The Influence of the Discharge Port Structure on the Infrared Characteristics of Underwater Vehicle Thermal Jets

Abstract

The circulating cooling water of underwater vehicle power systems is discharged through the discharge port and is mixed with the environmental water to form a thermal jet, which diffuses, floats up in the environmental water and displays infrared characteristics on the surface of the water body. In order to explore the influence of the discharge port structure on the infrared characteristics of underwater vehicle thermal jets, this paper adopts the methods of simulation analysis and experimental verification, and it establishes an underwater vehicle motion model based on the CFD computing software platform to design elliptic discharge port structures with different radius ratios and to compare their different thermal jet infrared characteristics. The influence of the oval discharge port radius ratio on the infrared characteristics of thermal jets is verified by the reduced-scale water tank experiment, and the authenticity of the simulation calculation method and design parameters is verified. On the basis of oval discharge ports, the number and distribution position of discharge ports are further designed to suppress the infrared characteristics of thermal jets and to improve the thermal stealth performance of underwater vehicles. According to the simulation calculation and experimental results, under the condition of the same discharge flow, as the radius ratio becomes smaller, the mixing heat transfer effect of the thermal jet becomes better, and the infrared characteristics become less obvious. Moreover, increasing the number of discharge ports and adopting the symmetrical arrangement of discharge ports can further strengthen the temperature attenuation of thermal jets and reduce the surface maximum temperature.