Research On Tonal Noise Characteristics And Noise Reduction Methods Of Diagonal Flow Fan

Fan is one of the most important power equipment at present,and diagonal flow fan has been widely used in chemical industry,energy,construction and other fields due to its high flow rate and high efficiency.With the development of science and technology and the improvement of people’s living standard,shortage of energy resources and noise pollution put forward higher requirements for the design of diagonal flow fan,which also marks that high performance and low noise will become an important direction for its design and development.At present,plenty of achievements have been made in the research on optimization of aerodynamic performance of diagonal fan,while the research on aerodynamic noise is still rare,so how to reduce the aerodynamic noise becomes an urgent problem for diagonal flow fan design.And tonal noise,which is the dominant component of aerodynamic noise,is the main target of noise reduction of diagonal flow fan.So it’s of great significance and application value to study the production and transmission mechanism of tonal noise of diagonal flow fan and put forward reasonable noise reduction methods to control its noise.This subject centers on the study of tonal noise characteristics and noise reduction methods of diagonal flow fan,and the research carried out by means of theoretical analysis,numerical simulation and experimental verification.Based on the analysis of sound source characteristics and propagation mechanism of diagonal flow fan,noise reduction methods are proposed from the point of view of sound source and sound transmission,and different methods and noise reduction effects are evaluated,which provides basis for engineering application.The basic contents of this paper are as follows:(1)Based on CFD numerical calculation method,the internal flow field of the diagonal flow fan is simulated,the corresponding flow field characteristics are obtained,the flow structure and loss of fan are analyzed,and the accuracy of numerical simulation results is verified by experiments.(2)Based on Lighthill’s acoustic analogy theory,the aeroacoustics calculation model of diagonal fan is established,and the sound field information is obtained by numerical simulation method,which provides the sound field characteristics and flow field characteristics for rotorstator interaction and tonal noise generation mechanism verification.The research shows that the main source of tonal noise is the unsteady pressure located at the leading edge of the guide vane.The influence of the rotor-stator spacing,leaned guide vanes and swept guide vanes on the sound source and tonal noise is studied,and the noise reduction effects of various modification methods are analyzed.(3)Based on theoretical analysis and experimental method,the influence of outlet pipe structure of diagonal flow fan on aerodynamic noise is studied.The result shows that outlet pipe structure has obvious cut-off effect on aerodynamic noise.Proper pipe diameter and number of rotor and stator are helpful to increase the cut-off frequency of pipe so as to reduce the noise.In this paper,the effect of stator vane parameters and outlet pipe structure on tonal noise characteristics of diagonal fan is studied by theorical analysis,numerical simulation and experimental methods from the prospective of sound source and sound transmission.And noise reduction methods suitable for industrial application are proposed,which provide a reference for lownoise design methods of diagonal fan.