| | 137 | '''Monday, September 26th, 2016''' |
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| | 139 | Experiment 1: fixstr1_2609a,b. Filenames: fixstr1_2609a, fixstr1_2609b. Location: Position 1 (75% down straight section, 58 cm upstream from the end of the straight section). Input rate 5.9 l/s. Density excess 19 kg/m3. Laser was not used in the experiments today. Running basal ADV with ADV #1 located 7.2 cm, ADV #2 located at 10 cm and ADV #3 located at 12 cm above channel bed. |
| | 140 | |
| | 141 | fixstr1_2609a: The main goal was to investigate if the concentration of the gravity current, inlet box and tank D were equal (19 kg/m3). The traverse sent one TTL signal to the ADV and didn’t send a return signal so only one measurement at one point was made by the ADVs (all ADVs collected data simultaneously). On the middle ADV (#2) wrapping occurred which indicates that velocity needs to be increased to 0.6 m/s. UVP files showed a fair amount of noise in the data which requires further investigation. We waited about 7:20 minutes for the flow rate to reach a constant value. One person took 6 samples (every 3 minutes, starting at t = 0) from the mixing tank on the third floor which contained the salt water mixture coming from tank D. A second person took 6 samples (every 3 minutes, starting at t = 0) from the inlet box at the upstream end of the channel. A third person took 3 sets of 12 siphon samples every 5 minutes (starting at t = 0, duration = 1 min). |
| | 142 | |
| | 143 | Density measurements of the samples showed that the density in the mixing tank on the third floor and tank D were equal (19 km/m3). However, there was a major decrease of density in the inlet box (max density = 14.8 kg/m3). Density of inlet box needs further investigation. |
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| | 145 | fixstr1_2609b: Goal was to determine flushing characteristics of the inlet box, and how long it takes to reach steady-state density conditions. Running basal ADV at 5 positions in the bottom cross section only at traverse positions y = 0.016, 0.116, 0.216, 0.316 and 0.416 m (with 5 repetitions). GoPro cameras were mounted at different positions including one inside the inlet box (front left corner, looking downstream), one outside the Coriolis tank looking upstream at the end of the channel and one overhead looking down (birds-eye-view) at the two curves, from the level of the computer centre. Dye was released to visualize the flow. One set of 12 siphon samples (duration = 1 min) was taken 5 minutes after flow rate stabilized. |
| | 146 | It took 2.5 min for the flow rate to stabilize. The ADV was initialized 5 minutes after flow stabilized. The ADV needed more seeding to improve the signal-to=noise ratio. The GoPro in the inlet box showed a lot of mixing between the current and the ambient which explains the decrease in density in the gravity current in the inlet box. The suggestion was to reduce the inlet box volume to reduce the time to reach steady-state density (by reduce the flushing time). |
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| | 149 | '''Tuesday, September 27, 2016''' |
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| | 151 | Density of siphon samples from Monday, Sept 26 were measured. Two large PVC tubes (dia ~ 40 cm) were placed in the inlet box and weighted down to reduce the volume (new vol ~ 150 L). |
| | 152 | |
| | 153 | Experiment 1: fixstr1_2709a,b. Filenames: fixstr1_2709a, fixstr1_2709b. Location: Position 1 (75% down straight section, 58 cm upstream from the end of the straight section). Input rate 6 l/s. Density excess 20 kg/m3. Laser was not used in the experiments today. Running basal ADV with ADV #1 located 7.2 cm, ADV #2 located at 10 cm and ADV #3 located at 12 cm above channel bed. |
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| | 155 | Fixstr1_2709a: The goal was to examine the flushing time of the inlet box to see how it behaves once the PVC tubes were installed. One conductivity probe was mounted at the centerline just before the flow straightener (metallic honeycomb). Started with 6 l/s and waited for 5 min to see how inlet box, UVP and pump behaved. The UVP and siphon pump were turned on to fix the suspected pulse that the pump imparted to the UVP. This did not resolve the SNR issue. |
| | 156 | |
| | 157 | Two conductivity probes were mounted in the cross section just before the flow straightener (metallic honeycomb): one at the centerline and one 5 cm?? from the right wall, looking downstream. The traverse is able to move vertically in every cross-section position and the previously outstanding issues have been resolved. |
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