VIEWS: 21 PAGES: 17 POSTED ON: 5/16/2011
G.H.RAISONI COLLEGE OF ENGINEERING DEPARTMENT OF MECHANICAL ENGINEERING QUESTION BANK III - SEMESTER SUBJECT: FLUID POWER-I UNIT-I Q. 1. Define the following fluid properties : Density, weight density, specific volume and specific gravity of a fluid. Q. 2. What is the difference between dynamic viscosity and kinematics viscosity ? Stats their unit of measurements. Q. 3. State the Newton’s law of viscosity and give examples of its application. Q. 4. Define Newtonian and Non-Newtonian fluids. Q.5. Explain the following terms briefly. 1) surface tension ii) compressibility iii) capillarity iv) weight density v) specific volume vi) viscosity vii) specific gravity Q.6. what is dimensional analysis and its homogeneity? Q.7. Two plates are placed at a distance of 0.15 mm apart. The lower plate is fixed while the upper plate having surface area 1.0 m2 is pulled at 0.3 m/s. Find the force and power required to maintain this speed, if the fluid separating them is having viscosity 1.5 poise. Q.8. Determine the specific gravity of a fluid having viscosity 0.07 poise and kinematics viscosity 0.042 stokes. Q.9. The Resisting Force R of a supersonic plane during flight can be considered as dependent upon the length of the aircraft 1, velocity v, air viscosity μ, air density ρ and the bunk modulus of air K. Express the functional relationship between these variables and the resisting force. Q.10. The drag force F exerted on a body immersed in fluid is a function of the following: - Fluid density ρ, Fluid viscosity μ, Diameter d and velocity u. Show that this force can be expressed as F = d2. u2 . ρ .Ø(Re) where Ø is some unknown function and re is the Reynold number. Q.11. Determine the pressure in N/m2 if the equivalent head is measured as 40 mm of (i) Mercury (specific gravity = 13.6) (ii) Water (iii) Oil of specific weight 7.9 kN/m3. Q.12. A 15 cm diameter vertical cylinder rotates concentrically inside another cylinder of diameter 15.10 cm, both cylinder are 30 cm high. The space between the cylinder is filled with a liquid, whose viscosity is unknown. If a torque of N-m is required to rotate the inner cylinder at 100 rpm, determine the viscosity of the liquid. Q.13 The resistance R experienced by a partially submersed body depends upon the velocity v, length of the body l , viscosity of the fluid μ, density of the fluid ρ and gravitation acceleration g. Obtain a dimensionless expression for : Lvρ v R = l2 v2 ρ Ø , μ √ lg Q.14. State and prove the Pascal’s law. Q. 15. What do you understand by Hydrostatic Law ? Q. 16. Differentiate between (i) Absolute and gauge pressure, (ii) Simple manometer and differential manometer, and (iii) piezometer and pressure gauges. Q. 17. What is the difference between U-tube differential manometers and inverted U- tube differential manometer ? Where are they used? Q. 18 A hydraulic press has a ram of 30 cm diameter and a plunger of 5 cm diameter. Find the weight lifted by the hydraulic press when the force applied at the plunger is 400 N. Q. 19 An open tank contains water Upto a depth of 1.5 m and above it an oil of sp. gr. 0.8 for a depth of 2 m. Find the pressure intensity : (i) at the interface of the two liquids, and (ii) at the bottom of the tank. UNIT-II Q.20 What do you understand by ‘Total Pressure’ and ‘Centre of Pressure’ ? Q.21 A rectangular sluice gate is situated on the vertical wall of a lock. The vertical side of the sluice is 6 m in length and depth of centroid of area is 8 m below the water surface. Prove that the depth of centre of pressure is given by 8.475 m. Q. 22 Determine the total pressure and centre of pressure on an isosceles triangular plate of base 5 m and altitude 5 m when the plate is immersed vertically is an oil of sp. gr. 0.8. The base of the plate is 1 m below the free surface of water. Q.23 A circular plate 3 m diameter is immersed in water in such a way that the plane of the plate makes an angle of 60o with the free surface of water. Determine the total pressure and position of center of pressure when the upper edge of the plate is 2 m below the free water surface. Q.24 A wooden block in the form of a rectangular prism floats with its shortest axis vertical. The block is 40 cm long, 20 cm wide and 15 cm deep with a depth of immersion of 12 cm. calculate the position of the met centre and comment on the stability of the block. Q.25 A solid cylinder of diameter 4.0 m has a height of 4 m. Find the meta centric height of the cylinder if s.g. of the material of the cylinder is equal to 0.6 and if it floating in water with its axis vertical. State whether the equilibrium is stable or unstable. Q.26 