950028_mcfarland

950028_mcfarland - NASA Technical Memorandum 108862...

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National Aeronautics and Space Administration R. E. McFarland and Ken Duisenberg NASA Technical Memorandum 108862 Simulation of Rotor Blade Element Turbulence January 1995
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National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035-1000 NASA Technical Memorandum 108862 January 1995 Simulation of Rotor Blade Element Turbulence R. E. McFarland, Ames Research Center, Moffett Field, California Ken Duisenberg, SYRE, SYSCON Corporation, Falls Church, Virginia
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Simulation of Rotor Blade Element Turbulence R. E. MCFARLAND AND KEN DUISENBERG * Ames Research Center Summary A turbulence model has been developed for blade- element helicopter simulation. This model, called Simu- lation of Rotor Blade Element Turbulence (SORBET), uses an innovative temporal and geometrical distribution algorithm that preserves the statistical characteristics of the turbulence spectra over the rotor disc, while providing velocity components in real time to each of five blade- element stations along each of four blades. An initial investigation of SORBET has been performed using a piloted, motion-based simulation of the Sikorsky UH60A Black Hawk. Although only the vertical compo- nent of stochastic turbulence was used in this investiga- tion, vertical turbulence components induce vehicle responses in all translational and rotational degrees of freedom of the helicopter. The single-degree-of-freedom configuration of SORBET was compared to a conventional full 6-degrees-of- freedom baseline configuration, where translational velocity inputs are superimposed at the vehicle center of gravity, and rotational velocity inputs are created from filters that approximate the immersion rate into the turbulent field. For high-speed flight the vehicle responses were satisfactory for both models. Test pilots could not distinguish differences between the baseline configuration and SORBET. In low-speed flight the baseline configuration received criticism for its high fre- quency content, whereas the SORBET model elicited favorable pilot opinion. For this helicopter, which has fully articulated blades, results from SORBET show that vehicle responses to turbulent blade-station disturbances are severely attenu- ated. This is corroborated by in-flight observation of the rotor tip path plane as compared to vehicle responses. The Simulation A piloted simulation was performed on NASA Ames Research Center’s Vertical Motion Simulator (VMS) in 1994 using the GENHEL UH60A Black Hawk math- * SYRE, SYSCON Corporation, 8110 Gatehouse Rd., Falls Church, VA 22042. ematical model of reference 1 as a platform to investigate the Simulation of Rotor Blade Element Turbulence (SORBET) model. This was a simulation technology experiment designed for the purpose of evaluating the influence of stochastic turbulence created at the blade- element stations of a rotor system.
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This note was uploaded on 01/05/2011 for the course DU 3 taught by Professor Frando during the Spring '10 term at University of Dundee.

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950028_mcfarland - NASA Technical Memorandum 108862...

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