Effect of film-hole shape on turbine blade heat transfer coefficient distribution

Teng, Shuye; Han, Je-Chin

doi:10.2514/6.2000-1035

“…They reported that, compared to the cylindrical hole, the two types of expanded holes in their study (the fan shaped hole and the laidback fan shaped hole) show significantly improved thermal protection of the surface downstream of the injection, particularly at the high blowing ratios. Teng et al (2001aTeng et al ( , 2001b studied the effect of film hole shape on turbine blade film cooling performance under unsteady wake flow conditions. They used the same unsteady wake simulation facility as Du et al (1998) and focused on only one row of film holes near the suction-side gill hole region in order to investigate the hole-shape effect on the curved blade surface under strong flow acceleration conditions.…”

Section: Film Hole Shape Effect On Turbine Blade Film Coolingmentioning

confidence: 99%

Recent Studies in Turbine Blade Cooling?

Han¹

2004

The International Journal of Rotating Machinery

Self Cite

View full text Add to dashboard Cite

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 coefficient and film-cooling effectiveness distributions for standard and shaped film-hole geometry using the newly developed transient liquid crystal image method.

show abstract

“…Details on the image-processing system are presented by Teng et al 15 The image-processingsystem consists of an RGB camera, monitor, and a personalcomputer with color frame grabber board. Figure 2 presentsthe three types of hole geometriesstudied:cylindrical hole, fan-shapedhole,and laidbackfan-shapedhole.The same hole geometries as used by Teng et al 24 are again used here. The hole geometries are similar to those used by Gritsch et al 21 They have shown that, in at-plate geometry, an expandedhole shows signi cantly improved thermal protection of the surface downstream of one hole ejection location as compared to one cylindrical hole.…”

Section: Experimental Apparatusmentioning

confidence: 98%

“…Figure 8 presents the effect of hole shape on spanwise-averaged heat-ux ratio for M D 0:6. The information on h and h 0 is obtained from Teng et al 24 The small arrow at X=D D 0 indicates the lm injection location. The rst three lines (1, 2, 3) in Fig.…”

Section: Effect Of Unsteady Wakementioning

confidence: 99%

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

2001

Journal of Thermophysics and Heat Transfer

View full text Add to dashboard Cite

Detailed coolant jet temperature pro les and lm effectiveness distributions on the suction side of a gas turbine blade are measured using a thermocouple probe and a transient liquid crystal image method, respectively. The blade has only one row of lm holes near the gill-hole portion on the suction side of the blade. The hole geometries studied include standard cylindrical holes and holes with diffuser-shaped exit portion (i.e., fan-shaped holes and laidback fan-shaped holes). Tests are performed on a ve-blade linear cascade in a low-speed wind tunnel. The mainstream Reynolds number based on cascade exit velocity is 5:3 £ £ 10 5 . Upstream unsteady wakes are simulated using a spoke-wheel-type wake generator. The wake Strouhal number is kept at 0 or 0.1. Coolant blowing ratio is varied from 0.4 to 1.2. Results show that both expanded holes have signi cantly improved thermal protection over the surface downstream of the ejection location, particularly at high blowing ratios. In general, the unsteady wake tends to reduce lm-cooling effectiveness. Nomenclatureconductivity of mainstream air L = lm-cooling hole length M = coolant-to-mainstreammass ux ratio or blowing ratio, ½ c V c =½ m V N = speed of rotating rods Nu = local Nusselt number based on axial chord, hC x =k air Nu = spanwise-averagedNusselt number n= number of rods on wake generator P = lm-hole pitch q 00 = local forced convection heat ux with lm injection q 00 0 = local forced convection heat ux for the no lm-hole case N q 00 = spanwise-averagedforced convection heat ux with lm injection N q 00 0 = spanwise-averagedforced convection heat ux for the no lm-hole case Re = Reynolds number based on exit velocity and axial chord, V 2 C x =º S = wake Strouhal number, 2¼ N dn=.60V 1 / SL = streamwise length on the suction surface (33.1 cm) T c = coolant temperature T f = lm temperature T i = initial temperature of blade surface T m = mainstream temperature T w = liquid crystal color change from green to red t = liquid crystal color change time V = local mainstream velocity along the blade suction surface at the lm-hole location V c = coolant hole exit velocity V 1 = cascade inlet velocity V 2 = cascade exit velocity X = streamwise distance starting from lm-hole centerline; streamwise distance measured from leading edge to lm-hole centerline Y = perpendicular distance from blade surface Z = spanwise distance from centerline of lm-cooling holes ® = thermal diffusivity of blade material .0:135 £ 10 6 m 2 /s) ± 2 = local momentum thicknesś = local lm-cooling effectiveness Ń = spanwise-averaged lm-cooling effectiveness µ = nondimensional coolant jet temperature .T T m /=.T c T m / º = kinematic viscosity of cascade inlet mainstream air ½ c = coolant density ½ m = mainstream ow density Á = overall cooling effectiveness given by Á D .T m T w /=.T m T c /

show abstract

“…A few previous studies have shown that expanding the exit of the cooling hole improves film-cooling performance compared to a standard cylindrical hole (e.g., Schmidt et al, 117 Gritsch et al, 118 and several papers reviewed and cited in Chapter 3 of Han et al 1 ). Teng et al 119,120 studied the effect of film-hole shape on turbine blade film-cooling performance under unsteady wake flow conditions. They used the same unsteady wake simulation facility as Du et al 114−116 and focused on only one row of film holes near the suction-side gill-hole region to investigate the hole-shape effect on the curved blade surface under strong flow acceleration conditions.…”

Section: Film Hole Shape Effect On Turbine Blade Film Coolingmentioning

confidence: 99%

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

Han

¹

2006

Journal of Thermophysics and Heat Transfer

Self Cite

View full text Add to dashboard Cite

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

show abstract

Effect of film-hole shape on turbine blade heat transfer coefficient distribution

Cited by 9 publications

References 15 publications

Recent Studies in Turbine Blade Cooling?

Recent Studies in Turbine Blade Cooling?

Evaluation of Real-Gas Phenomena in High-Enthalpy Aerothermal Test Facilities: A Review

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

Contact Info

Product

Resources

About