1 Overview 2 Details of the Model Construction - Canada France ...

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Figure 10: Dye probe port locations on the model Figure 11: Dye tubing running to the probes B1-B5 (blue) and B6 (red). Note the brass handles used to lift the model out of the terrain to allow for easy interchange of the domes, installation of the vent plugs and the windscreen plugs. The model was mounted upside down in the water tunnel with approximately 15 mm of the base plate submerged so that the rounded-over leading edge was halfway submerged. The total cross section of the model was 960 cm 2 , which corresponds to a blockage ratio of 20.6% with a 62 cm water tunnel depth. The water tunnel is located in the Fluid Dynamics lab, along with several other graduate student research areas and experimental set ups. The water tunnel is approximately 9-10 m long and consists of a test section 0.7 m wide by 0.7 m deep and 2.5 m long. The water flows through the test section down into a ~40 cm pipe back to a large centrifugal pump that sets up the flow. After exiting the pump the water enters a very wide section of tunnel in which a ~3-4 m wide bank of plastic drinking straws have been packed together; these act to set up laminar flow conditions in the tunnel. The tunnel then
gradually narrows down over a length of ~4-5 m to the dimensions of the test section. A smaller pump continuously filters the water in the tunnel. At night, we normally left the water tunnel running at a slow speed (~5 cm/s), with the filter pump on to help clarify the water and reduce bubbles due to entrained air. A large valve is provided on one side of the tunnel for draining out the water. The capacity of the water tunnel is ~5000 gallons, and it is filled directly from the mains through a 1” pipe. Other than the chlorine in the water supply, no additional bleach nor pH modifiers were used. The exact width of the test channel is 75.2 cm (29-5/8”) and was operated at a depth of 62 cm as measured approximately 80 cm from the model in the upstream direction. At this depth the free-stream water speed in cm/s is determined by multiplying the variable frequency pump drive frequency by 1.013 and adding the correction -0.224 cm/s. Thus at the selected operating frequency of 30 Hz that was used for most of the testing, the nominal free-speed water speed was 30.2 cm/s. For simplicity, in the following we rounded-off the water speed to the nearest cm/s, which is equivalent to the nominal pump frequency used with Hz units directly exchanged for cm/s.At the nominal speed of 30 cm/s, with water temperature at 5°C, the Reynolds number is 4x10 4 , using the dome diameter as the characteristic length. Figure 12: The observatory model installed in the University of Washington water tunnel facility. Note the two storyboards (to the left and above the model) used for noting the experimental conditions. The “side view” video camera was located immediately to the left of the vantage point seen here, centered on the model and perpendicular to the tank wall.
Page 1 and 2: Canada-France-Hawaii Telescope Corp
Page 3 and 4: Figure 3: Vent dimensions in inches
Page 5 and 6: Figure 6: View through the shutter
Page 7: 4 Dye Probe Locations Dye probe por
Page 11 and 12: 6.3 Video capture Two Panasonic Lum
Page 13 and 14: 4. Windscreen position (3): Either
Page 15 and 16: dye probe was held near each vent l
Page 17 and 18: 10 Lessons learned • A dome shutt
Page 19 and 20: Figure 17: Path structure used to o
Page 21 and 22: 11 University of Washington 36” W
Page 23 and 24: Note: at the expected operating win
Page 25 and 26: ing everything needed. • It takes

1 Overview 2 Details of the Model Construction - Canada France ...

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