| As the noise of underwater vehicles is more effectively controlled,various detection methods are used in underwater information confrontation,including wake detection.This research finds that if the characteristics of the external potential flow velocity and transient velocity distribution profile of the wake field of an underwater vehicle can be measured,general information about the diameter and the traveled distance of the vehicle can be obtained through the numerical simulation and the empirical database established in this paper.The quantitative relationship between the relevant hydrodynamic parameters of the wake field of the underwater vehicle and its diameter and travelled distance,is established through numerical simulation.By using FLUENT,the transient wake fields of a submarine model are simulated serially based on URANS and DES approaches in large computational domain to obtain the quantitative relationship between the hydro-dynamical characteristic quantities of the long-distance wake field and the key tracer parameters.The semi-empirical and semi-theoretical quantitative relations between the characteristic quantities of the wake field and the key tracer parameters are reasonably generalized to a very far wake field,so as to provide the theoretical basis and method guidance of hydrodynamics,for tracking the underwater vehicle through the wake detection in practical engineering.In addition,this article also conducted a numerical simulation analysis of the radiated noise of the wake of the underwater vehicles through the professional acoustic software ACTRAN,and reached the conclusion that the radiated noise of the long-distance wake is extremely low,thus completely submerged in the background noise of the ocean.The innovative work of this paper includes:（1）The similarity law of the velocity distribution of the near-field wake（within 15D）,in researches at home and abroad,is promoted to the mid-far field wake（within 50D）through the analysis of the numerical simulation of the multi-speed and multi-vehicle size in larger calculation domain,and further rationally extended to the super far field wake（with distance of 1000D）.（2）Multiple empirical parameters for generating the normalized curve of the velocity distribution profile of the wake field are obtained,through a series of numerical simulations,and these empirical parameters vary significantly with the diameter and speed of the underwater vehicle.A computer program based on the Gaussian fitting method was compiled to obtain the equation of the normalized curve,and an empirical formula reflecting the relationship between these empirical parameters and the diameter and the traveled distance of the SUBOFF was further determined.（3）In this paper,the value range of empirical parameters in the equation estimated by the characteristics of the velocity profile of the wake field of the underwater vehicle is obtained.In addition,it is found that the radial gradient k0 of the far-field wake velocity profile of the underwater vehicle is significantly different from that of the marine environment.It is also found that the radial gradient of the velocity profile of the vehicle far-field wake is significantly different from the marine environment,which is thought to be more easily identifiable by using the obvious refraction effect of ultrasonic wave through the flow velocity gradient field.Therefore,the typical velocity gradient can be used as a specific indication of the underwater vehicle,and to help determine other hydro-dynamical characteristic quantities,the ratio of the two characteristics,u0 and l0,mentioned above. |
