Overtip Choking and Its Implications on Turbine Blade-Tip Aerodynamic Performance

Zhang, Q.; He, L.

doi:10.2514/1.55134

Cited by 6 publications

(7 citation statements)

References 27 publications

(13 reference statements)

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“…Experimentally, Zhang et al [26] illustrated that the local heat transfer was directly affected by shock waves in a striped pattern within the tip gap. Zhang and He [27] also explored the differences of low and high-speed flows noting the difference in flow structures and tip leakage loss. Comparable findings were presented by Shyam et al.…”

mentioning

confidence: 99%

Aerothermal Performance of Shroudless Turbine Blade Tips with Relative Casing Movement Effects

Virdi¹,

Zhang²,

He³

et al. 2015

Journal of Propulsion and Power

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confidence: 99%

Aerothermal Performance of Shroudless Turbine Blade Tips with Relative Casing Movement Effects

Virdi¹,

Zhang²,

He³

et al. 2015

Journal of Propulsion and Power

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“…The chocking behaviour of the tip flow and the formation of the shockwave system within the tip gap were also studied by Harvey, 33 Molter et al, 34 and Zhange and He. 35 Tip leakage flow development exposes the tip surface to very high heat load. This erodes the sharp edges of the tip a while after being in operation and results into thermal damages such as in-service burn out.…”

Section: Introductionmentioning

confidence: 99%

Effect of in-service burnout effect on the transonic leakage flows over cavity tip model

Saleh

Avital

Korakianitis

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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Increasing the gas temperature at the inlet to the high pressure turbine of gas turbine engines is known as a proven method to increase the efficiency of these engines. However, this will expose the blades’ surface to very high heat load and thermal damages. In the case of the un-shrouded turbine blades, the blade tip will be exposed to a significant thermal load due to the developed leakage flows in the tip gap, this leads to in-service burnout which degrades the blade tip and shortens its operational life. This paper studies the in-service burnout effect of the transonic tip flows over a cavity tip which is a configuration commonly used to reduce the tip leakage flows. This investigation is carried out experimentally within a transonic wind tunnel and computationally using steady and unsteady Reynolds Averaged Navier Stokes approaches. Various flow measurements are established and different flow behaviour including separation bubbles, shockwave development and distinct flow interactions are captured and discussed. It is found that when the tip is exposed to the in-service burnout, leakage flow behaves in a significantly different way. In addition, the effective tip gap becomes much larger and allows higher leakage mass flow rate in comparison to the sharp-edge tip (i.e. a tip at the beginning of its operational life). The tip leakage losses are found much higher for the round-edge cavity tip (i.e. a tip exposed to burn-out effect). Experimental and computational flow visualisations, surface pressure measurements and discharge coefficient variation are given and analysed for several pressure ratios across the tip gap.

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“…They concluded that the full squealer case can decrease the total pressure loss due to the TLV. Zhang and He (2011) conducted a computational analysis of overtip choking flow on the high-pressure turbine blade at a transonic condition and focused on the flow behavior and the generation mechanisms of tip leakage loss. The flow distribution within the tip gap clearly illustrates the choked tip flow, which can block the overtip flow because of the influence of suction-surface side.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of high pressure turbine blade tip-shaping effects on the aerothermal and dynamic performance

Tong¹,

Gou²,

Li³

et al. 2019

MMMS

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Purpose In order to improve the engine reliability and efficiency, an effective way is to reform the turbine blade tip conformation. The paper aims to discuss this issue. Design/methodology/approach The present research provides several novel tip-shaping structures, which are considered to control the blade tip loss. Four different tip geometries have been studied: flat tip, squealer tip, flat tip with streamwise ribs and squealer tip with streamwise ribs. The tip heat transfer and leakage flow are both analyzed in detail, for example the tip heat transfer coefficient, tip flow and local pressure distributions. Findings The results show that the squealer seal and streamwise rib can reduce the tip heat transfer and leakage loss, especially for the squealer tip with streamwise ribs. The tip and near-tip flow patterns at the different locations of axial chord reflect that both the squealer seal and streamwise rib structure can control the tip leakage flow loss. In addition, the analysis of the aerodynamic parameters (the static pressure and turbine efficiency) also indicates that the squealer tip with streamwise ribs obtains the highest adiabatic efficiency with an increase of 2.34 percent, compared with that of the flat tip case. Originality/value The analysis of aerothermal and dynamic performance can provide a reference for the blade tip design and treatment.

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Overtip Choking and Its Implications on Turbine Blade-Tip Aerodynamic Performance

Abstract: This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link

Cited by 6 publications

References 27 publications

Aerothermal Performance of Shroudless Turbine Blade Tips with Relative Casing Movement Effects

Aerothermal Performance of Shroudless Turbine Blade Tips with Relative Casing Movement Effects

Effect of in-service burnout effect on the transonic leakage flows over cavity tip model

Numerical investigation of high pressure turbine blade tip-shaping effects on the aerothermal and dynamic performance

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