Application of Wavelet Transform and Higher-Order Spectrum to Monitor Gas/Liquid Two-Phase Flow

Based on wavelet transform and higher-order spectrum technique, a novel method was proposed to monitor the flow states of gas/liquid two-phase flow by analyzing the differential pressure signal. Firstly, the differential pressure signal was decomposed into many scaling functions with different frequencies by using wavelet multiresolution technique. The high-frequency noise of the signal was eliminated by a decision criterion, and then the denoised signal was reconstructed with a pyramid algorithm. Under different flow states, the bispectral eigenvalues of the denoised signal were extracted respectively. Meanwhile, the bispectral characteristics of the denoised signal were analyzed. Experimental results show that the bispectrum of the denoised signal can effectively suppress colored Gaussian noise and the extracted bispectral eigenvalue reflects the flow states inside pipeline. The proposed method can be used to monitor the flow states of gas/liquid two-phase flow in pipeline