Molecular tagging thermometry with adjustable temperature sensitivity

Hu, Haoran; Koochesfahani, Manoochehr; Lum, Chee

doi:10.1007/s00348-006-0112-2

Cited by 52 publications

(30 citation statements)

References 13 publications

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“…A planar grid of intersecting laser beams, formed from a pulsed ultraviolet (UV) laser, turns on the luminescence of the phosphorescent triplex FIGURE 2. Absorption and emission spectra of the 1-BrNp·Mβ-CD·ROH triplex (Hu, Lum & Koochesfahani 2006): (a) normalized absorption and emission spectra at room temperature; (b) emission spectra at different temperatures (280 nm excitation of spectrophotometer).…”

Section: Molecular Tagging Velocimetry and Thermometry (Mtvandt) Techniquementioning

confidence: 99%

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Koochesfahani

2011

J. Fluid Mech.

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The thermal effects on the wake flow behind a heated circular cylinder operating in the mixed convection regime were investigated experimentally in the present study. The experiments were conducted in a vertical water channel with the heated cylinder placed horizontally and the flow approaching the cylinder downwards. With such a flow arrangement, the direction of the thermally induced buoyancy force acting on the fluid surrounding the heated cylinder would be opposite to the approach flow. During the experiments, the temperature and Reynolds number of the approach flow were held constant. By adjusting the surface temperature of the heated cylinder, the corresponding Richardson number (Ri = Gr/Re 2 ) was varied between 0.0 (unheated) and 1.04, resulting in a change in the heat transfer process from forced convection to mixed convection. A novel flow diagnostic technique, molecular tagging velocimetry and thermometry (MTV&T), was used for qualitative flow visualization of thermally induced flow structures and quantitative, simultaneous measurements of flow velocity and temperature distributions in the wake of the heated cylinder. With increasing temperature of the heated cylinder (i.e. Richardson number), significant modifications of the wake flow pattern and wake vortex shedding process were clearly revealed. When the Richardson number was relatively small (Ri 0.31), the vortex shedding process in the wake of the heated cylinder was found to be quite similar to that of an unheated cylinder. As the Richardson number increased to ∼0.50, the wake vortex shedding process was found to be 'delayed', with the wake vortex structures beginning to shed much further downstream. As the Richardson number approached unity (Ri 0.72), instead of having 'Kármán' vortices shedding alternately at the two sides of the heated cylinder, concurrent shedding of smaller vortex structures was observed in the near wake of the heated cylinder. The smaller vortex structures were found to behave more like 'Kelvin-Helmholtz' vortices than 'Kármán' vortices, and adjacent small vortices would merge to form larger vortex structures further downstream. It was also found that the shedding frequency of the wake vortex structures decreased with increasing Richardson number. The wake closure length and the drag coefficient of the heated cylinder were found initially to decrease slightly when the Richardson number was relatively small (Ri < 0.31), and then to increase monotonically with increasing Richardson number as the Richardson number became relatively large (Ri > 0.31). The † Email address for correspondence: huhui@iastate.edu 236 H. Hu and M. M. Koochesfahani average Nusselt number (Nu) of the heated cylinder was found to decrease almost linearly with increasing Richardson number.

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Section: Molecular Tagging Velocimetry and Thermometry (Mtvandt) Techniquementioning

confidence: 99%

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Koochesfahani

2011

J. Fluid Mech.

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“…Molecules with a long-lived phosphorescence (on the order of a few ms) allow relatively easy measurements of the lifetime. A conventional camera operating in PIV mode can be used to characterize the phosphorescence decay in the molecular tagging thermometry (MTT) developed by Hu et al (2006). This approach, however, has its limitations.…”

Section: Partially Saturated Fluorescencementioning

confidence: 99%

The saturation of the fluorescence and its consequences for laser-induced fluorescence thermometry in liquid flows

et al. 2016

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“…Rhodamine B is a cationic dye which forms amide bonds with the N-terminus of amino groups in the protein. The temperature sensitivity of Rhodamine B fluorescence emission excited at various wavelengths is at best about À2% per°C, i.e., the fluorescence intensity decreases about 2% for every 1°C increase in temperature (Hu et al, 2006). Due to the temperature instability of the Rhodamine B, the micrographs obtained were processed using the image processing algorithms we developed previously.…”

Section: In Situ Image Acquisitionmentioning

confidence: 99%

In situ microstructure evaluation during gelation of β-lactoglobulin

Gunasekaran

2009

Journal of Food Engineering

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Molecular tagging thermometry with adjustable temperature sensitivity

Cited by 52 publications

References 13 publications

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime

The saturation of the fluorescence and its consequences for laser-induced fluorescence thermometry in liquid flows

In situ microstructure evaluation during gelation of β-lactoglobulin

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