Research On Nozzle Micro-EDM And Consistency Of Fuel Injection Amount

The precision of processing aviation machinery parts will have a huge impact on the quality and performance of parts.The nozzle is the key component of the combustion chamber head of the aircraft engine and gas turbine,and its function is to uniformly and stably supply well-atomized liquid fuel to the combustion chamber.The flow and atomization performance of the nozzle directly affects the combustion efficiency,the temperature distribution of the combustion chamber outlet and the life of the hot end components such as turbine blades,and ultimately affects the thrust(power),range and life of the entire engine.Aviation fuel injector nozzle orifice aperture is small,complex shape,processing quality requirements are high,the early stage of the enterprise using mechanical processing technology will produce a large number of burrs,and the accuracy of the nozzle is difficult to guarantee.In order to improve the above situation,this paper carries out the experimental research of microhole processing using micro-EDM(electrical discharge machining)process,and conducts nozzle flow simulation and test experimental research,and the specific research content and conclusions are as follows:Taking a certain nozzle material specimen as the research object,the micro-EDM experiment was carried out,and the orthogonal test was first used to study the influence of electrical parameters such as pulse width,discharge current,capacitance value on the performance index,and then the single-factor experiment was used to optimize the process parameters to verify the effectiveness of the process in improving the consistency of micropore size.The results show that the discharge capacitance has the greatest influence on the micropore diameter,and the micropore size increases with the increase of capacitance,current and pulse width.The discharge current has the greatest influence on the processing efficiency and electrode loss,with the increase of current and capacitance,the processing efficiency and electrode loss increase,and with the increase of pulse width,the processing efficiency and electrode loss first increase and then decrease;The EDM process can effectively improve micropore size consistency.Use UG software to design a special fixture for a certain type of aero-engine nozzle,calculate the size chain,and design the dimensional deviation and shape and position tolerance of positioning elements and pressing elements.The processing technology of the engine nozzle nozzle is studied by micro EDM process,and the results show that the EDM process will not appear burrs,and the accuracy of the nozzle aperture can be improved.The UG was used to establish a three-dimensional model of the nozzle after micro EDM,imported into gambit pre-processing software for meshing,and then selected to set the relevant parameters in the Fluent software to simulate the fuel mass flow at the nozzle nozzle hole.The results show that the mass flow rates of nozzle outlet at 0.3MPa and 2.2MPa input pressure are2.3521kg/h and 6.7797kg/h,respectively.The flow test experiments of engine nozzles using machining and micro EDM were carried out respectively,and the fuel injection amount,relative error of fuel injection volume and flow dispersion degree of engine nozzles under 0.3MPa and 2.2MPa test pressure conditions were compared and analyzed.Compare and analyze nozzle flow test results and nozzle mass flow simulation results.The results show that under different test pressures,the oil injection amount of the nozzle of fine EDM is reduced by 21.77% and 17.83% compared with the maximum relative error of the injection volume of the machined nozzle,and the standard deviation of the flow dispersion degree is reduced from 0.27 and 0.54 to 0.07 and 0.03,respectively,and the consistency of the injection amount of the nozzle of micro EDM is significantly improved.In summary: compared with the machining process,the use of fine EDM technology can improve the processing accuracy of the nozzle micropore aperture and meet the design requirements of the enterprise for the consistency of the fuel injection amount of the fuel injection nozzle.