Apr 11, 20202 min
Updated: Apr 21, 2020
181.The condition for complete similarity to exist between model and prototype, where both gravity and viscous forces are important, is
where μᵣ is kinematic viscosity ratio and Lᵣ is length scale ratio
182. A ship's model of scale 1 : 100 had a wave resistance of 1 kg at its design
speed. The corresponding wave resistance in prototype will be
1000000 kg
183. In which of the following situations, the inertia force would be unimportant ?
flow through a long capillary tube
184. For the resistance to motion of a ship's model through water, the basic similitude criteria is Reynolds Law,Froude's Law
185. The causes of cavitation are high suction lift and high pump speed
186. The cavitation parameter is given by
where p is the absolute pressure of the point of consideration, pₐ is atmosphere
pressure, pᵥ is vapour pressure of liquid, ρ is the density of the liquid and V is the
velocity.
187. An impulse turbine operates by initial complete conversion to kinetic energy
188. Water turbines may be put in the decreasing order of specific speeds as
propeller turbine, reaction turbine, impulse turbine
189. At a rated capacity of 44 cumecs, a centrifugal pump develops 36 m of head
when operating at 1450 rpm. Its specific speed is 654
190. A Francis turbine under a head of 25 m produces 2000 KW at a speed of 250 rpm. Its specific speed is 200
191. Two geometrically similar units are homologous if they have similar streamlines
192. A reaction type turbine discharges 10 cumecs under a head of 8 m and with an overall efficiency of 85 percent. The power developed is 667 kW
193 ) An impulse turbine is ideal for high head development.
ii) Speed ratio of a reaction turbine is in the range of 0.6 to 0.9
194.i) A reciprocating pump does not need priming,
ii) A centrifugal pump can run at high speed
195. Pumps may be put in the increasing order of specific speeds as centrifugal pumps, mixed flow pumps, axial flow pumps
196. The specific speed of a turbine is defined as the speed of a unit of such a size that it produces unit power for unit head
197. Water enters a turbine steadily at the rate of 100 litres per second with a pressure of 3 x lO⁵ N/m² and a velocity of 100 m/s. It leaves the turbine with a pressure of 10⁵ N/m² and a velocity of 50 m/sec. If no losses occur, the power produced by the 395 KW
198. An isentropic process is always frictionless and adiabatic
199. Which of the following equations are used momentum and continuity
200. critical pressure ratio 0.528
critical temperature ratio 0.833
critical density 0.634