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Record Details

Record 19 of 466
Computational Investigation of an F-18 Aircraft in the High-Alpha Regime
Author and Affiliation:
Murman, Scott M.(MCAT Inst., Moffett Field, CA United States)
Rizk, Yehia M.(NASA Ames Research Center, Moffett Field, CA United States)
Kutler, Paul [Technical Monitor]
Abstract: One of the goals of NASA's High Alpha Technology Program is to provide flight-validated design methods for the high-angle-of-attack regime. This is an integrated effort utilizing computational simulations, wind tunnel experiments, and flight tests using the F-18 High Alpha Research Vehicle (HARV). The dominant physics of the aircraft flows in the high alpha regime changes as the angle of attack is increased. At moderate angle of attack the flow is characterized by boundary layer separation and the formation of tight vortices. As the angle of attack is increased, these vortices break down producing unsteady wakes. With further increase in angle of attack, the, vortex breakdown moves progressively upstream until the entire flowfield becomes dominated by the unsteady wake. Previous computational work has demonstrated the ability to simulate flows about the F-18 HARV in the medium-to-high angle of attack range, where the flowfield is characterized by the vortex formation and subsequent breakdown. This paper extends the previous computations to include conditions of 45 degree angle of attack where the flowfield becomes dominated by the unsteady wake shed from the Leading Edge Extension (LEX), and regions of laminar and transitional flow appear on the fuselage forebody. A more complete surface geometry is utilized, which includes the features of the engine nacelle, inlet diffuser, and the boundary layer diverter duct. A volume grid sensitivity study was also performed to extend the accuracy of the results, most notably in the prediction of the LEX vortex breakdown position. This paper includes comparisons of computational results with both in-flight surface pressure measurements, and flow visualizations of the surface and off-surface particle trajectories.
Publication Date: Jan 01, 1994
Document ID:
20010048685
(Acquired Jun 08, 2001)
Subject Category: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
Document Type: Preprint
Meeting Information: 4th NASA High Alpha Conference/Workshop; 12-14 Jul. 1994; Edwards, CA; United States
Meeting Sponsor: NASA Dryden Flight Research Center; Edwards, CA United States
Contract/Grant/Task Num: RTOP 505-68-00
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA United States
Organization Source: NASA Ames Research Center; Moffett Field, CA United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: F-18 AIRCRAFT; COMPUTERIZED SIMULATION; WIND TUNNEL TESTS; FLIGHT TESTS; ANGLE OF ATTACK; FLOW VISUALIZATION; FLOW DISTRIBUTION; LEADING EDGES; BOUNDARY LAYER SEPARATION; PRESSURE MEASUREMENT
Availability Source: Other Sources
Availability Notes: Abstract Only
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