Rotating Heat Transfer

• Dimple plates of three different dimple depths (10%, 20%, and 30% of dimple diameter) have been manufactured using and CNC mill.

• Heat transfer experiments are completed and reported here for AR=4:1 channel with 30% depth dimple plates.

• Acrylic pins have been obtained for the pin-fin experiments. These experiments are currently underway to obtain the effect of rotation on the cooling channel with pin fins.

• The entry effect will be explored after the pin-fin experiments are finished. All test section inserts necessary to modify the test section inlet have been manufactured.

• Stationary pressure drop experiments are completed to determine the pressure drop in three different dimple depths (10%, 20%, and 30% of dimple diameter). The test section is make of acrylic and will later be used for liquid crystal thermography experiments.

• Rotation effects on heat transfer in 4:1 aspect ratio channels with 45-degree angled ribs were completed and reported in June 2001.

Part II: Stationary Heat Transfer and Flow Field

• Construction of test sections: The pin fins are completed, the rib turbulators are completed, and the dimples are completed except for heater installation, which is presently underway by Electrofilm Corp. Valencia, Ca.

• Flow structure measurements: The pin fins, the dimples, and the rib turbulators are completed.

• Heat transfer measurements (data obtained at one temperature ratio and different Reynolds numbers): The rib turbulators are completed, the pin fins are almost completed. Also, the dimples are scheduled for the near future.

• Heat transfer measurements (data obtained at different temperature ratios and one Reynolds number): The rib turbulators are completed, and the pin fins are almost done. The dimples are scheduled for the near future.

Part III: Numerical Prediction

• Boundary-fitted numerical grids were generated for a rectangular channel (AR = 4:1) with pin fins using the GRIDGEN code.

• Calculations of flow field, heat transfer coefficients, and pressure drops is currently being performed for the pin fin configurations under various combinations of rotation number, coolant to wall temperature ratio, and channel orientation. Both the two-layer k- e model and near-wall second-moment closure model will be used to quantify the effects of Reynolds stress anisotropy.

• The numerical results will be compared to the experimental data obtained in the above-mentioned flow and heat transfer measurements to assess the general performance of the RANS code and turbulence models.

• Boundary-fitted numerical grids will be generated for a rectangular channel (AR = 4:1) with dimples using the GRIDGEN code.

• Calculations of flow field, heat transfer coefficients, and pressure drops will be performed for the dimple configuration under various combinations of rotation number, coolant to wall temperature ratio, and channel orientation. Both the two-layer k- e model and near-wall second-moment closure model will be used to quantify the effects of Reynolds stress anisotropy.

• The numerical results will be compared to the experimental data obtained in the above-mentioned flow and heat transfer measurements to assess the general performance of the RANS code and turbulence models.

APPENDIX I: FIGURES FOR PART 1

Direction of rotation

6 in

6 in

Figure 1.2. Schematic of 4:1 dimpled test

Figure 1.2. Schematic of 4:1 dimpled test

Direction of rotation

Leading-inner

Leading-outer

Outer

Leading-inner

I I Trailing-inner

Trailing-outer

Figure 1.3. Annotation and datai legend for surfaces within the 4:1 Channel (=3=135°)

Inner

I I Trailing-inner

Trailing-outer

Figure 1.3. Annotation and datai legend for surfaces within the 4:1 Channel (=3=135°)

Cold Core Mainstream Flow

Cold Core Mainstream Flow

Figure 1.4. Dimple induced secondary flow (conceptualization)

mean flow

f\

0 0

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