Study On Vibration And Acoustic Characteristics Of Typical Structures Of The Large Cruise Chimneys

Sound vibration sources of large cruise ships are numerous and complex.The excitation generated by these sound vibration sources cause hull vibration and radiate noise to the air and water.When a cruise ship is sailing normally,the gas flow in its chimney exhaust system will produce flow noise directly,and the unstable flow of gas will excite the chimney exhaust pipe to vibrate,thereby causing radiation noise.The vibration noise of the cruise chimney exhaust system has an important impact on the comfort of the surrounding environment,especially the comfort of the public area around the chimney exit.Therefore,it is necessary to conduct in-depth research on the noise source analysis,numerical calculation method and model test of the cruise chimney exhaust system,avoid the phenomenon that the noise of the chimney exhaust system exceeds the standard after the construction of the target cruise,and ensure the acoustic and vibration comfort of the target cruise.Based on the study of vibration of similar structures such as factory chimneys and towers structure,this paper simplifies the ship chimneys into cylindrical shells and other shell structures,and takes the vibration radiation noise of these typical structures as the core.The acoustic and vibration characteristics of typical cruise chimney structures are systematically analyzed by three methods: finite element software(ABAQUS),Acoustic boundary element software(Virtual.Lab)and statistical energy method(VA One).Firstly,the structure of industrial chimney and marine chimney is analyzed,and the model is simplified.The actual engineering model is simplified and three kinds of mechanical models are selected.They are single-layer cylindrical shell,conical-cylindrical composite shell and elliptical cylindrical shell.In the aspect of vibration characteristics analysis,the finite element software(ABAQUS)is used to establish the typical numerical model of the chimney,and the free vibration analysis is carried out for the typical shell structure of the cruise chimney.The internal excitation source of the typical structure of the cruise chimney is determined,thus the vibration characteristics of the typical shell structures were analyzed.In the aspect of acoustic characteristics analysis,a structural acoustic modelis established by using boundary element software and statistical energy method(Virtual.Lab + VA One).The acoustic characteristics of a typical semi-enclosed internal vibration excitation source of shell structure are calculated and analyzed numerically.In the middle and low frequency band,the boundary element numerical model of typical structure of cruise chimney is established and the boundary conditions are determined;in the high frequency band,the statistical energy analysis model of typical structure of cruise chimney is established,and the excitation input,damping coefficient and coupling loss factor of the analysis model are determined.Based on the statistical energy method,the high-frequency acoustic characteristics of the semi-enclosed space are analyzed,and the acoustic vibration characteristics of the typical shell structure of the cruise chimney are completed.And then,a simplified model of the real ship chimney structure is established,and the acoustic vibration characteristics of the structure under different parameters and boundary conditions are discussed.Finally,the paper designs and processes the selected shell structure.The vibration and acoustic characteristics of the typical structure of the cruise chimney in the air are tested and compared with the numerical results.The reliability of the vibrating acoustic radiation prediction method is verified.It provides guidance for the prediction and control of vibration and noise of cruise ship chimney structure.It is of significance to reduce the local harmful vibration of the hull and improve the living environment of the cruise ship and improve its comfort.