Test 2 reflection

The test demonstrates exactly what an engineer will be expected to do in the industry. This is: Solving many small induvial parts and applying these solutions to the entire problem.

Mistake 1) I interpreted the problem statement incorrectly. The problem statement says that the average slope is 0.00015. I understood this as theta is equal to 0.00015. This mistake is early on in the test and has a far-reaching impact on parts A and F. To prevent this in the future I would ask a clarifying question on the prestest.

Mistake 2) I used the incorrect height of point 3 while calculating the energy loss in the discharge pipe. I used 50 feet and I should have used 40 feet or a different value. The solution uses the same equations but combines the equations before solving. I tried to solve the equations and then plug them into each other. In this process, I made an assumption that was not correct.

Mistake 3) I used the incorrect units for the value of the wave. You warned us about this in class but I did not use the correct units!! To avoid making this mistake on the next test, I will review my notes carefully BEFORE rushing into the math.

Mistake 4) I used the incorrect operational pressure to compare to the saturation pressure. However, I calculated the operational pressure that was used in the solution correct in part B. To avoid this in the future, I will use common sense rather than just look at the name of the variable. Of course I should not use the highest operational pressure when looking at cavitation!

Mistake 5) I used the incorrect equation to find the location of the force on the gate. This impacted the rest of the problem because it mess up the moment equation. To avoid this in the future, I will review my necessary equations and procedure carefully.

Mistake 6) This mistake relates back to mistake 1. I used the correct equations but got the incorrect answer because of my first mistake.

3) What your grade should be. Base it on the writing rubric provided in the test and the

correctness of your solution. What are the strengths and weaknesses of your test?

WRITING RUBRIC (APPLIES TO THE WHOLE TEST, NOT TO PARTICULAR PARTS)

  1. Purpose                                              0.5/10.0 out of 0.5/10.0
  2. Drawings                                            1.0/10.0 out of 1.0/10.0
  3. Sources                                               1.0/10.0 out of 1.0/10.0
  4. Design considerations                       1.0/10.0 out of 1.0/10.0
  5. Data and variables                             0.5/10.0 out of 0.5/10.0
  6. Procedure                                          2.0/10.0 out of 2.0/10.0
  7. Calculations                                       2.0/10.0 out of 2.0/10.0
  8. Summary                                            0.5/10.0 out of 0.5/10.0
  9. Materials                                            0.5/10.0 out of 0.5/10.0
  10. Analysis                                             1.0/10.0 out of 1.0/10.0

  TOTAL WRITING RUBRIC                   10.0/10.0 out of 10.0/10.0

PART 1)                    

  1. Correct equation                                                      1/4 out of 1/4
  2. Area calculation                                                       1/4 out of 1/4
  3. Hydraulic radius calculation                                    1/4 out of 1/4
  4. Correct results?                                                        0/4 out of 1/4

                                                                        3/4

PART 2)

  1. Free body diagram and correct forces                    1/4 out of 1/4
  2. Force in x                                                                0/4 out of 1/4
  3. Force in y (weight)                                                  1/4 out of 1/4
  4. Correct results?                                                       0.5/4 out of 1/4

                                                                                                2.5/4

PART 3)

  1. Right equation and A1/A2                                       1/3 out of 1/3
  2. C value                                                                     1/3 out of 1/3
  3. Correct results?                                                         1/3 out of 1/3

                                                                        3/3

PART 4)

  1. Water hammer
    1. Wave velocity (units?) & pressure increase        0.5/4 out of 1/4
    1. Operating pressure & pipe thickness                   1/4 out of 1/4
  2. Cavitation
    1. Lowest pressure & compare to sat pressure         1/4 out of 1/4
  3. Correct results?                                                        1/4 out of ¼                                   3.5/4

PART 5)

  1. Hydrostatic force on the gate
    1. Magnitude                                                           1/5 out of 1/5
    1. Location                                                              0/5 out of 1/5
  2. Solve for buoy force with moment conservation   1/5 out of 1/5
  3. Using buoyancy, get sphere diameter.                    1/5 out of 1/5
  4. Correct results?                                                       0.5/5 out of 1/5

                                                                                                3.5/5

PART 6)

  1. Correct area                                                              1/4 out of 1/4
  2. Correct velocity                                                        0.5/4 out of 1/4
  3. How Cd was obtained?                                             1/4 out of 1/4
  4. Correct results?                                                         0.5/4 out of 1/4

                                                                                                3/4

PART 7)

  1. Setting up the spreadsheet for all parts                     1/3 out of 1/3
  2. Case for flow rate when the pump power is half      1/3 out of 1/3
  3. Correct results?                                                         0.5/3 out of 1/3

                                                                                    2.5/3

FINAL GRADE:

10.0 + (80/7)*(4/4 + 4/4 + 3/3 + 4/4 + 5/5 + 4/4 + 3/3) = 90 (if everything is correct)

10+(80/7)*(3/4 + 2.5/4 + 3/3 + 3.5/4 + 3.5/5 + ¾ +2.5/3) = 73.2

The strengths of my test are my excel spreadsheet and my energy loss equations. The weakness of my test is using the correct units and interpretating the question statement correctly.

The only issue that I had while doing the test was finding the pressure change in the discharge pipe. I made a bad assumption while calculating these pressures. To troubleshoot this issue I took a step back and thought about the problem then I decided to use Bernoulli’s from point 1 to point 2 and point 1 to point 3. The steps that I took to complete the whole test was to do the pre-test, wait for feedback, then finished the test. I will not change that process. I learned about open channel flow, the forces due to the motion of fluids, the forces due to static fluid, the pressure drop across a flow nozzle, the effects of water hammer and cavitation, and the drag due to do a fluid. Engineers use open channel flow when controlling open water. Examples are dams, rivers, and streams. Engineers use the forces due to static fluids to find the force that must act on a surface to move it. Engineers use this concept when designing retaining walls, reservoirs, and zoo aquariums. Engineers use the forces due to the motion of fluids to design pipe supports with civil engineers. Engineers use the pressure drop across flow nozzle to measure the velocity of a flow inside a pipe. Examples of this are venturi tubes, and orifice plates. Engineers use the effects of water hammer and cavitation to design systems that will withstand the effects and to create procedures to prevent both of these from happening. These procedures are to slowly close the valve, stop the pump slowly, increase design diameter to decrease velocity, and increase pipe thickness. Any engineering designer will use these concepts along with many others. It is important to my career that I master these fluid mechanics concepts. I will use these skills and concepts developed in this class to design and perform calculations on complex engineering problems. I have not applied these concepts in any other course. However, I anticipate that I will be using these concepts in the near future. I was most successful with the energy losses in the system. I improved most with finding the force due to static fluids. I do not see myself working with these fluid concepts in my current career. However, I am open to any positions that are presented. I spent 3 hours on the pre-test and 9 hours on the test. These 12 hours was broken up into three separate days. If I had more time available I would have spend most time on part A because the mistake in that part effected the rest of the test.

MET330_JohnMiles_Test2