scholarly journals Large Eddy Simulation of Turbine Internal Cooling Ducts

2013 ◽  
Author(s):  
James Tyacke ◽  
Paul Tucker
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Large Scale ◽  
Minor Importance ◽  
Internal Cooling ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Cheap Method ◽  
A Minor ◽  
Les Model

Large-Eddy Simulation and hybrid RANS-LES methods are applied to a turbine blade ribbed internal duct with a 180 degree bend containing 24 pairs of ribs. Flow and heat transfer predictions are compared with experimental data and found to be in agreement. The choice of LES model is found to be of minor importance as the flow is dominated by large geometric scale structures. The influence of inlet turbulence is also tested and has a minor impact due to the strong turbulence generated by the ribs. Large scale turbulent motions destroy any classical boundary layer reducing near wall grid requirements. The wake-type flow structure makes this and similar flows nearly Reynolds number independent, allowing a range of flows to be studied at similar cost. Hence LES is a relatively cheap method for obtaining accurate heat transfer predictions in these types of flows.

Experimental and Large Eddy Simulation Study for Visualizing Complex Flow Phenomena of Gas Turbine Internal Blade Cooling Channel with No Bend

2021 ◽  
pp. 1-19
Author(s):  
Farah Nazifa Nourin ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Complex Flow ◽  
Pressure Drops ◽  
Two Circular Holes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Circular Holes

Abstract In this study, the internal cooling channel was investigated without any bend. Smooth surfaces and dimpled surfaces were investigated using the different combinations of connecting circular and rectangular holes. The computations were performed using the Large Eddy Simulation (LES) model for Reynolds (Re) numbers from 10,000 to 50,000. A total of six different connecting holes were investigated with a smooth and dimpled surface. A partial spherical dimple with two circular holes showed the highest heat transfer, but it has a higher pressure loss penalty. Even though the Leaf dimple with the rectangle indicated a low heat transfer because of low-pressure drops, it represents the highest efficiency at higher Reynolds numbers.

LES Investigation of Modified Rib Shapes on Heat Transfer in a Ribbed Duct

2021 ◽  
Author(s):  
K Sreekesh ◽  
Danesh K. Tafti ◽  
S Vengadesan
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Flow Direction ◽  
Internal Cooling ◽  
Square Duct ◽  
Flow Losses ◽  
Heat Transfer Augmentation ◽  
Eddy Simulation ◽  
Large Eddy

Abstract Internal cooling of gas turbine blade is critical for the durability of the blade material. One of the ways to accomplish this is by passing coolant through serpentine passages roughened with surface elements to enhance the heat transfer. In the present study, the traditional square rib (SQ-rib) placed normal to the flow direction is modified to a backward facing step rib (BS-rib) and a forward facing step rib (FS-rib). Large-eddy simulation (LES) is carried out for a square duct at Reb = 20000. Results show that the modified rib shapes result in substantial increase in heat transfer over the square rib with only a marginal increase in flow losses. The BS-rib shape produces the highest heat transfer augmentation followed by the FS-rib. The overall heat transfer augmentation for the BS-rib and FS-rib is 18% and 10% larger than the SQ-rib, respectively. Thermal-hydraulic performance is enhanced by 15%.

Large Eddy Simulation of the Developing Region of a Stationary Ribbed Internal Turbine Blade Cooling Channel

2004 ◽  
Author(s):  
Evan A. Sewall ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Turbine Blade ◽  
Internal Cooling ◽  
Mean Flow ◽  
Heat Transfer Augmentation ◽  
The Third ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Cooling Passage

This study reports on a Large Eddy Simulation (LES) of the entrance section of a gas turbine blade internal cooling passage. The channel is fitted with in-line turbulators orthogonal to the flow, and the domain studied covers the first six ribs of the channel. The rib height-to-hydraulic diameter ratio (e/Dh) is 0.1, and the rib pitch-to-rib height ratio (P/e) is 10. A constant temperature boundary condition is imposed on the walls and the ribs, and the flow Reynolds number is 20,000. Results indicate that the mean flow is essentially fully developed by the fifth rib. Turbulent kinetic energy near the ribbed wall approaches fully developed values very quickly by the third or fourth ribs. However, turbulent intensities at the center of the duct are not fully developed by the sixth rib. As a consequence, heat transfer augmentation on the ribbed walls reaches a fully developed state quickly after the third rib, whereas, the smooth wall heat transfer augmentation shows a slight but steady increasing trend toward the fully developed value up to the sixth rib. Both augmentation ratios are to within 10% of their fully developed values after the third rib.

