● So, use the thermometer to check the water's temperature before beginning the experiment. Figure 1- measuring the temperature ● We move the rectangular weir into place after the temperature is set for the experiment, making sure there is no space between the plate and the sliding slot to prevent leaks in the water flow. We next switch on the pump and completely open the bench valve.
● Record the reading, which is represented as (H + H0), where H corresponds to the height of the free surface in relation to the weir's lowest opening and H0 to the height of the weir's lowest opening in relation to a nominal reference elevation. ● We lower the water level height for the subsequent run by 5 mm by lowering the valve opening, and we note the water height reading (H + H0). The matching volume and time are also measured. ● Then, until the flow dribbles, we keep lowering the water level height by 5 mm at a time, recording each time the water height reading (H + H0), volume, and time. It is clear from the most recent run that the free surface height relative to the weir's lowest opening is H = 0. The most recent reading, therefore, matches H0. To determine the value of H pertaining to each run, we subtract that value H0 from all previously recorded values of H + H0. ● Close the bench valve and stop the pump at this time. We use a V-shaped weir in place of the rectangular one. The bench valve is then fully opened after turning on the pump. The ruler is moved until the point is perpendicular to the free surface. ● The same steps are then repeated. At each run, we take a volume and time reading. Then, we cut H + H0 by 5 mm until the flow dribbles. Required equipment ● Volumetric Bench
● Stopper Figure3- Stopper ● Thermometer ● A sliding ruler Figure4- A sliding ruler ● Stopwatch ● Graduated beaker
Figure5- mobile stopewatch Figure6- rectangular and V- shape Weir
Graph 1- log(Q) vs log(H) for Rectangular Weir
There might have been a number of sources for the deviations from the vendor figures and the literature. There was an inevitable leak in the channel during the V-shaped weir runs, which slightly raised the volumetric flow rate value. The hydraulic bench pump's power varies over time, as was previously seen in earlier studies, and this might have affected the measurements of the reservoir height. Last but not least, since instruments that must be read visually are known to be slightly imprecise, parallax may have contributed to the readings on the manometer tube. The vendor's figure for the three various discharge coefficients is the most reliable. This is so because they often discover their values via experimentation in a regulated professional setting. Incorrect or fabricated data might possibly constitute a safety concern and damage the manufacturer's reputation.
In this experiment, our primary objective was to measure the flow rates via a rectangular and v-shaped weir at various heights. After that, we used this knowledge to compute the coefficient of discharges for both weirs using their empirical formulae. The rectangular weir's coefficient of discharge is 0, while the v-shaped weir's coefficient of discharge is 2, both of which deviate significantly from what is known from the literature and the vendor.
There is a significant disparity between the experimental numbers since there was a lot of potential for error in this experiment. Instead of encouraging us to start at the highest flow rate possible in the future, I would advise this lab to specify the flow rate it wants us to start at.
With the help of [Roberto Marquez, Fabian Gutierrez, America Hernandez-Guillen, and Nicholas Constantino], all experimental data were gathered. We appreciate the facilities provided by San Diego State University and [Jose Roberto Moreto's] insightful advice.
Lab manual provided by the instructor in Canvas.
Run # (Rect ) Run # (V) H (cm) Volu me (m^ ) Volu me (m^ ) Time (seco nds) Time (seco nds) H+H 0 (m) H (m) Q ((m^ 3) /s) Q1 Q2 K Cd LogH Log Q 0 0. 7 1 0. 5 0. 5 5. 17. 2 0. 7 0. 0. 09 0. 09 0. 09 0. 86 0. 8 -1. 5 -3. 2 2 0. 5 0. 5 6. 21. 1 0. 4 0. 3 0. 07 0. 08 0. 07 0. -1. 1 -3. 1 3 0. 5 0. 5 7. 26. 4 0 0. 0. 06 0. 06 0. 06 avg cd 0. -1. 4 -3. 7 4 0. 5 0. 5 10. 32. 5 0. 7 0. 0. 05 0. 05 0. 05 0. 17 0. -1. 1 -3. 4 5 0. 5 0. 5 13. 3 42. 4 0. 4 0. 0. 04 0. 04 0. 04 0. -1. 7 -3. 4 6 0 0 19 56 0 0 0 0 0 0 -1 -3.