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 non-invasive way with high local and temporal resolutions. A device which makes such measurements possible is the so called Phase-Doppler-Anemometer (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. The PDA uses the additional information which is included in the phase position of the scattered light which in turn is a measure of the particle size. The Phase-Doppler-Anemometer is an extension of the classical Laser-Doppler-Velocimeter (LDV), with which one can measure the local flow velocity in a non-invasive manner. Similar to a LDV one can explain the working principle with the aid of a simple interference model. The LDV technique uses only one photo detector for catching the optical signal send by the tracer particle. In contrast to that, a PDA uses several photo detectors called photo multiplier. The figure below shows the situation of a particle in a measurement volume of crossing laser beams in the presence of two angularly shifted detectors. The frequency of both signals is equal, while the phase position of the signals is different. So the detectors collect Doppler signals of equal frequency but different phase position when the particle traverses the test volume, because relatively to each other they are differently positioned. While the measured frequency of the signals contains the velocity information of the particle, the phase positions contain the information of the particle size.
The optical/mechanical system of the PDA consists of a laser, the sending and receiving units, and an optical bench. The laser type one applies depends on the particle size range one expects to measure, the velocity range, and on the distance to the measurement location and its accessibility. The receiving optics consists of an integral set up and usually includes three photo multiplier. The signal processor is based on the application of a correlation function allowing a highly precise measurement of the frequency and phase of Doppler signals.
In our technical department, we apply PDA-techniques for the measurement of velocity fields and particle sizes of cyclone flows and similar separators, in order to obtain an optimal separator design. Also, the Phase-Doppler-Anemometer is applied to environmental measurements and gas cleaning processes for optimisation purposes. A further typical application is the analysis of atomisation and spray processes and the optimisation of spraying systems.
Our experts and our technical center will be happy to answer any questions you may have at any time.
This website uses cookies. Some of these cookies are essential for this website to work, others help us to understand how our website is used and how we can optimise our content for you in the future. You can learn more about cookies, your cookie preferences and our privacy policy.
You may not be able to do all of them without your consent Use functions of our website and external content our offer.
Here you can find an overview over all cookies we use. You can give your consent to whole categories or show further information and edit your preferences for specific cookies.
Notwendige Cookies helfen dabei, eine Webseite nutzbar zu machen, indem sie Grundfunktionen wie Seitennavigation und Zugriff auf sichere Bereiche der Webseite ermöglichen. Die Webseite kann ohne diese Cookies nicht richtig funktionieren.
Name | vf-cookie-settings |
---|---|
Provider | Suvis GmbH |
Purpose | Stores the user's consent status for cookies on the current domain. |
Expiry | 1 year |
Type | HTTP |
This website uses cookies. We use cookies to personalise content and ads, to be able to offer social media content and to analyse user behaviour on our platform. We also share parts of the collected data with our partners for social media, ads and analysis. These partners might combine our collected data with the information you provided while using their services. Cookies are small text files that are used by websites to optimise the user experience.According to German Laws, we are allowed to store essential cookies on your devices to ensure the proper functionality of our website. For all other types of cookies, we need your explicit consent. This website makes use of different types of cookies. Some of these cookies were provided by third parties if we use their services. You can withdraw or change your consent any time in your cookie preferences. You can learn more about who we are, how we process your data and how you can contact us in our privacy policy.