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Analysis of Pressure Fluctuation Signal in Water Flow Facility Based on EMD
DOI: 10.12677/IaE.2019.71002, PDF, HTML, XML, 下载: 667  浏览: 1,924  国家科技经费支持

Abstract: For the measurement requirement of flow stability, which is a key performance parameter of the flow standard facility, the flow fluctuation is often calculated indirectly by measuring the pressure fluctuation and through the stable relationship between pressure and flow in the flow standard facility. The calculation results depend on the accurate measurement of pressure fluctuation in the flow standard facility. In this paper, the flow fluctuation generator is used to generate the fluctuation in the water flow standard facility, and the measured pressure signal is processed by Empirical Mode Decomposition (EMD) method. The main pressure fluctuation signal is extracted by EMD method, and the amplitude and frequency of the fluctuation signal are obtained accurately, which can help to calculate the fluctuation of flow.

1. 引言

2. 实验方法与平台

2.1. EMD方法介绍

1) 找出原数据序列X(t)的所有极大值点和极小值点，将其用三次样条函数分别拟合为原序列的上包络线和下包络线，求上下包络线的均值为m1；2) 将原数据序列减去m1可得到一个减去低频成分的新序列，即h1 = X(t) − m1，计算h1的包络均值m11，去除该包络平均所代表的低频成分后的数据序列为h11，即h11 = h1 − m11；3)重复上述过程，这样就得到第一个本征模函数分量IMF1，它表示信号数据序列最高频率的成分；4) 用X(t)减去IMF1，得到一个去掉高频成分的新数据序列r1，并对r1再进行上述分解，得到第二个本征模函数分量IMF2；5) 如此重复直到最后一个数据序列rn不可被分解，此时，rn代表数据序列X(t)的趋势或均值。

2.2. 实验平台

Figure 1. Schematic diagram of a test instrument and a pipe connection

2.3. 数据采集装置

3. 压力传感器输出信号分析

Figure 2. Interface of NI data acquisition program

Figure 3. This figure shows the IMF1 and its frequency spectrum, (a) IMF1 from pressure sensor signal after EMD; (b) Frequency spectrum 1 from pressure sensor signal after EMD

Figure 4. This figure shows the IMF2 and its frequency spectrum, (a) IMF2 from pressure sensor signal after EMD; (b) Frequency spectrum 2 from pressure sensor signal after EMD

Figure 5. This figure shows the IMF3 and its frequency spectrum, (a) IMF3 from pressure sensor signal after EMD; (b) Frequency spectrum 3 from pressure sensor signal after EMD

Figure 6. This figure shows the IMF4 and its frequency spectrum, (a) IMF4 from pressure sensor signal after EMD; (b) Frequency spectrum 4 from pressure sensor signal after EMD

4. 结论

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