Computational fluid dynamics applied to internal gas-turbine blade cooling: a review

Iacovides, Hector; Launder, B. E.

doi:10.1016/0142-727x(95)00072-x

Cited by 66 publications

(20 citation statements)

References 26 publications

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“…The application of CFD models specifically to gas turbine cooling has also received attention in the literature [13][14][15][16] . Focus of this work has varied from improvements in turn-around time, capabilities in modeling impingement and pin-fin heat transfer, the need for low Reynolds number models, and efficient methodologies.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Heat Transfer Prediction for Various Turbulence Models in a Pin Fin Channel

Ricklick¹,

Carpenter²

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Heat transfer augmentation through the use of pin fins is commonly employed in gas turbine blades and vanes. This is particularly true in the trailing edge region, where the pin fins provide additional structural support, flow control, and heat transfer enhancement. In the industrial design process, commercial CAE packages are now routinely used for predicting the performance of such cooling configurations. The designer is often left with the timeconsuming task of validating their approach. The present study will investigate the accuracy of a selection of the turbulence models commercially available, comparing Nusselt numbers against those found in selected, well-established articles from the literature. With the industrial importance of simulation turn-around time in mind, this investigation will compare 4 RANS turbulence models, at various levels of mesh refinement and temporal resolution. Turbulence models investigated are: realizable k-ε, Menter's k-ω SST, the v 2 -f model, and a quadratic formulation of the realizable k-ε model. The geometry investigated is a staggered, 10 row pin-fin channel, with S/D= 2.19, H/D= 0.875, X/D=1.32, at a Reynolds number of 52.8k. Results show that quadratic versions of the realizable k-ε model tend to match between 6% and 21% of the experimental Nusselt number results on the surface of the pin. Nomenclature CFD = Computational Fluid Dynamics D = Pin Diameter (m) H = Channel Height (m) h = Heat Transfer Coefficient (W/m 2 K) Nu = Nusselt Number S = Spanwise Distance (m) q" = Heat flux (W/m 2 ) RANS = Reynolds Averaged Navier Stokes Re = Reynolds Number T s = Wall Temperature (K) T ref = Reference temperature (K) X = Streamwise coordinate (m)

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Section: Introductionmentioning

confidence: 99%

Comparison of Heat Transfer Prediction for Various Turbulence Models in a Pin Fin Channel

Ricklick¹,

Carpenter²

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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“…To cope with raised temperatures, the surface properties of turbine blades are modified by coating them with a ceramic (Goward 1998) or by introducing a flow through surface holes near the leading edge of the blades (Bogard & Thole 2006). The through-surface flow serves two purposes -first the air cools the blades by passing through their internal structure (Iacovides & Launder 1995), and second, the flow introduced at the leading edge displaces both the momentum and thermal boundary layer away from the blade surface reducing the rate of heat transfer. There is also evidence that introducing a blow flow near to the tip of the turbine blade reduces the pressure drop by altering the flow near the tip gap.…”

Section: Introductionmentioning

confidence: 99%

The effect of a uniform through-surface flow on a cylinder and sphere

et al. 2016

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The effect of a uniform through-surface flow (velocity U b ) on a rigid and stationary cylinder and sphere (radius a) fixed in a free stream (velocity U ∞ ) is analysed analytically and numerically. The flow is characterised by a dimensionless blow velocity Λ (= U b /U ∞ ) and Reynolds number Re (= 2aU ∞ /ν, where ν is the kinematic viscosity). High resolution numerical calculations are compared against theoretical predictions over the range −3 Λ 3 and Re = 1, 10, 100 for planar flow past a cylinder and axisymmetric flow past a sphere. For −Λ 1, the flow is viscously dominated in a thin boundary layer of thickness ν/|U b | adjacent to the rigid surface which develops in a time ν/U 2 b ; the surface vorticity scales as Re|Λ|U ∞ /a for a cylinder and sphere. A boundary layer analysis is developed to analyse the unsteady viscous forces. Numerical results show that the surface pressure and vorticity distribution within the boundary layer agrees with a steady state analysis. The flow downstream of the body is irrotational so the wake volume flux, Q w , is zero and the drag force is F D = −ρU ∞ Q b , where ρ is the density of the fluid and Q b is the normal flux through the body surface. The drag coefficient is therefore −2πΛ or −8Λ for a cylinder or sphere, respectively. A dissipation argument is applied to analyse the drag force; the rate of working of the drag force is balanced by viscous dissipation, flux of stagnation pressure and rate of work by viscous stresses due to sucking. At large Re|Λ|, the drag force is largely determined by viscous dissipation for a cylinder, with a weak contribution by the normal viscous stresses, while for a sphere, only 3/4 of the drag force is determined by viscous dissipation with the remaining 1/4 due to the flux of stagnation pressure through the sphere surface. When Λ 1, the boundary layer thickness initially grows linearly with time as vorticity is blown away from the rigid surface. The vorticity in the boundary layer is weakly dependent on viscous effects and scales as U ∞ /aΛ or U ∞ /aΛ 3/2 for a cylinder and sphere, respectively. For large blow velocity, the vorticity is swept into two well-separated shear layers and the maximum vorticity decreases due to diffusion. The drag force is related to the vorticity distribution on the body surface and an approximate expression can be derived by considering the first term of a Fourier expansion in the surface vorticity. It is found that the drag coefficient C D for a cylinder (corrected for flow boundedness) is weakly dependent on Λ while for a sphere, C D decreases with Λ.

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“…Lakshminarayana (1995) has examined the physics of such heat transfer mechanisms in detail. Computational fluid dynamics (CFD) tools have been typically applied for predicting flow and heat transfer in cooling passages of turbine blades (Iacovides & Launder 1995). Various experimental, theoretical and numerical approaches have been implemented for the study of blade temperatures and heat transfer (Bunker et al 2000;Aydin et al 2002;Carcasi & Facchini 1996).…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade

Coomar

Kadoli

2010

Sadhana

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Internal cooling passages and thermal barrier coatings (TBCs) are presently used to control metal temperatures in gas turbine blades. Functionally graded materials (FGMs), which are typically mixtures of ceramic and metal, have been proposed for use in turbine blades because they possess smooth property gradients thereby rendering them more durable under thermal loads. In the present work, a functionally graded model of an air-cooled turbine blade with airfoil geometry conforming to the NACA0012 is developed which is then used in a finite element algorithm to obtain a non-linear steady state solution to the heat equation for the blade under convection and radiation boundary conditions. The effects of external gas temperature, coolant temperature, surface emissivity changes and different average ceramic/metal content of the blade on the temperature distributions are examined. Simulations are also carried out to compare cooling effectiveness of functionally graded blades with that of blades having TBC. The results highlight the effect of including radiation in the simulation and also indicate that external gas temperature influences the blade heat transfer more strongly. It is also seen that graded blades with about 70% ceramic content can deliver better cooling effectiveness than conventional blades with TBC.

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Computational fluid dynamics applied to internal gas-turbine blade cooling: a review

Cited by 66 publications

References 26 publications

Comparison of Heat Transfer Prediction for Various Turbulence Models in a Pin Fin Channel

Comparison of Heat Transfer Prediction for Various Turbulence Models in a Pin Fin Channel

The effect of a uniform through-surface flow on a cylinder and sphere

Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade

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