518/3(N) March 2023 FLUID MECHANICS AND MACHINERY Time Allowed: 2.5 Hours Ful Marks: 60 ‘Answer to Question No. 1 of Group A Is compulsory and to be answered first. This answer is to be made In separate loose script(s) provided for the purpose. Maximum time allowed is 30 minutes, after which the loose ywer scripts will be collected and fresh answer scripts for answering the remaining part of the question will be provided, On early submission of answer scripts of Question No. 1, a student will get the remalning script earlier. Answer any Five (05) Questions from Group B. GROUP. 1 Answer the following questions (any twenty): 1*20=20 i) An ideal fuid is defined as the fluid which a) is compressible ») is incompressible ¢) is incompressible & non viscosity 4) has negligible surface tension ii) Stoke the unit of a) Surface tension _b) Dynamic viscosity) kinematic viscosity) none of the above iii) Fluid statics deals with a) Viscous and pressure forces b) Viscous and gravity forces gy gravity and pressure forces 4) none of these iv) ‘Surface tension has the units of “wk, Force per unit area f Force per unit length b)' Force per unit volume —_d) none of the above ¥) Atmospheric pressure head in terms of water column is Z a) 7.5m b) 8.5m ¢)9.81m ) 10.30m_ vi) Kinematic viscosity is defined as equal to aX’ Dynamic viscosity x densityb) Dynamic viscosity/density ¢) Dynamic viscosity * pressure A)pressure * density vii) When the fluid is at rest, the shear stress is a) maximum byzero ©) unpredictable 4) none of these viii) Reynolds number is defined as the 3. of inertia force to gravity force b) Ratio of viscous force to gravity force tio of viscous force to electric force 4) Ratio of inertia force to viscous force ix) Continuity equation can be in the form of a) A\Vi)=A:V2 — b)prAr = p2Ar PPA, = prAaVe 4) none of these x) Bemoulli’s theorem deals with the law of conservation of a) mass) momentum wyenergy _d) none of these xi) Pitot tube is used for measurement of a) pressure b) flow ¢) velocity at a point 4) discharge xii) The flow rate through a circular pipe is measured by a) pitot-tube b) venture-meter __c) orifice-meter d) none of the above xiii) ‘The term Z is known as ay potential energy b) pressure energy ¢) kinetic energy per unit weight 4) none of the above xiv) — Venture-meter is used to measure a) discharge b) average velocity _p}velocity at a point) pressure at a pointOo & ~) xvi) xvii) xviii) xix) xx) xxii) xxiii) xxv) The co-efficient of discharge (Cd) in terms of C,and C. is a) Cem CMCed)Ca= CIC, FCy=Cy x Ce 4) none of these ‘The range for co-efficient of discharge (Cd) for a venture-meter is 8) 0,60 100.7 b)0.7t008 )0.8t009 4) 0.95 100.99 The rate of flow through a venture meter varies as a) H b)VA co) H9/? dy H5/? Orifice are used to measure a) velocity b) pressure) viscosity df rate of flow The flow in open channel is turbulent if the Reynolds number is a) 2000 6) more than 2000) more than 4000 d) 40000 In Darcy Weisback formula f=16/Re a) Re<2000 —_) Re varying from 4000 to 10° gf fie=2000 t0 4000) Re>10* Chezy's formula is given as a) Veivme b)V = CVmi c)V = mvCi_ d) None of these The hydraulic mean depth is given by a) P/A b) PYA °) AP 4) fAyP ‘The discharge through a single a single acting reciprocating pump is LN d)Q=2ALN a) Q=ALN/60 6) Q=2ALN/60 )Q= A pump is defined as a device which converts 8) hydraulic energy into mechanical energy _b) mechanical energy into hydraulic energy c)Kinetic energy into mechanical energy _) electrical energy into mechanical energy In general the vanes of a centrifugal pump are a) curved forward b) curved backward ¢) radial ©) twisted GROUP-B {)State the Newton’s law of viscosity and write down its mathematical expression. Q@rwo large plane surface arg 1Smun apart and the gap Batains a liquid of viscosity 0.8 Pa S. within the gap a thin plate of cross-section ‘Smm from one surface: Determine the force required for pulling the plate. 0.5m? is to be pulled at a velocity of 0.5m/s at a distance of = 348 {)Define; atmospheric pressure, gauge pressure, vacuum pressure and absolute pressure tmospoene press: press ii)A differential manometer is connected at the two poiits A and B of two pipes 8s shown in Fig. 1. The pipe A contains a liquid of sp. gr. = 1.5 while pipe B contains a liquid of sp. gr. = 0.9. The pressure at A and B are 1 kgf/cm” and 1.80 kgficm’ respectively. Find the difference in mercury level in the differential manometer. https://www-wbscteonine.com 464 Sp. gr= 1.5 Paso kegt font Fig.4. Q arsiae the Bemouth @ ©. 8 i) Define the fluid properties: Density, weight density, specific volume and specific gravity. ii) Determine the total pressure on a circular plate of diameter 1.5 m which is placed vertically in water in such a way that the centre of the plate is 3 m below the free surface of water. Find the position of centre of pressure also. “4 theory. Write down its mathematical expression ii)An oil of sp. gr. 0.8 is flowing through a venturimeter having inlet diameter 20 cm and throat diameter 10 cm, The oil-mercury differential manometer shows a reading of 25 cm. Caleulate the discharge of oil through the horizontal venturimeter. Take Cd = .98. aS _D White the exsumption of Bemoul's equation ii) An orifice meter with orifice diameter 10 cm is inserted in a pipe of 20 cm diameter.The pressure gauge fitted upstream and downstream of the orifice meter given reading of 19.62 N/cm* and 9.81 Nicm* respectively. Co-efficient of discharge for the meter is given as 0.6. Find the discharge of water through pipe. > 345 i) What do you mean vytézahicd) 2 ii) Write down the expressions for minor energy losses in pipe. 246 i) Show that maximum efficiency of a jet of liquid on a series of flat plates fixed on the periphery of a wheel is 50%. ii) Water is flowing through a pipe at the end of which a nozzle is fitted. The diameter of the nozzle is 100 mm and the head of water at the center of nozzle is 100 m. Find the force exerted by the jet of water ona fixed vertical plate, The co-efficient of velocity is given as 0.95. a4 _peWat is priming? Why itis necessary? @ ii)A centrifugal pump is to discharge 0.118 m’/s at a speed of 1450rpm against a head of 25m. The impeller diameter is 250mm, its width at outlet is SOmm and manometric efficiency is 75%. Determine the vane angle at outer periphery of the impeller. 345 i) Differentiate between centrifugal pump and reciprocating pump. ii) A single acting reciprocating pump, running at SOrpm delivers 0.00736m’/s of water. The diameter of the piston is 200mm and stroke 300mm.The suction and delivery heads are 3.5m and 11.5m respectively. Determine theoretical discharge, coefficient of discharge, % slip and power required to run the pump. 2+6