Title page for ETD etd-07122006-141237


Type of Document Master's Thesis
Author Esposito, Eric Ian
URN etd-07122006-141237
Title Jet Impingement Cooling Configurations for Gas Turbine Combustion
Degree Master of Science in Mechanical Engineering (M.S.M.E.)
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Srinath Ekkad Committee Chair
Keith Gonthier Committee Member
Ram Devireddy Committee Member
Keywords
  • gas turbine
  • jet impingement
  • impingement
  • cooling
  • combustor
  • backside cooling
Date of Defense 2006-06-16
Availability unrestricted
Abstract
Impinging jets are commonly used to enhance heat transfer in modern gas turbine engines. Impinging jets used in turbine blade cooling typically operate at lower Reynolds numbers in the range of 10,000 to 20,000. In combustor liner cooling, the Reynolds numbers of the jets can be as high as 60,000. The present study is aimed at experimentally testing two different styles of jet impingement geometries to be used in backside combustor cooling. The higher jet Reynolds numbers lead to increased overall heat transfer characteristics, but also an increase in crossflow caused from spent air. The crossflow air has the effect of rapidly degrading the downstream jets at high jet Reynolds numbers. In an effort to increase the efficiency of the coolant air, configurations designed to reduce the harmful effects of crossflow are studied. Two main designs, a corrugated wall and extended ports, are tested. Variations of these configurations were tested for both sparse and dense arrays.

Local heat transfer coefficients are obtained for each test section through a transient liquid crystal technique. Results show that both geometries reduce the crossflow induced degradation on downstream jets, but the individual geometries perform better at different Reynolds numbers. The extended port and corrugated wall configurations show similar benefits at the high Reynolds numbers, but at low Reynolds numbers, the extended port design increases the overall level of heat transfer. This is attributed to the further developed jet profile that exits the tubes. The benefit of the developing velocity profile diminishes as jet velocities rise and the air has less time to develop prior to exiting.

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