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Unformatted text preview: CE 3101 Fall 2011 Homework 02 – Filling the Water Tower Due Tuesday, 20 September 2011, 11:55 P.M. (This is a 25 point group assignment.) Abstract In self-selected groups of up to three members, you will write an Excel spreadsheet program to compute the filling rate of a water tower, in a specific municipal network, as a function of a set of user-specified design parameters. A full written report is required in addition to the working code. This assignment does NOT have an early-submission requirement 1 . Group Evaluation and the Time Card After completing this assignment you are each required to INDIVIDUALLY complete the Homework 02 Group Evaluation , found on the course Moodle web site. One of the components of this evaluation is a reporting of effort. As you will all be required to do in professional practice, in this course you will be responsible for detailed time estimates and time tracking. At the beginning of this homework assignment – after the first reading of the project requirements – record an estimate of the total time necessary to complete the assignment 2 . After the task is complete, record the actual time spent. Time tracking should be recorded to the nearest 15 minutes (1/4 hour). Background Almost every city and town in Minnesota has at least one water tower 3 . A water tower provides access to a significant quantity of water at an almost constant pressure. Water towers must be filled. In Minnesota, water towers are filled from reservoirs and groundwater wells. Water towers are commonly filled at night, when the demand for water is lowest. Consider the piping system shown schematically in the Figure 1. The water is being drawn out of two reservoirs and pumped up into the elevated tank. This is not uncommon in Minnesota. The pressures in the reservoirs and the tank are atmospheric (i.e 0 [ Pa ] gauge pressure); however, the tank is elevated relative to the rest of the system. Let z i [ m ] denote the elevation of point i . Point 6 is at the top of the tank, which is setting on an elevated tower. Assume that z 1 = z 2 = z 3 = z 4 = z 5 , but z 6 > z 5 . Further, assume that the pipes from the reservoir to the pumps (from #1 to pump A, and #2 to pump B) are of insignificant length. Also note, points 3 and 4 are just after the pumps, so the pressure increases from the pumps are felt at points 3 and 4. Revisiting the Moody Friction Factor From your experience on Homework 01, you are familiar with the Reynolds number, Re [ ] 4 , which is defined by Re = VDρ μ (1) where V [ m/s ] is the average fluid velocity in the pipe, D [ m ] is the inside diameter of the pipe, ρ [ kg/m 3 ] is the density of the fluid, and μ [ kg/m/s ] is the dynamic viscosity of the fluid....
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- Spring '11
- Fluid Dynamics, Moody chart, energy balance equation, water tower, Moody friction factor