To understand the physics of volcanic ash impact on gas turbine hot-components and develop much-needed tools for engine design and fleet management, the behaviours of volcanic ash in a gas turbine combustor and nozzle guide vanes (NGV) have been numerically investigated. High-fidelity numerical models are generated, and volcanic ash sample, physical and thermal properties are identified. A simple critical particle viscosity - critical wall temperature model is proposed and implemented in all simulations to account for ash particles bouncing off or sticking on metal walls. The results indicate that due to the particle inertia and combustor geometry, the volcanic ash concentration in the NGV cooling passage increases with ash size, density and inlet velocity in general, and can reach three and half times as high as that at the air inlet for the conditions investigated. More importantly, the majority of the ash particles entering the NGV cooling chamber are trapped in the cooling flow passage for all four turbine inlet temperature conditions. This may reveal another volcanic ash damage mechanism originated from engine cooling flow passage. Finally, some suggestions are recommended for further research and development in this challenging field. To the authors' knowledge, it is the first study on detailed ash behaviours inside practical gas turbine hot-components in open literature.
American Society of Mechanical Engineers
Journal of Engineering for Gas Turbines and Power.