Investigation On Multiparameter Condition Monitoring And Fault Diagnosis Of Fan

The ventilating fan is one type of large rotating machinery in power plant and also is the power supply of the air/gas system, and the operating condition of which has obvious influence to security and economic of units. Therefore it is necessary to take effective monitoring and diagnosis on ventilating fan. Nowadays the study of monitoring and fault diagnosis of fan is mainly focus on vibration signal with respect to mechanical characteristic based on Fourier analysis. Till now the study of condition monitoring and fault diagnosis based on multi-parameter and multi-characteristic is attracting much more attention. But for a ventilating fan, multi-property condition monitoring and fault diagnosis integrating aerodynamic performance, mechanical characteristic and unstable flow property isn't systematically studied yet.In the paper the experimental study means is adopted. Aerodynamic performance monitoring is realized and characteristic analysis of unstable flow and feature extraction of mechanical trouble are carried through in this paper. Based on which multi-parameter condition monitoring and fault diagnosis of fan is put forward and the high dimensional features of multi-index and multi-parameter are reduced and fused by the feature selection means of statistical pattern recognition, and different neural network combined with which can deduce the single network and subnetwork fault diagnosis model. The proposed model accurately diagnoses the multi-property troubles, different severity troubles and coupling troubles using experimental samples. And based upon which the multiparameter condition monitoring and fault diagnosis system is developed in the paper.1. Experimental investigation on flow rate measurement of fan based on parameter mapping. It has been proved by our former study that the steady mapping law between performance parameters can be reflected by the dimensionless performance curves of a fan. In the paper four different approximating methods are put forward and the approximating performance of which is compared. It is proved that RBF network has better approximating performance. Therefore the RBF network is used for approaching the different nonlinear parameter mapping law and based on which the parameter mapping flow measurement model is derived. Aiming at the application of parameter mapping flow rate measurement model of fan the experiment is taken through on a 4-73No8D fan in the lab. And the related problem such as the similarity law application range of fan is also experimentally studied. It is verified that in the range of similarity law the measurement based on the model obtains high accuracy and the application range of similarity law of fan on the condition of speed change is the main influencing factor of model.2. Experimental investigation and characteristic analyze for rotating stall of centrifugal fan. Based on analyze for the flow field conditions of blade row of centrifugal fan the formation mechanism of two kinds of rotating stall (s-stall and p-stall) is explained. The unstable flow test system is developed and experimental investigation is carried through on a 4-73No8D centrifugal fan. The rotating pressure stall (p-stall) is found on a 4-73 fan for the first time. In the experiment the stall property in amplitude and frequency domain and the influence to performance parameter of stall are studied. In order to explaining the dynamic property of rotating stall Harmonic Wavelet Transform (HWT) is adopted for time-frequency characteristic analysis. The reformed HWT that has the adjustable time resolution is derived and its fast algorithm is also given in the paper. The orthogonal HWT and non-orthogonal HWT are respectively applied to analyze the feature of weak stall and progressive stall procedure and so on. The conclusion is given and the study results are also proved the advantage of HWT in analyzing the characteristic of rotating stall.3. The trouble simulating of fan and multi-index feature generation of fault diagnosis. Some classical mechanical troubles and unstab...