Our Phase Doppler Anemometry (PDA) systems measure the size, velocity, and concentration of spherical particles, droplets, or bubbles suspended in gaseous or liquid flows. PDA is also known as Phase Doppler Particle Analyzer (PDPA) and Phase Doppler Interferometer (PDI).
The Phase Doppler Particle Analyzer is an extension of the Laser Doppler Velocimeter, invented in the late 1980s. The transmitting optics part is identical to an LDV transmitting optics, so you can measure all three velocity components as well as the particle size.
The Phase Doppler Anemometer operates in off-axis scattering mode with a separate PDPA receiver with three apertures receiving the scattered light of particles, droplets, or bubbles at slightly different angles. Due to this, there will be a small time lag or phase difference between the signals received from the same particle.
The phase difference is proportional to the particle diameter, hence by measuring the frequency of the signal we get the velocity, and by measuring the phase difference we get the diameter of the particle.
Simultaneous particle velocity and diameter data are essential for understanding the dynamics of spray nozzles and fuel injectors or cavitation nuclei formation.
A very common Phase Doppler Particle Analyzer application is the analysis of atomized liquids (sprays).
In fuel injection, a uniform distribution of fuel droplets of small size is important for efficient evaporation before the ignition begins, to obtain good fuel efficiency and clean combustion. With Phase Doppler Anemometry you can measure the Sauter Mean Diameter (SMD or D32), a very important parameter for fuel injection processes.
In spray painting, the paint nozzle must distribute the paint droplets in a uniform way to obtain the desired finish of the painted surface. liquid metal spray and pharmaceutical sprays. With a Phase Doppler Particle Analyzer the droplet distribution, size, and velocity can be measured to help optimize the spray nozzle.
Pharmaceutical sprays issued from inhalers are designed to give patients medicine by inhalation. The droplet size and velocity are important for ensuring that the medicine makes it to the lungs where it can be absorbed into the blood. A Phase Doppler Interferometer helps quantify the essential parameters in this process.
Agricultural sprays can be divided into insecticides and fertilizers. For insecticides, the droplets must not be carried to e.g., neighbouring fields by wind. It is therefore important that the spray nozzles generate droplets large enough to avoid drift. The Phase Doppler Analyzer is the preferred tool to optimize the design of agricultural nozzles.
