当量比及航空煤油组分含量变化对喷嘴表面结焦积炭影响

Impact of Equivalence Ratio and Aviation KeroseneComponents on Nozzle Coking Deposition

关键词:  喷嘴  结焦积炭  正十六烷  丁基苯  当量比  燃料组分

Key words:  Nozzle  Coking deposition  Hexadecane  Butylbenzene  Equivalence ratio  Fuel compoment

摘要:

针对喷嘴表面结焦积炭问题会对航空发动机整体性能及安全性能产生重要影响，以当量比及航煤组分含量变化作为影响因素，采用动态燃烧实验方式，研究燃烧工况变化和正十六烷及丁基苯在与纯航煤掺混后的混合油中其质量分数的变化对喷嘴表面结焦积炭产生的影响。实验后发现喷嘴表面的结焦积炭量随着当量比的减小呈现出不同的变化趋势，其中喷嘴附近燃烧区温度变化及燃气的卷吸和回流作用增强是影响结焦积炭量变化的主要因素。在本文实验工况下，当掺混比例均为10%时，混合油中丁基苯的质量分数变化对结焦积炭量影响比同掺混比例下正十六烷大19%。并且在SEM(Scanning Electron Microscope)分析后发现，燃油小液滴及游离碳氢微团在燃烧态条件下通过高温裂解结焦过程，在喷嘴表面形成了复杂无序和疏松多孔的网片状结构，包括短丝状焦和颗粒球状焦炭的沉积和附着。因此适当的燃烧当量比及航煤中组分含量的变化，可减少喷嘴表面结焦积炭的沉积附着。

Abstract:

For the effects of nozzle coking on overall performance and safety of aircraft engines， the dynamic combustion experiments were carried out to investigate the effects of combustion condition and mass fraction of n-hexadecane and butylbenzene on nozzle coking deposition， while the equivalence ratio and fuel components variation being conducted as experiment factors. It shows that the amount of coking and carbon deposition on nozzle surface has different features with decrease of equivalence ratio， and combustion zone temperature and extent of entrainment and counterflow are the main factors on coking deposition amount. The influence of butylbenzene on nozzle coking deposition amount is 19% bigger than hexadecane under the same blending ratio， which is equal to 10% when mixed with RP-3. SEM (Scanning Electron Microscope) results show that fuel droplets and dissociative hydrocarbon form complicated and porous network structure， and it includes deposition and adsorption of short filamentous coking and amorphous coking. Thus， the amount of coking deposition on nozzle can be decreased under a proper extent of equivalence ratio and fuel components variation.