Study On Infrared Radiation Characteristics Of Marine Exhaust Ejector

With the development of infrared-guided weapons,it has become increasingly important to suppress infrared signals emitted from ships.In order to effectively improve the stealth performance and survivability of ships in high-risk sea areas,it is necessary to reduce the infrared signals radiated from the exhaust pipes and associated structures and smoke plumes.The exhaust ejector is a commonly used infrared suppression device in ship exhaust systems,which has the advantages of simple structure,good cooling effect,and no need for additional power devices.Therefore,it is of great significance to study the infrared radiation characteristics of ship exhaust jet injectors.In this paper,the computational fluid dynamics method was used to simulate the flow field and temperature field of the ship’s exhaust jet injector.Then,a calculation program based on the temperature field was written in Python language to solve the infrared radiation field.The numerical calculation of the ship’s exhaust jet injector’s infrared radiation characteristics was carried out,and multi-objective optimization of the ship’s exhaust jet injector was performed using the orthogonal experimental method and response surface method,resulting in a structure that balances fluid performance and radiation performance.The specific work of this paper is as follows:(1)Based on a certain type of ship exhaust system,the ship’s exhaust jet injector was designed using computational fluid dynamics method to simulate the complete flow field including the injector itself and the smoke plume ejected by the injector.The temperature and flow fields of the ship’s exhaust jet injector were analyzed,and the influence of the composition and structure of the ship’s exhaust jet injector on its overall performance was studied.(2)Combining the basic theory of infrared radiation and gas radiation spectral databases,a calculation program based on the temperature field was written in Python language to solve the infrared radiation field.The calculated results show that the program has high accuracy and applicability.Using the self-developed calculation program,the infrared radiation intensity distribution of the prototype ship’s exhaust jet injector was calculated,and the structural characteristics that affect the infrared radiation intensity of the ship’s exhaust jet injector were analyzed.(3)Based on the structure of the prototype ship’s exhaust jet injector,the orthogonal experimental method was used to analyze the influence of the structural parameters of the sleeve in the nozzle and the mixing chamber on the performance of the ship’s exhaust jet injector.The most significant structural parameters affecting the results were determined based on the orthogonal design table with multiple factors and fewer levels,and the optimal combination of other structural parameters that did not significantly affect the results was given.(4)The improved orthogonal experimental structure was used as the initial structure for response surface experiments,and the typical Box-Behnken design method was used to carry out the response surface experiments.A response surface experiment index was defined that considers both pressure loss and radiation intensity,and the function relationship between the structural parameters and the response value was fitted using the response surface method.Finally,a ship’s exhaust jet injector structure that balances pressure loss and radiation intensity was obtained.