Research On The Vibration And Noise Prediction And Control Technology Of 500 Feet Jack-up Platform

Nowadays,China's oil consumption has jumped to the second around the world,and the oil demand is increasing year by year,as “the main force” of oil supply,offshore oil is relatively more difficult to survey and exploit.As an important offshore structure for offshore oil exploitation,500 feet jack-up platform will inevitably be subjected to the combined action of various loads,such as wind current waves or mechanical equipment unbalanced loads,when working at sea,which will cause structural vibration and noise pollution,thus menacing the safety of the platform and affecting the comfort of the platform.Therefore,it is important to predict and control the vibration and noise of the 500 feet jack-up platform.First,this paper expounded the basic principles of vibration analysis and statistic energy analysis,and respectively presented the establishment process of the finite element model and the statistic energy analysis model.Next,the global vibration characteristics of 500 feet jack-up platform and the local vibration characteristics of each deck were predicted in this paper,and the results show that the platform has a typical low-frequency vibration characteristic,and the height of the main hull is the main factor governing the vibration mode.Due to the relatively dense local vibration modes of each deck,it is often difficult to meet the demand for frequency reserve,so it is necessary to calculate the forced vibration response to verify the safety of the structure.Next,common vibration control means of the platform was introduced in the paper,and the effect of vertical stiffness of shock absorber on vibration damping was studied.The results show that adding shock absorber under the base of the generator and other mechanical equipment can achieve good damping effect,during shock absorber selection,the damping effect and the static deformation of the shock absorber should be taken into consideration together.In addition,the conventional methods of calculating the wind-induced vibration response of the platform were discussed in this paper,and the wind-induced vibration characteristics of the platform caused by the ripple wind load in tailwind direction was also studied,and the contribution of each order mode to the wind-induced vibration response and the influence of the height of the node position on the mean square value of the displacement response were analyzed.Then,on the basis of the prediction of SPL of the 135 cabins,the distribution of the SPL of the cabin was analyzed,and the reasonable proposal for the layout of the cabin was given.Finally,the basic principle of vibration and noise reduction of the platform was discussed,and the noise reduction effect of the common methods of vibration and noise reduction were simulated,which provided a reference for the noise control of the platform.As the sub topic of the national high technology vessel scientific project,“The Brand Project of the Jack-up Drilling Platform”,the research results of this paper have guide and reference for the vibration and noise prediction and control of the platform.