Abstract
Gas turbines are used extensively for aircraft propulsion, land-based power generation, and industrial applications. Developments in turbine cooling technology play a critical role in increasing the thermal efficiency and power output of advanced gas turbines. Gas turbine blades are cooled internally by passing the coolant through several rib-enhanced serpentine passages to remove heat conducted from the outside surface. External cooling of turbine blades by film cooling is achieved by injecting relatively cooler air from the internal coolant passages out of the blade surface in order to form a protective layer between the blade surface and hot gas-path flow. For internal cooling, this presentation focuses on the effect of rotation on rotor blade coolant passage heat transfer with rib turbulators and impinging jets. The computational flow and heat transfer results are also presented and compared to experimental data using the RANS method with various turbulence models such as k-ε, and second-moment closure models. This presentation includes unsteady high free-stream turbulence effects on film cooling performance with a discussion of detailed heat transfer coef- ficient and film-cooling effectiveness distributions for standard and shaped film-hole geometry using the newly developed transient liquid crystal image method.
Highlights
Advanced gas turbine engines operate at high temperatures (1200–1500C) to improve thermal efficiency and power output.Received 13 February 2002; accepted 29 October 2002. ∗This paper was presented at the 9th International Symposium on Rotating Machinery
Results show that the channel shape, orientation, and aspect ratio significantly change local heat transfer coefficient distributions in rotor coolant passages with rib turbulators
Most experimental data available to date are for the main body of turbine blade external heat transfer, film cooling, and internal cooling studies
Summary
Advanced gas turbine engines operate at high temperatures (1200–1500C) to improve thermal efficiency and power output. The blades are cooled with extracted air from the compressor of the engine Since this extraction incurs a penalty on the thermal efficiency and power output of the engine, it is important to understand and optimize the cooling technology for a given turbine blade geometry under engine operating conditions. This article focuses on the rotational effects on the turbine blade internal cooling passage heat transfer and the unsteady high free-stream turbulence effects on the turbine blade film cooling performance with standard and shaped film-hole geometry. Interested readers are referred to several recent publications that address state-of-the-art reviews of turbine blade cooling and heat transfer. A recent book focusing entirely on the range of gas turbine heat transfer issues and the associated cooling technology is available by Han et al (2000). A detailed review of convective heat transfer and aerodynamics in axial flow turbines is available by Dunn (2001)
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