Study On Noise Of Ship HVAC System

Based on the theory of plane wave,computational fluid dynamics and aeroacoustics,the noise at the exit of HVAC system is analyzed and discussed by finite element method.Then,compared with previous experimental studies,it is pointed out that the main noise of HVAC system outlet airflow is low frequency.Some rules of ship HVAC system layout and design timing are summarized,and the influence of different air distributor cavity structures on exit noise is discussed.The main work of this paper is as follows:(1)The harmfulness of noise to the people on board and the noise limit of the ship cabin are briefly described,and the HVAC system of the ship is simply explained.The research status of noise in ventilation system at home and abroad is summarized.(2)The basic plane wave equation in plane wave theory and FW-H equation in aeroacoustics theory are briefly introduced.The turbulence model used in this paper is briefly explained.(3)Simple pipe elements are analyzed and discussed by using plane wave theory.The size of the different diameter part of the pipe element is studied,and the influence of the size change of the different diameter part on the fluctuating pressure of the gas flow through the pipe is summarized.Using CFD method,the fluctuating pressure at the outlet of air distributor with different structure is studied and discussed.It is considered that the fluctuating pressure at the outlet of air distributor with cylindrical cavity is the smallest.(4)Taking the HVAC system on B deck of a ship superstructure as an example,the layout and form of pipelines are optimized by using the plane wave method.Then the flow field of the original rectangular air distributor is analyzed by Fluent.Then the flow field data are imported into Virtual.Lab and the noise analysis is carried out to obtain the sound pressure level distribution near the outlet.Aiming at the problem of excessive noise at the outlet of the original air distributor,the structure of the air distributor was optimized,and the influence rule of the air distributor form on the outlet noise was summarized.