HOMEWORK ASSIGNMENT #5
ME 303 FLUID DYNAMICS/ WESTPHAL/ WSU/ FALL 2000
Due: Tuesday 10/31/2000 IN CLASS (submit by conclusion
of class)
FAX to (509)372-7471 -- use the FAX cover or any other cover
page that has "ME 303 R. WESTPHAL" written on it
- Follow the Homework Guidelines for preparing
your submission.
- You MUST show a CONTROL VOLUME on your diagram whenever using conservation
of ENERGY (or any other conservation principle).
- You MAY start with the hydraulic (mechanical) energy equation instead of the more
general creation rate mnemonic form if dealing with steady
incompressible fluid flow with a single inlet and single outlet.
- It is strongly recommended that you
identify each of the problems involving Hydraulic/ Mechanical
Conservation of Energy as "Type I" (rating), "TYPE II" (performance),
or "TYPE III" (sizing) BEFORE you try to solve.
- You are encouraged to work together with other students,
but the work you submit cannot be a machine-produced duplication
of another student's work - it must be an original, but can represent
your version of a collaborative effort.
- Late work not accepted!
- A homeowner uses a 30 ft long, 0.5 inch ID siphon tube to drain a waterbed located in a second-floor
bedroom. The siphon tube inlet is 10 feet above its outlet, and it is submerged 8 inches below
the water surface within the (vented) waterbed mattress. The tube is routed through a window whose ledge
is 15 feet above the siphon outlet. DIAGRAM
- What will be the discharge from the siphon, neglecting head losses?
- For this same case (no head losses), what would be the pressure at the point where the tube rests on the window ledge?
- What if the head losses amount to 0.005 * (L/D) * (velocity head in siphon tube),
where L=siphon tube length=30 feet and D=siphon tube ID?
- 7.22 DISCUSSION: qualitatively, how would losses alter the results for the discharge and pressure at point B?
- 7.32 Assume that the pressures given are GAUGE values, and that the water temperature is 80 F and the
local atmospheric pressure is 14.7 psia.
Calculate values for the suction head (inlet pressure head plus velocity head), net positive suction head available ("NPSHA" = inlet suction head less vapor pressure head), and specify a horsepower requirement
for the drive motor assuming 70% pumping efficiency, as well as
the requested value for the horsepower delivered to the flow. omit discussion
- 7.37 assume that the turbine efficiency is 80%; omit discussion
- 7.48 DISCUSSION: would other outlet shapes result in
lower head loss for the same discharge?
- 7.62 omit discussion
- The first stage of a small town's potable water system takes river water and pumps it
through a 5 cm diameter pipe into a holding tank. You are given a "pump curve" for the system's main supply pump:
hp = A - B * Q2, where A = 20 m and B = 5 x 104 s2/m5.
The total head losses in the system are 10 times the pipe velocity head, and the elevation difference between the river
and holding tank surface is 5 m. Determine the operating flow by making a graph showing the intersection point of
the system and pump curves. DIAGRAM You may omit any discussion for this problem.
- 8.1 omit discussion
- 8.5 DISCUSSION: compare your result here to that obtained in homework #1, problem 5.
- 8.6 DISCUSSION: how would the results change if the drag also depended on the fluid density?
- 8.11 omit discussion
