针对聚焦声场的特点，以及辐射力天平（RFB）只能获得单一功率指标的缺点，提出一种基于近场测量法的聚焦换能器声强和声功率评价方法。通过声场测量系统对聚焦换能器预聚焦区域中两个平面上的声压扫描测量，运用声强法得到聚焦换能器的声强分布以及辐射声功率。采用活塞换能器的远场测量法与近场测量法进行比对，两种方法得到的声功率误差不超过12%。比较预聚焦区域声功率值和焦点处声功率值，分析声功率评价方法的准确性。发现聚焦声场中不同位置处的声功率值一致性误差＜5%，同一位置处的声功率值重复性误差＜2%。结果表明，近场测量法适用于对聚焦换能器声强和声功率的评价，可有效避免直接测量对测量设备的损坏，同时还克服双水听器声强互谱法频率上限低以及测量系统相位不匹配的缺点。%According to the features of focused sound field and given that radiation force balance (RFB) can only obtain a single power indicator, the paper proposes a method for evaluating sound intensity and sound power of focused transducer based on near-field measurement method. Sound field measurement system is used to have scanning measurement of the sound pressure on two planes within pre-focus area of focused transducer. Sound intensity method is used to obtain the sound pressure distribution and radiant sound power of focused transducer. Comparing the near-field measurement method and far-field measurement method of piston transducer, it is found that the error rate of sound power of the two methods is less than 12%. By comparing the sound power of pre-focused area and the sound power at point of focus and analyzing the accuracy of sound power evaluating method, it is found that the sound power consistency error at different locations in focused sound field is less than 5% and the sound power repeatability of same location is less than 2%. Results show that the near-field measurement method is suitable for evaluating sound intensity and sound power of focused transducer as it avoids the damage of measured equipment caused by direct measurement effectively and also overcomes the disadvantages of the low upper limit of frequency in measuring the cross-spectrum density of sound pressure between two hydrophones and the unmatched phase in measurement system.
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