Objectives  To reduce the thermal wake of submarine during snorkeling,

  Methods  a two-stage cooling method is proposed, which can suppress the infrared radiation of high-temperature exhaust gas under water; and then the water surface temperature fields before and after infrared suppression are analyzed on the basis of the finite element fluid analysis method; and finally, an underwater exhaust gas experiment platform is built on the basis of the preliminary data obtained by simulation, so as to test the infrared radiation brightness of water surface and the temperature of underwater section before and after infrared suppression.

  Results  The results show that the two-stage cooling measure has an excellent infrared suppression effect on the high-temperature exhaust gas of diesel engine, and the maximum infrared brightness of the water surface can be reduced by 90%.

  Conclusions  This method has a good engineering application value and military significance for the improvement of submarine's concealment.