Operation of Gas Turbine Engines in Volcanic Ash Clouds

Dunn, Michael G.; Baran, Adam J.; Miatech, Jerry

doi:10.1115/1.2816987

Cited by 78 publications

(45 citation statements)

References 8 publications

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“…Permission was obtained to release limited features of the data set described in this paper for inclusion in the Boeing video and to publish some of the general features of the data set [8]. The full data set was released for public distribution in Sept. 2010 following the April of 2010 eruption of the Iceland volcano 'Eyjafjallajökull,' which caused havoc with trans Atlantic flights.…”

Section: Introductionmentioning

confidence: 99%

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

Dunn

2012

Journal of Turbomachinery

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Airborne volcanic ash poses a significant threat to the safe operation of gas turbine powered aircraft. Recent volcanic activity in Iceland and other parts of the world have resulted in interruption of air traffic and in the case of the April 2010 eruption of the Eyjafjallajökull volcano in Iceland, the interruption resulted in a significant loss of revenue. Over the past 30 years there have been several events involving commercial aircraft that have suffered significant damage to the propulsion system as a result of ingesting volcanic ash during a flight event, but a relevant engine focused database to provide guidance for dealing with the problem has not been generally available until recently. In Sept. 2010 after the Iceland volcano activity, a body of data that had not been in the public domain was released and those measurements that are described in some detail herein can be helpful to the airlines, the aircraft manufacturers, the engine manufacturers, those responsible for flight operations, and hopefully to the flight crews. The intent of this paper is to describe some of the more notable aircraft/ash cloud events, the available data associated with those encounters and how those data can be used to effectively deal with this problem while maintaining safe flight operations. The paper specifically (a) illustrates the engine damage mechanisms, (b) estimates the potential operational life of a particular class of engines if the ash concentration is at a very low level, and (c) illustrates how this database is helpful in dealing with future interruptions of flight routes caused by volcanic eruptions. A section at the end of this paper provides the comments and concerns of the industry and government stakeholders regarding this general problem area.

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Section: Introductionmentioning

confidence: 99%

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

Dunn

2012

Journal of Turbomachinery

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“…The size of the coal ash is 2 -10 µm in diameter, which corresponds to particle Stokes numbers of 0.07 -1.9, where the Stokes number is defined as [4] Where is the particle density, is the particle diameter, and is the fluid viscosity. is a characteristic velocity and is the leading edge diameter of the vane.…”

Section: E Coal Ash Propertiesmentioning

confidence: 99%

“…They found that deposition can clog film cooling holes and can lead to failure of the turbine vanes. Dunn et al [4] also studied the effects of volcanic ash and found that damage due to deposition was related to the turbine inlet temperature, concentration of particulate and the material properties of the volcanic ash. Ash preferentially deposited on the hottest regions of the nozzle guide vanes, downstream of the fuel injectors associated with regions of hot gas, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 96%

Effect of Hot Streaks on Ash Deposition in an Uncooled Turbine Vane Passage

Casaday

Ameri

Bons

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Coal ash deposition was numerically modeled on an uncooled GE-E 3 high pressure turbine vane passage. A model was developed, in conjunction with Fluent™ software, to track individual particles through the turbine passage. Particles that strike the adiabatic surface become deposits if their viscosity drops below a predetermined value based on temperature. The computational model incorporated non-uniform inlet temperature conditions to account for the existence of a hot streak. The distribution of the temperature non-uniformity affects the location and amount of deposition measured on the nozzle guide vanes. Using a periodic condition that simulates one combustor nozzle per two nozzle guide vanes, the computational model predicts the optimal location for the combustor nozzle location to minimize total deposition rates in the vane passage. The deposition rates are strongly correlated to the average surface temperature of the vanes, but the clocking position with minimum deposition does not correlate to the clocking position with lowest average surface temperatures. The effect of particle size, or Stokes number, on deposition is studied and discussed. Nomenclature A = constant used to define critical viscosity model B = constant used to define critical viscosity model d P = diameter of particle 2 d le = vane leading edge diameter P S = probability of particle sticking St k = Stokes number, T P = temperature of particle V i = Velocity scale in Stokes number equation = capture efficiency = density of particle = viscosity of fluid = viscosity of particle  crit = viscosity of particle at critical sticking temperature

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“…When a simi lar test was repeated with a TIT of 1010°C (1850 °F) which was below the melting point of the ash, the problems observed above were not seen [24], The rate of deposition and therefore the approach to compressor surge was decreased to a level that would allow the safe return to an airport. The shape of the pressure change curve was similar to the shape of a constant speed curve on a compressor map.…”

Section: Major Effects Of Volcanic Ash Ingestion and Mitigation Of Damentioning

confidence: 99%

Assessment and Characterization of Volcanic Ash Threat to Gas Turbine Engine Performance

Davison

Rutke

2014

Journal of Engineering for Gas Turbines and Power

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Multiple volcanoes erupt yearly propelling volcanic ash into the atmosphere and creating an aviation hazard. The plinian eruption type is most likely to create a significant aviation hazard. Plinian eruptions can eject large quantities of fine ash up to an altitude of 50,000 m (164,000 ft). While large airborne particles rapidly fall, smaller particles at reduced concentrations drift for days to weeks as they gradually descend and deposit on the ground. Very small particles, less than 1 μm, can remain aloft for years. An average of three aircraft encounters with volcanic ash was reported every year between 1973 and 2003. Of these, eight resulted in some loss of engine power, including a complete shutdown of all four engines on a Boeing 747. However, no crashes have been attributed to volcanic ash. The major forms of engine damage caused by volcanic ash are: (1) deposition of ash on turbine nozzles and blades due to glassification (2) erosion of compressor and turbine blades (3) carbon deposits on fuel nozzles. The combination of these effects can push the engine to surge and flame out. If a flame out occurs, engine restart may be possible. Less serious engine damage can also occur. In most cases the major damage will require an engine overhaul long before the minor damage becomes an operational issue, but under some conditions no sign of volcanic ash is evident and the turbine cooling system blockage could go unnoticed until an engine inspection is performed. Several organizations provide aircrew procedures to respond to encounters with a volcanic ash cloud. If a volcanic ash encounter is suspected, then an engine inspection, including borescope, should be performed with particular attention given to the turbine cooling system.

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Operation of Gas Turbine Engines in Volcanic Ash Clouds

Cited by 78 publications

References 8 publications

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

Effect of Hot Streaks on Ash Deposition in an Uncooled Turbine Vane Passage

Assessment and Characterization of Volcanic Ash Threat to Gas Turbine Engine Performance

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