Lab01_07_01

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Apr 3, 2024

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LAB REPORT Course Number: ENGR3345 Section 07 Course Title: Fluid Mechanics Laboratory Experiment No: 1 Viscosity Measurement and Equipment Calibration Date of Experiment Performed: January 25, 2024 Date of Report Submitted: February 1, 2024 Group Number: 1 Experiment Performed By: Ava Giffen-001048751 Jazmin Herrera-001118067 Madeline Holland-001035305 Ashlei Hutcheson-001034328 Jade Crisp-001007744 Contributions: Jazmin: Document Formation/ Procedure and Set Up Ava: Discussions Jade: Objective & Background of the Experiment Madeline: Data Analysis & Results Ashlei: Conclusions

1 Viscosity Measurement and Equipment Calibration Table of Contents CONTENTS 1. ObjecƟve of the Experiment ………………………………… 2 2. Background of the Experiment ……………………………… 2-3 3. Experimental Setup and Procedure …………………………… 3 4. Experimental Data and StaƟsƟcal Analysis of Data ………………… 4-7 5. Discussions ……………………………………………… 8-9 6. Conclusions ……………………………………………… 9-10 7. References ……………………………………………… 11 Page No.

2 Objective of the Experiment This experiment’s objective is to determine the viscosity of motor oil. This is done by using two different quantitative machines; a mechanical device known as the Thomas Stormer viscometer and the Brookfield viscometer, a digital device. After recording the data for SAE 30 oil measured using both devices and comparing the two different sets, the group must decide on which viscometer is better. Background of the Experiment Viscosity is the thickness of a liquid. More accurately, it’s the internal friction of a moving liquid. The higher the viscosity, the harder it is to move it or move through it. The easier it is to move the liquid or to move through it equals a lower viscosity. Viscosity and temperature are inversely related; the higher the temperature, the lower the viscosity. This is because when particles are heated up, they move around faster which then in turn makes their interaction time shorter. The less time interacted, the less particles grouping and slowing the manipulation of the liquid. The Thomas Stormer viscometer was invented in 1909 by Edward J. Stormer, a chemist at Case Threshing Machine Co. This version of the viscometer has a weight that falls at a constant speed, continuously turning a rod, called the spindle, which is fully immersed in the liquid of interest. The liquid must be kept at a constant temperature in order to get an accurate reading. The measurement would be taken by either the number of rotations that occurred within a set time, or the amount of time needed for the rod to make a rotation. The Brookfield viscometer is an electric version of the aforementioned Thomas Stromer viscometer. This version also uses a spindle, but the speed can be adjusted by the touch of a

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3 button rather than changing out the weight. The measurement of viscosity can be taken by the displayed amount of force required to keep this speed constant. Experimental Set up and Procedure. To perform the first part of the experiment, one needs to use the Thomas Stormer Viscometer. This machine consists of an outer cylinder filled with SAE 30 motor oil, a rotor, a spindle, and a 50g weight. The viscosity of the fluid in the outer cylinder resists the rotating drum as the spindle rotates. The first step is to place the viscometer near the edge of the table so the 50g weight is hanging. Next, the outer cylinder is filled with SAE 30 motor oil until the drum is completely immersed. There is a gauge on the viscometer that measures the number of revolutions as the drum rotates. This gauge and a stopwatch are used to record how long it takes for the drum to reach one hundred revolutions. The last step is to release the weight and let it descend until the drum reaches one hundred revolutions. This process is repeated 5 times to gather enough data. For the second part of the experiment, one needs to use the Brookfield viscometer. The first step is to turn the machine on and auto zero the viscometer. Next, the #2 spindle is located and attached to the viscometer. It is important to use room temperature SAE 30 motor oil to fill the beaker with before placing it on the plate. Then, the spindle is lowered into the center of the beaker until the groove is at liquid level. The speed is set to 50 RPM and the spindle is initiated. One waits for the value to stabilize and then records the viscosity five times for sufficient data.

4 Data Analysis & Results Sample Data Sheet for Experiment 1: Viscosity Table 1: Thomas Stormer Viscometer Trial Time to 100 revolutions (s) Viscosity (cP) Viscosity (mPa • s) * 1 105.43 128 128 2 105.90 128 128 3 105.59 128 128 4 105.28 128 128 5 104.75 128 128 * Calculated value(s) Table 2: Brookfield Viscometer Trial Viscosity (cP) 1 22.58 2 22.58 3 22.58 4 22.58 5 22.50 Equation 1. Average Viscosity 𝑣 ௔௩௚ [𝑐𝑃] = |𝑣 ଵ + 𝑣 ଶ + 𝑣 ଷ + 𝑣 ௡ … | 𝑛 (𝑣 ஻ ) ௔௩௚ [𝑐𝑃] = |22.58 + 22.58 + 22.58 + 22.58 + 22.50| 5 = 22.56𝑐𝑃 (𝑣 ்ௌ ) ௔௩௚ [𝑐𝑃] = |128 + 128 + 128 + 128 + 128| 5 = 128𝑐𝑃 Equation 2. Conversion from cP to mPa*s 𝑣[𝑐𝑃] = 𝑣[𝑚𝑃𝑎 ∙ 𝑠] Equation 3. Percentage difference % ௗ௜௙௙௘௥௘௡௖௘ = |𝑣 ஻ − 𝑣 ்ௌ | ቚ 𝑣 ஻ − 𝑣 ்ௌ 2 ቚ ∙ 100%

