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首页> 外文期刊>Journal of Engineering for Gas Turbines and Power >An Experimental Study of Spark Anemometry for In-Cylinder Velocity Measurements
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An Experimental Study of Spark Anemometry for In-Cylinder Velocity Measurements

机译：火花内风速测量的缸内速度实验研究

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摘要

It has been demonstrated by previous researchers that an approximate value of the hulk flow velocity through the spark plug gap of a running spark ignition engine may he deduced from the voltage and current wave forms 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. While 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 freestream 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 freestream 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.
机译：先前的研究人员已经证明，可以从火花的电压和电流波形推导出通过运行中的火花点火发动机的火花塞间隙的绿巨人流速的近似值。该技术已被称为火花风速计，并为发动机燃烧室和其他高温环境提供了可靠的速度感测手段。本文介绍了一项旨在提高火花风速仪性能作为发动机研究工具的实验研究。使用由排放到大气压的校准喷嘴设备提供的流量进行基准测试。尽管较早的研究依靠对伸展火花通道形状的假设来将火花电压与流速相关联，但在本研究中使用高速视频记录了实际火花通道形状。可编程点火系统用于产生可控的恒定电流放电。然后在轻型汽车发动机中测试了火花风速仪。在本研究中对火花通道形状进行图像分析的结果表明，火花核的运动速度小于自由气流的速度。下方存在一个较低的速度阈值，该火花没有响应。如果恒定电流火花的维持电压的一阶导数在一定范围内，则可以获得恒定的近似线性关系。发动机测试显示，缸内速度测量结果存在很大的周期变化。为了避免错误的速度指示，还必须识别在循环过程中发生火花再激的情况。

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