Failure analysis of a gas turbine nozzle

Mazur, Z.; Hernandez-Rossette, A.; García–Illescas, Rafael; Luna-Ramírez, A.

doi:10.1016/j.engfailanal.2007.10.009

Cited by 36 publications

(12 citation statements)

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“…Moreover they show that the conditions of maximum temperature and maximum gradients happen at two different operating conditions. A similar conclusion has been obtained by Mazur et al [4] analysing the failure of a high pressure nozzle of a 70MW gas turbine. The authors identified the origin of the cracks in nozzles by using numerical analysis and investigating the metal grain alterations.…”

Section: Introductionsupporting

confidence: 86%

“…In particular the effect is evident in the area around the exit of the cooling holes. This area is the zone where the thermal stresses are critical and cracks are likely to occur, as highlighted by Mazur et al [4].…”

Section: Numerical Resultsmentioning

confidence: 97%

“…The first surface shows the metal gradients that can generate structural cracks as highlight in [4]. The second surface is useful to identify problems such as excessive gradients in the ceramic surface that can induce spallation.…”

Section: Numerical Resultsmentioning

confidence: 99%

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The benefit of high-conductivity materials in film cooled turbine nozzles

Montomoli

Massini

Yang

et al. 2012

International Journal of Heat and Fluid Flow

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This study presents an experimental and numerical investigation of the beneficial effect of higher conductivity materials in HP turbine nozzles. Most of the literature studies focus on the maximum temperature that a nozzle can withstand, whereas the effect of thermal gradients is often neglected. However thermal gradients have higher influence on the life of the components and they have to be given careful consideration. In this work it is shown that thermal gradients are reduced by using high conductivity materials and, as a consequence, the nozzles life is appreciably increased.A representative film cooled leading edge with an internal impingement plate was studied experimentally at Texas AM University. Two materials were used, namely polycarbonate and stainless steel, in order to highlight the impact of conduction on coolant effectiveness. Numerically conjugate heat transfer simulations have been carried out with an in house solver to analyse in detail the impact of conduction and internal convection. Both experimental and numerical results show that by increasing the conductivity in the solid region, the thermal gradients are strongly reduced. Numerically it is shown that using inserts of nickel-aluminide alloys in nozzles may reduce the thermal gradients from 3 to 4 times if compared to nowadays design.

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Section: Introductionsupporting

confidence: 86%

Section: Numerical Resultsmentioning

confidence: 97%

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The benefit of high-conductivity materials in film cooled turbine nozzles

Montomoli

Massini

Yang

et al. 2012

International Journal of Heat and Fluid Flow

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“…There have been a few studies on blogging behaviors of submerged entry nozzles, through which liquid steel flows in a process of the continuous casting process . Several studies on the failure mechanism of nozzles used in petrochemical plants, gas combustion turbines, nuclear power plants, and so on have been reported . Nevertheless, studies on degradation of the cooling nozzles in the hot strip mill process have not been found by our literature survey.…”

Section: Introductionmentioning

confidence: 99%

Formation of a scale on the hole surface of cooling nozzles in the hot strip mill process, obstructing a laminar flow of coolant

Huh

Park

Jung

et al. 2012

Surface & Interface Analysis

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We investigated on the formation of a scale on the hole surface of brass cooling nozzles in the hot strip mill process of steel manufacturing. High roughness of a nozzle hole surface due to the scale formation obstructs a laminar flow of coolant, which can result in the diminution of cooling efficiency of strips. Morphology and elemental composition of a scale formed on the hole surface of cooling nozzles used in the hot strip mill process for a long time were characterized with an electron microscope equipped with an energy dispersive X‐ray spectroscope. The scale is mainly composed of a foreign substance layer and an oxide layer. In addition, three kinds of cooling water were analyzed to investigate an inflow source for elemental constituents of the foreign substance layer. Copyright © 2012 John Wiley & Sons, Ltd.

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“…However, Secondary carbides (mainly M 23 C 6 ) precipitate during service at high temperature from primary carbides [5,6]. In X-45 cobalt-base alloy, metallurgical embrittlement occurs when primary carbides M 6 C type transform to secondary carbides M 23 C 6 type leading to the formation of continuous films of carbide at the grain boundaries of the base material [7].…”

Section: Introductionmentioning

confidence: 99%