University of athens

UNIVERSITY OF ATHENS SCHOOL OF PHYSICS, DIVISION OF ENVIRONMENT AND METEOROLOGY ATMOSPHERIC MODELING AND WEATHER FORECASTING GROUP DUST INGESTION BY AIRCRAFT JET ENGINES Theodore Lekas1, George Kallos2, Jonilda Kushta2, Stavros Solomos2 1Dpt. of aerodynamics and flight mechanics, Hellenic Air Force Academy 2University of Athens, School of Physics, AMWFG, Athens, Greece

OBJECTIVES THE MAJOR OBJECTIVE IS TO DRAW ATTENTION ON A SERIES OF POTENTIAL PROBLEMS THAT MIGHT BE ASSOCIATED WITH THE FLIGHT OF AIRCRAFTS IN DUST LOADED AREAS

PREREQUISITES THE OPERATIONAL PROCEDURES MUST TAKE INTO ACCOUNT QUANTITATIVE PREDICTIONS OF THE DUST AIR MASSES ALONG THE ROUTES AND ESPECIALLY NEAR APPROACHING AND TAKING OFF THE QUANTITATIVE PREDICTION OF DUST MASS IN THE ATMOSPHERE IS AVAILABLE DESPITE THE UNCERTAINTIES ASSOCIATED TO IT BY UTILIZING SUCH PREDICTIONS THE AREA,TIMING AND THE AMOUNT OF INGESTED DUST CAN BE CALCULATED ALONG THE FLIGHT PATH

DUST MODEL PHYSICAL PROCESS INITIATED AND FAVORED BY CERTAIN METEROLOGICAL CONDITIONS LAND USE INFORMATION TO CHARACTERIZE POSSIBLE DUST SOURCES COMBINE SURFACE GEOPHYSICAL CHARACTERISTICS WITH THE METEOROLOGICAL FEATURES TO QUANTIFY THE DUST MASS MOBILIZED AND THE SPATIOTEMPORAL PATTERNS OF ITS TRANSPORT FORECASTING OF DUST EVENTS AS PARALLEL PORCESS IN WEATHER FORECASTING SYSTEMS

VISIBILITY DUST FORECASTING IS UTILIZED: DIRECTION INFORMATION ON THE PRESENT DUST CONCENTRATIONS FOR THE ASSESSMENT OF THE NUMBER OF PARTICLES INJECTED INTO THE ENGINE INDIRECT INFORMATION ON VISIBILITY AND METEOROLOGICAL CONDITION OF THE FLYING SECTORS Surface visibility Aerosol Optical Depth Visibility at 2km

CONCERNED GEOGRAPHICAL AREAS DESERT AREAS ARE THE MAIN SOURCE OF DUST AND SAND IN THE ATMOSPHERE DESERT COVER A CONSIDERABLE AMOUNT OF LAND DESERT DUST IS A MAJOR SOURCE OF PARTICULATE IN THE ATMOSPHERE WITH SEVERAL IMPLICATIONS DUE TO ATMOSPHERIC CIRCULATION THE PROBLEMS ASSOCIATED WITH DESERT DUST BECOMES GLOBAL OF COURSE THERE ARE OTHER SOURCES OF DUST SUCH AS THE VOLCANIC ERUPTIONS OR VENTING SO2

SAHARAN DUST DUST OVER NORTH SEA DUST OVER EUROPE DUST OVER GREECE & MEDITERRANEAN Pictures taken from NASA/GSFC satellite

THE PROBLEM DESERT DUST CAN CAUSE SIGNIFICANT PROBLEMS IN AVIATION SUCH AS: REROUTING DUE TO POOR VISIBILITY DISTURBANCES IN AIRPORT OPERATIONS MECHANICAL PROBLEMS SUCH AS EROSION AND CORROSION IN THIS PRESENTATION WE WILL DISCUSS ONLY ABOUT SOME MECHANICAL PROBLEMS

JET ENGINE

EROSION SAND PARTICLES IMPACT AND BOUNCE ON COLD AERAS OF THE ENGINE CAUSING SURFACE DAMAGES AND GAP SIZE AUGMENTATION LEADING TO GAS FLOW DETERIORATION AND GRADUAL LOSS OF PERFORMANCE OF THE ENGINE

CORROSION IF HOT SAND PARTICLES IMPACT ON HOT SURFACES ( COMBUSTOR WALLS, TURBINE BLADES…) THEY CAN FORM A DEPOSIT WITH A ROUGH SURFACE WHICH MAY LEAD TO A RAPID LOSS OF PERFORMANCE (POTENTIAL RISK DURING TAKE-OFF OR LANDING OPERATIONS) BY DISTURBING THE FLOW FIELD. THIS DEPOSIT MAY ALSO LEAD TO THERMAL CORROSION OF A COMPONENT OF THE ENGINE BY BLOCKING ITS COOLING HOLES.

