Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part II:
                    Heat Transfer Measurements

Christophel, J. R.; Thole, Karen A.; Cunha, F. J.

doi:10.1115/1.1811096

Cited by 25 publications

(8 citation statements)

References 19 publications

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“…Quite a few high-pressure turbines have cooling holes on the near-tip region of the pressure side. Christophel et al [13,14] studied the cooling effectiveness, the heat-transfer coefficient, and the NHFR for this configuration. The coolant ejected from the dust holes near the leading edge of the blade tip effectively improved the thermal performance near the leading edge of the tip.…”

mentioning

confidence: 99%

Thermal Performance of Different Cooled Tips in A High-Pressure Turbine Cascade

Zhou

Hodson

Lock

2012

Journal of Propulsion and Power

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The thermal performance of the three turbine tips was investigated. The results are presented in terms of heattransfer coefficient (h), cooling effectiveness (), net heat-flux reduction (NHFR), and heat load. The calculations were performed using a cooled flat tip, a cooled cavity tip, and a cooled suction-side squealer tip in a cascade at a tip gap of 1.6%C. The results were validated using experimental data where possible. For an uncooled flat tip, the fluid dynamics are dominated by flow separation at the pressure-side edge. A significant benefit of ejecting coolant inside this separation bubble is shown. At the coolant mass-flow ratio M c 0:52%, both the cooled flat tip and the cooled cavity tip are well-protected by the coolant. For the cooled suction-side squealer tip, the coolant lifts off from the tip floor and leads to not only low cooling effectiveness, but also to high heat-transfer coefficients. The effects of the coolant mass-flow ratio on the thermal performance of the tip were presented. The effects of end-wall motion on the thermal performance of the blade tip are found to be small in the current study.

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confidence: 99%

Thermal Performance of Different Cooled Tips in A High-Pressure Turbine Cascade

Zhou

Hodson

Lock

2012

Journal of Propulsion and Power

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“…In the open literature [24][25][26][27], NHFR was mainly used to evaluate turbine endwall and blades cooling systems and the dimensionless temperature was set within the range of = 1.5-1.6. Since the overall effectiveness of a combustor cooling system is generally higher than the one of a turbine airfoil, more recently Facchini et al [10,11] updated this parameter to evaluate the NHFR of a cooled liner, imposing a value of = 1.2.…”

Section: Net Heat Flux Reduction and Overall Effectiveness Netmentioning

confidence: 99%

Experimental Evaluation of the Density Ratio Effects on the Cooling Performance of a Combined Slot/Effusion Combustor Cooling System

Andreini

Caciolli

Facchini

et al. 2013

ISRN Aerospace Engineering

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The purpose of this study is to investigate the effects of coolant-to-mainstream density ratio on a real engine cooling scheme of a combustor liner composed of a slot injection and an effusion array with a central dilution hole. Measurements of heat transfer coefficient and adiabatic effectiveness were performed by means of steady-state thermochromic liquid crystals technique; experimental results were used to estimate, through a 1D thermal procedure, the Net Heat Flux Reduction and the overall effectiveness in realistic engine working conditions. To reproduce a representative value of combustor coolant-to-mainstream density ratio, tests were carried out feeding the cooling system with carbon dioxide, while air was used in the main channel; to highlight the effects of density ratio, tests were replicated using air both as coolant and as mainstream and results were compared. Experiments were carried out imposing values of effusion blowing and velocity ratios within a range of typical modern engine working conditions. Results point out the influence of density ratio on film cooling performance, suggesting that velocity ratio is the driving parameter for the heat transfer phenomena; on the other hand, the adiabatic effectiveness is less sensitive to the cooling flow parameters, especially at the higher blowing/velocity ratios.

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“…Kwak et al [16] further studied the effects of the positions of squealer rims, and it was found that the suction side squealer tip provided the lowest HTC on the blade tip and near tip regions compared to the other layouts. To assess the overall film-cooling benefit of the pressure side blowing, Christophel et al [17,18] measured the adiabatic effectiveness levels and the HTC.…”

Section: Introductionmentioning

confidence: 99%

Aerothermal characteristics of transonic over-tip leakage flow for different tip geometries with cooling injection

Tang

Liu

et al. 2019

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In turbomachinery, the effect of cooling injection on the over-tip leakage (OTL) flow has been the focus. In the present work, the flow and heat transfer on the blade tip surfaces of two typical different tip structures including a flat tip and a squealer tip are investigated. The grid independence verification and turbulence model validation (including Shear Stress Transport k-ω model and Spalart-Allmaras model) are conducted. Numerical results are compared with the existing experimental results. It is found that there exists the shock wave near the corner of the pressure side, and a striped high-pressure coefficient region appears on the tip surface near the pressure side. The cooling injection could alter the range of high striped pressure coefficient region. The tip leakage vortex (TLV) was formed by the blending between the OTL flow and mainstream, causing a large aerodynamic penalty. In comparison, the flat tip shows a greater loss near the casing and the tip surface than the squealer tip. An interesting observation is that the coolant ejecting from the cooling jet hole bifurcates and then forms a counter-rotating vortex pair (CRVP) for both the flat tip and the squealer tip, which greatly changes the flow structures and heat transfer characteristics within the tip region. The branches of the CRVP cause the thermal stripes on the surfaces of blade tip and the suction side rim. The present results reveal the cooling injection has a strong effect on OTL flow and enlighten the design and optimization of blade tips.

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Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part II: Heat Transfer Measurements

Cited by 25 publications

References 19 publications

Thermal Performance of Different Cooled Tips in A High-Pressure Turbine Cascade

Thermal Performance of Different Cooled Tips in A High-Pressure Turbine Cascade

Experimental Evaluation of the Density Ratio Effects on the Cooling Performance of a Combined Slot/Effusion Combustor Cooling System

Aerothermal characteristics of transonic over-tip leakage flow for different tip geometries with cooling injection

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