Analysis of Knock Phenomenon and Proposal of the Solution

通过恒容实验验证了负温度系数对爆震现象的影响。但由于压力、燃油、非定常、温度、湍流等条件与生产发动机存在较大差异，因此设计并制造了一台能够模拟实际发动机条件的快速压缩机。该机器以九州大学开发的机器为基础，具有结构紧凑、活塞运动曲线可变、振动适中等特点。使用这台机器，气体温度和压力的测量，可视化，气体分析可以实现。由于局部气体温度测量被认为是爆震最重要的因素，因此使用双线热电偶进行测量，即使在壁附近也可以进行测量。因此，尽管精度取决于流动方向，密度和速度，但测量误差在2%以内。同时，对恒容室采集的数据进行了零维数值分析。通过这项研究，获得了对爆震分析有用的信息，特别是是否发生爆震的条件。NTC被发现是有效的，这取决于实验条件。为了避免爆震，降低燃气温度、高温持续时间和爆震起爆时刻的未燃燃料是有效的。

Knock phenomenon was found affected by Negative Temperature Coefficient(NTC), examined by experiments using a constant volume chamber. However, as the conditions such as pressure, fuel, unsteadiness, temperature and turbulence are quite different from production engines, a rapid compression machine, which can simulate the conditions in actual engines, was designed and built. As this machine is based on a machine developed at Kyusyu Univ., it has features such as compact, variable piston-motion profile, moderate vibration. Using this machine, measurements of gas temperature and pressure, visualization, and gas analysis can be achieved. Because the local gas temperature measurement is considered as the most important factor for knock, it was made by using two-wired thermocouples, allowable the measurement even in the vicinity of wall As a result, although the accuracy depends on the flow direction, density, and velocity, measurement was made within 2% error. Meanwhile, 0-dimensional numerical analyses were carried out for data taken with the constant volume chamber. Through this study, useful information for knock analysis was obtained, especially conditions whether knock occurs or not. NTC was found affective, depending on experimental conditions. To avoid knock, reductions in the gas temperature, the duration in high temperature and unbumed fuel at the moment of knock initiation are affective.