Deflection and Vibration Reduction of a Wind Tunnel Test Stand

Lyons, Michael J.; Wilhelm, Jay; Kweder, Jonathan; Angle, Gerald M.; Hard, Steven; Hubbell, Meagan; Smith, James E.

doi:10.2514/6.2008-3702

Cited by 1 publication

(3 citation statements)

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“…An environmental study for this experiment was performed by means of a wind tunnel frequency experiment (also documented by Lyons, 2008) to determine if any environmental variables or wind tunnel components such as breakers, fans, lights, motor vibrations, fan blade turbulence, etc. significantly contributed to the calculation of the forces.…”

Section: Facility/environmental Studymentioning

confidence: 99%

“…Therefore, these loadings would not provide any impact on the experimental readings including the geometry or the force calculation. [Lyons, 2008] To summarize this section, the deflection and vibration on the test stand generated from aerodynamic loading and from the natural environment including the test conditions were small enough to be neglected for this experiment.…”

Section: Facility/environmental Studymentioning

confidence: 99%

“…1: Experimental Setup Review and Comparison ............................................................................................ 16 Table 4.1: Average Frequency and Voltage Magnitudes for Various Wind Tunnel Components[Lyons, 2008] ....... 23Table 4.2: Values for Base Factors  fromAllen and Vincenti, 1944 ........................................................................ 29 Table 4.3: Mass Flow and Jet Velocity Results ........................................................................................................... 35 Table 4.4: Area and Velocity Ratios Used in Mass Flow Calculations ....................................................................... 35 Table 4.5: Lift and Drag Coefficient Uncertainties (Sample: Tunnel Velocity = 80 fps, No Blowing) ...................... 38 Table 4.6: Lift and Drag Force Uncertainties (Tunnel Velocity = 80 fps, No Blowing) ............................................. 39 Table 4.7: Uncertainties of Various Parameters (Tunnel Velocity = 80 fps, No Blowing) ......................................... 39 Table 5.1: Summarized Effects of Various Blowing Configurations in Reverse Flow, Leading or Trailing Edge Blowing Only .............................................................................................................................................................. 52 Table 5.2: : Summarized Effects of Various Blowing Configurations in Reverse Flow, Combined Blowing ............ 52 Table A.1: Description of Calibration Testing Schedule Terms ............................................................................... A-1 Table A.2: Calibration Load Definitions .................................................................................................................. A-1 Table A.3: Calibration Testing Schedule for Single Loads ...................................................................................... A-2 Table A.4: Example Gain Parameter Calculation (Top Lift Force Applied) ............................................................ A-5 Table A.5: Forces Calculated Using On-Axis Calibration Curves Only ................................................................ A-10 Table A.6: Forces Calculated Using On and Off Axis Calibration Curves Only ................................................... A-11 Table A.7: Forces Calculated Using All Calibration Curves (Matrix) ................................................................... A-12 Table A.8: Error Comparison for Calibration Methods Using Calibration Data .................................................... A-13 Table A.9: Multiple-Loading Validation Using On-Axis Calibration Curves Only ............................................... A-13 Table A.10: Multiple-Loading Validation Using On and Off Axis Calibration Curves .…”

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Circulation control improvements to rotor lift asymmetry due to reverse flow

Lyons¹

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Circulation control has been applied to airfoils since the late 1960's, and has been proven to change the aerodynamic performance by altering the interaction of the streamlines without changing the physical characteristics of the airfoil itself. This has many applications in fluid dynamics; the focus of this application is for the replacement of the conventional helicopter rotor blade system with a fly-by-wire, active circulation controlled system. Conventional helicopters use a swashplate and a series of mechanical linkages, bearings, and dampers to create a fully articulated rotor hub system. This system is required to achieve the blade characteristics required for stable flight. The need for such a system stems from the asymmetric lift developed in maneuvering flight conditions, which requires the angle of attack of the blades to be changed based on the rotational position within the rotor plane, also known as the azimuth angle. By alternatively activating blowing slots along the leading and trailing edges of the airfoil, the aerodynamic parameters (i.e. lift and drag) can be changed, effectively changing the angle of attack through streamline alteration thus eliminating the need for physical blade pitch changes. Mathematical models/codes are used to model and simulate the complex blade dynamics of a full-scale rotorcraft. Many of these codes use a blade element method that separates the rotor into small segments and The author would like to thank all who have provided their assistance in any part of the research documented here. The patience and contribution of time by all those involved has been greatly appreciated.

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Section: Facility/environmental Studymentioning

confidence: 99%

Section: Facility/environmental Studymentioning

confidence: 99%

mentioning

confidence: 99%

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