ENGR3345_Group3_Lab2_FluidStatics

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Lab 1: Viscosity Fluid Mechanics Laboratory Section 1 Prepared by Mr. Robert Norman robert@studentmailhmu.com

November 24, 2021 Table of Contents: Cover Page ………………………………………………………………………………………………………………. 1 Table of Contents …………………………………………………………………………………………………….. 2 Executive Summary …………………………………………………………………………………………………. 3 Results …………………………………………………………………………………………………………………….. 4

Executive Summary Experiment 1: Viscosity, aimed to assess the benefits and limitations of utilizing the Thomas Stormer viscometer and the Brookfield viscometer for measuring viscosity, specifically with the use of SAE 30 oil. The experiment involved two parts: one utilizing the Thomas Stormer viscometer and the other using the Brookfield viscometer. In the lab, measurements were first taken by observing the Thomas Stormer viscometer, and the time taken for the drum to rotate 100 times. The second measurements were obtained by reading the digital output of viscosity displayed on the Brookfield viscometer. Both measurements were repeated five times to ensure a correct collection of data points. Analysis of the data revealed that the Brookfield viscometer exhibited higher accuracy compared to the Thomas Stormer viscometer. The Brookfield viscometer's elimination of potential human error and external influences, along with its precise digital readout, contributed to its superior performance. This research suggests that the Brookfield viscometer is recommended for measuring viscosity, offering a more reliable and precise approach in comparison to the Thomas Stormer viscometer.

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Results Thomas Stormer Viscometer Trial Time to 100 revolutions (s) Viscosity ( 𝑚𝑃𝑎 ⋅ 𝑠 ) 1 102 136 2 112 143 3 112 143 4 112 143 5 110 140 Brookfield Viscometer Trial Viscosity ( 𝑐𝑃 ) 1 23.13 2 23.13 3 23.06 4 23.06 5 23.00

Discussion The viscosity obtained from the Thomas Stromer viscometer is much lower than the published value [2]. This discrepancy could be due to human error. These human errors include the delay from when the dial does a full revolution to the time it takes for the stopwatch to be stopped. Also, it could be due to the wear of the equipment. The time that was recorded is dependent on the weight that is being used. If a heavier mass had been used the time would have been reduced. For example, if a 100-gram weight was used the time would have been approximately 60 seconds to measure the same viscosity of the 50-gram weight. If a lighter weight was used, it would take longer to measure the same viscosity. For example, if a 25-gram weight was used it would have taken approximately 200 seconds to measure the same viscosity as the 50-gram weight. The viscosity measurement on the Brookfield viscometer is much lower than the viscosity measurement recorded by the Thomas Stormer viscometer. This could be due to the fact that the Brookfield viscometers are designed to produce a low amount of shear stress. With a low amount of shear stress will give a lower viscosity measurement [1]. The Brookfield viscometer is highly precise. It gave very consistent data over the 60- second intervals. When it comes to accuracy, the Brookfield viscometers gave very different measurements than the published values of the viscosity of SAE 30 oil. The Thomas Stormer viscometer is less precise, but it gave a much different viscosity reading compared to the

published viscosity value. This leads to the conclusion that the Thomas Stormer viscometer is also not very accurate.

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Materials and Methods For this experiment, SAE 30 oil was used in both the Thomas Stormer viscometer and the Brookfield digital viscometer. For the Stormer viscometer the average of three stopwatch times was taken for each of the five tests. On the first test with the Stormer viscometer, the cylinder was not fully submerged in the oil, which slightly decreased the time needed to complete 100 revolutions. This was corrected for all subsequent tests. When testing with the Brookfield viscometer, it was observed that the table on which the viscometer was set was not completely stable and could move slightly. Bumping the table caused the viscometer to temporarily show unstable readings. Each of the five measurements were taken one minute after starting the viscometer.

Conclusion Based on the information gathered from the Thomas Stormer and Brookfield viscometers, we conclude that the Brookfield viscometer is more accurate than the Stormer viscometer because it eliminates human error in timekeeping and most other potential external influences, such as the potential for the weight to catch on a foreign object as it is lowered. The rotation gauge on the Stormer viscometer is also much less precise than the digital readout on the Brookfield viscometer, potentially leading to further errors due to incorrect reading of the gauge.

References: [1] T. Chen, “More Solutions to Sticky problems - University of Utah,” my.che.utah.edu, https://my.che.utah.edu/~tony/chen4903/equipment/A_Viscometers/MIS_Brookfield_Viscom etry_Guide.pdf (accessed Aug. 28, 2023). [2] “Motor oils – dynamic viscosities,” Engineering ToolBox, https://www.engineeringtoolbox.com/dynamic-viscocity-motor-oils-d_1759.html (accesed Aug. 28, 2023).

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