Effect of free-stream turbulence on turbine blade heat transfer and pressure coefficients in low Reynolds number flows

Choi, J. M.; Teng, Shuye; Han, Je-Chin; Ladeinde, Foluso

doi:10.1016/j.ijheatmasstransfer.2004.01.015

Cited by 36 publications

(13 citation statements)

References 19 publications

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“…It has been well-recognized that the high inflow turbulence enhances the heat transfer on various locations of the turbine blade, such as blade surface [6,7], end wall [8,9], and trailing edge [10]. Up to 50% increase in blade leading edge heat transfer was reported by a high inflow turbulence by Mehendale et al [11].…”

Section: Introductionmentioning

confidence: 99%

Effects of Inlet Turbulence and End-Wall Boundary Layer on Aerothermal Performance of a Transonic Turbine Blade Tip

Zhang

Rawlinson

2014

Journal of Engineering for Gas Turbines and Power

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Most of the previous researches of inlet turbulence effects on blade tip have been carried out for low speed situations. Recent work has indicated that for a transonic turbine tip, turbulent diffusion tends to have a distinctively different impact on tip heat transfer than for its subsonic counterpart. It is hence of interest to examine how inlet turbulence flow conditioning would affect heat transfer characteristics for a transonic tip. The present work is aimed to identify and understand the effects of both inlet freestream turbulence and end wall boundary layer on a transonic turbine blade tip aerothermal performance. Spatially-resolved heat transfer data are obtained at aerodynamic conditions representative of a high-pressure turbine, using the transient infrared thermógraphy technique with the Oxford High-Speed Linear Cascade research facility. With and without turbulence grids, the turbulence levels achieved are 7%-9% and 1%, respectively. On the blade tip surface, no apparent change in heat transfer was observed with high and low inlet turbulence intensity levels investigated. On the blade suction suiface, however, substantially different local heat transfer distributions for the suction side near tip surface have been observed, indicating a strong local dependence of the local vortical flow structure on the freestream turbulence. These experimentally observed trends have also been confirmed by CFD examinations using the Rolls-Royce HYDRA. A further CFD analysis suggests that the level of inflow turbulence alters the balance between the passage vortex associated secondaiy flow and the over tip leakage (OTL) flow. Consequently, an enhanced inertia of near wall fluid at a higher inflow turbulence weakens the cross-passage flow. As such, the weaker passage vortex leads the tip leakage vortex to move further into the mid passage, with the less spanwise coverage on the suction surface, as consistently indicated by the heat transfer signature. Different inlet end wall boundary layer profiles are employed in the computational study with HYDRA. All CFD results indicate the inlet boundary layer thickness has little impact on the heat transfer over the tip surface as well as the pressure side near-tip suiface. However, noticeable changes in heat transfer are obsei-vedfor the suction side near-tip surface. Similar to the inlet turbulence effect, such changes can be attributed to the interaction between the passage vortex and the OTL flow.

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Section: Introductionmentioning

confidence: 99%

Effects of Inlet Turbulence and End-Wall Boundary Layer on Aerothermal Performance of a Transonic Turbine Blade Tip

Zhang

Rawlinson

2014

Journal of Engineering for Gas Turbines and Power

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“…With increasing wake-frequency, the heat transfer along both the pressure side -with its strong acceleration -and the favourable pressure gradient portion of the suction side, was found to increase, see also Wissink and Rodi (2006). In the recent experiments of Choi et al (2004), studying the effect of free-stream turbulence on turbine blade heat transfer, the grid-generated turbulence was shown to affect the heat transfer along both areas of the turbine blade with flow acceleration (i.e. the entire pressure side and approximately the upstream half of the suction side) and also along those areas which exhibit transition to turbulence.…”

Section: Introductionmentioning

confidence: 91%

DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

Wissink

Rodi

2009

International Journal of Heat and Fluid Flow

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“…The complex internal structure of the atomizing nozzle leads to increased free stream turbulence, which has been noted by Viskanta [5] to increase the surface heat transfer rate. Thus, the air jet itself is expected to give higher heat transfer coefficients than correlations predict [6,7].…”

Section: Introductionmentioning

confidence: 99%

Time Averaged and Fluctuating Heat Transfer Measurements in an Atomising Mist Jet Nozzle

Lyons

Murray

Byrne

et al. 2009

Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C

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Much is already known about the heat transfer characteristics of impinging air jets, and they are widely used in many engineering applications. There currently exist many correlations describing such characteristics. However, the complex internal structure of many nozzles can lead these to produce results which deviate from those predicted by correlations. One such nozzle is currently used in this research group to produce a water mist flow and this paper describes the experimental characteristics of its single phase behaviour.

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Effect of free-stream turbulence on turbine blade heat transfer and pressure coefficients in low Reynolds number flows

Cited by 36 publications

References 19 publications

Effects of Inlet Turbulence and End-Wall Boundary Layer on Aerothermal Performance of a Transonic Turbine Blade Tip

Effects of Inlet Turbulence and End-Wall Boundary Layer on Aerothermal Performance of a Transonic Turbine Blade Tip

DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

Time Averaged and Fluctuating Heat Transfer Measurements in an Atomising Mist Jet Nozzle

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