Engine Ingestion as a Result of Cross Wind During Take-offs from Water Contaminated Runways

Joop H.M. Gooden, National Aerospace Laboratory NLR, Marknesse, The Netherlands

Abstract

A method is developed for calculating the spray generated by tyres on water-contaminated runways and the resulting precipitation drag and engine ingestion. The method is based on droplet trajectory calculations. The initial conditions for these trajectories are based on (semi) empirical relations. The spray is then calculated using a Monte Carlo approach with variations on the initial spray conditions. Partial reflection of the spray on the aircraft surface as well as the flow of the remaining water film along the surface is taken into account.

The method, named ‘CRspray’, has been validated using laboratory and flight test experiments. Contaminated runway drag and ingestion can be determined depending on the pool depth, wind conditions, aircraft geometry, tyre geometry and pressure, aircraft weight, the wing lift and the horizontal tail plane vertical force.

This paper deals specifically with crosswind-effects on the spray. Crosswind may lead to high engine water ingestion rates, exceeding ingestion limits. This may cause engine performance decrease, but at excessive ingestion quantities also surge, stall or even flame-out may occur. The airworthiness requirements state that an airplane may not ingest hazardous quantities of water or slush into engines and APUs during take-off, landing and taxiing. Therefore, evaluating the crosswind effects on contaminated runway operation is inevitable.