Measurement of droplet size and velocity based on a single tapered fiber optical reflectometer

A single optical fiber probe (OFP) is used to measure the velocity and size of droplet falling in the air. By analyzing the interference waves formed by two reflected lights from the droplet surface and the fiber core interface, the fiber optical reflectometer (FOR) is mainly studied in this paper. The wave optics simulation was firstly applied to verify the FOR principle of velocity measurement. Then an experiment system which can generate droplets with different velocities and sizes was designed. Through comparing the results of OFP with photography method, the absolute relative error of chord length measured was within 1.3%. During the study, it was observed that the intensity of oscillation waves is closely related to the contact position between probe and droplet, so a method for predicting droplet diameter by OFP is proposed. Compared with photography method, the root mean square error of the predicted diameter is 0.051 mm.

Automated summary

This study mainly focuses on the principle of using a fiber optical reflectometer (FOR) to measure the velocity and size of falling droplets. The feasibility of the method is verified through experiments, and a method for predicting droplet diameter using a fiber probe is proposed.