Turbine Blade Cooling Studies at Texas A&M University: 1980-2004

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 high-temperature gas turbine engines. 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 to form a protective layer between the blade surface and hot gas-path flow. The most important research contributions on turbine blade cooling studies at Texas A&M University's Turbine Heat Transfer Laboratory from 1980 to 2004 are summarized. For turbine blade internal cooling, the focus is on the effect of rotation on rotor blade coolant passage heat transfer with rib turbulators, pin fins, dimples, and impinging jets. For turbine blade external cooling, the focus is on unsteady high freestream turbulence effects on film-cooling performance with a special emphasis on turbine blade edge region heat transfer and cooling problems. Nomenclature A = cooling channel width A R = cooling channel aspect ratio, A:B B = cooling channel height Bo = buoyancy parameter, ( ρ/ρ)Ro 2 (R/D h ) D = cooling channel hydraulic diameter, dimple diameter d = pin-fin diameter e = rib height F c,cor = Coriolis force acting on the coolant flow F cen = centrifugal force F j,cor = Coriolis force acting on the jet flow f = friction factor f 0 = Blasius fully developed friction factor in a nonrotating, smooth tube H = cooling channel height h = heat transfer coefficient L = cooling channel length; cooling channel leading surface M = blowing ratio for film coolant, (ρV ) c /(ρV ) ∞ N u = regionally averaged Nusselt number, h D/k N u r = ribbed-side Nusselt Number N u 0 = Nusselt number for fully-developed, turbulent flow in a non-rotating, smooth tube P = rib pitch R = cooling channel rotating radius Re = Reynolds number, ρV D/μ Ro = rotation number, D/V s = equivalent slot length for film cooling holes T = cooling channel trailing surface= bulk velocity in streamwise direction x = streamwise location within cooling channel z 0 = cooling channel streamwise location β = angle of cooling channel orientation ρ/ρ = coolant-to-wall density ratio δ = dimple depth η = film cooling effectiveness, (T − T

Numerical predictions of jet impingement heat transfer on square pin-fin roughened plates

“…Compared to the impingement onto the flat plate, the impingement heat transfer of the pin-finned surface may increase or decrease depending on the spent air direction. Akella and Han [15,16] found that the pin-finned surface performed better than the dimpled surface at a lower jet Reynolds number. However, at higher jet Reynolds numbers, the dimpled surface performed better than the pin-finned surface.…”

“… 16. showed the comparison of the local Nusselt number distributions on the inline and staggered pin-fin plates at the Reynolds number of 35,000 with the maximum crossflow scheme.…”

Design Optimization and Performance Analysis of Internal Cooling Passage With Various Type of Rib Turbulator for High Pressure Turbine Nozzle

“…유동간섭물 중 요철의 경우 다양한 형상과 배열이 가능하 며 이러한 여러 가지 요철 형상에 대한 냉각성능 평가 및 최 적화에 관련된 연구가 Han [1], Taslim et al [2], Kim and Kim [3], Lee and Kim [4] …”

Effect of jet nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge

“…Gas turbines are widely applied to electric power generation, aviation propulsion, gas transportation and ship manufacture [1]. With the purpose to enhance turbine efficiency and output, the inlet temperature of modern gas turbines grows higher and higher.…”