8.9: Questions
- Page ID
- 44585
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Explain the three energy forms in irrigation system hydraulics.
- List three things that will increase pressure loss due to friction and explain why they impact this loss of energy.
- Discuss the components of total dynamic head and how they are impacted by the setting of the irrigation site, such as water source, etc.
- A water surface elevation of mountain reservoir (lake) is 240 ft above and irrigated valley. A pipeline conveys water from the reservoir to the irrigated valley and the pressure loss due to friction and minor losses in the pipeline is 40 psi. If at least 60 psi is needed to operate the sprinklers in the valley, will there be adequate pressure without using a pump?
- A furrow irrigated field uses 10-in gated pipe and the well flow rate is 1000 gpm. The last irrigation set in the field starts 900 ft from the well and there is a 9-ft elevation rise or gain from the well to the last set.
a. If the discharge pressure at the well is 10 psi, what is the water pressure at the beginning of the last set?
b. In the last set there are 50 gates open and the spacing between open gates is 5 ft. There is an additional 2.5-ft elevation rise or gain from the start of the set and the last gate. What is the water pressure at the last gate?
c. If you inserted a clear plastic tube in the last gate and held it vertical, how high would the water rise in the tube?
- An irrigated field has a highly variable demand for water. On some days 750 gpm are required, and on other days 1300 gpm are required. The water is stored in a nearby reservoir and the elevation of the water surface in the reservoir is 34 ft lower than the elevation of the field. It was decided to connect two pumps in parallel to meet this variable demand. The pressure required in the irrigation system is 40 psi. The pumps selected were the 12 SKL pump shown in Figure 8.11 and they will be powered by electric motors with speeds of 1770 rpm.
a. If pump number one is to deliver 750 gpm and the impeller diameter is 7.25 inches, how many pump stages will be required?
b. What will be the efficiency of this pump?
c. If electric motors come in nominal sizes of 10, 15, 20, 25, 30, 40, and 50 hp, what size motor would you select for this pump?
d. The second pump must deliver 550 gpm to the system. It was decided to use 3 stages of the 12 SKL for this pump. What diameter impeller would you recommend? e. What will be the efficiency of this pump?mf. What motor size would you recommend for the second pump?
- Water is flowing at 500 gpm in a 6-in inside diameter pipeline.
a. What is the velocity head of the water (ft of head)?
b. If the water flows through a 90° regular flanged elbow, what is the head loss in ft (minor loss) in the elbow?
c. What is the pressure loss in the elbow in psi?
- A farmer kept records of diesel fuel consumption and water applications for a center pivot irrigated field. The field conditions are: Q = 800 gpm Volume of water applied for the year was 1300 ac-in. Discharge pressure at the pump was 50 psi. Pumping lift from the well is 150 ft. Amount of diesel full consumed for the year was 3900 gal.
a. Estimate the performance rating of this farmer’s irrigation pumping plant.
b. Based on what you learned in Chapter 3, how many hours did the pump operate in a season in Question 8?
c. How many gallons of diesel fuel were consumed per hour?
d. If the performance rating were improved to 1.0, how many gallons of fuel would be consumed in a year?