低频换能器水池测试新技术研究
文献类型：学位论文
| 作者 | 吴本玉 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-31 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 空间域处理 低频换能器 非消声水池 宽频技术 校准 |
| 其他题名 | Study on the new technique for low frequency transducer measurement in a reverberant tank |
| 学位专业 | 声学 |
| 中文摘要 | 随着水声换能器技术向低频、宽带、大功率的方向发展，需要校准的低频范围大大超出了水池中利用声脉冲技术校准换能器的适用频率下限，对于低频、高Q值换能器而言，在水池中校准它们的低频性能更加困难。为了解决上述困难，又有许多新的低频测试技术不断出现，但对于完全被反射声干扰混叠的直达声波信号，提取出来仍然非常困难。 本文通过对声波在有限区域介质中的传播和对声场进行理论分析，结合水声测量中的常规脉冲技术，提出了有限区域介质中利用空间域处理技术提取直达波信号波形的方法。并以长方体有限区域介质为模型，对区域中声波的反射声程进行了推导，确定了长方体有限区域介质内可提取出声波频率下限的一个必要条件。对长方体有限区域介质中的声场进行ANSYS仿真，仿真结果证明此方法是有效的。 根据实验要求设计并加工了水下机械回转三维姿态变换装置，利用常规的测量仪器设备搭建了实验测试系统及编制配套软件。在频率400～2500Hz范围内，对中科院声学所水池内不同频率和不同位置的声场混叠信号进行了实验研究。根据校准原理，对得到的测试结果比较，分析了可能造成偏差的原因，得到了能够满足测量要求的三种解决方法。确定了根据直达波提取情况，筛选出频带内各频率点能够获得最佳直达波提取效果的测试点，通过测试位置与测试频率有效匹配的方法，完成发射响应曲线的测试，是一种较经济的可行方案。 此方法克服了脉冲技术无法去除的同频反射声干扰的影响，使得有效测试频率下限降低至400Hz，约为脉冲测试技术低频下限的1/10以下，即向下拓展了3个倍频程以上，提升了水声测试水池的测量能力。此方法使得同样的空间尺度可以测量到更低的频率范围，降低了实验设施的建设投资，一定程度上避免了进行湖试的高昂花费，使得测量的经济性得到提高。此方法还可用于其它介质中的测量，经过对测量装置进行改进，还可以进行接收灵敏度和指向性的测量，使得测量的适用性变得更加宽广。 上述有限区域介质中发射换能器的低频测量方法，解决了在低频段测量“能与不能”的问题，为了能够快速高效的完成测量，还要解决“快与不快”的问题，这就依赖于宽频技术的应用。 宽频噪声技术从频域分析的角度，利用宽频噪声脉冲，实现宽频范围内一次测量就可获得频段内的频响曲线，大大缩短了测量时间。利用现代信号处理技术和数字化硬件系统实现快速测量，是对脉冲比较法扫频测量技术的一个重要补充。对于高Q值水声换能器的测量，避免信号瞬态效应的影响，采用宽频噪声技术更有优势。本文还对不同采样频率条件下的测量结果进行了比较，结果表明宽频噪声比较法采用脉冲序列内多个脉冲处理结果累加取平均的方法，可以降低对采样频率的要求，或者在设备最高采样频率一定的条件下可以实现更高频率范围的测试。 |
| 英文摘要 | With the development of the low frequency, broadband and high power underwater transducer, the low frequency range of their calibrations exceeds the applicable lower frequency limit in a reverberant tank by using acoustic pulse calibration technology. Especially for low frequency and high Q-factor transducer, it is more difficult to calibrate their low frequency performance in a reverberant tank. In order to overcome the difficulties, there are many new low frequency measuring techniques to come out, but for the direct wave superposed entirely, it is still difficult to separate the direct wave and the reflections. By the theoretical analysis of the sound wave propagating in a limited medium area, combined with the conventional pulse technique in the underwater measurement, a spatial domain processing technique for extracting the direct wave from the superposed waves in a limited medium area is proposed. By modeling a rectangular tank filled with acoustic medium, the reflection propagation length in the area is deduced. The necessary condition for the lower frequency limit that the direct wave can be extracted in the area is determined. The sound field simulation in the limited medium area is processed by using ANSYS software, and the result also proves the method to be effective. An underwater three-dimension gyration transform machine is designed and manufactured according to the experimental requirements, and an experimental measurement system is built by using the conventional measuring instruments, including the supporting software. According to different locations and different frequencies from 400Hz to 2500Hz, a lot of fundamental and experimental study about the aliasing acoustic signals is processed in the reverberant tank of Institute of Acoustics, Chinese Academy of Sciences. In accordance with the calibration principle, by comparing with the measurement results each other, the reasons for the deviations are to be analyzed and three acceptable solutions are to be obtained. Finally the economical and feasible method is determined that by selecting the proper location where the suitable direct wave is obtained in the frequency of the band, the transmitting response measurement is completed by matching the frequencies with the suitable measuring locations. This technique overcomes the difficulty that conventional pulse comparison technique can’t obtain the direct signal because of the effect of reflections. The lower frequency limit is obtained down to 400Hz, about one-tenth of using pulse technique, that is, the lower limit of the effective measuring frequency range is expanded beyond three octaves. The technique makes rapid progress in the measurement ability for low frequency transducer in a reverberant tank. It makes the same space obtain the measurement result in a lower frequency range, but it also reduces the capital investment about experimental facilities. To a certain degree, it avoids the expensive testing costs in lake and makes the economical efficiency to be improved. The technique also can be used for acoustic measurements in other mediums except water and it proves to be suitable. By improving the measuring apparatus, the receive sensitivity and the directivity of transducer can be measured, and the applicability of the technique becomes more spacious. In what mentioned above the problem whether it has the ability or not is solved，but the problem whether it has the efficiency or not is to be solved depending on the application of broadband techniques. From the viewpoint of frequency domain analysis，the broadband noise technique uses the noise signal source and applies modern signal processing technique and digitalizer hardware system. The rapid and efficient measurement has been made in the broadband frequency range under the broadband noise comparison calibration system. This is an important supplement to single-frequency pulse comparison method. For the measurement about high Q-factor underwater transducers, the broadband noise comparison method has a good advantage of prevention the transient effect. Also by comparing with the measuring results in different sampling rate, we draw a conclusion that the broadband noise comparison method adopting the average sum of pulse sequences processing results can reduce requirement for sampling rate. That is to say, the higher frequency measurement can be achieved under the certain condition of the fixed maximum sampling rate of the instrument. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 124 |
| 源URL | [http://159.226.59.140/handle/311008/446]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 吴本玉. 低频换能器水池测试新技术研究[D]. 声学研究所. 中国科学院声学研究所. 2009. |
入库方式： OAI收割
来源：声学研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。