Kinematic Analysis - RV

                Some interesting findings of this mechanism was the adjustability of the mechanism. By changing out the dial spring, one would be able to change the torsional spring factor and measure a different range of viscosities for the device. For the measurement of crude oil samples, only one torsional spring is needed to measure the full range of viscosities. The mechanism had two input motor speeds of 900 and 1800 rpm and three different gearing ratios (0.0039, 0.1158, 0.3474). These three different settings were needed in order to cover the range of viscosities that could be seen in the oilfield. According to Petrowiki¹, the range of crude oil viscosity is between 0.001N-m/s² and 1 0.001N-m/s². With a torsional spring constant of 0.002 N-m/rad and the three gear settings, the whole range of oilfield sample viscosities may be tested. The angular velocities of the sample with the varied motor input and gear setting are as follows:

As we can see, the different gear trains and motor speeds can allow for a wide range of angular velocities of the sample. Therefore, the sample can be subjected to a variety of shear rates and a variety of shear forces. These shear forces are converted into an angular displacement in the dial, which is measured.

The range of viscosities that can be tested accurately (0.5°<θ<300°) at are as follows:

This table shows that the viscometer can accurately measure the expected range of crude oil samples with just one machine and one torsional spring. There is no need to switch out springs to adjust for an extreme viscous sample. This fact is one of the wonders of this mechanism.