研究目的
Investigating the application of a supercontinuum white light laser for simultaneous measurements of temperature and velocity fields using thermochromic liquid crystals in Rayleigh-Bénard cells with high aspect ratio.
研究成果
The supercontinuum white light laser is suitable for simultaneous PIV and PIT measurements with high spatial resolution, provided an appropriate two-dimensional calibration is applied. The technique allows for reliable measurements of velocity and temperature fields in Rayleigh-Bénard convection, offering insights into thermally-driven turbulence.
研究不足
The effective temperature sensitivity range of TLCs may be reduced to about one-tenth of their nominal range at large observation angles. Chromatic aberrations and the numerical aperture of detection optics affect temperature measurements. The study is limited to a specific setup with a cylindrical Rayleigh-Bénard cell and may not be directly applicable to other configurations.
1:Experimental Design and Method Selection:
The study employs a supercontinuum laser for illuminating thermochromic liquid crystals (TLCs) to simultaneously measure velocity and temperature fields in a Rayleigh-Bénard cell. The methodology includes PIV and PIT techniques.
2:Sample Selection and Data Sources:
Encapsulated TLCs of chiral nematic type with a mean diameter of about 10 μm are suspended in de-ionized water within a cylindrical Rayleigh-Bénard cell.
3:List of Experimental Equipment and Materials:
Supercontinuum white light laser (SuperK EXTREME EXR-20), spectrometer (Blue wave, StellarNet Inc.), color-sensitive camera (sCMOS PCO edge 5.5, LaVision GmbH), and LED-system (SPECTRA X light engine, Lumencor).
4:5, LaVision GmbH), and LED-system (SPECTRA X light engine, Lumencor).
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Calibration measurements are conducted at isothermal conditions with varying observation angles. Simultaneous PIV and PIT measurements are performed in a Rayleigh-Bénard convection setup.
5:Data Analysis Methods:
The light scattered from TLCs is analyzed using spectrometer measurements. Velocity and temperature fields are derived from PIV and PIT algorithms, respectively, with data processing including image preprocessing, cross-correlation, and vector post-processing.
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