摘要
在JP10和煤油点火特性激波管实验的基础上,实验研究了硅烷对这两种典型高碳数碳氢燃料点火特性的影响．在预加热到70℃的激波管上,采用缝合运行条件获得了近7ms的实验时间,将实验延伸至低温区．采用气相色谱分析和高精度真空仪直接测定压力相结合的方法,确定了燃料气相浓度,解决了高碳数碳氢燃料点火激波管实验时由于管壁吸附影响燃料气相浓度确定的困难．实验记录了点火过程中OH自由基发射强度变化,并作为判断点火发生的标志．实验温度范围880～1800K,压力范围0．16～0．53MPa．当硅烷加入量约为燃料的10%～15%(摩尔比),质量比为2%～3%,观测到明显的点火促进作用．该研究对超燃研究中发动机设计、燃料选择等方面具有直接的工程意义,也可用于检验燃烧化学动力学模型的合理性．
On the basis of the ignition experiments of JP10 and kerosene, experiments were carried out to study the effect of silane addition on ignition characteristics of these two typical heavy hydrocarbon fuels behind reflected shock waves over the temperature range of 880N1800 K and pressure range of 0.16N0.53 MPa.
A longer observation time is required as the ignition time increases at the lower temperature region. The shock tube worked under conditions for a tailored interface, resulting in an observation time of about 7 ms, and the lower temperature bound of experiments was extended in the current study. The uncertainty in the concentration of the fuel vapor due to the adsorption of the fuel vapor on the shock tube wall is one of the largest sources of errors in ignition time measurements of heavy hydrocarbon fuels, thus the gaseous concentrations of JP10 and kerosene were determined in the shock tube by measuring the gas pressure with a high-precision vacuum gauge combined with gas chromatography. Since kerosene is a complex mixture of many hydrocarbon components, the adsorption content of different components differs, so the gas composition different from the liquid composition. In the present study, a simulant modified fuel for kerosene was prepared by adding some heavy hydrocarbon components into the original kerosene in proportion to the adsorption content to compensate the loss in the gas phase through the adsorption. To minimize the degree of adsorption and increase the test fuel vapor pressure, the shock tube was preheated and maintained at 70~C throughout the experiments. The conditions behind the reflected shock were calculated from the incident shock speed using the one-dimensional shock relations. A quartz window was installed on the sidewall very close to the endplate of the driven section to monitor the emission from the ignition process in the reflected shock region. The emission focused through a lens was detected by using a photomultiplier after passing through a monochromator centered at the emission line of OH radical at 306.5 nm as a marker to identify the instant of ignition.
When the molar ratio of the added silane with the fuel was in the range of 10%-15%, the corresponding mass ratio was 2%-3%, a significant reduction in the ignition delay time was observed experimentally. An increase of the addition of silane shortened the ignition delay for JP10 at the lower end of temperature range studied. Specifically, the ignition time for JP10 decreased from 3.7 to 0.87ms at 1100K and from 0.17 to 0.10ms at 1500K. By contrast, the addition of silane shortened the ignition delay for kerosene throughout the temperature range considered. Specifically, the ignition time for kerosene decreased from 3.6 to 0.91 ms at 1000 K and from 0.75 to 0.16 ms at 1220 K. The results presented herein are useful for the engine design and fuel selection in supersonic combustion researches, and also can be used to validate chemical kinetics models of heavy hydrocarbon fuel combustion with silane addition.
出处
《力学学报》
EI
CSCD
北大核心
2007年第4期460-465,共6页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金(90305021).~~
关键词
点火延时
促进剂
硅烷
JP10
煤油
激波管
ignition delay time, enhancer, silane, JPIO, kerosene, shock tube
