利用OH自由基特征发射谱测量正庚烷的点火延迟时间

在化学激波管中利用反射激波进行点火,采用OH自由基在306.4nm处特征发射谱线强度的急剧变化标志燃料的着火,由光谱单色仪、光电倍增管、压力传感器和示波器组成测量系统,测量了正庚烷/氧气的点火延迟时间,点火压力(1.0±0.1)和(0.75±0.05)atm,点火温度1 170～1 730K,当量比1.0,得到了在此实验条件下正庚烷/氧气点火延迟时间随温度变化的关系式。研究结果表明正庚烷/氧气点火延迟时间随温度的增加呈指数减小,点火压力为0.75atm时,随着点火温度的增加,点火延迟时间的变化率要小于1.0atm条件时。实验结果为建立正庚烷燃烧反应动力学模型,验证正庚烷燃烧反应机理提供了实验依据。

Measurements of the ignition delay times of n-heptane by using characteristic emission from OH radical

Using a measurement system consisting of a monochromator, a photomultiplier tube (PMT), piezoelectric pressure sensors and a digital oscilloscope, the ignition delay times of n-heptane/O2 mixture were measured behind reflected shock waves in a chemical shock tube, the onset of ignition was indicated by the steepest rise of the characteristic emission from OH radical at 306.4 nm. The experimental conditions cover temperatures from 1 170 to 1 730 K, pressures at (1.0 +/- 0.1) and (0.75 +/- 0.05) atm, and equivalence ratio of 1.0. Under these experimental conditions, the correlation formulas of ignition delay time dependence on the temperature for n-heptane have been obtained. Present results indicate that the ignition delay times of n-heptane decreases exponentially with the increase in temperatures. While temperature increases, the change rate of ignition delay time of n-heptane under the pressure of 0.75 atm is less than that of 1.0 atm. Present ignition delay data are important for constructing the kinetic model of the combustion reaction and provide an experimental criterion for validating the combustion reaction mechanism of n-heptane.