5 % ௗ௜௙௙௘௥௘௡௖௘ = |22.56𝑐𝑃 − 128𝑐𝑃| ቚ 22.56𝑐𝑃 − 128𝑐𝑃 2 ቚ ∙ 100% = 200% Equation 3. Percentage error % ௘௥௥௢௥ = ห𝑣 ௘௫௣ − 𝑣 ௔௖௧௨௔௟ ห 𝑣 ௔௖௧௨௔௟ ∙ 100% % ௘௥௥௢௥ = |128𝑐𝑃 − 300𝑐𝑃| 300𝑐𝑃 ∙ 100% = 57.3% Figure 1. Thomas Stormer viscometer calibration curve. The viscosity from the Thomas Stormer viscometer was determined by comparing the measured times it took to complete 100 revolutions to the curve in Figure 1. We then converted the viscosity unit from the curve, centipoise, to millipascal-seconds using the direct conversion 1cP = 1 mPa•s. We observed relatively consistent times for each 100 revolutions, and the slight

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6 differences in time did not carry over into the viscosity values pulled from the curve. Although there was a difference of over 1 second on some trials, the viscosity was measured to be 128 cP each time. This directly converted to 128 mPa•s for each trial. The viscosity measured from the Brookfield viscometer was also consistent, measuring 22.58 cP for all but one trial, with the exception measuring 22.50 cP. Experiment 1a: Thomas Stormer viscometer What are the advantages and disadvantages of using the Thomas Stormer viscometer? The Thomas Stormer viscometer has several different advantages and disadvantages. While the Stormer viscometer is more affordable, compared to the Brookfield viscometer, and it yielded fairly consistent and precise results, our experience with it led us to believe it is not accurate and allows for a large amount of human error. Do you think the graph that was provided for the Thomas Stormer viscometer may be used to measure the viscosity of other fluids? Why or why not? When using the graph with our data from the SAE 30 motor oil, it yielded a value that was not accurate. Therefore, one might assume that the graph should not be used to measure the viscosity of other fluids. However, if there were issues with our viscometer, that would not justify the graph not being able to measure the viscosity of other fluids. Experiment 1b: Brookfield viscometer What are the advantages and disadvantages of using the Brookfield viscometer? The Brookfield viscometer also has several advantages and disadvantages. The Brookfield viscometer is much more expensive than the Stormer viscometer, but it was

7 also more precise and easier to use than the Stormer viscometer. Our usage of the Brookfield viscometer yielded far less accurate results than the Stormer viscometer as well, therefore, the pros and cons of the Brookfield viscometer are mixed. Both experiments: Identify factors that could have led to the corruption of data in this experiment. Also identify the assumptions being made in this experiment that can compromise the data or the way we compute our results. There were many factors that could have corrupted the data we collected from this experiment. One such factor could be the temperature of the room and/or oil. The published value for the viscosity of SAE 30 motor oil is 310 cP, but this is only when the oil is at a room temperature of 20 degrees Celsius. The temperature of our lab room was measured to be 72 degrees Fahrenheit. Temperature does affect viscosity, so this factor could have led to the corruption of our data. Another factor could be human error: we might have not been accurate or precise when recording the 100 revolutions for the Thomas Stormer viscometer, there could have been human error when comparing the times to the graph in order to obtain the viscosity, and we might have jostled the Brookfield viscometer, causing it to misread the viscosity. Yet another factor could have simply been that our machines for the experiment were faulty. This is highly likely as several groups recorded similar data from each viscometer, and both of our sets of data were significantly different from the published value in different ways, meaning that it is not likely that human error caused such precise, yet completely incorrect, data.

