基于稀疏性贝叶斯推断的泵空化高动态-高分辨频谱纹理表征方法研究

This project aims to study how to represent the signal characteristics of bump cavitations from limited signal samples with strong background interference. A Bayesian inference approach via sparsity prior will be proposed for this challenging problem. Though the acoustic and vibration signals induced by different cavitations are usually of non-stationary and large bandwidth, the proposed approach can detect the most probable cavitation forms by using the sparse distribution of signal features. Therefore, the most representative features are able to be extracted by maximizing the post-prior criterion in Bayesian framework. High dynamics and high resolution will be also achieved in signal spectrum textures, since sparse prior can regularize the spectrum analysis . This study will be verified by bump cavitation, hydrofoil cavitation and cavitation simulations. The proposed Bayesian inference approach will build up the relationship between the signal feature representation and cavitation bubbles, sheet and cloud cavitation respectively. And it will provide solid research foundation for preventing the cavitation fault in fluid machinery.

本项目针对“在强烈背景干扰下、从有限的多源信号中，高动态-高分辨率表征出泵空化的初生、发展和转捩特性”这一科学问题，开展“基于稀疏性贝叶斯推断的泵空化表征”方法研究，旨在运用有限的泵空化现象先验知识、从不确定性的泵空化信号征兆中，推理出基于后验概率最大化的空化类型组合，获得“高动态-高分辨率”的空化信号频谱纹理，借助解调-降噪、解卷积-消混响等技术，从中提取能够表征空化类型的特征参数分布，最终实现对泵空化离散气泡初生、片空化与云空化转捩的高动态-高分辨表征方法。通过对离心泵空化实验和水翼空化实验，以及3D空化形态数值模拟来验证方法的有效性。为建立空化形态与信号表征关系提供理论支撑，也为预防空化故障危害奠定研究基础。

本项目紧密围绕立项要求，“在强烈背景干扰下、从有限的多源信号中，高动态-高分辨率表征出泵空化的初生、发展和转捩特性”这一科学问题，开展了“基于稀疏性贝叶斯推断的泵空化表征”方法研究。为此，申请人首先从理论上开展了空化形态的声学表征方法研究：针对水翼空化试验，通过优化水听器阵列与先进信号处理技术，从原始空化的采集数据中抑制机械噪声干扰、提高信噪比，初步建立了与空化初生、片空化和云空化形态相对应的声信号特征参数提取和特性曲线分布，形成出一套从测量到诊断的“空化声表征”分析方法和侧量技术。然后，申请人瞄准“如何高动态-高分辨率表征出泵空化泡初生、片空化和云空化的问题”，开展“基于稀疏性贝叶斯推断”的泵空化表征方法研究，利用泵空化现象的稀疏性先验知识、以贝叶斯后验概率最大化为准则、从不确定性的泵空化多源信号中推理出空化信号特征的最优概率组合；并结合“叶频解调-降噪”、“解卷积-消混响”等一系列先进信号处理方法来获得“高动态-高分辨率”的空化信号频谱纹理，从中提取能够表征空化形态的特征参数分布，实现对空化泡初生、片空化与云空化的高动态-高分辨表征方法；建立了典型空化形态与信号表征的对应关系、阐明了空化产生机理与特征参数的紧密联系，离心泵和其他水力机械实现实时监测空化形态特性、控制空化发展程度和预防空化故障危害等提供了基础。