Pressure and Suction Surfaces Redesign for High Lift Low Pressure Turbines

González, P.; Ulizar, Iñaki; Vázquez, Raúl; Hodson, H. P.

doi:10.1115/2001-gt-0439

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…The inlet angle and the shape of the blade were modified to take into account of the compressibility effect as well as the stream tube divergence. González P. et al [10] redesigned a high-lift low-pressure turbine blade, and more attention was paid to effect of blade thickness on the profile loss. Their low speed experiment with the same Reynolds number aimed to ensure the dynamic similarity.…”

Section: Introductionmentioning

confidence: 99%

On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

Jiang

Zhang

et al. 2018

Journal of Engineering for Gas Turbines and Power

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Modern high-pressure turbine blades operate at high-speed conditions. The over-tip-leakage (OTL) flow can be high-subsonic or even transonic. From the consideration of problem simplification and cost reduction, the OTL flow has been studied extensively in low-speed experiments. It has been assumed a redesigned low-speed blade profile with a matched blade loading should be sufficient to scale the high-speed OTL flow down to the low-speed condition. In this paper, the validity of this conventional scaling approach is computationally examined. The computational fluid dynamics (CFD) methodology was first validated by experimental data conducted in both high- and low-speed conditions. Detailed analyses on the OTL flows at high- and low-speed conditions indicate that, only matching the loading distribution with a redesigned blade cannot ensure the match of the aerodynamic performance at the low-speed condition with that at the high-speed condition. Specifically, the discrepancy in the peak tip leakage mass flux can be as high as 22%, and the total pressure loss at the low-speed condition is 6% higher than the high-speed case. An improved scaling method is proposed hereof. As an additional dimension variable, the tip clearance can also be “scaled” down from the high-speed to low-speed case to match the cross-tip pressure gradient between pressure and suction surfaces. The similarity in terms of the overall aerodynamic loss and local leakage flow distribution can be improved by adjusting the tip clearance, either uniformly or locally.

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Section: Introductionmentioning

confidence: 99%

On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

Jiang

Zhang

et al. 2018

Journal of Engineering for Gas Turbines and Power

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Experimental Investigation of Pressure Side Flow Separation on the T106C Airfoil at High Suction Side Incidence Flow

Stotz

Niehuis

Guendogdu

2016

Volume 2B: Turbomachinery

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The objective of this work is to study the influence of a pressure side separation bubble on the profile losses and the development of the bubble in the blade passage. For the experimental investigations the T106 profile is used, with an increased loading due to an enlarged pitch to chord ratio from 0.799 to 0.95 (T106C). The experiments were performed at the high-speed cascade wind tunnel of the Institute of Jet Propulsion at the University of the Federal Armed Forces Munich. The main feature of the wind tunnel is to vary Reynolds and Mach number independently to achieve realistic turbomachinery conditions. The focus of this work is to determine the influence of a pressure side separation on the profile losses and hence the robustness to suction side incidence flow. The cascade is tested at four incidence angles from 0° to −22.7° to create separation bubbles of different sizes. The influence of the Reynolds number is investigated for a wide range at constant exit Mach number. Therefore a typical exit Mach number for low pressure turbines in the range of 0.5–0.8 is chosen in order to consider compressible effects. Furthermore, two inlet turbulence levels of about 3% and 7.5% have been considered. The characteristics of the separation bubble are identified by using the profile pressure distributions, whereas wake traverses with a five hole probe are used to determine the influence of the pressure side separation on the profile losses. Further, time-resolved pressure measurements near the trailing edge as well as single hot wire measurements in the blade passage are conducted to investigate the unsteady behavior of the pressure side separation process itself and also its influence on the midspan passage flow.

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On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

Jiang

Zhang³

et al. 2017

Volume 2A: Turbomachinery

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Modern High Pressure Turbine (HPT) blades operate at high speed conditions. The Over-Tip-Leakage (OTL) flow, which plays a major role in the overall loss generation for HPT, can be high-subsonic or even transonic. In practice from the consideration of problem simplification and cost reduction, the OTL flow has been studied extensively in low speed experiments. It has been assumed a redesigned low speed blade profile with a matched blade loading should be sufficient to scale the high speed OTL flow down to the low speed condition. In this paper, the validity of this conventional scaling approach is computationally examined. The CFD methodology was firstly validated by experimental data conducted in both high and low speed conditions. Detailed analyses on the OTL flows at high and low speed conditions indicate that, only matching the loading distribution with a redesigned blade cannot ensure the match of the aerodynamic performance at the low speed condition with that at the high-speed condition. Specifically, the discrepancy in the peak tip leakage mass flux can be as high as 22.2%, and the total pressure loss at the low speed condition is 10.7% higher than the high speed case. An improved scaling method is proposed hereof. As an additional dimension variable, the tip clearance can also be “scaled” down from the high speed to low speed case to match the cross-tip pressure gradient between pressure and suction surfaces. The similarity in terms of the overall aerodynamic loss and local leakage flow distribution can be improved by adjusting the tip clearance, either uniformly or locally. The limitations of this proposed method are also addressed in this paper.

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Pressure and Suction Surfaces Redesign for High Lift Low Pressure Turbines

Cited by 4 publications

References 12 publications

On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

Experimental Investigation of Pressure Side Flow Separation on the T106C Airfoil at High Suction Side Incidence Flow

On Scaling Method to Investigate High-Speed Over-Tip-Leakage Flow at Low-Speed Condition

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