Impact of Wall Temperature on Turbine Blade Tip Aerothermal Performance

Zhang, Q.; He, L.

doi:10.1115/1.4026001

Cited by 21 publications

(12 citation statements)

References 24 publications

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“…Such non-linear behavior has also been recently reported in the previous CFD analysis by Zhang et al 2014and Maffulli and He 2014. The experimental evidence obtained in the present study confirmed their previous numerical analysis and findings.…”

Section: Tr Effect On Small Tip Gapssupporting

confidence: 92%

“…The TR effect on tip aerothermal performance has been addressed numerically by some recent CFD studies. Zhang et al (2014) found that the wall-gas temperature ratio could greatly affect the transonic OTL flow field, and there is a strong two-way coupling between aerodynamics and heat transfer. The feedbacks of the thermal boundary condition to aerodynamics behave differently at different flow regimes over the tip, clearly indicating a highly localized dependence of the HTC upon wall temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer

Jiang¹,

Zhang

et al. 2018

Journal of Turbomachinery

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Determination of a scalable Nusselt number (based on “adiabatic heat transfer coefficient”) has been the primary objective of the most existing heat transfer experimental studies. Based on the assumption that the wall thermal boundary conditions do not affect the flow field, the thermal measurements were mostly carried out at near adiabatic condition without matching the engine realistic wall-to-gas temperature ratio (TR). Recent numerical studies raised a question on the validity of this conventional practice in some applications, especially for turbine blade. Due to the relatively low thermal inertia of the over-tip-leakage (OTL) flow within the thin clearance, the fluids' transport properties vary greatly with different wall thermal boundary conditions and the two-way coupling between OTL aerodynamics and heat transfer cannot be neglected. The issue could become more severe when the gas turbine manufacturers are making effort to achieve much tighter clearance. However, there has been no experimental evidence to back up these numerical findings. In this study, transient thermal measurements were conducted in a high-temperature linear cascade rig for a range of tip clearance ratio (G/S) (0.3%, 0.4%, 0.6%, and 1%). Surface temperature history was captured by infrared thermography at a range of wall-to-gas TRs. Heat transfer coefficient (HTC) distributions were obtained based on a conventional data processing technique. The profound influence of tip surface thermal boundary condition on heat transfer and OTL flow was revealed by the first-of-its-kind experimental data obtained in the present experimental study.

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Section: Tr Effect On Small Tip Gapssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer

Jiang¹,

Zhang

et al. 2018

Journal of Turbomachinery

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“…Within the figure, color variations denote tip surface heat flux variations, and greyscale variations denote flow density gradient distributions which were employed in these studies utilized squealer configurations [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72], partial squealer configurations [61,64,69], and winglet configurations [73,74]. Smooth blade tips were employed by Thorpe et al [75], Green et al [59], Key and Arts [62], O'Dowd et al [76,77], Wheeler et al [78], Zhang et al [55,56], Shyam et al [79], Atkins et al [80], Wheeler and Saleh [70], Anto et al [81], Virdi et al [68], Wheeler and Sandberg [82], Li et al [65], Zhang et al [83], Zhang and He [84], Wang et al [69], Zhou [71], Jung et al [61], Gao et al [85], and Kim et al [64]. Most of these investigations (which involved experimental measurements) employed annular or linear cascades with stationary blades.…”

Section: Interactions Which Included Thermal Transport and Convectivementioning

confidence: 99%

Recent investigations of shock wave effects and interactions

et al. 2020

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Despite over fifty years of research on shock wave boundary layer effects and interactions, many related technical issues continue to be controversial and debated. The present survey provides an overview of the present state of knowledge on such effects and interactions, including discussions of: (i) general features of shock wave interactions, (ii) test section configurations for investigation of shock wave boundary layer interactions, (iii) origins and sources of unsteadiness associated with the interaction region, (iv) interactions which included thermal transport and convective heat transfer, and (v) shock wave interaction control investigations. Of particular interest are origins and sources of low-frequency, large-scale shock wave unsteadiness, flow physics of shock wave boundary layer interactions, and overall structure of different types of interactions. Information is also provided in regard to shock wave investigations, where heat transfer and thermal transport were important. Also considered are investigations of shock wave interaction control strategies, which overall, indicate that no single shock wave control strategy is available, which may be successfully applied to different shock wave arrangements, over a wide range of Mach numbers. Overall, the survey highlights the need for additional understanding of fundamental transport mechanisms, as related to shock waves, which are applicable to turbomachinery, aerospace, and aeronautical academic disciplines.

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“…The resulting adiabatic wall temperature, T * ad =540.5 K, is in the range of typical turbine rotor applications. The ratio of the wall temperature to the adiabatic wall temperature T * w /T * ad =0.7 is chosen to mimic realistic aero-engine conditions (Zhang & He 2014), where blade cooling is most often applied to avoid excessive surface temperature. The resulting non-dimensional wall temperature is T w =0.75.…”

Section: Turbomachinery Applicationsmentioning

confidence: 99%

Nonlinear unsteady streaks engendered by the interaction of free-stream vorticity with a compressible boundary layer

Marensi

Riccó

2017

J. Fluid Mech.

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The nonlinear response of a compressible boundary layer to unsteady free-stream vortical fluctuations of the convected-gust type is investigated theoretically and numerically. The free-stream Mach number is assumed to be of O(1) and the effects of compressibility, including aerodynamic heating and heat transfer at the wall, are taken into account. Attention is focused on low-frequency perturbations, which induce strong streamwise-elongated components of the boundary-layer disturbances, known as streaks or Klebanoff modes. The amplitude of the disturbances is intense enough for nonlinear interactions to occur within the boundary layer. The generation and nonlinear evolution of the streaks, which acquire an O(1) magnitude, are described on a self-consistent and first-principle basis using the mathematical framework of the nonlinear unsteady compressible boundary-region equations, which are derived herein for the first time. The free-stream flow is studied by including the boundary-layer displacement effect and the solution is matched asymptotically with the boundary-layer flow. The nonlinear interactions inside the boundary layer drive an unsteady two-dimensional flow of acoustic nature in the outer inviscid region through the displacement effect. A close analogy with the flow over a thin oscillating airfoil is exploited to find analytical solutions. This analogy has been widely employed to investigate steady flows over boundary layers, but is considered herein for the first time for unsteady boundary layers. In the subsonic regime the perturbation is felt from the plate in all directions, while at supersonic speeds the disturbance only propagates within the dihedron defined by the Mach line. Numerical computations are performed for carefully chosen parameters that characterize three practical applications: turbomachinery systems, supersonic flight conditions and wind tunnel experiments. The results show that nonlinearity plays a marked stabilizing role on the velocity and temperature streaks, and this is found to be the case for low-disturbance environment such as flight conditions. Increasing the free-stream Mach number inhibits the kinematic fluctuations but enhances the thermal streaks, relative to the free-stream velocity and temperature respectively, and the overall effect of nonlinearity becomes weaker. An abrupt deviation of the nonlinear solution from the linear one is observed in the case pertaining to a supersonic wind tunnel. Large-amplitude thermal streaks and the strong abrupt stabilizing effect of nonlinearity are two new features of supersonic flows. The present study provides an accurate signature of nonlinear streaks in compressible boundary layers, which is indispensable for the secondary instability analysis of unsteady streaky boundary-layer flows.

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Impact of Wall Temperature on Turbine Blade Tip Aerothermal Performance

Cited by 21 publications

References 24 publications

Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer

Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer

Recent investigations of shock wave effects and interactions

Nonlinear unsteady streaks engendered by the interaction of free-stream vorticity with a compressible boundary layer

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