Investigation On The Characteristic Of Thermal Oxidation Deposition Of RP-3 Kerosene In Serpentine Tubes Under Supercritical Pressure

As the flight Mach number and supercharging ratio of aircraft continue to increase,higher requirements are placed on the cooling system of aero engines.At present,using aviation fuel as a cold source to cool the neutron subsystem of aeroengines is a reliable and efficient cooling method.However,when aviation fuel is heated to 150°C,thermal oxidation and coking reaction will occur,which will cause coking inside the pipeline.Based on the analysis of domestic and foreign thermal oxidation coking research,this paper aims to enhance the pipe heat transfer performance and reduce the pipe coking.The serpentine pipe is taken as the research object.The oxidative coking and heat transfer characteristics of aviation fuel in a serpentine tube were studied through a combination of theoretical analysis,experimental research and simulation calculations,and the effects of flow parameters,structural parameters and component concentration distribution on oxidative coking inside the tube were analyzed to provide theoretical support for the engineering design of heat transfer tubes.According to the research objectives,on the basis of the high temperature fuel oil cracking test bed of Harbin Institute of Technology,a serpentine tube electric heating oxidation coking test bed was built.Based on this experimental system,the number of bending parts,reaction pressure,kerosene oxygen content,and fuel temperature can be completed.Experiments on the influence of other parameters on the oxidation and coking of serpentine tubes.After the above experimental design is completed,the current experimental bench measurement methods and measurement accuracy are analyzed by repeated experiments,and then the empty tube heating is performed according to the experimental data processing needs to obtain the heat dissipation loss of the serpentine tube at different temperatures.On this basis,the law of oxidation coking deposition in the serpentine tube under typical working conditions was analyzed,laying the foundation for the following investigation into the influence of multiple factors.Then,the control variable method was used to analyze the influence of fuel temperature,working pressure,kerosene oxygen content,and the number of pipe elbows on the oxidation and coking of the serpentine tube.During the experiment,after heating the pipeline continuously for 120 minutes,the coking rate along the pipeline was obtained by the weighing method,the temperature change of the pipeline was obtained through the measurement and control system,and the changes in the fuel temperature and dissolved oxygen content along the way were analyzed to analyze the effect of different flow parameters and structural parameters on the serpentine shape.The mechanism of tube oxidation and coking points out how to reduce the local heat transfer deterioration area and the direction of reducing coking.Finally,by simplifying the geometric model of the serpentine tube,using the U-shaped tube as the numerical simulation object of this article,based on the ANSYS Fluent simulation software,a thermal-chemical-fluid coupling model containing 19 steps of 24-component oxidation coking kinetic models was constructed.After verifying the accuracy of the model,the coking mechanism of the pipe elbow was analyzed.