WHAT IS NEEDED? UNDERSTANDING OF THE PHYSICS OF SAND EROSION AND CORROSION IN ORDER TO ADEQUATELY MODIFY : - THE ENGINE DESIGN - MAINTENANCE PROCEDURES - ROUTING AND APPROACHING PROCEDURES

PROPOSED STUDY METHODOLOGY EXPERIMENTAL THEORETICAL BOTH APPROACHES ARE COUPLED

OBJECTIVE ONCE THE DUST PARTICLE CONCENTRATION IS KNOWN THE ERODED AREA AND THE SHAPE OF THE DEPOSIT WHICH MAY BE FORMED CAN BE FOUND THIS KNOWLEDGE IS IMPORTANT IN ORDER TO DETERMINE THE CRITICAL AREAS OF THE ENGINE AS WELL AS PARAMETERS LEADING TO AN ENGINE LOSS OF PERFORMANCE IN A SHORT OR LONG TERM

EXPERIMENTAL APPROACH ADVANTAGES POSSIBILITY OF REALISTIC SIMULATION OF THE PHYSICAL PHENOMENA DISADVANTAGES NEED FOR COMPLEX AND RATHER EXPENSIVE EQUIPMENT CURRENT STATUS THERE ARE SPECIALIZED RESEARCH CENTERS ABLE TO SIMULATE DUST STORMS OF VARIOUS INTENSITIES AND WITH VARIOUS DUST PARTICLES DIAMETERS

THEORETICAL APPROACH ADVANTAGES PHYSICAL APPROACH AS GOOD AS THE EFFICIENCY OF THE MATHEMATICAL MODEL IN USE NO NEED FOR IMPORTANT INFRASTRUCTURE DISADVANTAGES SIGNIFICANT NUMERICAL PROBLEMS MAY OCCUR COMPUTATIONAL TIME CAN BE PROHIBITIVE CURRENT STATUS THE CONTINOUSLY INCREASING COMPUTATIONAL POWER ALLOWS FOR VERY ACCURATE COMPUTATION OF THE FLOW FIELD AND DUST PARTICLES TRAJECTORIES AROUND AN OBSTACLE WITH COMPLEX GEOMETRY

STEPS OF THE THEORETICAL APPROACH DESCRIPTION OF THE GEOMETRY OF A GIVEN OBSTACLE (AIRCRAFT) COMPUTATION OF THE FLOW FIELD AROUND THE OBSTACLE COMPUTATION OF SAND PARTICLE TRAJECTORIES DUE TO THE FLOW FIELD AROUND THE OBSTACLE DETERMINATION OF IMPACT POINTS KNOWLEDGE ABOUT THE CONTAMINATED AREA AND THE SHAPE OF THE DEPOSIT ON THE OBSTACLE

GEOMETRY

TRAJECTORIES

SAND MASS INGESTED Total dust mass injected for a 1 hour period as a function of the angle of attack in kg/hr

SAND MASS INGESTED Total dust mass injected for a 1 hour period as a function of the particle size in kg/hr

ANOTHER PROBLEM SIMILAR PROBLEMS SHOULD BE ENCOUNTERED IN AIRPORTS ADJACENT TO COASTAL AREAS DUE TO THE INGESTION OF SEA SALT PARTICLES FROM EVAPORATION OF WATER DROPLETS PRODUCED BY WAVE BREAKING VOLCANIC ASH IS AN ADDITIONAL SOURCE OF NATURAL PARTICLES IN THE ATMOSPHERE

CONCLUSIONS (1/2) NATURAL PARTICLES AFFECT AVIATION BY DETERIORATING THE FLIGHT CONDITIONS (REDUCED VISIBILITY, FOG FORMATION) THEY CAN DECREASE ENGINE PERFORMANCE BY THE ROSION AND CORROSION PROCESSES IMPORTANT ASSET FOR THE SOUTHERN EUROPE COUNTRIES FOR FORECASTING DUST STORM EVENTS. EARLY PREDICTION CAN LEAD TO BETTER AIR TRAFFIC MANAGEMENT AND INPROVED FLIGHT SAFETY

CONCLUSION (2/2) WITH A DETAILED PREDICTION OF THE DUST CONCENTRATIONS DURING THE FLIGHT ROUTE OF AN AIRCRAFT IT IS POSSIBLE TO: CALCULATE THE TOTAL EXPOSURE OF THE ENGINE TO DUST MODIFY MAINTENANCE PROGRAMMING TAKING INTO ACCOUNT THE ENGINE PERFORMANCE DETERIORATION DUE TO THE DUST MASS INGESTED DURING THE FLIGHT ESTIMATE A POSSIBLE IMMEDIATE LOSS OF ENGINE PERFORMANCE IMPROVE THE EFFICIENCY OF AIR TRASPORTATION

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