Study The Thermal Properties Of Simulated Ship Wakes

When the ship is sailing on the sea,there will form a band-shaped bubble curtain in its following water,also called the wake flow,the reasons for which include the operation of propeller,rolling and breaking of wave,and air entrainment and so on.The wake flow has the characteristics of stability,long duration,obvious physical properties,and being effectively detected.The key information about the ship can be obtained from its physical characteristics of optics,acoustics,thermodynamics and electromagnetism etc.,such as speed,direction,and position and so on,which are the physical basis of target tracking and guidance of anti-submarine weapons.In the paper,the thermal characteristic of ship wake is analyzed based on the hydromechanics theory,and then the basic mathematical and physical model of ship thermal wake is established by using the energy equation and turbulent model,which is used to simulate the process from formation to attenuation.Then the experiment is designed,the results of which are processed by image processing,and the formation reasons and changing rules of thermal wake are obtained at the same time of verifying the model.This study provides a theoretical basis for the use of thermal wake to detect ship information in theory,and lays a foundation for the research of target tracking of military torpedo by guidance of thermal wake.The main contents of the paper include the following aspects:Firstly,the formation,scope and diffusion method of thermal wake are studied,the basic laws of floating,mixing and diffusion of thermal wake are obtained,the images of multiple stages from formation to attenuation of thermal wake are drawn,and a part of the parameters are analyzed.On the basis of these studies,a basic calculating model for simulating the characteristics of temperature distribution of thermal wake is established.Secondly,a set of experiment system for simulating thennal wake is designed,and the temperature signal can be extracted under different conditions,by adjusting the position of the probe.Then several sets of the experimental data are compared with the theoretical calculation data under the corresponding conditions,and the images are drawn by MATLAB.The effectiveness of the model is verified,and the temperature variation and attenuation law of the simulated thermal wake are also discussed.At the same time,the conclusion is drawn that the signal of thermal wake reaches the maximum value near the propeller at the back of the ship,and attenuates along each direction of the wake with its expansion.Thirdly,the thermal wake in the far field of a large vessel formed in the environment of a uniform temperature is simulated by the model,and the results are show in 3D images,while the main features of thermal wake is that the temperature is approximately inversely proportional with the width and length of the wake in a certain range.At the same time,the shortcomings of this study are analyzed,and some personal views and prospects about the future research direction in this field are put forward,combined with the research status of thermal wake in recent years.