Compressed sensing based turbine impeller ultrasonic phased array signal compression method

An ultrasonic phased array and compressed sensing technology, which is applied in the processing of detection response signals, analysis materials, instruments, etc., can solve problems such as the inability to fundamentally reduce the amount of sampled data

Inactive Publication Date: 2017-05-31
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These methods have achieved good compression effects, but still follow the traditional Nyquist sampling theorem, and cannot fundamentally reduce the amount of sampled data

Method used

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  • Compressed sensing based turbine impeller ultrasonic phased array signal compression method
  • Compressed sensing based turbine impeller ultrasonic phased array signal compression method
  • Compressed sensing based turbine impeller ultrasonic phased array signal compression method

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Embodiment 1

[0045] A compressive sensing based ultrasonic phased array signal compression method for steam turbine impellers, see figure 1 , the compression method includes the following steps:

[0046] 101: Build a steam turbine impeller ultrasonic phased array defect detection system for laboratory analysis, and obtain the ultrasonic phased array signal reflected by the defect position of the test piece;

[0047] 102: Perform sparse transformation on the ultrasonic phased array signal, and select the optimal sparse basis by calculating the degree of sparsity;

[0048] 103: According to the optimal sparse basis, use different algorithms to reconstruct the ultrasonic phased array signal;

[0049] 104: Use different algorithms to calculate the reconstruction error of the crack echo signal of the steam turbine impeller under different compression ratios, and select the optimal algorithm according to the results;

[0050] 105: Use the 3σ evaluation criterion to evaluate the above optimal a...

Embodiment 2

[0068] The scheme in embodiment 1 is introduced in detail below in conjunction with specific calculation formulas and examples, see the following description for details:

[0069] 201: Build a steam turbine impeller ultrasonic phased array defect detection system for laboratory analysis, and obtain the ultrasonic phased array signal reflected by the defect position of the test piece for subsequent analysis;

[0070] The detailed operation of this step is:

[0071] 1) The size of the impeller of the steam turbine is very large. For the convenience of laboratory research, a small part of the impeller of the steam turbine is cut off and a simulated test block of equal proportion is made. The material is 20# steel, as shown in Figure 2(a). As shown in Figure 2(b). Six crack defects were machined at the groove position using electric discharge (EDM) machining technology, and the crack size and angle are shown in Table 1.

[0072] 2) Build an ultrasonic phased array defect detecti...

Embodiment 3

[0132] Below in conjunction with concrete test data, the scheme in embodiment 1 and 2 is carried out feasibility verification, see the following description for details:

[0133] The device parameters used in this embodiment are: a 64-element ultrasonic phased array probe with a center frequency of 5 MHz, the center distance of the array elements is 0.6 mm, the material of the test piece is 20# steel, and the AD sampling frequency is 100 MHz. The upper computer CPU is AMD AthlonX4 quad-core, 4GB memory, and the operating system is Windows 7 64bit.

[0134] 1) Take defect No. 2 as an example for follow-up analysis. The defect echo A-scan signal is shown in Fig. 4(a), and then a series of sparse transformations are performed on it, and the signal length N=1024 is selected.

[0135] 2) Perform discrete Fourier transform, discrete cosine transform, and discrete wavelet transform on the above signals respectively, and the results of the transform are shown in Figure 4(b), (c), and...

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Abstract

The invention discloses a compressed sensing based turbine impeller ultrasonic phased array signal compression method. The compression method comprises the following steps: constructing a turbine impeller ultrasonic phased array defect detection system for laboratory analysis, acquiring an ultrasonic phased array signal reflected by a defect location of a tested piece; conducting sparse conversion on the ultrasonic phased array signal, choosing an optimal sparse base by calculating the sparseness; reconstructing the ultrasonic phased array signal according to the optimal sparse base; using different algorithms to calculate the turbine impeller fracture echo signal reconstruction error at different compression ratios, and choosing the optimal algorithm according to the result; and using the 3sigma assessing criterion to evaluate the optimal algorithm. The method uses a plurality of groups of fracture signals with different sizes and different angles to test, and the result shows that the average PRD reconstructed by using the compressed sensing algorithm is only 3.9117% and completely meets the requirements of industrial inspection when the compression ratio reaches 70%.

Description

technical field [0001] The invention relates to the field of steam turbine impeller ultrasonic phased array signal processing, in particular to a steam turbine impeller ultrasonic phased array signal compression method based on compressed sensing. Background technique [0002] my country is currently the country with the most nuclear power plants under construction in the world, and it is very important to ensure the safe operation of nuclear power plants. As the core component of a nuclear power plant, the steam turbine works in a high-temperature and high-pressure environment for a long time, and the impeller part is prone to cracks under the simultaneous action of stress and corrosion. If the cracks are not found in time, the cracks will continue to expand with the continuous operation of the steam turbine, and eventually may be damaged. The blades will fly apart, causing immeasurable property losses and even endangering personal safety. Researchers all over the world ha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/44
CPCG01N29/44G01N2291/023G01N2291/0289G01N2291/2693
Inventor 白志亮陈世利贾乐成徐天舒曾周末
Owner TIANJIN UNIV
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