Changes between Version 132 and Version 133 of WikiStart


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Timestamp:
Oct 3, 2016, 11:44:10 AM (4 years ago)
Author:
davarpan1s
Comment:

Finished Wednesday the 28th of Sept, Added 29th and 30th

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  • WikiStart

    v132 v133  
    177177fixstr1_2809a: The goal is to increase the seeding and test the ADVs and UVP for less noise. A new stem ADV was mounted to reduce the noise. The UVP didn’t change in terms of noise issue, so the problem does not lie with the seeding density. Another suggestion was to move the UVP box back to the back bench to reduce interference from the electronics on the traverse. Minimal improvement was seen on the ADV profile. The seeding seems to be getting stuck in the inlet box behind the flow straightening baffles - this was visually observed by a buildup of foam in the inlet box.
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    179 fixapex_2809b: The siphons were moved up by 20 cm and the UVP 17 cm. The traverse was also moved to the second apex. The goal for this experiment was to take siphon and UVP data higher than 23.6 cm above the channel bed (previously not possible due to the siphon and UVP configuration), because we want to be able to draw velocity and concentration profiles fro 40 cm flow thickness. It was also intended to verify if moving the physical position of the UVP box would impact the data quality. Traverse moved to apex 2 position and siphon samples were taken every 1 minute after flow rate stabilized, for 1 minute sampling time (5-6 min, 7-8 min, 9-10 min).
     179fixapex_2809b: The siphons were moved up by 20 cm and the UVP 17 cm. The traverse was also moved to the second apex. The goal for this experiment was to take siphon and UVP data higher than 23.6 cm above the channel bed (previously not possible due to the siphon and UVP configuration), because we want to be able to draw velocity and concentration profiles for 40 cm flow thickness. It was also intended to verify if moving the physical position of the UVP box would impact the data quality. Traverse moved to apex 2 position and siphon samples were taken every 1 minute after flow rate stabilized, for 1 minute sampling time (5-6 min, 7-8 min, 9-10 min).
    180180When the flow was released a large cloud of seeding flowed through the channel as a gravity current (presumably seeding caught in inlet box from previous run) and the data on the ADV improved substantially. It was thus concluded that seeding is a viable solution to the noisy data problem (provided a reliable mechanism for seeding the flow, without it getting caught in the inlet box, can be devised). The other suggestion is to increase their distance further apart to avoid side lobe interference. UVP data remained noisy. It is speculated from pressing and !GoPro videos that surface waves are produced where the channel sides plunge under the free surface, and that this is the source of the noise in the UVP data.
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     182fixapex_2809c: The goal for this experiment was to turn off the transverse completely then turn on ADV and UVP to check if noise can be reduced. Almost all electronics were turned off on the transverse. Both the UVP and ADV still show a lot of noise. This implies there is either seeding or side lobe effect for the ADV and speculation on surface wave for the UVP.
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     184fixapex_2809d: The new stem ADV was damaged, so the old cable ADV was used instead. Only one experiment was run with just one ADV to see if it will show noise. It didn’t show noise. Since running multiple ADVs showed noise, this means that they are talking to each other. SNR was low, but according to Nortek, in the arms it is still possible to take good data even with low SNR.
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    184186'''Thursday, September 29th 2016'''
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     187The tank was drained, cleaned, washed, and refilled. The tank was spun with 0.083 rad/s rotation rate (0.8 rpm).
     188
     189Experiment name: rotstr_2909a, b. Filenames: rotstr1_2909a, rotstr1_2909b. Location: Position X1 (75% down straight section, 58 cm upstream from the end of the straight section). Input rate started from 20 L/s for the first two minutes and then was decreased to 5.64 L/s.
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     191rotstr1_2909a: Density excess was 20.3 kg/m^3^. Two sets of siphon samples were collected every 5 to 6 minutes and 15 to 16 minutes after the start of experiment. Siphons and UVPs were at the top part of the flow. Gopros took movies from the ping pong balls moving on top of the rotating tank.
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     193rotstr1_2909b: Density contract was 20.5 kg/m^3^. Siphons and UVPs were moved down to their original location. Three set of siphon samples were collected every 5 minutes after the start of the experiment. The experiment lasted for 15 minutes.
    187194
    188195'''Friday, September 30th 2016'''
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    195 
     197Experiment name: rotstr1_3009a, b, c. Filenames: rotstr1_3009a, rotstr1_3009b, rotstr1_3009c.
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     199rotstr1_3009a: The total experiment time was 30 minutes. The goal was to use UVPs and switch between them within the experiment. ADV samples were taking at the straight section (Position X1 -75% down straight section, 58 cm upstream from the end of the straight section). The stream wise UVP collected data for the first 10 minutes of the experiment. In the second 10 minutes, the UVP was switched to the cross stream and collected data in the cross stream section for the third 10 minutes. It should be noted that the cycle for the cross stream UVP was set to 1500 mistakenly, instead of 666. Bottom check data was collected for both ADVs. Siphon samples were collected every 5  minutes after the flow rate became constant. The 3 sets were sampled at 5 to 6 minutes (Set !#1), 15 to 16 minutes (Set !#2) and 25 to 26 minutes (Set !#3). The laser was used in this experiment.
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     201rotstr1_3009b: The goal was to see how much better the UVP data would be later in the experiment. Input flow rate started from 20 L/s for the first 2 minutes and then was decreased to 5.5 L/s. Density excess and temperature were 20.4 kg/m^3^ and 23.7 degrees C respectively. The experiment lasted for 35 minutes as opposed to 30 minutes because it was concluded from previous experiments that would show better results later in the experiment. Therefore 5 minutes after the flow rate became constant, the stream wise UVP collected data for 10 minutes. Then, the two UVPs were switched in the next 10 minutes and, finally, the cross stream UVP collected data from 25 to 35 min. A complete sequence of data was collected by the ADV, but it did not restart for some time. Then, it started collecting a second sequence later which was not complete because the experiment ended. The laser did not work in this experiment.
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     203rotstr1_3009c: Input flow rate started from 20 L/s for the first 2 minutes and then was decreased to 5.5 L/s. The goal for this experiment was to add dye and visualize the behavior of the current at different locations. Gopros were placed at different locations to take movies of the current and to test which location is the best fit for taking movies.
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