A square plate of 3 m side is immersed in a liquid of specific gravity 1.2 in such a way that its greatest and least depth below the free surface are 3.5 m and 1.5 m respectively. Determine the total pressure on the one face of the plate and position of the centre of pressure. Q.27 Write short note on Stability of floating bodies and submerged body. Q.28 A closed rectangular tank full of water is 1.5 m wide, 3 m long and 2 m deep. The pressure at the top of water is raises to 98.1 KPa. If now the tank is accelerated horizontally along its length at 6 m/s2, find the force on the front and the rear end of the tank. Q.29 A rectangular timber block 3 m long, 2 m wide and 1.5 m deep is immersed in water. If the specific gravity of the timber is 0.65, determine its stability. Q.30 A circular plate 2.5m diameter is immersed in water, it’s greatest and least depth below the free surface being 3m and 1m respectively. Find i) Total pressure ii) position of centre of pressure UNIT-III Q.31 Explain the briefly- i)Path lines ii) Stream function iii)Velocity potential function Q.32 Write short notes on - i) Laminar and Turbulent flow ii) Flow net and Equipotential line Q.33 Derive Bernoulli’s equation from Euler’s equation Q.34 What are velocity potential and stream functions ? Also explain line of constant steam function. Q.35 Explain the following terms :- (i) Path Line (ii) Streak Line (iii) Stream Line (iv) Stream Tube Q.36 Derive Euler’s equation of motion Q.37 Explain briefly the following heads : (i) Potential head (ii) Velocity heat (iii) Datum head Q.38 List the assumption which are made while deriving Bernoulli’s of equation. Q.39 Derive an expression for the depth of parabo-loid format by the surface of a liquid contained in a cylindrical tank which is rotated at a constant angular velocity ω about it’s vertical axis. Q.40 A flow is described by the stream function Ψ = 2√3xy. Locate the point at which the velocity vector has a magnitude of 4 units and makes an angle of 150o with the X – axis. Q.41 Determine the components of rotation about the various axes given u = xy3 z, v = -y2z2, w = yz2 – y3 z2 2 (ii) Verify whether the following functions are valid potential functions : (a) ψ = m/nx (b) ψ = A cos x Q.42 Does velocity field given by U=5x3i-15x2y j +tk represent fluid motion of an incompressible fluid. If so evaluate the velocity &acceleration at a point of interest (1,2,3) and t=1. Q.43 In a fluid flow, the velocity components are given by u = 3x + 2y and v = 2x – 3y. (i) State if the flow is possible (ii) If possible, then check whether it is rotational or irrotationl. (iii) In flow is rotational, find stream function. (iv) If flow is irrotational find velocity potential function Q.44 A pipe line carrying oil s. g. 0.87 changes diameter from 200 mm at a position a to 500 mm at a position B which is 4 meters at a higher lever. If the pressures at A and B are 9.81 N/cm2 and 5.886 N/cm2 respectively and the discharge is 200 liters/sec, determine the loss of heat and direction of flow. Q.45 A conical tube of length 3 m is fixed vertically with its smaller end upwards. The velocity of flow at the smaller end is 4m/s while at the lower end is it is 2 m/s. The pressure heat at the smaller end is 2 m of liquid. The loss of the heat in the tube is 0.95 (V1 – V2)2 , 2g Where V1 is the velocity at the smaller end V2 at the lower end respectively. Determine the pressure head at the lower end. Flow takes place in downward direction. Q.46 If for a two dimensional potential flow, the velocity potential is given by, Ө = x (2y-1) Determine the velocity at the point P (4, 5). Determine also the value of the stream function Ψ at the point P. UNIT-IV Q.47 What is a pitot tube? How is it used to measure velocity of flow at any point in a pipe or channel? Q.48 Find an expression for the discharge over a triangular notch or weir in terms of head of water over the crest of the notch or weir. Q.49 Derive an expression for the discharge over a rectangular notch or weir in terms of head of water over the crest of the notch or weir. Q.50 An inclined Venturimeter with an entrance diameter of 0.3 m and throat diameter of 0.2 m is used to measure a volume of gas flowing through the pipe. The coefficient of discharge is 0.92. Assuming specific weight of the gas to be constant at 19.62 N/m3, calculate the volume the entrance and the throat is difference as 0.06 m on the water U- tube manometer. Q.51 A tank of the length 5 m and width 3 m has a 90o V-notch. The initial height of water above the apex of the notch is 40 cm. Determine the height of the water above apex if the time required to lower the head in