An Experimental Study of Spark Anemometry for In-Cylinder Velocity Measurements
An Experimental Study of Spark Anemometry for In-Cylinder Velocity Measurements
复制标题
火花风速仪测量缸内速度的实验研究
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
W. Allan
中科院分区：
文献类型：
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作者：
D. Gardiner;G. Wang;M. Bardon;M. LaViolette;W. Allan
以往的研究人员已经证明，可以从火花的电压和电流波形中推导出通过运行的火花塞间隙的整体流动速度的近似值。这项技术被称为火花测速，为发动机燃烧室和其他高温环境提供了一种强大的速度传感手段。本文描述了一项旨在提高火花测速作为发动机研究工具的性能的实验研究。台架试验是使用校准的喷嘴装置提供的流量进行的，该装置排放到大气压。虽然早期的研究依赖于对拉伸火花通道形状的假设，以将火花电压与流速联系起来，但在本研究中，使用高速视频记录了实际的火花通道形状。可编程点火系统被用来产生控制良好的恒流放电。火花测速装置随后在一台轻型汽车发动机上进行了测试。本文对火花通道形状进行的图像分析结果表明，火花核的运动速度小于自由气流的速度。存在一个较低的速度阈值，低于该阈值时，火花不会有任何响应。如果恒流火花的维持电压的一阶导数与自由水流速度在一定范围内，则有可能获得一致的、近乎线性的关系。发动机测试显示，缸内速度测量存在很大的循环变化。还必须识别周期内发生火花重击的情况，以避免错误的速度指示。
It has been demonstrated by previous researchers that an approximate value of the bulk flow velocity through the spark plug gap of a running spark ignition engine may be deduced from the voltage and current waveforms of the spark. The technique has become known as spark anemometry and offers a robust means of velocity sensing for engine combustion chambers and other high temperature environments. This paper describes an experimental study aimed at improving performance of spark anemometry as an engine research tool. Bench tests were conducted using flow provided by a calibrated nozzle apparatus discharging to atmospheric pressure. Whereas earlier studies had relied upon assumptions about the shape of the stretching spark channel to relate the spark voltage to the flow velocity, the actual spark channel shape was documented using high speed video in the present study. A programmable ignition system was used to generate well-controlled constant current discharges. The spark anemometry apparatus was then tested in a light duty automotive engine. Results from the image analysis of the spark channel shape undertaken in the present study have shown that the spark kernel moves at a velocity of less than that of the free stream gas velocity. A lower velocity threshold exists below which there is no response from the spark. It is possible to obtain a consistent, nearly linear relationship between the first derivative of the sustaining voltage of a constant current spark and the free stream velocity if the velocity falls within certain limits. The engine tests revealed a great deal of cycle-to-cycle variation in the in-cylinder velocity measurements. Instances where the spark restrikes occur during the cycle must also be recognized in order to avoid false velocity indications.© 2006 ASME