Quote:
Originally Posted by Michael Hill
I'm not exactly sure of the capabilities of a hall-effect sensor, especially at these high frequencies.
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At its most basic, a Hall effect sensor responds to a magnetic field. Current through the sensor is affected by the field to produce a voltage output. If you could perform tight enough calibration, you might be able to measure in the range of distances you're looking at, but it seems to me that it would be difficult to maintain accuracy. Any stray magnetization of the turbine blade or housing could throw off the results completely.
I wonder whether something like Doppler rangefinding can tell you what you want to know. The shape of a plot of the beat frequency vs time ought to be related to the minimum distance as the turbine tip goes by.
There's also the possibility of using optical interference of laser light as a gauge, though the maximum distance is rather large for that to work well.