Desensitization of Tip Clearance Effects in Axial Flow Turbines

El-Ghandour, Mohamed; Mori, Koichi; Nakamura, Yoshiaki

doi:10.1299/jfst.5.317

Cited by 7 publications

(5 citation statements)

References 21 publications

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“…The pressure arm of tip leading edge horseshoe vortex (PHV) can be identified by blue streamlines, and the suction arm of tip leading edge horseshoe vortex (SHV) can be identified by black streamlines. These vortexes have also been reported in previous studies [31,32]. The SHV moves along the suction side edge, and then exits in a certain distance to shear with the mainstream.…”

Section: Effect Of Winglet Width On Efficiencysupporting

confidence: 85%

Numerical investigations on the effect of blade tip winglet on leakage flow loss reduction for a zero inlet swirl turbine rotor

Zhou

Zhao

et al. 2022

Aeronaut. j.

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The tip leakage flow generates a large amount of aerodynamic losses in a zero inlet swirl turbine rotor (ZISTR), which directly uses the axial exit flow downstream of a combustion chamber without any nozzles. To reduce the tip leakage flow loss and improve the efficiency for the ZISTR, a front suction side winglet is employed on the blade tip, and the effect of winglet width is numerically investigated to explore its design space. It is found that, a suction side leading edge horseshoe vortex (SHV) on the blade tip plays a crucial role in mitigating the tip leakage flow loss. This SHV rotates in the reverse direction to the leakage vortex, so it tends to break the formation of the leakage vortex near the front part of suction side. With a larger winglet width, the SHV stays longer time on the blade tip and leaves it at a further downstream location. This increases the time and the contact area of the interaction between the SHV and the leakage vortex, so the leakage vortex is further weakened. Thus, the tip leakage flow loss is reduced, and the efficiency is improved. However, a larger winglet width also increases the heat load of the blade due to a larger blade surface area. The ZISTR designed with the winglet width equal to 2.1% blade pitch achieves a great trade-off between efficiency and heat load that the efficiency is improved by 0.85% at an expense of 1.2% increment of the heat load. Besides, for the blade using this winglet, the mechanical stress due to the centrifugal, aerodynamic and thermal load is acceptable for the engine application. This investigation indicates a great potential in the improvement of efficiency for the ZISTR using a blade tip winglet designed on the front suction side.

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Section: Effect Of Winglet Width On Efficiencysupporting

confidence: 85%

Numerical investigations on the effect of blade tip winglet on leakage flow loss reduction for a zero inlet swirl turbine rotor

Zhou

Zhao

et al. 2022

Aeronaut. j.

View full text Add to dashboard Cite

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“…Liao et al [54] analyzed the internal flow in a Kaplan turbine runner with the Triangle Acute Clearance. Control of the leakage flow by modifying the blade tip shape has been the main subject for much research [55]. Actually cavitation easily occurs in the tip clearance, so two-phase cavitation model should be taken into account in the CFD approach.…”

Section: Cfd In Tip Clearancementioning

confidence: 99%

“…Reducing the negative effects of the tip leakage is generally referred to as tip desensitization. The desensitization methods include active and passive methods [55]. The latter is the major form in hydraulic turbines.…”

Section: Better Design or Optimizationmentioning

confidence: 99%

A selected literature review of efficiency improvements in hydraulic turbines

Liu

Luo

Karney

et al. 2015

Renewable and Sustainable Energy Reviews

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“…The blade profile is the same as the tip section of NASA/GE Energy Efficient Engine (GE-E 3 ) first-stage rotor blade because results of several studies have been reported regarding it and were used to validate the numerical code. 8,9,[13][14][15][16][17] Calculations were performed for a three-times scaled-up model in the same way as El-Ghandour et al 13,14) and Yang et al 16) This scaled-up model has an axial chord of 86.1 mm (Cx = 86.1), a span of 122 mm (h = 122), and an aspect ratio (span/chord) of 1.4. The blade model is two-dimensional with the same profile in the span direction.…”

Section: Model In Studymentioning

confidence: 99%

Effects of Tip Cavity Depth, Width, and Location on the Leakage Flow in an Axial Turbine Cascade

El-Ghandour

Ibrahim

Doi

et al. 2010

JFST

Self Cite

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In this study, effects of the tip cavity with various depths, widths, and locations on the leakage flow and performance of an axial turbine cascade have been investigated numerically. The blade was a linear model of the tip section of the GE-E 3 high-pressure turbine first-stage rotor blade. The Delayed Detached Eddy Simulation (DDES) model was used in the simulations. The computational results showed that the leakage mass flow rate and mass-averaged total pressure loss decreased as the depth and width of the tip cavity increased. And, it was shown that the cavity near the pressure side is more effective than that near the suction side. These effects depend on a vortex generated behind the pressure side in the cavity, which is changed with the depth, width, and location. The vortex entrains the leakage flow through the clearance toward the bottom of the cavity and in the chord wise direction, which reduces the flow leaking out.

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Desensitization of Tip Clearance Effects in Axial Flow Turbines

Cited by 7 publications

References 21 publications

Numerical investigations on the effect of blade tip winglet on leakage flow loss reduction for a zero inlet swirl turbine rotor

Numerical investigations on the effect of blade tip winglet on leakage flow loss reduction for a zero inlet swirl turbine rotor

A selected literature review of efficiency improvements in hydraulic turbines

Effects of Tip Cavity Depth, Width, and Location on the Leakage Flow in an Axial Turbine Cascade

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