GSMT Assembly

AURA New Initiatives Office

Technical Studies: Wind Loading: Wind Pressure (Average, RMS) and Wind Velocity (Average, RMS)


A data reduction scheme of the wind tests was developed for a total of 116 test cases. For each test case, three plots are displayed as follows:

Average Wind pressure distribution (pressure range = 5 Pascals)
RMS Wind pressure distribution (pressure range = 0 - 3 Pascals)
Resultant wind speed (range = 0 to 20 m/s)

The data reduction was achieved based on 3000 samples of the data (300 seconds at 10 samples per second). In order to use the same data reduction program, the wind pressures in the first test data sets were extrapolated to 32 pressure sensor locations (as shown in a small dot). At each sensor location a temporal average pressure and RMS pressure were calculated. Regions in red on the wind pressure distribution represent positive values and in blue represent negative values.

The resultant wind speed was calculated at each of the five anemometer locations (+X, -X, -Y, M2, Dome). At each anemometer location, a temporal average resultant velocity was calculated from the measured three orthogonal wind components (U,V,W). The average resultant wind velocities were plotted for the five anemometer locations. The velocity components were temporally averaged. These velocity components (U,V,W) are parallel to the primary mirror axes (X,Y,Z) when the mirror is in zenith. In addition, the RMS resultant wind velocity (V_RMS) was calculated.

The file name of the test case encodes the test setup and the conditions of the test. The first character identifies the test set depending on the test dates, test study cases, or test setups (24 or 32 pressure sensors). The following three numbers in the name indicate the azimuth orientation of the dome slit relative to the incoming wind direction. The next two numbers indicate the zenith angle of the telescope, and the final two letters indicate the status of the large vents on the side of the Gemini enclosure, the first letter indicating the upwind vent gate. So, for example, 04530oc indicates the telescope was pointing 45 degrees away from the wind in azimuth, was at a zenith angle of 30 degrees (elevation of 60 degrees), the upwind vent gate was open and the downwind vent gate was closed.

List of Wind Test Cases

Additionally, a lowered scale on the pressure distribution was employed. For each of the test cases, three plots are displayed as follows:

Average Wind pressure distribution (pressure range = 1 Pascals)
RMS Wind pressure distribution (pressure range = 0 0.5 Pascals)
Resultant wind speed (range = 0 to 20 m/s)

List of Wind Test Cases (Lowered Scale)

 

 


Myung Cho / mcho@noao.edu / February 19, 2002