| IR suppressor is widely used in modern design of marine engine exhaust system in order to reduce the infrared radiation of marine gas turbine exhaust and improve the survivability of ships.A typical infrared suppressor is usually made up of a mixer and a series of diffusers. The cold flow which ejected through the slots of diffusers increases the second flow and also cools down the diffusers by forming a cooling film on the surface of diffusers. Former researches focused on the main structure and characteristics of a ship exhaust system, but pay less attention on the cooling film on the diffusers. This paper focus on the ejection flow at slot place and different slot structures.Fluent numerical computation had been carried out to study the structure and characteristics of a 2-D ejection flow in single grade. The ejection ratio and film cooling length had been discussed. Three parameters had been considered: the slot height, the overlap length and the mainstream speed. With the analysis of the vortex position to find the length of the film cooling, and compares the different structure changes. At the same time, in the simulation of the incline opening models, determined the best angle and the best arc angle. In the simulation of multi-stage slot, analysis of the influence by wall length, and also discussed the interactions between upstream and downstream. The quantitative analysis of the ejection ratio and wall temperature changes at all levels has been taken. The optimized inclined model is also been simulated, and compared the film cooling in different stage. |
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