The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine

Reid, Kevin; Denton, J. D.; Pullan, Graham; Curtis, Eric; Longley, John P.

doi:10.1115/gt2006-90838

Cited by 52 publications

(23 citation statements)

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“…Mclean et al [4] found that reducing the radial momentum and the circumferential momentum difference between the purge flow and the mainstream can weaken the strength of the viscous shear layer near the hub. Similar conclusions were found in Rield et al [5] , Hunter et al [6] and Gier et al [7] . Jia and Liu [8] classify the losses caused by the leakagemainstream interaction into four categories.…”

Section: Introductionsupporting

confidence: 90%

The Sealing Efficiency and Interaction between Purge Flow and Mainstream Flow for Novel Rim Seal Configurations

Zhang¹,

Tao²,

Song³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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The rim seal is used to prevent the mainstream ingestion to the gap between the turbine vane and blade. In this research, the dolphin lip with a hook configuration and a large seal cavity with hook structures are designed based on the high-pressure turbine datum single shark lip rim seal configuration. Sealing effect and flow field parameters are measured by the experiment method, and numerical simulation is used to supplement the mechanism. For three configurations, the effect of leakage slot vortex on seal efficiency and the influence of leakage vortex generated by the interaction between purge flow and mainstream are discussed in depth.The results show that the dolphin lip with hook structure form a reverse vortex which contrary to the leakage slot vortex to increase the sealing efficiency, and the large seal cavity makes the sealing efficiency is higher than the datum structure. With different purge flow rates and unequal seal structures, purge flow produces three types of leakage vortexes in the passage. Besides, the seal configuration with dolphin lip will produce Kelvin-Helmholtz instability at the interface between the purge flow and mainstream at a lower purge flow rate, and thus induce new leakage vortex branches in the blade passage.

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Section: Introductionsupporting

confidence: 90%

The Sealing Efficiency and Interaction between Purge Flow and Mainstream Flow for Novel Rim Seal Configurations

Zhang¹,

Tao²,

Song³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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show abstract

“…The same conclusions were drawn by Shabbir et al, 14 in experiments and computational simulations made in a high-speed compressor rotor and by Hunter and Manwaring's 7 investigation in turbine. Reid et al, 15 qualified the efficiency penalty caused by the rim seal flow to be about 0.56% for 1.0% of injection mass flow. Denton 16 reviewed the limitations of turbomachinery CFD and directly pointed out that leakage from rim seals on the hub or casing had a large influence on the endwall boundary layer and hence on the endwall loss which are usually neglected during routine design.…”

Section: Introductionmentioning

confidence: 98%

Numerical investigation of the interaction between upstream cavity purge flow and main flow in low aspect ratio turbine cascade

Wei¹,

Liu²

2013

Chinese Journal of Aeronautics

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In modern gas turbines, rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine. However, the purge flow supplied to the cavity through the rim seal interacts with the main flow, producing additional aerodynamic loss due to the mixing process which plays a significant role in the formation, development and evolution of downstream secondary flow. In this paper, a set of cascade representative of low aspect ratio turbine is selected to numerically investigate the influence of upstream cavity purge flow on the hub secondary flow structure and aerodynamic loss. Cascade with/without upstream cavity and four different purge mass flow rates are all taken into account in this simulation. Then, a deep insight into the loss mechanism of interaction between purge flow and main flow is gained. The results show that the presence of cavity and purge flow has a significant impact on the main flow which not only changes the vortex structure in both the passage and upstream cavity, but also alters the cascade exit flow angle distribution along the spanwise. Moreover, aerodynamic loss in the cascade rises with the increase of purge flow rate while the sealing effect is also enhanced. Therefore, the effect of upstream cavity purge flow must be considered in the process of turbine aerodynamic design. What is more, it is necessary to minimize the purge flow rate in order to reduce aerodynamic loss on the premise of satisfying cooling requirements.

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“…Piggush and Simon [3] indicated an increase in the loss roughly following the increase in momentum flux ratio for leakage flow through an upstream slot simulating the combustor-vane gap. Turbine stage efficiency decreased with increasing stator-rotor leakage flowrate in the study by Reid et al [4]. Simulations showed an increase in entropy generation (loss generation) where the leakage flow mixed into the freestream.…”

Section: Relevant Past Studiesmentioning

confidence: 89%

Heat Transfer and Film Cooling on a Contoured Blade Endwall With Platform Gap Leakage

Lynch

Thole

2015

Volume 5B: Heat Transfer

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Turbine blade components in an engine are typically designed with gaps between parts due to manufacturing, assembly, and operational considerations. Coolant is provided to these gaps to limit the ingestion of hot combustion gases. The interaction of the gaps, their leakage flows, and the complex vortical flow at the endwall of a turbine blade can significantly impact endwall heat transfer coefficients and the effectiveness of the leakage flow in providing localized cooling. In particular, a platform gap through the passage, representing the mating interface between adjacent blades in a wheel, has been shown to have a significant effect. Other important turbine blade features present in the engine environment are non-axisymmetric contouring of the endwall, and an upstream rim seal with a gaspath cavity, which can reduce and increase endwall vortical flow, respectively. To understand the platform gap leakage effect in this environment, measurements of endwall heat transfer and film cooling effectiveness were performed in a scaled blade cascade with a non-axisymmetric contour in the passage. A rim seal with a cavity, representing the overlap interface between a stator and rotor, was included upstream of the blades and a nominal purge flowrate of 0.75% of the mainstream was supplied to the rim seal. Results indicated that endwall heat transfer coefficients increased as platform gap net leakage increased from 0% to 0.6% of the mainstream flowrate, but net heat flux to the endwall was reduced due to high cooling effectiveness of the leakage flow.

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The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine

Cited by 52 publications

References 0 publications

The Sealing Efficiency and Interaction between Purge Flow and Mainstream Flow for Novel Rim Seal Configurations

The Sealing Efficiency and Interaction between Purge Flow and Mainstream Flow for Novel Rim Seal Configurations

Numerical investigation of the interaction between upstream cavity purge flow and main flow in low aspect ratio turbine cascade

Heat Transfer and Film Cooling on a Contoured Blade Endwall With Platform Gap Leakage

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