The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Donald B Dingwell - One of the best experts on this subject based on the ideXlab platform.
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Impact interaction of in-flight high-energy molten volcanic ash droplets with Jet Engines
'Elsevier BV', 2019Co-Authors: Song W, Yang S, Fukumoto M, Lavallée Y, Lokachari S, Guo H, You Y, Donald B DingwellAbstract:© 2019 The turbine technology incorporated in Jet Engines is inherently vulnerable to attack by environmental silicate debris. Amongst the various kinds of such debris, volcanic ash is a particular threat as its glass softens to a liquid at temperatures of 500–800 °C, far below Jet engine operating temperatures of ∼1500 °C. As a result, ingested re-molten droplets impact and form splats on the protective thermal barrier coatings (TBCs). Investigation of the damage to Jet Engines ensuing from this process has, to date been restricted to forensic observations after critical encounters. Here, we employ a thermal spray technology to recreate the ‘in-situ’ generation of molten volcanic ash droplets and observe their morphological evolution and interaction with TBCs. The mechanism of splat formation is found to depend both on substrate topography and on in-flight droplet characteristics, whereby splat circularity increases with surface roughness and with the product of the Weber and Reynolds numbers. The experiments reveal that the molten ash droplet adhesion rate is dictated by droplet temperature and viscosity, ash concentration and substrate roughness. A new dimensionless number, S, is developed to quantify the molten ash droplet adhesion rate to both substrate topography and in-flight droplet characteristics. These findings provide a greatly improved basis for the quantification of the hazard potential of volcanic ash to Jet Engines and should be incorporated into protocols for operational aviation response during volcanic crises
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Wetting and Spreading of Molten Volcanic Ash in Jet Engines
Journal of Physical Chemistry Letters, 2017Co-Authors: Wenjia Song, Kaiuwe Hess, Fabian B Wadsworth, Yan Lavallée, Donald B DingwellAbstract:A major hazard to Jet Engines posed by volcanic ash is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Here, using the sessile drop method, we study the evolution of the wettability and spreading of volcanic ash. We employ rapid temperature changes up to 1040–1450 °C, to replicate the heating conditions experienced by volcanic ash entering an operating Jet engine. In this scenario, samples densify as particles coalesce under surface tension until they form a large system-sized droplet (containing remnant gas bubbles and crystals), which subsequently spreads on the surface. The data exhibit a transition from a heterogeneous to a homogeneous wetting regime above 1315 °C as crystals in the drops are dissolved in the melt. We infer that both viscosity and microstructural evolution are key controls on the attainment of equilibrium in the wetting of molten volcanic ash droplets.
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volcanic ash melting under conditions relevant to ash turbine interactions
Nature Communications, 2016Co-Authors: Wenjia Song, Kaiuwe Hess, Yan Lavallée, Ulrich Kueppers, Corrado Cimarelli, Donald B DingwellAbstract:Volcanic ash is hazardous to Jet Engines, with high temperatures in turbines causing ash particles to melt and stick to the engine, adversely affecting turbine function. Here, the authors explore the spectrum of natural ash compositions and their behaviour and impact at high temperatures.
Wenjia Song - One of the best experts on this subject based on the ideXlab platform.
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Wetting and Spreading of Molten Volcanic Ash in Jet Engines
Journal of Physical Chemistry Letters, 2017Co-Authors: Wenjia Song, Kaiuwe Hess, Fabian B Wadsworth, Yan Lavallée, Donald B DingwellAbstract:A major hazard to Jet Engines posed by volcanic ash is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Here, using the sessile drop method, we study the evolution of the wettability and spreading of volcanic ash. We employ rapid temperature changes up to 1040–1450 °C, to replicate the heating conditions experienced by volcanic ash entering an operating Jet engine. In this scenario, samples densify as particles coalesce under surface tension until they form a large system-sized droplet (containing remnant gas bubbles and crystals), which subsequently spreads on the surface. The data exhibit a transition from a heterogeneous to a homogeneous wetting regime above 1315 °C as crystals in the drops are dissolved in the melt. We infer that both viscosity and microstructural evolution are key controls on the attainment of equilibrium in the wetting of molten volcanic ash droplets.
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volcanic ash melting under conditions relevant to ash turbine interactions
Nature Communications, 2016Co-Authors: Wenjia Song, Kaiuwe Hess, Yan Lavallée, Ulrich Kueppers, Corrado Cimarelli, Donald B DingwellAbstract:Volcanic ash is hazardous to Jet Engines, with high temperatures in turbines causing ash particles to melt and stick to the engine, adversely affecting turbine function. Here, the authors explore the spectrum of natural ash compositions and their behaviour and impact at high temperatures.
