With the advanced casting technology used to manufacture modern gas turbine blades, the internal cooling passages within the airfoils are tapered both from the leading edge to the trailing edge and from the hub to tip. Due to the rising rotor inlet temperatures, these three dimensional, internal passages must be cooled with air extracted from the high pressure compressor. So far, the internal cooling passages near the blade trailing edge have been modeled and investigated as high aspect ratio channels with several configurations of pin-fins. However, there are few studies, and limited information found in open literature using a converging profile in the streamwise direction to simulate the trailing edge, internal cooling channel, which is most close to the blade profile. Therefore, in the current study, the heat transfer and pressure drop characteristics of a rotating cooling channel that has trapezoidal cross-section and converges from the hub to tip in both the streamwise and spanwise directions are experimentally investigated. The channel is oriented 120° 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. Pressure drop is measured utilizing 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 results of the smooth surface, converging channel are compared to a smooth surface wedge-shaped channel from literature. In addition, 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° channel orientation, the rotation has a positive impact on the leading and trailing surfaces heat transfer. Furthermore, the convergence decreases the aspect ratio while increasing Reynolds number. The convergence significantly enhances heat transfer on both the leading and trailing surfaces along the streamwise and spanwise directions. The converging passage results can be useful for trailing edge, turbine blade internal cooling design and heat transfer analysis.


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

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.