Novel Phase Doppler Profile Sensor For Simultaneous Measurement Of Size, Velocity, And Position Of Droplets

In numerous technical flow applications knowing size, velocity, and position of dispersed structures simultaneously enables the comprehensive characterization of the underlying dynamics. A suitable interferometric measurement technique capable of measuring simultaneously the three droplet characteristics is introduced for the first time. This novel measurement technique called phase Doppler profile sensor (PDPS) combines the measuring principles of the laser Doppler profile sensor (LDV-PS) for velocity measurement along a measuring line with the phase Doppler technique for particle size determination. A proof-of-concept of this technique was successfully performed by comparison to another established measurement technique on a controlled use case of a displaceable mono-disperse droplet stream. In this first optical setup, a conventional phase-Doppler sensor is used as receiving unit with a conventional pinhole aperture cutting the measurement volume. Hence, the resulting performance for simultaneously measuring the droplet diameter, velocity and position along a measuring line mark the preliminary status reached and are supposed to improve in future measurements with a removed pinhole aperture. So far, the average relative deviation of PDPS compared to the reference technique simultaneously measuring diameter, position, and velocity is 1.14% (diameter), 2.18% (position), and 0.4% (velocity) when using a general laboratory setup.