Yan Lavallée - One of the best experts on this subject based on the ideXlab platform.
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Wetting and Spreading of Molten Volcanic Ash in Jet Engines
Journal of Physical Chemistry Letters, 2017Co-Authors: Wenjia Song, Kaiuwe Hess, Fabian B Wadsworth, Yan Lavallée, Donald B DingwellAbstract:A major hazard to Jet Engines posed by volcanic ash is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Here, using the sessile drop method, we study the evolution of the wettability and spreading of volcanic ash. We employ rapid temperature changes up to 1040–1450 °C, to replicate the heating conditions experienced by volcanic ash entering an operating Jet engine. In this scenario, samples densify as particles coalesce under surface tension until they form a large system-sized droplet (containing remnant gas bubbles and crystals), which subsequently spreads on the surface. The data exhibit a transition from a heterogeneous to a homogeneous wetting regime above 1315 °C as crystals in the drops are dissolved in the melt. We infer that both viscosity and microstructural evolution are key controls on the attainment of equilibrium in the wetting of molten volcanic ash droplets.
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volcanic ash melting under conditions relevant to ash turbine interactions
Nature Communications, 2016Co-Authors: Wenjia Song, Kaiuwe Hess, Yan Lavallée, Ulrich Kueppers, Corrado Cimarelli, Donald B DingwellAbstract:Volcanic ash is hazardous to Jet Engines, with high temperatures in turbines causing ash particles to melt and stick to the engine, adversely affecting turbine function. Here, the authors explore the spectrum of natural ash compositions and their behaviour and impact at high temperatures.
Kaiuwe Hess - One of the best experts on this subject based on the ideXlab platform.
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Wetting and Spreading of Molten Volcanic Ash in Jet Engines
Journal of Physical Chemistry Letters, 2017Co-Authors: Wenjia Song, Kaiuwe Hess, Fabian B Wadsworth, Yan Lavallée, Donald B DingwellAbstract:A major hazard to Jet Engines posed by volcanic ash is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Here, using the sessile drop method, we study the evolution of the wettability and spreading of volcanic ash. We employ rapid temperature changes up to 1040–1450 °C, to replicate the heating conditions experienced by volcanic ash entering an operating Jet engine. In this scenario, samples densify as particles coalesce under surface tension until they form a large system-sized droplet (containing remnant gas bubbles and crystals), which subsequently spreads on the surface. The data exhibit a transition from a heterogeneous to a homogeneous wetting regime above 1315 °C as crystals in the drops are dissolved in the melt. We infer that both viscosity and microstructural evolution are key controls on the attainment of equilibrium in the wetting of molten volcanic ash droplets.
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volcanic ash melting under conditions relevant to ash turbine interactions
Nature Communications, 2016Co-Authors: Wenjia Song, Kaiuwe Hess, Yan Lavallée, Ulrich Kueppers, Corrado Cimarelli, Donald B DingwellAbstract:Volcanic ash is hazardous to Jet Engines, with high temperatures in turbines causing ash particles to melt and stick to the engine, adversely affecting turbine function. Here, the authors explore the spectrum of natural ash compositions and their behaviour and impact at high temperatures.
R. Smashey - One of the best experts on this subject based on the ideXlab platform.
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the use of cast ti 48al 2cr 2nb in Jet Engines
JOM, 1997Co-Authors: P. Bartolotta, J. Barrett, T. Kelly, R. SmasheyAbstract:Although it has been recognized for almost three decades that titanium-aluminide systems have the potential for significant weight reductions in Jet Engines, Ti−48Al−2Cr−2Nb has emerged as the first to enter commercial Jet engine service. Cast gamma titanium aluminides are evolving from an intriguing idea into the next materials revolution for aircraft Engines. Its potential appears to be similar to the changes caused by the introduction of cast titanium alloys in the 1970s.
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The use of cast Ti−48Al−2Cr−2Nb in Jet Engines
JOM, 1997Co-Authors: P. Bartolotta, J. Barrett, T. Kelly, R. SmasheyAbstract:Although it has been recognized for almost three decades that titanium-aluminide systems have the potential for significant weight reductions in Jet Engines, Ti−48Al−2Cr−2Nb has emerged as the first to enter commercial Jet engine service. Cast gamma titanium aluminides are evolving from an intriguing idea into the next materials revolution for aircraft Engines. Its potential appears to be similar to the changes caused by the introduction of cast titanium alloys in the 1970s.