Research On Flow Field Around Submarine Based On PIV Test And Numerical Simulation

The submarine has the advantages of good concealment,flexible maneuverability and strong strike ability,which can complete the relatively concealed strategic tasks,The submarine’s stealth performance is not only the basic performance to ensure the completion of its combat mission,but also helps the submarine to better play its strong strike ability in the naval battle.However,due to the geometric characteristics of the submarine,there will inevitably be separated vortices in the flow field,and the wake will cause the propeller to vibrate obviously,resulting in greater noise.With the increasing diversity of combat tasks,submarines will inevitably involve near free surface navigation,which is a greater challenge to the stealth performance of submarines.The interaction between submarine and water environment shows the hydrodynamic performance of submarine at macro level and the flow around the water particle around submarine at micro level.The flow field around the submarine,especially the wake field,is directly related to the resistance,propulsion,vibration and noise performance of the submarine.Based on the PIV technology and numerical simulation,this paper studies the flow field around the SUBOFF submarine in infinite depth and near free surface depth.Through the mutual verification of the test and simulation results,the flow characteristics such as the velocity and vortex characteristics of the flow field around the submarine and the law of the change with the speed and depth of the submarine are obtained.The main work of this paper is as follows:(1)Based on the research progress of PIV test and numerical simulation of submarine flow field,this paper reviews the PIV test technology and numerical simulation technology of submarine flow field,analyzes and summarizes the current research status,and finds the shortcomings and problems to be solved.(2)This paper introduces the test equipment and method of submarine PIV flow field test,including the selection of test equipment and test model.This paper focuses on the structure,principle and selection of model fixing device of underwater 2D-3C Stereo-PIV and underwater 2D-2C TR-PIV respectively located in the towing tank and circulating tank,and selects the appropriate test conditions according to the test ability.As the basis of PIV measurement,the test equipment,structure and principle provide guidance for the test.(3)The Stereo-PIV system is built in the towing tank and the test process is introduced in detail,including calibration,seeding of tracer particles,test measurement methods and post-processing analysis.The test uncertainty is calculated by the method proposed by INSEAN and the convergence is analyzed.Then the test value is verified by the experimental data of SUBOFF standard model.Finally,the flow field of the propeller surface in the depth of 1.5 and 4 times of the maximum diameter D of submarine is tested under different speeds,Fr=0.3,0.4,0.5,0.6 and 0.7,and the influence with the change of speed and the existence of free surface on the wake field is analyzed.(4)The TR-PIV system is built in the circulating tank and the test process is introduced in detail.The error analysis of the test is carried out and then the test value is verified by the experimental data of SUBOFF standard model.Finally,the flow field in the longitudinal section of the submarine with 4 times of the maximum diameter D submergence at Fr=0.3,0.4 and 0.5 is tested,and the influence of the speed change on the flow field in the longitudinal section of the submarine is analyzed.(5)Based on the method of numerical simulation,the PIV method is verified and supplemented with each other,and the flow field around the submarine under different depths and speeds is simulated.Firstly,the numerical method is verified;secondly,the flow field around the submarine is simulated based on the verified CFD calculation strategy,and the influence with the change of speed and the existence of free surface on the flow field and the separation vortex of submarine is explained in detail.The interaction mechanism of the submarine and the free surface is preliminarily explored.