Characteristic Analysis Fluid Structure Interaction Of Flexible Seals Of Partial Air Cushion Supported Catamaran Under Wave Action

The partial air cushion supported catamaran(PACSCAT)is a new type of hybrid ship based on a slender catamaran and supported by a partial air-cushion.It combines many advantages of ordinary catamarans,hovercrafts,planning boats,etc.Therefore,it has great application value in high-speed transportation.The research on the motion of the PACSCAT in waves is of great significance to the design and development of the ship,the optimization of hydrodynamic performance,and the performance improvement of the air cushion system.The mechanism of the flexible air seal of the PACSCAT reflects the interaction between the fluid and the flexible air seals structure,which has a typical fluid structure interaction(FSI)mechanical characteristic.In this article,the multi-degree-of-freedom motion of the PACSCAT in a complex flow field and the fluid structure interaction problem of the flexible seals are studied.The main purpose of this article is to carry out the research on the bow and stern flexible seal model suitable for the PACSCAT through the study of the force of the air-cushion air seal structure,and on this basis,this article carried out the ship model test in the waves Analysis;On the basis of the numerical simulation of rigid seals,this article researches on the fluid structure interaction problem of flexible seals,especially the bow flexible skirt fingers,and solved the problem that the flexible skirt fingers with actual shapes which could not be carried out in numerical calculations in waves,and then a series of in-depth studies on the motion characteristics of flexible seals in waves are carried out.The more detailed works of the thesis are as follows1.Through the research on the numerical method and fluid-solid coupling method of the flexible air seal of the hovercraft,the basic theory of the seal forms and the mechanical characteristics of the different seal forms were analyzed.According to the ship form characteristics of the PACSCAT studied,a suitable bow and stern seal model was established,based on this,the calculation and analysis of the force and deformation of the flexible air seal were carried out2.Based on the established bow and stern flexible air seal,an experimental study on the motion of PACSCAT in waves is carried out,focusing on the nonlinear discharge of the air cushion and the internal free wave surface conditions that are greatly affected by the flexible seals;At the same time,the motion parameters of the hull model in waves such as resistance,pitch,heave and acceleration are obtained,and compared and analyzed with the resistance characteristics and wave making characteristics in still water.Through the experimental research,the motion characteristics of the rigid-flexible coupling body of the local air-cushion catamaran in waves are obtained,which provides actual physical phenomena and necessary data support for the subsequent research work of the thesis.3.Through computational fluid dynamics(CFD),the numerical calculation method of the rigid air seal is studied,focusing on the analysis of the calculation accuracy of the moving grid and the overlapped grid;Through the study of numerical waves,a numerical wave pool that meets the requirements of calculation accuracy has been established,and based on this,this article carried out the calculation of the wave motion of the rigid seals,which provides the necessary theoretical and numerical support for the subsequent numerical simulation of the flexible air seal based on FSI4.Based on the FSI,a deformable bow seal form which is consistent with the test model and a simplified stern air seal form were established;Through preliminary iterative coupling calculations,the grid independence of the numerical calculation is verified,compared with the analysis of the test values,the three-dimensional numerical calculation method verifies the feasibility and accuracy.By extracting the various resistance components of the PACSCAT,the wave resistance characteristics of the rigid and flexible air seals are analyzed in depth.5.The feasibility and accuracy of the force deformation of the seals of SES based on the FSI method were verified by establishing a FSI seals model for the bow of a thin-walled hovercraft in the form of a large skirt;Based on the established FSI seals model,a study on the motion characteristics of PACSCAT in waves is carried out,and the resistance characteristics and the pressure characteristics of the pressurized chamber and the air-cushion chamber are analyzed.This paper carried out the analysis of the deformation characteristics of the flexible air seal in waves,and studied the deformation of the flexible bow and stern air seal under different wave parameters.And according to the air-cushion wave making,the internal and external free surface of the PACSCAT were researched and analyzed.