Heat Transfer in Rotating, Trailing-Edge, Converging Channels With Smooth Walls and Pin-Fins

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Abstract
The heat transfer and pressure drop characteristics of a rotating cooling channel that has an angled trapezoidal cross section and converges from the hub to the tip in both the streamwise and spanwise directions are experimentally investigated. The channel is oriented 120 deg with respect to the direction of rotation to model the geometry of an internal, trailing-edge cooling passage. Both the leading and trailing sides of the channel are divided into three and six regions in the spanwise and streamwise directions, respectively. The copper plate method is used to obtain regionally averaged heat transfer coefficients. The pressure drop is measured using pressure taps placed at the inlet and outlet of the channel. Experiments were conducted with the inlet Reynolds number ranging from 10,000 to 40,000. The rotational speed varies from 0 rpm to 300 rpm, resulting in the highest rotation number of 0.21. The effects of full pin-fins on the heat transfer and pressure drop characteristics are obtained and compared to the smooth surface converging channel results. The impact of the convergence, which causes variations of flow and geometric parameters through the passage, such as aspect ratio, Reynolds number, and rotation number, on the heat transfer coefficients and pressure drop are addressed. Results show that due to the 120 deg channel orientation, the rotation has a positive impact on the leading and trailing surface heat transfer. Furthermore, the convergence decreases the aspect ratio while increasing the Reynolds number. The convergence significantly enhances heat transfer on both the leading and trailing surfaces along the streamwise and spanwise directions. The convergence also reduces the rotation effect in the streamwise direction for a given mass flow rate.

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