Assignment Task

Question

1. Sketch and define boundary layer for fluid flow over a plane surface. What will be the characteristic length (name it) to be taken in the critical Reynolds number (Re _crit = 10 ⁵ ) equation in boundary layer
2. Sketch qualitatively and label the EGL and HGL and their components for the following two systems. Note: T = turbine.

• A fluid ( μ = 0.01 N.s/m ² , ρ = 800 kg/m ³ ) flows with a mean velocity of 4 cm/s in a 10 cm smooth pipe. (a) What is the value of Reynolds number? (b) What is the magnitude of the maximum velocity in the pipe? (c) What is the magnitude of the friction factor f What is the shear stress at the wall?
• What is the kinetic-energy correction factor? Why we use this term? Indicate the typical values for different flows

Question

1. The pipe diameter D is 30 cm and atmospheric pressure is 99 kPa. What diameter of constriction is expected ( d = ?) to produce incipient cavitation at the throat of the constriction if H = 11 m? Assuming all the frictional head losses equal to 3( V ² /2 g ).

1. When you were plotting your System Curve on to the manufacturers supplied Pump Curve, you found that the System Operating Point (SOP) was not providing adequate discharge. So what options you have to achieve the required discharge. 
2. In open channel flow, what is called best hydraulic section for uniform flows?
3. A bridge is planned on a 100 m wide rectangular channel carrying a flow of 240 m ³ /s at a flow depth of 2.35 m. For reducing the length of the bridge, what is the minimum channel width such that the up-stream water level is not influenced for this discharge?

Question

1. A circular sewer line is to be constructed of concrete pipe to be laid on a slope of 005. If Manning’s n = 0.025 and if the design discharge is 2.3 m ³ /s, what size pipe should be selected for a half-full flow condition? What will be the mean velocity in the sewer pipe for this condition? 
2. What assumptions need to be satisfied to apply the Darcy-Weisbach equation?
3. Water is held back by this radial gate. Where does the resultant of the pressure forces acting on the gate? Show the direction of the resultant force.

1. Explain why and where negative pressure may occur in a pipeline and pump system. Illustrate your answer using a sketch.
2. Water (specific weight = 9810 N/m³ and dynamic viscosity = 1.31×10^-3 N.s/m² at 10˚C) is pumped from a reservoir (A) to a large, pressurized tank (B) as shown. The steel pipe is 10 cm in diameter and 100 m long. The discharge is 0.03 m³/s. The initial water levels in the tanks are the same, but the pressure in tank B is 260 kPa and tank A is open to the atmosphere. The pump efficiency is 90%. Find the power necessary to operate the pump for the given conditions. Assume the entrance to the pipe is not that smooth (K_e = 0.5) and α = 1.0 at all locations.