Sizing - Import export

Particle size measurements are important in various applied sciences and in engineering, for example in fuel burning or in cavitation research as well as in particle size control. In all these applications it necessary to have knowledge about the particle dynamics. To gain that knowledge one has to measure the particle size and its velocity if possible in a noninvasive way with high local and temporal resolutions. A device which makes such measurements possible is the so called PhaseDopplerAnemometer (PDA), which has several advantages. First, it exhibits a large dynamic range from micrometer particles up to sizes in the millimetre range. Then it is very precise and no calibration procedure is necessary. Moreover, it is very robust against optical distortions. In the following the working principle of this flow and particle measurement technique will be explained.

For the generation and production of a spray the knowledge of information like the desired droplet size and its distribution is of fundamental importance. In order to characterise a spray correctly, one has to know the droplet size distribution of the droplets, which were generated out of a given liquid. In many applications it is desired to produce very small droplets. For the design and lay out of inhalers for example, it is necessary to achieve droplet sizes not larger than approximately 10 μm to be absorbed by the lungs. When one designs an atomisation nozzle in view of the desired droplet size distribution, one has to make sure via measurements, that the nozzle is really able the produce the expected droplet size distribution within an acceptable uncertainty range. Besides the droplet size distribution, the droplet velocity is an important parameter since it is a measure of the droplet momentum.