Fluid Mechanics-II 2018 Question Paper — Government College of Engine…
The 2018 Fluid Mechanics-II previous year question paper (Government College of Engineering and Technology, Jammu), with every question and its marks.
- University: Government College of Engineering and Technology, Jammu
- Subject: Fluid Mechanics-II
- Course: Advanced Fluid Mechanics
- Branch: Civil Engineering
- Year: 2018
- Paper: end-term
- Duration: 180 minutes
- Total marks: 100
Instructions
- Attempt five questions in all selecting at least one question from each Section.
- Each question carries 20 marks.
- Assume missing data suitably, if any.
Questions
Section - I
- Q1 a. Derive Hagen Poiseuille equation of motion for laminar flow in circular pipes.. [10 marks]
- Qb. A pipe line 10 cm dia carries Glycerine of specific weight 1.3 and dynamic viscosity 7 poise. If the maximum shear stress at the pipe wall is 20 kg/cm2, calculate (i) the pressure gradient along the flow, (ii) the discharge (iii) Reynolds number and (iv) the velocity and shear stress at a radius of 2.5 cm from the pipe centre. [10 marks]
- Q2 a. What is meant by boundary layer formation ? illustrate with reference to flow over a flat plate. [10 marks]
- Qb. Calculate the friction drag on a plate 15 cm wide and 45 cm long placed longitudinally in a stream of oil of sp. gravity 0.925 and kinematic viscosity 0.9 stokes flowing with a free stream velocity of 6 m/s. find also the thickness of the boundary layer and shear stress at the trailing edge. [10 marks]
Section - II
- Q3 a. Show that for turbulent flow in rough pipes the expression relating point velocity and average velocity is given by $\frac{u-u_{max}}{u_{*}} = 5.75 \log_{10} \frac{y}{R} + 3.75$ [10 marks]
- Qb. Fresh water flows through a 7.5 cm diameter pipe at the rate of $0.037\text{ m}^3\text{/s}$. Observations indicate that loss of head equivalent to 9 m occurs over a length 60 m of the pipe. Presuming that kinematic viscosity for water $\nu = 1.14 \times 10^{-6}\text{ m}^2\text{/s}$, make calculations for (i) friction factor (ii) shear friction velocity (iii) thickness of laminar sub layer. [10 marks]
- Q4 a. Explain the phenomenon of water hammer ? Water main of concrete, 3 km long x 25 cm dia, discharges water into a reservoir at the rate of $10 \times 10^4$ lpd. The pipe line is gradually closed in 20 seconds by operating a valve at the reservoir end. If the test pressure for concrete pain is 30 m, indicate whether there is any risk of pipe burst. [11 marks]
- Qb. Write short notes on : i. Boussniseq's eddy viscosity theory ii. Prandtl mixing length theory iii. Moody diagram [9 marks]
Section - III
- Q5 a. What is a specific energy curve? Explain it with a neat diagram. Further show that the Froude number is unity for critical flow condition. [8 marks]
- Qb. In a rectangular channel of width 20 m and depth of flow 5 m, the rate of flow of water is $50\text{ m}^3\text{/s}$. If the bed slope of the channel is 1 in 4000, find the slope of the free water surface. Take Chezy's constant = 60. [6 marks]
- Qc. Write down the equation for gradually varied flow and state various types of channel slopes and flow profile possible on them. [6 marks]
- Q6 a. The loss of energy head in a hydraulic jump is 4.25 m. the Froude number just before the jump is 7.50. Determine: i. Discharge per metre width of the channel ii. Depths before after the hydraulic jump iii. Percentage loss of energy head due to jump iv. Froude number after the jump v. Length of jump. [10 marks]
- Qb. A rectangular channel 2.40 m wide carries a uniform flow of $7\text{ m}^3\text{/sec}$ at a depth of 1.50 m. if there is a local rise of 0.15 m in the bed level, calculate the change in the water surface elevation What can be the maximum rise in the bed elevation such that the upstream depth is not affected? [10 marks]
Section - IV
- Q7 a. Explain the factors that decide the choice of a particular hydraulic turbine for a hydro power project. [6 marks]
- Qb. A Francis turbine runner is to be designed for the following data: Net head = 50 m, shaft power = 400 kW, speed = 450 rpm, hydraulic efficiency = 85%, overall efficiency = 80 %, flow ratio = 0.15, breadth and dia ratio = 0.1. Assume the inner dia as one half the outer dia. The velocity of flow is constant throughout. The discharge is radial. Neglect vane thickness. [14 marks]
- Q8 a. With the help of neat sketches, explain classification of centrifugal pumps on the basis of their casing. [8 marks]
- QB. Write short notes on: i. Unit power and unit discharge with reference to a hydraulic turbine ii. Specific speed of turbine iii. Working of reciprocating pump [12 marks]