Simulation of Rotor Blade Element Turbulence

Details

• Creators:
  McFarland, R.E. ; Duisenberg, Ken
• Corporate Creators:
  Ames Research Center
• Corporate Contributors:
  United States. National Aeronautics and Space Administration
• Subject/TRT Terms:
  Helicopters Rotor Blades Rotors Simulation Turbulence Turbulence Modeling
• DOI:
  https://doi.org/10.21949/1403609
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Corporate Publisher:
  United States. National Aeronautics and Space Administration
• Abstract:
  A piloted, motion-based simulation of Sikorsky's Black Hawk helicopter was used as a platform for the investigation of rotorcraft responses to vertical turbulence. By using an innovative temporal and geometrical distribution algorithm that preserved the statistical characteristics of the turbulence over the rotor disc, stochastic velocity components were applied at each of twenty blade-element stations. This model was implemented on NASA Ames' Vertical Motion Simulator (VMS), and ten test pilots were used to establish that the model created realistic cues. The objectives of this research included the establishment of simulation- technology basis for future investigations into real-time turbulence modeling. This goal was achieved; our extensive additions to the rotor model added less than a 10 percent computational overhead. Using a VAX9000 computer the entire simulation required a cycle time of less than 12 msec. Pilot opinion during this simulation was generally quite favorable. For low speed flight the consensus was that SORBET (acronym for title) was better than the conventional body-fixed model, which was used for comparison purposes, and was determined to be too violent (like a washboard). For high speed flight the pilots could not identify differences between these models. These opinions were something of a surprise because only the vertical turbulence component on the rotor system was implemented in SORBET. Because of the finite-element distribution of the inputs, induced outputs were observed in all translational and rotational axes. Extensive post-simulation spectral analyses of the SORBET model suggest that proper rotorcraft turbulence modeling requires that vertical atmospheric disturbances not be superimposed at the vehicle center of gravity but, rather, be input into the rotor system, where the rotor-to-body transfer function severely attenuates high frequency rotorcraft responses.
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:d3afb8e62355652fcd5ba6f5b0ba7881f5bd637c10a97929847fdfc247661d17188df168de2e257708b69f3b1f4427b6a80238cfe5143d47cb2965719771d3c7
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/12951/dot_12951_DS1.pdf
• File Type:
  [PDF - 2.50 MB ]