorption performance of materials, it is necessary to carry out tests on relevant sound absorption parameters. The acoustic performance measurement of underwater acoustic passive materials includes the measurement of insertion loss / transmission coefficient, echo reduction / reflection coefficient and other parameters. Background technique [0002] Underwater acoustic material components are widely used and crucial underwater components in underwater acoustic engineering. Different application backgrounds have special requirements for the acoustic properties of materials. With the advancement of material science, new high-performance sound-absorbing materials such as viscoel...
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IPC IPC(8): G01N29/04
Inventor 李建龙孔祥东闫孝伟何元安卢少杰常鹏善王欣
Owner ZHEJIANG UNIV