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Birla Institute of Technology and Science, Pilani - KK Birla Goa Campus SECOND SEMESTER 2014-2015

ME F341/ME C332 Prime Movers and Fluid Machines Test I Answer key

______________________________________________________________________________ Q1. The model of a turbine runs at 1200 rpm and produces 6kW under a head of 6 m

while utilizing a discharge of 0.12 m3/s. The prototype has to work at 300 rpm under a head of 60 m and will be able to have a discharge of 60m3/s. Estimate the diameter ratio of the prototype to the model, the efficiency and power output that may be expected from the prototype. Also determine the specific speed and identify the type of the turbine. Assume the efficiency of the prototype and the model are related by Moody’s formula under 150 m head which is provided below. [15] 

1/51 (1 )( / )p m m pD Dη η= − −

Also

Efficiency of model and prototype

2

Power estimation

 

Q2. Derive the Euler’s equation for Turbomachines in various forms.    [15]             Refer text book  

Q3. A Pelton wheel has a mean diameter of 1.25 m and runs at a synchronous speed of

1000 rpm while operating under a net head of 850m. If the bucket deflection angle is 165o and the discharge is 0.125m3/s, find the actual output of the machine and the hydraulic efficiency. Assume the value of blade friction coefficient as 0.9, the jet velocity coefficient as 0.98, and volumetric efficiency as 100 percent and mechanical efficiency as 95 percent. Also determine the specific speed of the turbine. [15]