Torsional ultrasonic waveguide sensor

The present study continues the torsional guided-wave temperature (T) and liquid level (H) investigation we reported in 2009. For H, the present focus was on sensor shape and other parameters that significantly influence the guided torsional stress reflection coefficient (R), signal to noise ratio (SNR), and the insertion loss (IL) at liquid/vapor and slurry/vapor interfaces. Results showed a diamond cross section has 6 times larger R and 3 times larger S than the rounded rectangle sensors used in 2009. Increasing the area of the transducer contacting a 316 Stainless Steel (SS) sensor increased the SNR 4 dB and reduced the IL by 2 dB. The torsional wave mass loading method was applied to measuring the width of a water column. The width is related to flow rate. Here we used a ~100 mm long SS sensor, welded into a shallow "v" shape from two segments initially of diamond cross section, AR (aspect ratio) = 3. The torsional through-transmitted transit time in the sensor increased from 79.4 μs in air to 81.4 μs when wetted by a water column of N17 mm. Response was nonlinear, attributed partly to the sensor's cross section being non-uniform in the region wet by the water column.