TY - JOUR
T1 - Thermal performances of corrugated channel with skewed wall waves at rolling and pitching conditions
AU - Chang, Shyy Woei
AU - Huang, Bo Jyun
N1 - Funding Information:
The research facilities and numerical software were respectively supported by National Science Council, Taiwan, under NSC 99-2221-E-022-015MY3 project.
PY - 2012/8
Y1 - 2012/8
N2 - This experimental study investigates the thermal performances of a narrow wavy channel which swings about two orthogonal axes under single and compound rolling and pitching oscillations. Full-field Nusselt number (Nu) images over the wavy channel wall are detected at static and swinging conditions by infrared thermography method and examined comparatively to highlight the influences of rolling and pitching oscillations on heat transfer performances. A set of selected heat transfer data illustrates the individual and interdependent influences of rolling and pitching oscillations on the detailed Nu distributions and the area-averaged Nusselt numbers (Nu). Pressure drop coefficients (f) for isothermal flows and thermal performance factors (TPF) at static and swinging conditions are subsequently analyzed. For this particular channel configuration, the single rolling or pitching oscillation elevates Nu from the static references; whereas the synergistic effects of compound rolling and pitching oscillations with either harmonic or non-harmonic rhythms suppress the beneficial heat transfer impacts by single rolling or single pitching oscillations. Buoyancy effects in isolation elevate Nu but are weakened as the relative strength of swinging force enhances. Pressure drop coefficients (f) consistently increase as the relative strength of swinging forces increases. At the expense of increased pressure drop penalties for heat transfer augmentations by swinging oscillations, the thermal performance factor (TPF) respectively increases and decreases as Reynolds number (Re) increases with laminar and turbulent reference conditions. Empirical heat-transfer and pressure-drop correlations are generated to permit the evaluations of individual and interactive effects of single and compound swinging force effects with buoyancy interactions on Nu and f coefficients. By the aid of these Nu and f correlations, the favorable and worse operating conditions in terms of the swinging parameters for the TPF properties of this corrugated wavy channel are identified.
AB - This experimental study investigates the thermal performances of a narrow wavy channel which swings about two orthogonal axes under single and compound rolling and pitching oscillations. Full-field Nusselt number (Nu) images over the wavy channel wall are detected at static and swinging conditions by infrared thermography method and examined comparatively to highlight the influences of rolling and pitching oscillations on heat transfer performances. A set of selected heat transfer data illustrates the individual and interdependent influences of rolling and pitching oscillations on the detailed Nu distributions and the area-averaged Nusselt numbers (Nu). Pressure drop coefficients (f) for isothermal flows and thermal performance factors (TPF) at static and swinging conditions are subsequently analyzed. For this particular channel configuration, the single rolling or pitching oscillation elevates Nu from the static references; whereas the synergistic effects of compound rolling and pitching oscillations with either harmonic or non-harmonic rhythms suppress the beneficial heat transfer impacts by single rolling or single pitching oscillations. Buoyancy effects in isolation elevate Nu but are weakened as the relative strength of swinging force enhances. Pressure drop coefficients (f) consistently increase as the relative strength of swinging forces increases. At the expense of increased pressure drop penalties for heat transfer augmentations by swinging oscillations, the thermal performance factor (TPF) respectively increases and decreases as Reynolds number (Re) increases with laminar and turbulent reference conditions. Empirical heat-transfer and pressure-drop correlations are generated to permit the evaluations of individual and interactive effects of single and compound swinging force effects with buoyancy interactions on Nu and f coefficients. By the aid of these Nu and f correlations, the favorable and worse operating conditions in terms of the swinging parameters for the TPF properties of this corrugated wavy channel are identified.
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U2 - 10.1016/j.ijheatmasstransfer.2012.03.076
DO - 10.1016/j.ijheatmasstransfer.2012.03.076
M3 - Article
AN - SCOPUS:84862116158
SN - 0017-9310
VL - 55
SP - 4548
EP - 4565
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
IS - 17-18
ER -