Analysis of enhanced turbulent heat transfer in a sharp turn channel having novel designed endwall with longitudinal vortex generator

This paper describes the turbulent heat transfer and the flow characteristics of the longitudinal vortices downstream of vortex generator array on the flat surface. Understanding on the heat transfer and flow characteristics is strongly required from the viewpoint of the heat transfer enhancement in an actual turbine blade design. The experiment was conducted in the test section of the wind tunnel which had a rectangular cross section and length of 2000mm. The reference velocity at the test section was 16 m/s and Reynolds number based on the momentum thickness was 1670. An array of the vortex generators with equal and/or unequal wing height was installed in the turbulent boundary layer. The experiments of the heat transfer on the flat surface were conducted by using the temperature sensitive liquid crystal. The surface of the test section was heated electrically by a thin stainless steel foil. The calibration of the hue of the liquid crystal and temperature was made by Neural Network method. Nusselt number corresponding to the turbulent heat transfer downstream of the array of the vortex generators is strongly affected by the longitudinal vortex motion. The local heat transfer depends on arrangement of the unequal wings of the vortex generator in co-rotating configuration. It is quite interesting that the longitudinal vortex located in the region of downwash motion of the adjacent vortex plays an important role in the merging process of the vortices. In conclusion, the array of the vortex generators is an effective device which can control the heat transfer and flow characteristics in the actual turbine blade cooling design.

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2105 Numerical Analysis of Turbulent Heat Transfer in a Square Duct with 90-Degree Sharp Turn

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2008.3.0_9 ◽

2008 ◽

Vol 2008.3 (0) ◽

pp. 9-10

Author(s):

Hitoshi SUGIYAMA ◽

Takayuki SEKIYA ◽

Naoto KATO

Keyword(s):

Heat Transfer ◽

Numerical Analysis ◽

Turbulent Heat Transfer ◽

Turbulent Heat ◽

Square Duct ◽

Sharp Turn

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A Fundamental Study on Active Control of Turbulent Heat Transfer using Active Vortex Generator

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2004.2.0_329 ◽

2004 ◽

Vol 2004.2 (0) ◽

pp. 329-330

Author(s):

Hiroshi KURIHARA ◽

Daisuke SUGIZAKI ◽

Takashi NAGUMO ◽

Shinji HONAMI

Keyword(s):

Heat Transfer ◽

Active Control ◽

Vortex Generator ◽

Turbulent Heat Transfer ◽

Turbulent Heat ◽

Fundamental Study

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Effects of Centrifugal Buoyancy and Reynolds Number on Turbulent Heat Transfer in a Two-Pass Angled-RIB-Roughened Channel with Sharp 180° Turns Investigated by Using Large Eddy Simulation

International Journal of Rotating Machinery ◽

10.1155/2008/764720 ◽

2008 ◽

Vol 2008 ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

Akira Murata ◽

Sadanari Mochizuki

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Large Eddy Simulation ◽

Rotation Speed ◽

Turbulent Heat Transfer ◽

Turbulent Heat ◽

Eddy Simulation ◽

Sharp Turn ◽

Large Eddy ◽

Rib Roughened

The effects of the centrifugal buoyancy and the Reynolds number on heat transfer in a rotating two-pass rib-roughened channel with 180° sharp turns were numerically investigated by using the large eddy simulation. The effect of the Reynolds number was seen in the finer flow structure. The effect of the aiding/opposing buoyancy contributions was seen more vigorously on the pressure surface than that on the suction surface, though the details depended on the Reynolds number, the rotation number, and the existence of the ribs. As the buoyancy increased, the friction factor dominated by the pressure loss of the sharp turn decreased, and the decreasing rate is smaller for the higher rotation speed case. The Colburn'sjfactor stayed almost constant irrespective of the rotation speed. As a result, the heat transfer efficiency index slightly increased by the buoyancy, and it became smaller for the higher rotation speed and higher Reynolds number cases.

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