please answer all the questions(objectives) thanks a lot!!

Post by **answerhappygod** » Mon May 16, 2022 8:55 am

: Please Answer All The Questions Objectives Thanks A Lot 1 (243.26 KiB) Viewed 55 times

: Please Answer All The Questions Objectives Thanks A Lot 2 (131.9 KiB) Viewed 55 times

Objectives: 1. To calibrate rectangular and V notch weirs - develop the rating curves for both weirs i.e. Plot Head (H and ?, H52) vs Flow rate (Q) data. 2. To see how the co-efficient of discharge (Ca) changes (slightly) with flow rates for both weirs). 3. To find the mean Ca for both weirs. 4. To predict flow accurately (for both weirs) using the H, and constants (i.e. K and Ca) values. 5. To compare the actual and predicted flows for each type of weir used (i.e. rectangular and V shape). 6. To compare the actual flow rates for the two types of weirs used (rectangular and V-notch). V-Notch Weir Rectangular Notch Weir V-Notch Weir Depth or Weight Gauge Open Channel of the volumetric Bench Figure 2: Set of weirs to be used with the self-contained hydraulic bench.
V-Notch Weir Lab Data Remember: The flow rate can be predicted using the estimated Cav and/or K (for the V-notch shape weir) values in the following equations. K, Mean C. C (This equation would give you a mean Car for a V-notch) 2.36 tan (Eq. 1) 2 Estimated C- -(This equation would give you estimated Cev i.e. co-efficient discharge V2g tanH2 15 value for V-notch weir using actual results) (Eq. 2) . 8 9, - Meancer is v2g tan)” (This would give you Q, using mean Cav and actual B and H values) (%'? (Eq. 3) Where K 2. H2 #32 (This would give you estimated K value from you actual results) (. (Eq. 4) Note: Notch total angle, H = head over crest (m) 0.268 Total angle theta for the V-notch weir used = 30 degree Tan (30/2) Initial datumn value = 141 mm Mean Ky (from the graph between Q and 1/2) Mean Cav (using Eq. 1) I Percentage Prediction Error = 100*(Measured value - Predicted Value)/(Measured Value 45/2 (m) S. No. 1 2 3 4 5 6 45 Actual Measured Data Set Predicted V (L) T(S) Q(m/s) Estimated Esitamed Q. (m/s) Error (%) between Cdy using Ky using using Measured Q and Qp |Eq.2 Eq.4 Eq.3 0.000281 4.5 0.00010 0.000559 10 45 0.00022 0.000810 13.5 45 0.00030 0.001206 21.15 45 0.00047 0.001754 29.25 45 0.00065 0.002106 35.1 45 0.00078 Guagging (m) H reading (mm) 103 0.038 91 0.05 83 0.058 73 0.068 62 0.079 56 0.085
Procedure 2 - V-Notch Weir (10 marks): 1. Equipment is already set up for you, and is safe to use. 2. Measure the total angle of the V-notch used. 3. Set up the initial water level (i.e. Datum of Head). This can be done by running the pump of the hydraulic bench until the upstream water level just starts to pour over the bottom of the notch of the weir, then stop the pump. Now, wait for the water level to stabilise and use the reflection of the weir in the water to help you to see the water level matches with the bottom of the V-notch. 4. Now, carefully adjust the depth gauge so that its tip touches the surface of the water. This is the datum head value. 5. Start the pump of the hydraulic bench and adjust for the highest flow rate (around 1 L/s or 60 L in one minute). 6. Wait for the flow rate and the upstream water level to stabilise and note the water quantity you collect and the time taken. Convert this into flow rate (L/s or mº/s). 7. Use the depth scale or gauge to measure the new water height. Subtract the datum value from your reading to get the actual head vale, and convert this into meters. This is the 'head over weir crest' (H) for this particular flow rate 8. Allow time for flow over the weir to become steady. Ensure that the flow rate is sufficient to have a nappe (i.e. free fall) that clears away from the outer weir wall below the crest. Stop taking readings when this happens. 9. Repeat the experiment for FIVE times with lower Q that give equal decrease in H values (roughly 10 mm steps should work). 10. Plot the results on a graph of estimated Car for V-notch weir and actual flow rate (L/s or m®/s – on X-axis). Discuss your results. 11. Plot the results on a graph of H over weir crest (on X-axis) Vs actual Q. Draw the best-fitting curve you can to the points. 12. Plot (on the same graph as drawn for the above bullet point 11) H 52 vs actual Q results - you should get a straight line, and its slope will be the mean value of constant Ky for V-notch weir from your graph. Use this Ky value to determine the mean Cav (using Eq. 1) for the V-notch weir. Discuss all your results. 13. Then, use (Eq. 2) to predict Q, using mean Cav value and actual B and H values (for each reading). 14. Determine the estimated error (%) between the actual and predicted Q values. Are the results expected? Discuss and explain why? 15. Compare and contrast the rating curves of the two types of weir used (i.e. rectangular and V-notch). Are the results expected? Discuss and explain why?
Remember: The flow rate can be predicted using the estimated Cav and/or K (for the V-notch shape weir) values in the following equations. Mean Cav K, -(This equation would give you a mean Car for a V-notch) (Eq. 1) 2.36 tan% Estimated Cav -(This equation would give you estimated Cav i.e. co-efficient discharge 8 2g tan(%$12 15 value for V-notch weir using actual results) (Eq. 2) 8 9, = MeanCav V2g tan(%)H$'? (This would give you Q, using mean Cav and actual B and H values) 15 (Eq. 3) Where K = Q. (This would give you estimated K value from your actual results) (Eq. 4) Note: 0 = Notch total angle, H = head over crest (m) = H$/2