Changes between Version 245 and Version 246 of WikiStart


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Timestamp:
Oct 19, 2016, 6:33:06 PM (4 years ago)
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peakall3je
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    117117
    118118'''PME Microscale Conductivity and Temperature Instrument (MSCTI)'''
    119 The Microscale Conductivity and Temperature Instrument (MSCTI) is designed to measure the electrical conductivity and temperature of solutions containing conductive ions. This instrument provides two analog outputs, one linearly proportional to the solution conductivity, and one non-linearly proportional to the solution temperature. One probe is positioned on the traverse, alongside the ADVs, whilst a second probe is positioned at the base of the input box. For the main experiments, the conductivity probe in the channel is located 7.3 cm downstream from ADV1, and is offset by 5.5 cm such that its initial position is 20.5 cm from the wall. The second conductivity probe, positioned in the header box, is situated in the middle of the box and is approximately 1.5 cm above the floor. The MSCTI outputs two continuous voltage signals, one for conductivity and one for temperature, and these are recorded as part of the LVM file [C0 and T0 are conductivity and temperature for the probe on the traverse (though T0 does not work, since that part of the instrument is broken), and C1 and T1 are conductivity and temperature from the probe mounted in the inlet box]. We briefly had a second probe [just C2] in the inlet but this broke when it was damaged by a large input flow. Later files continue to have C2, but these just consist of noise. The probes are calibrated after each drain. To calibrate, samples of different densities (as measured with the hand-held Anton Paar density meter) are prepared at a given temperature of 21-22C and these are compared to the voltage output for conductivity of each probe. Because the water is so constant in the experiments, around 21-22C then this calibration approach enables a direct correlation between the voltage representing conductivity, and flow density. As such the temperature output from the two probes (note again that T0 is broken) are not required.The effects of temperature are small, a 1C change in temperature for fresh water changes the conductivity by only 2% (see Barron and Ashton, Reagecon Technical Paper).
     119The Microscale Conductivity and Temperature Instrument (MSCTI) is designed to measure the electrical conductivity and temperature of solutions containing conductive ions. This instrument provides two analog outputs, one linearly proportional to the solution conductivity, and one non-linearly proportional to the solution temperature. One probe is positioned on the traverse, alongside the ADVs, whilst a second probe is positioned at the base of the input box, in the centreline, immediately upstream of the honeycomb. For the main experiments, the conductivity probe in the channel is located 7.3 cm downstream from ADV1, and is offset by 5.5 cm such that its initial position is 20.5 cm from the wall; it is positioned xx cm from the floor. The second conductivity probe, positioned in the header box, is situated in the middle of the box and is approximately 1.5 cm above the floor. The MSCTI outputs two continuous voltage signals, one for conductivity and one for temperature, and these are recorded as part of the LVM file [C0 and T0 are conductivity and temperature for the probe on the traverse (though T0 does not work, since that part of the instrument is broken), and C1 and T1 are conductivity and temperature from the probe mounted in the inlet box]. We briefly had a second probe [just C2] in the inlet but this broke when it was damaged by a large input flow. Later files continue to have C2, but these just consist of noise. The probes are calibrated after each draining of the tank. To calibrate, samples of different densities (as measured with the hand-held Anton Paar density meter) are prepared at a given temperature of 21-22C and these are compared to the voltage output for conductivity of each probe. Because the water is so constant in the experiments, around 21-22C then this calibration approach enables a direct correlation between the voltage representing conductivity, and flow density. As such the temperature output from the two probes (note again that T0 is broken) are not required. The effects of temperature are small, a 1 degree C change in temperature for fresh water changes the conductivity by only 2% (see Barron and Ashton, Reagecon Technical Paper). For the test experiments the Conductivity probe was positioned 0.4 cm upstream, and with a lateral offset of 6.1 cm to the left hand side of the channel as looking downstream; it was 4.2 cm above the bed at the lowermost ADV setting.
    120120
    121121'''Particle Imaging Velocimetry (PIV)'''