Browsing by Author "Hung, Shuo-Cheng"

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Effect of nonuniform pin size on heat transfer in a rotating rectangular channel with pin-fin arrays
(2019-12-25)
Hung, Shuo-Cheng
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Huang, Szu-Chi
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Liu, Yao-Hsien
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機械工程學系
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Department of Mechanical Engineering
Internal channels to cool the trailing edges of gas turbine blades were typically installed with pin-fin arrays for higher heat transfer enhancement. In this study, the heat transfer characteristics in a rotating rectangular channel (aspect ratio = 4:1) with differently sized pin-fin arrays were experimentally investigated. Liquid crystal thermography was used to measure heat transfer on the endwall in a staggered pin-fin array at a channel orientation of 135 degrees. The staggered array was composed of four or three pins in a row. Pins of varying diameters were inserted in every row exhibiting four pins; either two or four pins were replaced. The rotation numbers ranged from 0 to 0.33, and the Reynolds numbers ranged from 10,000 to 20,000. The results revealed that flow acceleration, separation, and wake flow contributed to various heat transfer contours. Larger pins contributed to higher local flow velocities through fin spacing and produced higher heat transfer distributions. The effect of rotation improved heat transfer enhancement on both trailing and leading surfaces. The friction factor ratio increased when more large-sized pins were installed in the array.
Experimental investigation of the effect of compound protrusion-pin array on heat transfer in an internal rotating cooling channel
(2018-07-25)
Ullal, Ankith
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Hung, Shuo-Cheng
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Huang, Szu-Chi
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Liu, Yao-Hsien
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機械工程學系
An experimental investigation was conducted to study the effect of protrusions and their combination with pins on heat transfer enhancement in a rotating internal passage with an orientation angle of 90 degrees for Reynolds numbers (Re) of 10,000 and 20,000. The trailing surface showed the highest Nusselt number (Nu). The highest and lowest local Nusselt number was at the front and back of the protrusion respectively. A short disturbed wake region was observed behind the protrusion as a result of complex three dimensional flow. Addition of pins in the configuration resulted in an increase of the average Nusselt number, specifically a 35%, 50% and 142% for trailing, static and leading surfaces respectively, compared to protrusions only case for Re of 10,000. On removal of the third column of protrusions, average Nusselt number showed a decrease of 8.25%, 3.1% and 2.3% for trailing, static and leading cases respectively, compared to the protrusion-pin case for Re of 10,000. It also caused elongation of the stagnation and wake flow fields around the fourth column comprising of pins. Pressure drop results indicated that the protrusion only case was the lowest compared to protrusion-pin.
INFLUENCES OF THE NON-UNIFORM PIN-FIN ARRAY ON HEAT TRANSFER DISTRIBUTION IN A ROTATING RECTANGULAR CHANNEL
(2018-01-01)
Hung, Shuo-Cheng
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Huang, Szu-Chi
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Liu, Yao-Hsien
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交大名義發表
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National Chiao Tung University
The liquid crystal thermography was used to investigate the heat transfer of non-uniform pin-fin arrays in a rotating rectangular channel (AR = 4:1) at a channel orientation of 135 degrees. The pin-fin array consisted of four and three pins in a staggered arrangement. The different sized pins were inserted at the rows exhibiting four pins, which produced a non-uniform distribution of the pin-fin array. The experiments were operated at Reynolds numbers of 10,000 and 20,000 for both stationary and rotating conditions. The rotation number varied from 0 to 0.33 and the buoyancy parameter ranged from 0 to 0.27. Results indicated that various heat transfer contours were observed as a result of flow separation and vortices caused by non-uniform pins. Compared to the stationary case, rotation increased heat transfer on both trailing and leading surfaces. The pin-fin array consisted of 6 and 9 mm pins produced the highest heat transfer and frictional losses under rotation condition.