FLUID MECHANICS-I 2022 Question Paper — Government College of Enginee…

Instructions

• Attempt five questions in all, selecting at least two questions from each section.
• Assume missing data suitably, if any.

Questions

Section A

• Q1. (a) Differentiate between : (i) Practical and Ideal fluids (ii) Cohesion and Adhesion (iii) Dynamic viscosity and Kinematic viscosity. (b) A plate $1\text{ sq m}$ in area and weighing $150\text{ N}$ slides down an inclined plane of angle $\theta = \sin^{-1} 5/13$, with a velocity of $0.5\text{ m/s}$. If the thickness of the oil film over the plane is $1.5\text{ mm}$, calculate the dynamic viscosity of the oil. (c) A wooden beam $0.1\text{ m} \times 0.15\text{ m} \times 3\text{ m}$ floats on water. When the beam carries a $30\text{ N}$ load at the right end, it gets tilted by $1.5^\circ$ so that the right end is exactly at the water surface, find the specific weight of wood. [20 marks]
• Q2. (a) State and prove Pascal's law. (b) Derive an expression to find centre of pressure of inclined plane submerged in liquid. (c) An inverted differential manometer is used to measure the pressure difference between two horizontal pipes carrying water. Pipe A is at a higher level compared to pipe B. The manometric fluid is oil of sp.gr. $0.8$. The common level is at $35\text{ cm}$ above pipe A and $65\text{ cm}$ above pipe B. The $65\text{ cm}$ is made of $h\text{ m}$ of oil and the remaining water. The difference in pressure between B and A is $2354.4\text{ N/m}^2$. Determine the value of $h$. [20 marks]
• Q3. (a) State and prove Euler's equation of motion. Obtain Bernoulli's equation from Euler's equation. (b) A horizontal venturimeter is provided in a $250\text{ mm}$ diameter pipe line conveying water. The throat diameter of the venturimeter is $25\text{ mm}$. If the pressure in the pipe is $147.15\text{ kPa}$ and the vacuum pressure at the throat is $280\text{ mm}$ of mercury, calculate the rate of flow in the pipe. Assume $Cd = 0.98$. (c) A pitot static tube is mounted on an aircraft travelling at a speed $300\text{ kmph}$ against a wind velocity of $20\text{ kmph}$. If the specific weight of air is $12\text{ N/m}^3$, determine the pressure difference the instrument will register. Take $Cv = 0.98$. [20 marks]
• Q4. (a) The $x$ and $y$ components of velocity in a 2-D flow fields are : $u = y^3/3 + 2x - x^2y$ and $v = xy^2 - 2y - x^3/3$. Show that the flow is steady and irrotational. Also determine expressions for $\phi$ and $\psi$. (b) Derive the expression to calculate the discharge through an external mouthpiece. Further show that the pressure of the Vena contracta is less than the atmospheric. [20 marks]

Section B

• Q5. (a) Derive and explain the significance of : (i) Froude's number (ii) Mach number (iii) Reynolds number. (b) A pipe of diameter $1.8\text{ m}$ is required to transport an oil of sp. gr. $0.8$ and viscosity $0.04\text{ Poise}$ at a rate of $4\text{ m}^3\text{/s}$. Tests were conducted on a $20\text{ cm}$ dia. pipe using water at $20^\circ\text{C}$. Find the velocity and rate of flow in the model. Take viscosity of water at $20^\circ\text{C}$ as $0.01\text{ Poise}$. [20 marks]
• Q6. (a) Show that the efficiency of a free jet striking normally on a series of flat plates mounted on the periphery of a wheel never exceeds $50\%$. (b) A jet of water moving at $25\text{ m/s}$ impinges on a symmetrical vane shaped to deflect the jet through an angle of $120^\circ$ when the vane is stationary. If the vane is moving at $10\text{ m/s}$, find the angle of the jet so that there is no shock at inlet. Also determine the absolute velocity at exit. Neglect friction of vanes. [20 marks]
• Q7. (a) Derive an expression from the fundamentals for the loss of head due to Friction in a pipe line. Why this loss is called Major loss ? (b) A straight $25\text{ cm}$ diameter pipeline $5\text{ km}$ long is laid between two reservoirs having a difference in level of $40\text{ m}$. To increase the capacity of the system an additional $2.5\text{ km}$ long $25\text{ cm}$ pipe is laid parallel from the first reservoir to the midpoint of the original pipe. Assuming $f = 0.025$ for both the pipes find the increase in discharge due to installation of the new pipe. [20 marks]
• Q8. (a) When a sudden contraction is introduced in a horizontal pipeline from $50\text{ cm}$ dia to $25\text{ cm}$ dia, the pressure changes from $105\text{ kPa}$ to $69\text{ kPa}$. If coefficient of contraction is assumed to be $0.65$, calculate the water flow rate. The contraction is subsequently followed by a sudden enlargement from $25\text{ cm}$ dia to $50\text{ cm}$ dia. If the pressure at the $25\text{ cm}$ section is $69\text{ kPa}$, work out the pressure at the $50\text{ cm}$ enlarged section. Take specific weight of water as $10\text{ kN/m}^3$. (b) Write a note on Distorted models and their uses. (c) Obtain an expression for resistance ratio for a model satisfying Froude's law. [20 marks]

Related pages

• FLUID MECHANICS-I syllabus
• All FLUID MECHANICS-I papers from 2022

Other years

• FLUID MECHANICS-I 2022 question paper — end-term