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Analysis of the Gemini data. By Oleg Likhatchev Aerospace and Mechanical Engineering Department University of Arizona. Contents in Brief. Introduction: What can we learn from the Gemini data? • Pressure and velocity data analysis for the primary mirror:
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Analysis of the Gemini data By Oleg Likhatchev Aerospace and Mechanical Engineering Department University of Arizona
Contents in Brief • Introduction: What can we learn from the Gemini data? • Pressure and velocity data analysis for the primary mirror: *Autocorrelation functions * Power Spectral Densities • Buffeting forces on thesecondary mirror: * Semi-empirical theory * Spectral analysis of unsteady forces on the secondary mirror
Pressure Sensors Layout +Y -X +X -Y
c00030oo Pressure Autocorrelations <U>=5.81 m/s t=4.4 sec St=0.2 L=5.1 m <U>=1.78 m/s t=14 sec St=0.2 L=4.98 m
Pressure Sensor #7Velocity at –Xc00030oo <U>=5.81 m/s; f=0.8 Hz; St=0.2; L=1.45 m <U>=5.81 m/s; f=1.0 Hz; St=0.2; L=1.14 m
Pressure Sensor #12Velocity at +Xc00030oo <U>=1.78 m/s; f=0.26 Hz; St=0.2; L=1.4 m
Pressure Sensor #23Velocity at -Yc00030oo <U>=0.74 m/s; f=0.67 Hz; St=0.2; L=0.22 m
Pressure PSD’s for Sensor #12(+X)Upwind Side of the Mirror 1Cases c04530oo and c04530co <U>=7.94 m/s L=1.2 m St=0.2 <U>=7.3 m/s L=1.2 m St=0.2
Pressure PSD’s for Sensor #12(+X)Upwind Side of the Mirror 1Cases c04530oo and t04530oo <U>=7.94 m/s L=1.2 m St=0.2 <U>=7.3 m/s L=1.2 m St=0.2
Buffeting Forces on a Rigid Circular Cylinder in Cross Flows(Water Tunnel Experiment, So & Savkar 1981 ) Lift Drag Strouhal Lift & Drag Re=1E+5 Buffeting Lift & Drag Re=2E+5 Re=3E+5