Abstract

To measure airborne particulate matter concentration over a wide range, a measurement system is mounted on various types of moving vehicles, such as high-speed trains, small drones, and airplanes. Depending on the purpose and range of measurement, the size of the moving vehicle used varies, and the sampling flow rate of the measurement system mounted on the vehicle also varies accordingly. Therefore, an isokinetic sampling inlet with a size suitable for each mobile measurement system must be used. In this study, the aspiration ratio according to various sizes of double-shrouded probes developed to enable representative sampling, including under high-speed flow conditions, was investigated. Considering the various speed ranges of the moving vehicle and relative angle between the moving direction of the vehicle and the surrounding flow direction, the free-stream velocity range around the double-shrouded probe was set to 0–300 km/h and the angle of attack was set to 0–30°. As the angle of attack increased, the aspiration ratio tended to decrease. When the angle of attack is fixed, we found that the aspiration ratio of the double-shrouded probe of various sizes can be made non-dimensional using the square root of the Stokes number. Based on these results, it is expected that the size of the double-shrouded probe suitable for various mobile measurement systems can be easily determined, and accurate measurement of dust concentration is possible through quick prediction of the aspiration ratio according to the velocity of the moving vehicle and angle of attack.

Copyright © 2021 American Association for Aerosol Research

摘要

为了在大范围内测量空气中的颗粒物浓度，测量系统安装在各种类型的移动车辆上，例如高速火车、小型无人机和飞机。根据测量的目的和范围，所使用的移动车辆的大小不同，安装在车辆上的测量系统的采样流量也相应地变化。因此，必须使用尺寸适合每个移动测量系统的等速采样入口。在这项研究中，研究了根据各种尺寸的双护罩探头的抽吸比，以实现具有代表性的采样，包括在高速流动条件下。考虑到移动车辆的各种速度范围以及车辆的移动方向与周围流向之间的相对角度，双罩探测器周围的自由流速度范围设置为 0-300 公里/小时，攻角设置为 0-30°。随着迎角的增加，吸入比趋于降低。当攻角固定时，我们发现使用斯托克斯数的平方根可以使各种尺寸的双护罩探头的吸入比无量纲化。基于这些结果，预计可以很容易地确定适用于各种移动测量系统的双护罩探头的尺寸，并且通过根据移动速度快速预测吸入比，可以准确测量粉尘浓度。车辆和攻角。随着迎角的增加，吸入比趋于降低。当攻角固定时，我们发现使用斯托克斯数的平方根可以使各种尺寸的双护罩探头的吸入比无量纲化。基于这些结果，预计可以很容易地确定适用于各种移动测量系统的双护罩探头的尺寸，并且通过根据移动速度快速预测吸入比，可以准确测量粉尘浓度。车辆和攻角。随着迎角的增加，吸入比趋于降低。当攻角固定时，我们发现使用斯托克斯数的平方根可以使各种尺寸的双护罩探头的吸入比无量纲化。基于这些结果，预计可以很容易地确定适用于各种移动测量系统的双护罩探头的尺寸，并且通过根据移动速度快速预测吸入比，可以准确测量粉尘浓度。车辆和攻角。

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