Development of a Probe-Type Freezing Method for Droplet-Size Measurement

发明了一种所谓的探针式冷冻方法，并将其应用于由加湿器（超声振动器型）和雾化器（数万个微孔与超声振动器组合，用于医疗抽吸）产生的具有较小尺寸液滴的喷雾。随后，他透露了一些情况。(1)采用探针式冷冻法可以成功地制备出球形冷冻颗粒，并可用于液滴尺寸的测量。(2)利用探针式冻结法，在蒸发和聚结影响最小的条件下，对液滴粒径进行了测量，并阐明了与之相关的几种物理现象。(3)与传统的相位多普勒测速技术和窄角前向散射技术相比，探针式冻结法在测量小于10 μ m的液滴时具有优势，因为冻结法在较小范围内的液滴直径分布更均匀， ...更多信息 而在探针式冻结法中，当用数码显微镜直接观察冻结液滴下落过程时，放大率大于1000时，聚焦深度严重变窄，一张照片上平均可测液滴数仅为5个。因此，出现了数据速率较低的问题。为了解决这一问题，开发了一种直接冷冻取样方法。该方法将喷雾直接引入绝热容器中的取样皿中。特别是，由于一个现代化的相位多普勒风速测量系统在去年，以下揭示。(1)对于由加湿器和喷雾器产生的小于10微米Sauter平均直径（SMD）的较小液滴，最新的相位多普勒风速计比直接冷冻取样方法提供更多小于2微米的液滴。这一定是由于相位多普勒风速计系统的改进或进步。然而，对于大于2微米的雾滴，这种简单的直接冷冻取样方法与最新的相位多普勒风速仪之间的雾滴粒径分布有很好的一致性。验证了该简易冻结方法的实用有效性。(2)对于由旋流喷嘴产生的中空锥形喷雾的SMD大于50微米的较大液滴，直接冷冻取样法的液滴尺寸分布比最新的相位多普勒风速计的液滴尺寸分布更大。这可能是由于最新的相位多普勒风速计的动态范围有限，这一定是这种冻结方法的一个很大的优点。(3)因此，这种直接冷冻取样方法具有比传统相位多普勒风速计更好的小液滴测量性能，但比最新的一种差。它的动态范围比两种相位多普勒风速计都要大。少

A so-called probe-type freezing method was invented, and applied to sprays with smaller size droplets produced from a humidifier (ultrasonic vibrator type) and a nebulizer (tens of thousands micro-holes combined with ultrasonic vibrator, used for medical sucking). Followings were revealed.(1) With the probe-type freezing method, sphere shaped frozen particles could successfully be produced, and it is useful to be applied for droplet-size measurement.(2) With the probe-type freezing method, it is useful to measure droplet size measurement under the condition that the effect of evaporation and coalescence could be minimized, and thus several physical phenomena were clarified related to them.(3) The probe-type freezing method has an advantage in the measurement of droplets less than 10 micro-meter comparing with a conventional phase Doppler anemometry and a narrow-angle forward scattering technique, since the droplet diameter distribution in smaller range for the freezing method is more t … More han those obtained with a phase Doppler and a scattering technique.However, in the probe-type freezing method, when the frozen droplets were observed directly during their falling process with a digital microscope, the enlargement rate greater than 1000 caused seriously narrower focusing depth, and the average measurable number of droplets captured on one photograph was only five. Thus, there appeared a problem of less data rate. In order to solve this problem, a direct freezing sampling method was developed. This method introduced spray directly into a sampling dish in a thermally insulated vessel. Especially, since a modern phase Doppler anemometry system was available in the last year, followings were revealed.(1) For smaller droplets less than 10 micro-meter of the Sauter mean diameter (SMD) produced by a humidifier and a nebulizer, the newest phase Doppler anemometer gives more droplets less than 2 micro-meter than the direct freezing sampling method. This must be due to the improvement or the progress of the phase Doppler anemometer system. However, there was pretty well consistency of droplet size distribution for droplets greater than 2 micro-meter between this simple direct freezing sampling method and the newest phase Doppler anemometer. This verifies the practical validity of this simple freezing method.(2) For larger droplets more than 50 micro-meter of SMD for a hollow cone spray produced by a swirl nozzle, the droplet size distribution of the direct-freezing sampling method shifted to greater size than that of the newest phase Doppler anemometer. It would be due to the limited dynamic range for the newest phase Doppler anemometer, which must be a great advantage of this freezing method.(3) Thus, this direct-freezing sampling method has better performance of smaller droplet measurement than a conventional phase Doppler anemometer but has inferior than a newest one. It has better dynamic range than both phase Doppler anemometers. Less