Infrared simulation of Kelvin wake on sea surface under different conditions

The wakes generated by ships on the sea contain a wide range of information. We applied the Kelvin wake model and obtained the wake maximum wave height of 0.5 m, 1.5 m and 2.5 m,respectively, corresponding to the warships velocity of 5 m/s, 10 m/s and 15 m/s. We described the complex sea backgrounds with different wind speeds of 5 m/s, 8 m/s and 10 m/s by the PiersonMoscowitz sea spectrum model. The infrared emission model of the wake on the sea was established by geometry differences of the wake and the background, and infrared images were got in different speeds of the sea wind, different speeds of the ship and different detection angles of the detector. The simulation results show that the maximum gray value of infrared image is at the wake wave peak, and when the wind speed increases from 5 m/s to 10 m/s, the average gray difference between the wake area and sea surface background gradually reduces from 100, until no difference. Under the same sea surface wind speed, the wake wavelength increases from 10 m to 40 m with the ship speed increasing from 5 m/s to 15 m/s,and the infrared feature is obvious.The infrared image difference is insignificant when the detector zenith angle is 0 and 30. When the zenith angle increases to 60, the wake region gray scale is closed to the sea background gray scale, the difference value is less than 30, so it becomes more difficult to recognize targets.