Study On Flow Field,Vibration And Noise Of Submarine And Propeller Coupled Model

Submarines play a pivotal role in military vessels,and are the focus of naval development for many countries.The biggest advantages of submarines are the high concealment,flexibility,self-sufficiency.They are able to stay under water for a long time,which is suitable for assaults to enemies.Due to their unique shapes,there exists nonuniform flow field around the hull when submarines move forward.Investigation of the nonuniform flow field is meaningful for reducing the hull resistance,promoting the propulsion efficiency and steady sailing of submarines.Meanwhile,unsteady loads are generated on the surface of propeller blades by the nonuniform flow field,which significantly influences the hydrodynamic performances of propeller.Fluctuating pressure distribution is also formed on the surface of propeller blades under the synthetic effects of flow field and submarine,which results in vibration and even periodic deformations of blades.The mutual impacts of submarine and propeller,as well as the influences of flow field,are responsible for the radiation noise;the periodic deformations are the major source of the structural noise of propeller.Therefore,research on flow field,vibration and noise characteristics for submarine and propeller coupled model is the key procedure when designing and fabricating submarines and propellers.In this article,efforts were devoted into the study of flow field,vibration and noise characteristics of submarine and propeller based on numerical simulation,whose results could serve as data references for optimal design as well as vibration and acoustic performances improvements of submarine and propeller.Firstly,modeling,meshing and open water performance simulation of DTMB 4383 propeller were conducted,which was the basis for the follow-up study.Secondly,selfpropulsion characteristics of DARPA SUBOFF submarine were simulated to investigate the flow field and hydrodynamic characteristics of submarine and propeller coupled model.Then,regarding the propeller as elastomer and calculation results of flow field being the input,single-side fluid structure interaction(FSI)for propeller was carried out.Finally,calculation results of flow field and FSI being the input,the radiation noise submarine and propeller as well as the structural noise of elastic propeller were calculated.The results showed that the meshing of submarine and propeller met the precision standards of calculation,and the simulation results of open water performance were near those of tests.The sail and stern appendages of the submarine could induce nonuniform flow field around the hull,which had considerable impacts on the hydrodynamic performances of the propeller.The elastic blades were periodically deformed under the influence of flow field.The hydrodynamic and noise performances of elastic and rigid propellers are different.When submarines sail under water,the radiation noise submarine and propeller as well as the structural noise of elastic propeller are usually concentrated in low frequency bands.The synthetic noises at low frequencies are generally 110~130 dB,while the ones at middle and high frequencies are normally 90~110 dB.