8 Discussions From our experiment, we obtained a value of 128cP for the viscosity of SAE 30 motor oil using the Thomas Stormer viscometer. According to Engineering Toolbox, the actual value for the viscosity of SAE 30 motor oil at room temperature (20 degrees Celsius) is 0.310 Ns/m^2. When converted to cP at a conversion rate of 1 Ns/m^2 equal to 1000 cP, this value becomes 310 cP. The percentage error is 57.3%. There are a few reasons for the difference in these values. The first difference can be attributed to the difference in room temperature for the experimental data and the actual data. The room was set to 72 degrees Fahrenheit during the experiment, whereas the actual data was taken at a temperature of roughly 68 degrees Fahrenheit (20 degrees Celsius). Another contributing factor is the manual process of the testing. The equipment relied on a human factor when starting and stopping the timer and therefore may have led to testing error. After collecting the data, a printed graph was used to determine the values for the viscosity. This transfer of data using the graph relied on human eyes and easily may have caused error. These factors should only have been attributed to minor discrepancies in percentage error. Based on our observation, the main reason for the error can be attributed to the unreliability of the equipment provided in the laboratory to be functioning properly. The mass used in the experiment affected the time measured to achieve 100 rotations of the drum. By increasing the mass to 100g, the time to achieve 100 revolutions of the drum would be faster than at the experimented weight of 50g. The opposite would be true if the weight were decreased. Had we used 100g weight, 25s would pass before 100 revolutions were completed. Had the weight been decreased to 25g, roughly 190s would pass before 100 revolutions were completed. These values were determined using data from Figure 1.

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9 The measured viscosity utilizing the Thomas Stormer Viscometer was 128cP, whereas the measured viscosity of the Brookfield viscometer was 22.56cP. The percentage difference between these values was found to be 200%. The Brookfield viscometer measures viscosity at given shear rates by “driving the immersed element, which is called a spindle, through a beryllium copper spring” (Brookfield Engineering Laboratories). Different models of the tool have different springs. The software then calculates the viscosity by recognizing the viscosity’s proportionality to “the spindle speed and is related to the spindle's size and shape” (Brookfield Engineering Laboratories). This setup is similar to that of the Thomas Stormer Viscometer, though computerized. Due to the lack of human input for data collection using the Brookfield viscometer, errors relating to the human factor should be minimal. Movement of the surface upon which the Brookfield viscometer is placed could also result in inaccurate measurements. Based on this research, the Thomas Stormer and Brookfield viscometers should measure the same viscosity with similar precision. Since these values are so drastically different, we can expect that the equipment used in our laboratory is not functioning properly and should be replaced. Conclusion In the end, our experiment using the Thomas Stormer Viscometer gave a consistent reading of 128cP, yielding a percent error of 57.3%. As stated in the discussions, many factors contribute to this high percentage of error. Therefore, it is safe to conclude that while the Thomas Stormer Viscometer gives consistent readings, there are too many variables that could affect the outcome. If the variables were reduced then the Thomas Stormer Viscometer would work more accurately. For example, if the viscometer was placed in a room at a constant 68 degrees Fahrenheit (20 degrees Celsius), then the reading may be more accurate. However, this was not

10 the case for our experiment. On the other hand, the Brookfield Viscometer, in theory, should eliminate all the variables that the Thomas Stormer Viscometer has because it is digital. Unfortunately, our data showed a 200% difference between the Brookfield data and the Thomas Stormer Viscometer. We have concluded that this is caused by faulty equipment in our laboratory. A brand-new Brookfield Viscometer would most likely give more accurate results, but our data from this lab does not support that. Therefore, based on our data we conclude that the Thomas Stormer Viscometer is more accurate at determining the viscosity of the SAE 30 motor oil. We, then, also recommend the Thomas Stormer Viscometer over the Brookfield Viscometer.

11 References Brookfield viscosity. (n.d.). https://en.oelcheck.com/analyses/test-methods/brookfield- viscosity/#:~:text=The%20Brookfield%20viscometer%20is%20a,measurement%20for% 20the%20dynamic%20viscosity Hydramotion. (n.d.). Units of Viscosity. https://hydramotion.com/uploads/view/20160224144736_Hydramotion_Viscosity_Units.pdf Motor oils - dynamic viscosities . Engineering ToolBox. (n.d.). https://www.engineeringtoolbox.com/dynamic-viscosity-motor-oils-d_1759.html Operating manuals. (n.d.). https://www.brookfieldengineering.com/services/downloads/operating-manuals Reid, E. (2021, August 3). The importance of temperature and viscosity . RheoSense Blog: Viscosity, Viscometers, & More. https://blog.rheosense.com/temperature-and- viscosity#:~:text=Viscosity%20will%20decrease%20with%20increased,also%20influenc es%20interactions%20of%20particles . Smithsonian Institution. (n.d.). Stormer viscometer . https://www.si.edu/object/stormer-viscosimeter%3Anmah_2957 The Trustees of Princeton University. (n.d.). Definition of viscosity . Princeton University. https://www.princeton.edu/~gasdyn/Research/T-C_Research_Folder/Viscosity_def.html

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