近距碰撞式航空发动机喷嘴燃油雾化特性研究

发布时间：2018-07-17 01:18

【摘要】：喷嘴是发动机燃料供给系统的终端部件，其雾化质量的优劣已经成为影响能源利用效率和污染物排放水平的一个关键因素，因此开展喷嘴雾化过程研究对于喷嘴结构优化、提高发动机的整体性能有着重要的意义。本文在借鉴内燃机碰撞喷雾方式的基础上，设计了应用于航空发动机的碰撞喷雾喷嘴，并从喷嘴结构和喷雾特性研究入手，探索利用碰撞喷雾来优化航空发动机燃烧室油气混合及过程的方法和效果。本文开展的具体研究工作如下: (1)设计了A-K十一种喷嘴方案，，其中A-I九种喷嘴保持相同的燃油进口直径、过渡段长度及喷孔到碰撞面的距离，]A、B、C三种喷嘴的喷孔直径不同，分别为0.2mm、0.3mm、0.4mm；D、E、F三种喷嘴较A喷嘴的不同之处是碰撞角度，分别为75°、85°、105°；G、F、I三种喷嘴的碰撞面弧度与A喷嘴不同，分比为5°、10°、15°。J、K两种喷嘴与以上九种喷嘴的燃油进口直径、过渡段长度相同，但碰撞距离不同，其中J喷嘴到碰撞面的距离为1mm，K喷嘴到碰撞面的距离为2mm，两种喷嘴的其余参数与A喷嘴相同。 (2)在不同当量比条件下对嘴的雾化特性进行数值模拟研究，结果表明：随着当量比的增大，SMD减小且逐渐趋于一个极值，在试验条件下，当量比为0.4时，喷嘴雾化效果最好。 (3)通过对不同碰撞方案喷嘴的数值模拟研究表明：喷孔直径、碰撞角度、碰撞面弧度、碰撞距离等参数对碰撞喷雾的空间分布及雾化特性具有较大影响；喷孔直径为0.2mm较0.3mm和0.4mm更加有利于碰撞后喷雾发展和燃油雾化。随着碰撞角度的增大，雾化效果并不是一直改进，而是存在一个最佳值；在相同当量比下SMD随着碰撞面弧度的增大而增大，本文中碰撞面弧度为0°时喷嘴的雾化效果最好；此外，当碰撞距离较小时，喷孔喷出的燃油初次雾化的空间较小，燃油与碰撞面的接触面积较小，不利于燃油雾化，合适的碰撞距离较短的碰撞距离有更好的雾化效果，本文中碰撞距离为3mm时雾化效果最佳。 (4)为了进一步分析近距碰撞式航空发动机喷嘴的雾化特性，本文对A喷嘴的流场、喷雾场及质量分布情况及雾化室下游截面燃油雾化粒径的分布情况进行了详细的分析。结果表明，在碰撞柱下游距离碰撞柱100mm处的截面粒径分布比较均匀。
[Abstract]:Nozzle is the terminal part of engine fuel supply system, and its atomization quality has become a key factor affecting energy utilization efficiency and pollutant emission level. Therefore, the nozzle atomization process is studied to optimize the nozzle structure. It is of great significance to improve the overall performance of the engine. In this paper, the impact spray nozzle used for aero-engine is designed on the basis of the impingement spray mode of internal combustion engine, and the structure and spray characteristic of the nozzle are studied. To explore the method and effect of using collision spray to optimize the mixture and process of gas and oil in the combustion chamber of aero-engine. The specific research work carried out in this paper is as follows: (1) eleven kinds of A-K nozzles are designed, in which nine A-I nozzles maintain the same fuel inlet diameter. The length of the transition section and the distance between the jet hole and the impact surface,] the diameter of the jet holes of the three nozzles AZBZC are different. The difference between the three kinds of nozzles (0.2mm / 0.3mm) and that of nozzles A is the collision angle. The arc of the impact surface of the three nozzles is different from that of the A-nozzles, which are 75 掳/ 85 掳/ 105 掳/ GfFI, respectively, and the diameter of the three kinds of nozzles are different from that of the A-nozzles. The fuel inlet diameters of the two nozzles with the ratio of 5 掳10 掳15 掳.JnK are the same as those of the above nine nozzles, and the length of the transition section is the same, but the collision distance is different. The distance from J nozzle to impact surface is 1 mm K nozzle to impact surface is 2 mm, and the other parameters of the two nozzles are the same as that of A nozzle. (2) the atomization characteristics of nozzle are numerically simulated under different equivalent ratios. The results show that with the increase of the equivalent ratio, the SMD decreases and tends to an extreme value. Under the experimental conditions, the equivalent ratio is 0.4. The atomization effect of the nozzle is the best. (3) through the numerical simulation of the nozzles with different impact schemes, it is shown that the diameter of the nozzle, the impact angle, the arc of the impact surface, The impact distance and other parameters have a great influence on the spatial distribution and atomization characteristics of the impact spray, and the nozzle diameter of 0.2mm is more favorable to the post-collision spray development and fuel atomization than 0.3mm and 0.4mm. With the increase of the impact angle, the atomization effect is not always improved, but there is an optimum value. At the same equivalent ratio, the spray effect of the nozzle is the best when the impact surface arc is 0 掳, and the SMD increases with the increase of the impact surface arc at the same equivalent ratio. In addition, when the impact distance is small, the initial atomization space is smaller, the contact area between the fuel and the impact surface is smaller, which is not conducive to fuel atomization, and the suitable impact distance with shorter impact distance has better atomization effect. In this paper, the atomization effect is the best when the collision distance is 3mm. (4) in order to further analyze the atomization characteristics of the jet nozzle of the short-range collisional aeroengine, the flow field of the A-nozzle is studied in this paper. The distribution of spray field and mass and the distribution of fuel atomization particle size in downstream section of atomizing chamber were analyzed in detail. The results show that the cross section particle size distribution is more uniform at the lower reaches of the impact column than the impact column 100mm.
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V233.22

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