Large-Eddy Simulation for Turbine Heat Transfer

2013 ◽  
Author(s):  
Gorazd Medic ◽  
Jongwook Joo ◽  
Ivana Milanovic ◽  
Om Sharma
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Large Scale ◽  
Leading Edge ◽  
Pressure Side ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy ◽  
The Impact ◽  
Side Flow

Heat transfer in a high-pressure turbine configuration (from an experiment documented in [1–2]) has been analyzed by means of large-eddy simulation. Blair’s large-scale rotating rig consists of a first stator, a rotor and an exit stator. Flow and heat transfer in the first stator are assessed for two configurations — with and without the presence of turbulence generating grid. A particular challenge here is that turbulence grid generates fairly high levels of inlet turbulence with turbulence intensity (TU) of about 10% just upstream of leading edge; this in turn moves the transition location upstream in a dramatic fashion. As far as the rotor blade is concerned, the flow and heat transfer is also analyzed experimentally for a range of incidence angles assessing the pressure side heat transfer increase at negative incidence angles. Several challenging aspects relevant to flow in the rotor are also considered — the three-dimensionality of pressure side flow separation at negative incidence, the impact of upstream stator wakes, as well as the role of surface roughness.

Large Eddy Simulation of Rotating Ribbed Channel

2013 ◽  
Author(s):  
Rémy Fransen ◽  
Laurence Vial ◽  
Laurent Y. M. Gicquel
Keyword(s):  
Large Eddy Simulation ◽  
Large Scale ◽  
Cooling System ◽  
Internal Cooling ◽  
Time Resolved ◽  
Ribbed Channel ◽  
Eddy Simulation ◽  
Rotating Blade ◽  
Image Velocimetry ◽  
Large Eddy

Large Eddy Simulation (LES) of isothermal flow in stationary and wall-normal rotating blade internal cooling system is evaluated against experimental data. The studied case is a 3D one wall ribbed straight channel for which time resolved two-dimensional Particle Image Velocimetry (PIV) measurements have been performed at the Von Karman Institute (VKI) in a near gas turbine operating condition. Thanks to these experimental mean and time-resolved quantities, advanced numerical computations can be adequately evaluated. In this work LES results show that this high fidelity CFD model is able to reproduce the turbulence increase (decrease) around the rib in destabilizing (stabilizing) rotation of the ribbed channel. Such effects are not only captured at the mean level but also at the unsteady level as confirmed by the comparison of the LES large-scale coherent motions with these obtained by PIV.

Large-Eddy Simulation of the Onset of the Sea Breeze

2007 ◽  
Vol 64 (12) ◽  
pp. 4445-4457 ◽  
Author(s):  
M. Antonelli ◽  
R. Rotunno
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Large Scale ◽  
Three Dimensional ◽  
Sea Breeze ◽  
Small Scale ◽  
Computational Domain ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Les Model

Abstract This paper describes results from a large-eddy simulation (LES) model used in an idealized setting to simulate the onset of the sea breeze. As the LES is capable of simulating boundary layer–scale, three-dimensional turbulence along with the mesoscale sea-breeze circulation, a parameterization of the planetary boundary layer was unnecessary. The basic experimental design considers a rotating, uniformly stratified, resting atmosphere that is suddenly heated at the surface over the “land” half of the domain. To focus on the simplest nontrivial problem, the diurnal cycle, effects of moisture, interactions with large-scale winds, and coastline curvature were all neglected in this study. The assumption of a straight coastline allows the use of a rectangular computational domain that extends to 50 km on either side of the coast, but only 5 km along the coast, with 100-m grid intervals so that the small-scale turbulent convective eddies together with the mesoscale sea breeze may be accurately computed. Through dimensional analysis of the simulation results, the length and velocity scales characterizing the simulated sea breeze as functions of the externally specified parameters are identified.

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