Hydrodynamic Numerical Calculation And Characteristic Analysis Of Remotely Operated Vehicle For Jacket Inspection

With the rapid development of marine resource exploration,the Remotely Operated Vehicle(ROV)has become more and more important and has been widely used in some fields including marine engineering,marine scientific exploration,salvage rescue,marine military,fisheries,aquaculture.To develop a ROV for Jacket Inspection,the hydrodynamic force is one of the main properties that must be considered.In this paper,the hydrodynamic performance calculation and characteristic analysis of the ROV are the main research content.The calculation of the hydrodynamic force of ROV is used to optimize the structure design and provide data support for the design of the control system.The structure of ROV body has been preliminarily designed by means of modularization design idea.The design includes carrier frame,propeller,buoyancy module,electronic cabin.The strength of the main components was analyzed by finite element method.This provided a calculation model for the calculation of the hydrodynamic force.Establishment of ROV hydrodynamic model and space motion model.The basic theory,the control equation,the turbulence model,the algorithm,the grid technology and the CFD solution were briefly summarized.These provided the theoretical basis for the calculation of hydrodynamic coefficients.A method of using numerical simulation to obtain important hydrodynamic coefficients instead of constraint model test was proposed.Firstly,the pre-processing of numerical simulation was carried out,including simplification of the model,determination of the size of the computational domain,and mesh division(type,quantity,boundary layer).Then the drag tests at different speeds along different axes were simulated.The variation law of drag coefficient under different Reynolds numbers was analyzed,and the value of drag coefficient along different coordinate axes is obtained.Numerical simulation of ROV skew motion test was carried out using least square method and curve fitting and regression analysis to solve linear and related nonlinear hydrodynamic coefficients.Dynamic mesh technology and UDF were used to simulate planar motion mechanism experiments.The inertial hydrodynamic coefficients and some viscous hydrodynamic coefficients related to pure heave,pure bow and pure roll motion were calculated respectively.Other nonlinear and coupled hydrodynamic coefficients were estimated by using the calculated hydrodynamic coefficients,and all the hydrodynamic coefficients needed were summarized.Based on the hydrodynamic characteristics obtained,the characteristic analysis was carried out.The force and torque curves obtained by simulation and the pressure and velocity cloud diagram were used to analyze the hydrodynamic characteristics of ROV in differentmotion states.The influence of scaled model and near-jacket motion on hydrodynamics of ROV was also discussed.