Estimating Engine Airflow in Gas-Turbine Powered Aircraft With Clean and Distorted Inlet Flows

Williams, J. G. and Steenken, W. G. and Yuhas, A. J. (1996) Estimating Engine Airflow in Gas-Turbine Powered Aircraft With Clean and Distorted Inlet Flows. Technical Report NASA CR-198052, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

The F404-GE-400 powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the impact of inlet-generated total-pressure distortion on estimating levels of engine airflow. Five airflow estimation methods were studied. The Reference Method was a fan corrected airflow to fan corrected speed calibration from an uninstalled engine test. In-flight airflow estimation methods utilized the average, or individual, inlet duct static- to total-pressure ratios, and the average fan-discharge static-pressure to average inlet total-pressure ratio. Correlations were established at low distortion conditions for each method relative to the Reference Method. A range of distorted inlet flow conditions were obtained from -10° to +60° angle of attack and -7° to +11° angle of sideslip. The individual inlet duct pressure ratio correlation resulted in a 2.3 percent airflow spread for all distorted flow levels with a bias error of –0.7 percent. The fan discharge pressure ratio correlation gave results with a 0.6 percent airflow spread with essentially no systematic error. Inlet-generated total-pressure distortion and turbulence had no significant impact on the F404-GE-400 engine airflow pumping. Therefore, a speed-flow relationship may provide the best airflow estimate for a specific engine under all flight conditions.

EPrint Type:	NASA Contractor Report
Keywords:	Airflow correlation techniques, Airflow errors, Distorted inlet airflow, Engine airflow, F404 engine, Thrust vectoring
Subjects:	Aircraft/Project: F-18 HARV (01 - 09) Aeronautics: (07) Aircraft Propulsion And Power
ID Code:	202
Deposited On:	16 July 2004
Additional Information:	78 pages. Dryden Technical Monitor: Kevin Walsh. J.G. Williams and W.G. Steenken, GE Aircraft Engines, Cincinnati, Ohio. A.J. Yuhas, AS&M, Inc., Hampton, VA. Presented at the High-Angle-of-Attack Technology Conference, NASA Langley Research Center, Hampton, Virginia, Sept. 17–19, 1996.