Research On Measurement And Reconstruction Of Boiler Furnace Acoustic Wave Method Based On Wavelet Method

For a long time,the problem of coal combustion in world energy has always been the main component of energy.The combustion of coal is massive,which brings us energy and resources,and also causes relatively serious pollution problems.The coal combustion system of power station boilers is complicated.The boilers belong to high temperature and low pressure.The coal combustion process has the characteristics of transient changes,turbulence,harsh combustion environment,and huge combustion equipment.Therefore,the specific measurement of the furnace combustion process will be a worldwide problem.The research on the aerodynamic field of coal combustion in boilers will become very important.A full understanding of the flow field and temperature field of the combustion process will be of great significance for reducing environmental pollution and improving combustion efficiency.Whether optimized or not of the aerodynamic field in the boiler furnace determines the operation effectiveness of the boiler.Efficient and adaptive measurement technique is requisite but not available yet.Acoustic method is non-intrusive and full-field measurement.This paper proposed a model with an adaptive reconstruction algorithm for the acoustic measurement of the aerodynamic field.It utilizes the character of wavelet of focusing automatically on scale and position.As one of the few explicit wavelets,two-dimensional continuous Mexican-hat wavelet is adopted to build 2-D basis functions for the reconstruction of the aerodynamic field with sound projection data.On the other hand,since the measured acoustic data are scarce,the ill-conditioned equations will be formed during the reconstruction process.This process uses a regularization matrix method,and a satisfactory solution is obtained in the reconstruction of the furnace dynamic field.In the algorithm,for a defined scale of basis function,a series of regularization factors are traversed to achieve a locally optimized reconstruction of the flow field;and further,by scanning a series of wavelet scales,an optimal scale is got to give a global optimal reconstruction of the measured flow field as well as related optimal regularization factor.Wherein,novel target functions were empirically proposed for the determination of optimal regularization factor and scale respectively.The model was compared between wavelet and Gaussian basis functions with the same overallframe.The wavelet method turned out to give reliable and better results,by means of validations with simulations and experiments respectively.In addition,the wavelet model proposed in this paper is expected to be applicable to any form of complex aerodynamic field.