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Lawler Thesis_VFINAL5.pdf (11.92 MB)

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Heat Transfer for a Stationary Serpentine Passage using a Transient Thermochromatic Liquid Crystal Paint Technique

Lawler, Timothy Robert
http://orcid.org/0000-0002-3720-984X
http://rave.ohiolink.edu/etdc/view?acc_num=osu1449240391

Abstract Details

2015, Master of Science, Ohio State University, Aero/Astro Engineering.
As demand for greater and greater fuel efficiency is felt in the airline industry, there is a need to decrease specific fuel consumption of gas turbine engines. One method for improving specific fuel consumption is elevating the overall operating temperature of the engine, resulting in higher efficiency. Over time, the turbine inlet temperature of modern gas turbine engines has increased to above the working temperature of the materials used to construct the high-pressure turbine stages. To maintain safety, performance, and maintainability of these parts, active cooling techniques have been developed for the high-pressure turbine. Among these methods is internal cooling, wherein core flow is bled from the high-pressure compressor and is forced through serpentine passages within the blades of the high-pressure turbine. As this practice reduces the mass flow of air through the combustor, it reduces overall efficiency. Therefore, the amount of air bled from the compressor must be optimized. A stationary three passage serpentine is presented to represent the internal cooling passages of the high-pressure turbine blades. Heat transfer measurements are provided for a square aspect ratio, 1:1, geometry representative of some gas turbine engines and comparable to existing datasets. Departing from previous experiments, this project focused on employing transient thermal liquid crystals (TLC) to gain a fully two-dimensional temperature distribution throughout the test section. Turbulators are mounted at 45° skew to the flow direction with a fixed pitch to height ratio (e/P) of ten and a height to hydraulic diameter ratio (e/D_h) of 0.058. This experiment is similar to previous projects performed at The Ohio State Gas Turbine Laboratory, with the exception of the TLC technique. The TLC technique requires painting a thin layer of thermal paint upon the surfaces of interest, followed by a thin layer of black paint as a background. Video is taken during the experiment with a GoPro video camera, an off the shelf consumer product. Hue values from the colors captured are determined and correlated to temperatures. Since every pixel of the captured images corresponds to a data point, extremely high-resolution data is obtained in two dimensions. The aim of this experiment is to match the results from previous, nominally identical experiments, with the new TLC technique. This technique will then be employed for a fully rotating experiment that will better reflect real operating conditions of an engine. Results are presented for three Reynolds Numbers: Re 25000, Re 34000, and Re 50000. Run to run repeatability is discussed and found to be acceptable, but there are areas of improvement. These include masking areas of poor data integrity and removing some of the manual data manipulation to remove the human factor. Comparisons are made to existing datasets at Re 25000 and Re 50000. The trends between the two data sets match at both Reynolds numbers and over the full length of the serpentine passage. Magnitude of the results is comparable between the TLC data and existing datasets, with the TLC consistently predicting lower heat transfer than the previous dataset. This can be improved by removing the human factor in determining synchronization between data acquisition systems and capturing video data at a higher resolution.
Randall Mathison, PhD (Advisor)
Michael Dunn, PhD (Committee Member)
353 p.
Aerospace Engineering

Recommended Citations

Citations

  • Lawler, T. R. (2015). Heat Transfer for a Stationary Serpentine Passage using a Transient Thermochromatic Liquid Crystal Paint Technique [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449240391

    APA Style (7th edition)

  • Lawler, Timothy. Heat Transfer for a Stationary Serpentine Passage using a Transient Thermochromatic Liquid Crystal Paint Technique. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1449240391.

    MLA Style (8th edition)

  • Lawler, Timothy. "Heat Transfer for a Stationary Serpentine Passage using a Transient Thermochromatic Liquid Crystal Paint Technique." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449240391

    Chicago Manual of Style (17th edition)

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