the tank from 40 cm to final height is 2.5 minutes. Take Cd = 0.6. Q.52 A circular tank of diameter 5 m contains water up to a height of 7 m. The tank is provided with an orifice of diameter 0.6 m at the bottom. Find the time taken by water : (i) to fall from 5 m to 2 m and (ii) for completely emptying the tank Assume coefficient of discharge = 0.6 Q.53 The water is flowing a pipe of diameter 30 cm. The pipe is inclined and a Venturimeter is inserted in the pipe. The diameter of the Venturimeter at throat is 15 cm. The difference of pressure between the inlet and throat of the Venturimeter is measured by a liquid of sp. Gravity 0.8 in U-Tube differential which gives a reading of 40 cm. The loss of heat between the inlet and throat is 0.3 times the kinetic heat of the pipe. Find the discharge. Q.54 Find the discharge through a trapezoidal notch which is 1.2 m wide at the top and 0.5 m at the bottom and is 40 cm in height. The head of water on the notch is 30 cm. Assume Cd for rectangular portion as 0.62 while for triangular portion = 0.60. Q.55 A rectangular orifice, 1 m wide and 1.5 m deep is discharging water from a vessel. The top edge of the orifice is 0.8 m below the water surface in the vessel. Calculate the discharge through the orifice if Cd = 0.6. Also calculate the % age error if the orifice is treated as the small orifice. Q.56 A right angled V – notch is used for measuring a discharge of 30 lit/s. An error of 2 mm was made in measuring the head of the notch. Calculate the % age error in the discharge. Take C = 0.62. Q.57 Explain the principle of Venturimeter with neat sketch. Derive an expression for the rate of flow of fluid through it. Q.58 In order to determine the coefficient of velocity of a small circular sharp edge orifice, the horizontal and vertical coordinates of a point on the centre line of the jet were found to be 400 mm and 16.7 mm respectively with respect to the centre of the jet at vena contracta. The head of the orifice is 2.5 m. Calculate the coefficient of velocity. Q.59 Find the depth and top width of a triangular notch to discharge a maximum quantity of 0.60 cumec and such that the head shall be 65 mm when the discharge is 0.004 cumec. Take Cd = 0.62. Q.60 A 300 mm X 150 mm Venturimeter is provided in a vertical pipe line carrying oil of specific gravity 0.9, the flow being upwards. The difference in elevation of the throat section and the entrance section of the Venturimeter is mm. The differential U-tube mercury manometer shows a gauge deflection of 250 mm. Calculate , (i) The discharge of the oil. (ii) The pressure difference between the entrance section and the throat section. Take the coefficient of the meter as 0.98 and the specific gravity of mercury as 13.6. Q.61 A swimming pool 12m long 7m wide holds water to a depth of 2m. If the water is discharged through an opening of area 0.2 m2 at the bottom of the pool. Find time required to empty the tank. Take cd = 0.6. Q.62 What is the function of vane anemometer? Explain with neat sketc Q.63 Write applications of Rota meters and Turbine meters. UNIT-V Q.64 Define the following terms :- (i) Energy thickness (ii) Displacement thickness (iii) Boundary layer thickness. Q.65 Show that the value of coefficient of friction for viscous flow through a circular pipe is given by 16 f= . Re Where Re = Reynolds number. Q.66 Define the following terms :- (i) Kinetic Energy Correction Factor (ii) Momentum Correction Faction. Q.67 Define the following terms :- (i) Momentum thickness (ii) Drag (iii) Lift. Q.68 The velocity distribution in the boundary layer is given by 1/7 u y = U б Calculate the following : (i) Displacement thickness (ii) Momentum thickness (iii) Shape factor (iv) Energy thickness. Q.69 A pipe 60 mm diameter and 450 m long slopes upwards at 1 in 50. An oil of viscosity 0.9 N-s/m2 and specific gravity 0.9 is required to be pumped at the rate of 5 lit/s. (i) Is the flow laminar? (ii) What Pressure difference is required to attain this condition ? (iii) What is the power of pump required assuming an overall efficiency of 65% ? (iv) What is the center-line velocity and gradient at pipe wall ? Q.70 The velocity profile for a laminar boundary Layer is given by : 2 u 4 y 1 y = - U 3 б 3 б . Determine the boundary layer thickness, shear stress, drag force and coefficient of drag in terms of Reynold number. Q.71 Determine the wall shearing stress in a pipe of diameter 120 mm which carries water. The velocities of the pipe centre and 40 mm from pipe centre are 2.5 m/s and 2 m/s respectively. The flow in pipe is turbulent. Q.72 Explain Streamlined and bluff bodies. Q.73 Laminar flow of fluid of viscosity 0.9 