Assessment of Liquid Propellant Injectors. Part 2. The Measurement of Droplet Size Distribution by Direct Photography With Microflash Illumination.

摘要

Object of investigation: To explore the usefulness of direct photography in the measurement of droplet size distribution in sprays from liquid propellant injectors. Scope of Investigation: An apparatus for the low power photomicrography of sprays with spark illumination has been set up, and a technique developed for the :measurement and counting of the droplet images. The optimum conditions and possible accuracy of the measurement of the distribution of droplet sizes within the spray have been investigated. The results obtained with several types of injector are given in illustration of the method. Conclusions: The use of direct photography for the assessment of injector sprays has great advantages in flexibility of application to varying types of injector and conditions of operation. It is the only method which can give information on the incipient state of atomization close to the orifice and under conditions other than those in the free atmospheres. The instantaneous character and the limited volume of the sampling are disadvantages when the average distributions over a large spray volume are required. A measuring and counting technique is described which reduces to a minimum the time and labor consumed in measuring up a large number of photographs.