Research On Prediction And Control Of Self-noise Characteristics Of Ship’s Acoustic Platform

Surface ships are an important part of naval power and play an indispensable role in maritime defense.It is necessary to find the target in advance to prepare for the battle before it can strike the enemy.The sonar installed in the ship’s acoustic platform is an electronic device that uses acoustic signals to detect and locate,and the noise level in the acoustic platform will directly affect the sonar working distance.This research takes a ship as the research object,and focuses on the prediction and control of the self-noise characteristics of the ship’s acoustic platform,and focuses on the following methods:Three prediction models for the mechanical noise,flow-induced noise and propeller noise of the ship bow acoustic platform were established,and according to the principle of frequency band division,the finite element-statistical energy hybrid method and statistical energy method are used to predict and analyze the self-noise in the middle and high frequency bands,and based on the influencing factors of self-noise forecasting,the regularity investigation of the loss factor in the structure and the division of the platform’s acoustic cavity was conducted.Due to the special position of the ship’s acoustic platform,the contribution of each excitation source to the acoustic platform was first calculated,the main excitation source was determined,and the transmission characteristics of the entire ship’s vibration and sound were analyzed.To the main noise types in the ship bow acoustic platform.The reverberation chamber-semi-anechoic chamber method was used to study the noise reduction effect of different structural types of bulkheads,and it was applied to the excitation source cabin and ship bow acoustic platform for noise reduction processing.According to the relationship between the modal energy and the temperature of the acoustic vibration,the main transmission path between the main excitation source and the acoustic platform of the bow was screened,and the accuracy was verified by laying damping on the path for vibration reduction.The influences of three control measures,such as laying of sound-absorbing spikes,laying of polyurethane damping,and setting of a concave-angle acoustic baffle,on the ship’s bow acoustic platform were analyzed in turn.The effects of single-layer sound transmission windows,double-layer composite sound transmission windows and sandwich-type sound transmission windows of different materials on the suppression of flow-induced noise in the ship bow acoustic platform and the influence of sound pressure distribution on the platform were investigated.The performance experimental verification of the concave-angle acoustic baffle was carried out,and the good performance of the concave-angle acoustic baffle was obtained in practical engineering applications.By comparing the experimental results with the simulation values,the ship’s bow acoustics platform based on statistical energy method was verified Feasibility and reliability of self-noise prediction and related control research.