Pa-S and density 1260 kg/m3 occurs between a pair of parallel plates of extensive width, inclined at 45o to horizontal plates being 10 mm apart. The upper plate moves with a velocity of 1.5 m/s relative to lower plate and in direction opposite to the fluid flow, Pressure gauges, mounted at two point 1 m vertically apart on the upper plate record pressures of 250 KPa and 80 Kpa respectively (Refer figure). Determine (i) Velocity distribution between the plates [velocity profile – u = f(y)]. (ii) Shear stress distribution between the plates. (iii) Maximum flow velocity. (iv) Shear stress on upper plate. UNIT-VI Q.74 1 Differentiate between a laminar flow and a turbulent flow. Q.75 Define the terms : Major energy losses and minor energy losses in pipe. Q.76 Derive Darcy’s Weisbach formula for calculating loss of head due to friction in a pipe. Q.77 Derive Chezy’s formulae for loss of head due to friction in a pipe. Q.78 Derive formulae for calculating loss of head due to (i) Sudden enlargement, and (ii) Sudden contraction. Q.79 Explain briefly the following : (i) Hydraulic gradient line (H.G.L.) (ii) Energy gradient line (E.G.L.) Q.80 Derive an expression for the power transmission through the pipes. Find also the condition for maximum transmission of power and corresponding efficiency of transmission. Q.81 Find an expression for the ratio of the outlet area of the nozzle to the area of pipe for maximum transmission of power. Q.82 What is meant by water hammer ? Derive an expression for the rise of pressure when the flowing water in a pipe is brought to rest by closing the valve gradually. Q.83 Show that the diameter of the nozzle for maximum transmission of power is given by ¼ D5 d= 8 fL where, D = Diameter of the pipe L = Length of the pipe, and f = Friction co-efficient. Q.84 Two reservoirs whose surface levels differ by 30 m are connected by a pipe 600 mm diameter and diameter and 3000 m long. The pipe line crosses a ridge whose summit is 9 m above the lever of and 300 m distant from the higher reservoir. Find the minimum depth below the ridge at which the pipe must be laid if the absolute pressure head in the pipe is not fall below 2.5 m of water, and calculate the discharge. Take atmospheric pressure head = 10.3 m of water and f = 0.0075. Q.85 A horizontal pipe line, 40 m long is connected to a water tank at one end discharges freely into the atmosphere at the other end. For the first 25 m of its length from the tank, the pipe is 150 mm diameter and its diameter is suddenly enlarged to 300 mm. The height of water level in the tank is 8 m above the centre of the pipe. Considering all losses of head which occur, determine the rate of flow. Take f = 0.01. Q.86 The two tanks are connected by three pipes in series of length 400 m, 200 m and 300 m and of diameters 350 mm, 250 mm and 400 mm respectively. The coefficient of friction are 0.0052, 0.005 and 0.0051 respectively. Determine the rate of flow considering : (i) minor losses and (ii) neglecting minor losses if the difference of water surface levels in two tanks is 15 m. Q.87 In a pipe of diameter 350 mm and length 75 m water is flowing at a velocity of 2.8 m/s. Find the head lost due to friction using Darcy-Weisbach formula. Assume kinematics viscosity of water as 0.012 stroke and frication factor is give 0.0791 f= (Re)1/4 Q.88 In a pipe of diameter 450 mm and length 95 m water is flowing at a velocity of 4.8 m/s. Find the head lost due to friction using Darcy-Weisbach formula. Assume kinematics viscosity of water as 0.021 stroke and frication factor is give 0.0791 f= (Re)1/4 Q.89 Water flow through a pipeline whose diameter varies from 250 mm to 150 mm in a length of 10 m. If the Darcy- Weibach friction factor is assumed constant at 0.018 for the whole pipe, determine the head loss in friction when the pipe is flowing full with a discharge of 0.06m3/s. Q.90 A pipeline of 600 mm diameter is 1.5 km long. To increase the discharge another line of the same diameter is introduced parallel to the first in the second-half of the length. If F = 0.01 and head at inlet is 300 mm, calculate the increase in discharge. Q.91 A 2500 m long pipeline is used for transmission of power. 120 kW power is to be transmitted through the pipe in which water having a pressure of 4000 kN/m2 at inlet is flowing. If the pressure drop over the length of pipe is 800kN/m2 and F = 0.006, find (i) Determine of the pipe (ii) Efficiency of transmission. Q.92. A pipe of diameter 30 cm and length 3.5 km is used for transmission of power by water. The total head at the inlet of the pipe is 500 m. Find the maximum power available at the outlet of the pipe if f = 0.024.