Pre-Testing
This section looks at the procedures undertaken to confirm the suitability of the apparatus used for the experiment
Load Cell CalibrationSince the load cell produces an electrical voltage when force is applied, it was important to calibrate so that the voltage registered could be converted to the force applied. By applying masses of known weight, the voltage gain per unit force could be calculated. It was found within all planes of movement (+X,-X,+Y,-Y) that the excitation voltage was proportional to the weight applied on the load cell, which is what was expected.
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Cross-Talk CalibrationCross-Talk is 'any phenomenon by which a signal transmitted on one circuit or channel of a transmission system ceeates an undesired effect in another circuit or channel' [25]. This concerns the signal transmitted from the voltage rading in the X direction being affected by the signal transmitted in the Y direction. Upon carrying out the Cross-Talk calibration, it was found that the load cell did not suffer from this
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Strain Gauge Calibration
As with the load cell, the full wheatstone bridge circuits applied to the spar were calibrated to confirm the voltage gain per unit force. Upon completion, this allows for the force applied to the spar by the fluid in the recirculating flume to be calculated
AS Nortek Vectrino Calibration
Before carrying out the full experiment, the current Vectrino velocimeter was used to assess what the flume could acheive in terms of flow velocity range and turbulecne intensity. With these results, a velocity test matrix was created. Below is an image showing the data collection tool, using the ASCII format, within the software program Vectrino Plus.
Data Collection of Flow velocity using Vectrino Plus Software