Development of novel Particle Image Thermometry methods for highly resolved measurements of temperature and velocity fields in fluids.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2014)
2014_01_08_Dissertation_Vogt.pdf - Accepted Version
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|Item Type:||Ph.D. Thesis|
|Title:||Development of novel Particle Image Thermometry methods for highly resolved measurements of temperature and velocity fields in fluids|
The subject of present thesis is the development of a technique for simultaneous measurement of temperature and velocity fields in liquids based on the luminescence of particles. This technique is intended to be used for the experimental investigation of transient phase change phenomena like nucleate boiling that takes place on a small spatial scale. For that reason, the main requirement for the developed technique is the ability for temporally and spatially highly resolving measurements. Existing methods either do not offer such high resolution or do not facilitate simultaneous temperature and velocity measurements. Two different approaches for particle-based temperature measurements are presented, one using microcapsules with a temperature-sensitive dye solution in the core and the other using particles fabricated from dyed polymers. The developed microcapsules have a fluorescence characteristic that enables the implementation of a 2-colour-LIF procedure. Fluorescence is excited using a laser with a wavelength of 532 nm and the resulting signals (temperature-sensitive signal and reference signal) are detected by two separate high-speed cameras with appropriate filters. While the brightness of the particles in the images of both cameras serves as temperature indicator, velocity information is extracted from subsequent images of a single camera by means of the PIV method. The applicability of this technique for highly resolved measurements is shown for light-sheet and volume illumination. Therefore, experimental results from a stationary flow driven by natural convection and a flow through a capillary tube driven by a pressure difference are compared to the respective numerical solution of these flows. Moreover, the technique is characterized with regard to accuracy and possible sources of error. The dyed polymers on the contrary, are only investigated with regard to their general applicability for temperature measurements. Laser induced fluorescence with dyes dissolved in acetone is used to measure the temperature field around a growing vapour bubble and the suitability of optical methods for this future application is analyzed.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||LIF Mikroverkapselung Temperatur Messung Partikel|
|Classification DDC:||500 Naturwissenschaften und Mathematik > 530 Physik
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
|Divisions:||16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute for Technical Thermodynamics (TTD)
|Date Deposited:||21 Jan 2014 09:24|
|Last Modified:||21 Jan 2014 09:24|
|Referees:||Stephan, Prof. Peter and Tropea, Prof. Cameron|
|Refereed:||11 July 2013|