Heat Transfer and Pressure Measurements in a Lattice-Cooled Trailing Edge of a Turbine Airfoil

Saha, Kaushik; Guo, Shengmin; Acharya, Sumanta; Nakamata, Chiyuki

doi:10.1115/gt2008-51324

Cited by 18 publications

(9 citation statements)

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“…The experimental study on heat transfer in the lattice cooling channel has been conducted by several authors [3][4][5][6]. In the early stage, Goreloff et al [3] has measured heat transfer and pressure loss of a turbine blade with lattice cooling structure using Zinc melt technique, varying sub-channel inclination angle () from 15 to 60 degrees.…”

Section: Figmentioning

confidence: 99%

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Study on Thermofluid Characteristics of a Lattice Cooling Channel

Tsuru

Morozumi

Takeishi

2020

JGPP

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Thermal fluid characteristics of the lattice cooling channel have been investigated by measuring distributions of heat transfer coefficient. The heat transfer coefficient distributions have been obtained by visualizing steady-state local temperatures using temperature sensitive liquid crystal and foil heater. The measurement has been performed for all surfaces consisting of a single passage, while past studies focused only on the bottom (primary) surface. By comparing heat transfer coefficient distributions on the primary surface, sidewalls and turning regions with velocity field which was measured in the previous study, the heat transfer mechanism of the lattice cooling channel is discussed. The lattice cooling channel consists of two sets of inclined parallel ribs, which cross each other at right angles. Reynolds number is varied from 2,000 to 9,000, which is based on hydraulic diameter and bulk velocity in a sub-channel. Heat transfer patterns on the sub-channel before and after turning are compared. Overall, the heat transfer distribution was well-correlated with the velocity field. In the sub-channel before turning, heat transfer is enhanced at the entrance of the primary surface due to flow acceleration. Heat transfer is also enhanced on the sidewalls. Whether the coolant turns or not, shear force exerted by the crossing flow at the diamond-shaped openings generates swirl flow motion, leading to enhanced heat transfer. In the sub-channel after turning, this trend is further increased due to longitudinal vortex formed by the turning. Moreover, comparison of heat transfer patterns on the sidewalls with that on the primary surface suggested that they are comparable due to the flow interaction. It suggests that contribution of the rib surface on total heat release should be taken into account for reasonable cooling design. NOMENCLATURE A Area D hs Sub-channel hydraulic diameter H s Sub-channel height h Heat transfer coefficient L Streamwise distance from the sub-channel inlet Q Heat flux Nu Nusselt number Nu s Nusselt number of a smooth channel Pr Prandtl number Re s Sub-channel Reynolds number T a Air temperature T w Wall temperature V s Bulk velocity of sub-channel W s

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Section: Figmentioning

confidence: 99%

“…Gillespie et al [4] and Saha et al [5] have reported detailed heat transfer coefficient distributions of primary (bottom) surfaces of a tapered lattice cooling channel. As mentioned in Ref.…”

Section: Figmentioning

confidence: 99%

Study on Thermofluid Characteristics of a Lattice Cooling Channel

Tsuru

Morozumi

Takeishi

2020

JGPP

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“…Therefore, knowing htc eq,i values and using Eqs. (6) and 7, htc r,i coefficients are determined through an iterative cycle.…”

Section: Matrix Geometriesmentioning

confidence: 99%

“…Saha et al [6,7] studied the heat transfer augmentation and pressure drop in a converging trailing edge matrix structure where ribs are inclined at 45 deg to the flow direction. Two matrix geometries with two and four subchannels were considered and the combination of 90 deg turn of the flow at the entry and a converging cross section was also investigated varying Reynolds number from 4000 to 60,000.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer and Pressure Loss Measurements of Matrix Cooling Geometries for Gas Turbine Airfoils

Carcasci

Facchini

Pievaroli

et al. 2014

Journal of Turbomachinery

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Matrix cooling systems are relatively unknown among gas turbines manufacturers of the western world. In comparison to conventional turbulated serpentines or pin–fin geometries, a lattice–matrix structure can potentially provide higher heat transfer enhancement levels with similar overall pressure losses. This experimental investigation provides heat transfer distribution and pressure drop of four different lattice–matrix geometries with crossing angle of 45 deg between ribs. The four geometries are characterized by two different values of rib height, which span from a possible application in the midchord region up to the trailing edge region of a gas turbine airfoil. For each rib height, two different configurations have been studied: one having four entry channels and lower rib thickness (open area 84.5%), one having six entry channels and higher rib thickness (open area 53.5%). Experiments were performed varying the Reynolds number Res, based on the inlet subchannel hydraulic diameter, from 2000 to 12,000. Heat transfer coefficients (HTCs) were measured using steady state tests and applying a regional average method; test models have been divided into 20 stainless steel elements in order to have a Biot number similitude with real conditions. Elements are 10 per side, five in the main flow direction, and two in the tangential one. Metal temperature was measured with embedded thermocouples, and 20 thin-foil heaters were used to provide a constant heat flux during each test. A specific data reduction procedure has been developed so as to take into account the fin effectiveness and the increased heat transfer surface area provided by the ribs. Pressure drops were also evaluated measuring pressure along the test models. Uniform streamwise distributions of Nusselt number Nus have been obtained for each Reynolds number. Measurements show that the heat transfer enhancement level Nus/Nu0 decreases with Reynolds but is always higher than 2. Results have been compared with previous literature data on similar geometries and show a good agreement.

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“…Bunker showed that lattice cooling is capable of providing heat transfer enhancement ratios approaching 3.0, which is comparable to that provided by rib turbulated passages. Saha et al [85,86] considered the use of lattice cooling in a wedgeshaped, trailing edge cooling passage.…”

Section: Lattice Cooling Schemesmentioning

confidence: 99%

Heat Transfer Enhancement for Turbine Blade Internal Cooling

Wright

Han

2013

Volume 3: Gas Turbine Heat Transfer; Transport Phenomena in Materials Processing and Manufacturing; Heat Transfer in Electronic

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Gas turbines are used extensively for aircraft propulsion, land-based power generation, and industrial applications. The turbine inlet temperatures are far above the permissible metal temperatures. Therefore, there is a need to cool the blades for safe operation. Modern developments in turbine cooling technology play a critical role in increasing the thermal efficiency and power output of advanced gas turbine designs. Turbine blades and vanes are cooled internally and externally. This paper focuses on heat transfer augmentation of turbine blade internal cooling. Internal cooling is typically achieved by passing the cooling air through rib-enhanced serpentine passages inside the blades. Impinging jets, pin fins and dimples are also used for enhancing internal cooling heat transfer. In the past 10 years, there has been considerable progress in turbine blade internal cooling research and this paper is emphasized on reviewing selected publications to reflect recent developments in this area. In particular, this paper focuses on the newly developed design concepts as well as the combination of existing cooling techniques for turbine airfoil internal heat transfer augmentation. Rotation effects on the turbine blade leading-edge, triangular-shaped channel, mid-chord multi-pass channel and trailing-edge, wedge-shaped channel with coolant ejection are also considered.

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Heat Transfer and Pressure Measurements in a Lattice-Cooled Trailing Edge of a Turbine Airfoil

Cited by 18 publications

References 0 publications

Study on Thermofluid Characteristics of a Lattice Cooling Channel

Study on Thermofluid Characteristics of a Lattice Cooling Channel

Heat Transfer and Pressure Loss Measurements of Matrix Cooling Geometries for Gas Turbine Airfoils

Heat Transfer Enhancement for Turbine Blade Internal Cooling

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