Willneff, Lüthi 1 PARTICLE TRACKING VELOCIMETRY MEASUREMENTS FOR LAGRANGIAN ANALYSIS OF TURBULENT FLOWS

3D Particle Tracking Velocimetry offers a flexible technique for the determination of velocity fields in flows. At ETH Zürich an operational and reliable system was developed at the Institute of Geodesy and Photogrammetry and was used for manifold applications in the past decade. In cooperation with the Institute of Hydromechanics and Water Resources Management further progress has been achieved in the improvement of the existing hard- and software solutions. Regarding the improvements of the hardware setup, the image acquisition with an online digitization was upgraded from a recording rate of ¢¤£¤¥§¦ to a ¨ Further progress was also made on the software implementation. A new spatio-temporal matching algorithm was developed, implemented and tested. The most important result of this method is a substantial increase of the tracking rate in 3D-PTV. This is of importance mainly in the context of a Lagrangian analysis of particle trajectories. The hard- and software improvements of the 3D-PTV method are described in this paper. Investigations about velocity derivatives could benefit from the improvements of both- the software as well as the hardware- solutions. The paper will show the contribution of the PTV method for the Langragian analysis of turbulent flows

Design And Calibration Of A Four-Headed Camera System For Use In Microgravity Research

In a cooperation of the Swedish Space Corporation, the Microgravity Research Center of the Universit Libre de Bruxelles and the Institute of Geodesy and Photogrammetry at ETH Zurich, a system for the measurement of three-dimensional particle motion field in an experimental vessel under micro-gravity conditions has been designed and constructed. The system consists of four CCD cameras and a mirror system allowing a good photogrammetric network quality in combination with an extremely compact design. The paper shows the basic design of the system, discusses a calibration strategy and presents first results. The experiment unit was made for the MASER 8 sounding rocket JET experiment with the aim of a first direct observation of the so-called chemojet motion of free flying small growing crystals. It takes place in a reactor chamber with a dimension of 10x11x14 mm 3 , into which several hundred particles are injected during the flight. The particles are imaged by four synchronized CCD cam..

Digital Surface Models for the estimation

Various applications such as meteorology, climatology or hydrology require information about the soil hydraulic properties over large areas. Microwave radiometry is a promising approach to gather this type of information. The microwave emission from soils is strongly affected by the roughness of the soil surface. This effect has therefore to be quantified to get a reasonable estimation of the hydraulic properties. In a cooperation of the Institute of Terrestrial Ecology, Soil Physics with the Instutitue of Geodesy and Photogrammetry digital surface models of soils were generated to study the influence of the surface roughness on the soil moisture measurements. Accurate Digital Surface Models (DSM) can be derived by the application of photogrammetric measurement techniques and provide the spatial basis to extract roughness information. In this paper an approach to determine the roughness of the topsoil surface is presented

Localisation of Ultrasonic NDT Data Using Hybrid Tracking of Component and Probe

Knowledge about the location of a defect is essential for damage assessment. In terms of a digitalised maintenance, inspection data is combined with position information. The presented approach regards the manual ultrasonic inspection, where the ultrasonic probe and the inspected component are both hand-held. By using markerless tracking technologies, it is possible to track the component without any markers. The ultrasonic probe is tracked by a more stable marker-based tracking technology. This results in a hybrid tracking system, which allows a referencing of the non-destructive testing (NDT) data directly to the local coordinate system of the 3D model that corresponds to the inspected component. Transferring this approach to other manual inspection technologies allows for a superimposition of recorded NDT data without any postprocessing or transformation. A better damage assessment is thus enabled. The inspection system, the inspection tool calibration and the camera registration process are described and analysed in detail. This work is focused on the analysis of the system accuracy, which is realised by using a reference body

Photogrammetric set-up for the analysis of particle motion in aerosol under miorogravity conditions

SCOPUS: ar.jinfo:eu-repo/semantics/publishe