Preliminary Rotor Wake Measurements with a Laser VelocimeterNational Aeronautics and Space Administration, Scientific and Technical Information Branch, 1983 - Laser Doppler velocimeter - 89 pages |
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Page 9
... turbulence level and its periodic nature obscured the time - dependent characteristics of the velocity measurements . However , it is important to note that this is only a definite possibility and has not yet been proven . Spectral ...
... turbulence level and its periodic nature obscured the time - dependent characteristics of the velocity measurements . However , it is important to note that this is only a definite possibility and has not yet been proven . Spectral ...
Page 10
... periodic turbulence in the open test section , then spectral transformation of the experimental data will show no periodic content . This trans- formation was performed on the experimental LV data , and the results are presented in ...
... periodic turbulence in the open test section , then spectral transformation of the experimental data will show no periodic content . This trans- formation was performed on the experimental LV data , and the results are presented in ...
Page 11
... periodic content . However , it is important to point out that operation at higher rotor disk loadings or different tunnel velocities , where these periodic turbulence levels are lower , might have produced better results . It is ...
... periodic content . However , it is important to point out that operation at higher rotor disk loadings or different tunnel velocities , where these periodic turbulence levels are lower , might have produced better results . It is ...
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200 Azimuth 7-Meter Tunnel American Helicopter Soc apparent time-dependent veloc autocovariance function axis system beam buffer interface calculations Continued cross-beam angle data set deg Velocity described in reference discrete-frequency ensemble fast Fourier transform Figure A3 flow field frequency fuselage width Helicopter Rotor Histograms Hoad horizontal I(j+k investigation lack of time-dependent Landgrebe Langley Research Center laser velocimeter LV Laser velocimeter measurements LV data LV measurements LV sample m/sec 9 m/sec Rotor azimuth mean velocity measurement measurement location N₁ NASA nonstationary flow open test section open-throat optics particle percent 15 periodic turbulence Power spectral density presented in figure probability density function quantizing error rotor blades ROTOR WAKE MEASUREMENTS rotor wake velocity Rotor-Fuselage Configuration rotor-fuselage spacing S/R S/R sample volume Spectral transformation technique theoretically determined velocity time-averaged time-dependent velocity characteristics velocity components velocity fluctuation velocity gradient velocity measurements obtained velocity time history vertical wwwwwww wwwwwwwwwww لس لسا