| This paper makes a detailed analysis on the deep sea classic Spar platform withininternal resonance mechanism. The deep-sea classic Spar platform is a platformstructure which is suitable for deep-sea oil and gas resources exploitation. Because ofits response stability and many other advantages, it has gained great attention from thedevelopment of offshore oil and gas resources. Classic Spar platform in the deep-seahas natural frequency of the longitudinal roll but the same is rendered as a2:1ratio,so excitation energy in the long-period waves under extreme ocean conditions willharm response situation of deep-sea classic Spar platform safety campaign.Resonance mechanism of deep sea classic Spar platform can effectively provideguidance based on the design and practical application of the classic Spar platform indeep-sea engineering practical significance. The main work and application methodsare summarized as follows:The historical background and its development of deep classic Spar platform areintroduced. Its progress made by experts at home and abroad is summarized. Thenthis paper introduces the research direction of this study.Based on six degrees of freedom motion equations of the deep sea classic Sparplatform, the stability problems of classic Spar platform in the deep sea within theresonance equation are solved by using multi-scale method, so as to get first-ordersteady approximate solution of heave, pitch motion response. Then it comes to anconclusion that classic Spar platform in deep-sea has natural frequency of the halfwith a vertical shake when the natural frequency is approximately equal. Undercertain wave excitation energy, deep sea classic Spar platform will occur within theresonance response. The heave amplitude of Spar platform will significantly increase.The heave amplitude of Classic Spar platform in deep sea reaches a saturation case,and the excess wave excitation energy will be passed to the pitching, which causessubstantial increase of the pitch motion response amplitude, called the Mathieuinstability. This paper selects parameters of instances platform to analyze numericalverification of Internal resonance of the classic deep-sea Spar platform and Mathieuinstability theory. Then each mechanism of resonance in the occurrence of the classicdeep-sea Spar platform is obtained. When the classic deep-sea Spar platform indeep-sea heave natural frequency of the half with a vertical shaking is equal to thenatural frequency of the classic Spar platform in deep-sea heave natural frequencyequal wave excitation energy under the platform motion, the response may occurwithin the resonance. At this time, when the amplitude of the wave excitation energyreaches a certain level, the classic Spar platform in deep sea motion response ofinternal resonance phenomenon occurs. Heave motion response first reaches thesaturation to excess wave excitation energy, then it delivers the response to thepitching motion. At last, The Matthew instability of deep sea classic Spar platformhappens.According to the analysis within the internal resonance mechanism for theclassic deep-sea Spar platform, the internal resonance to increase mooring system andadding heave plates in both directions of movement response are analyzed, and themovement AQWA calculation software is used for analysis. Then there is a conclusionthat increasing the mooring system and adding heave plates classic Spar platform indeep-sea within the resonance amplitude wave excitation energy needs increase andinhibition classic Spar platform heave motion response amplitude, thus avoiding thedeep-sea internal resonance motion response occurs.Finally, internal resonance excitation analysis of the classic deep-sea Spar platformis summarized, and the lack of this paper as well as the expectations of the futureresearch direction is also pointed out. |
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