Sardar Vallabhbhai National Institute of Technology 2012 M.Tech. Turbo machines Hydro Turbo Machines - Question Paper
Hydro Turbo Machines
Sardar vallabhbhai national institute of TECHNOLOGY, SURAT
Mechanical engineering department M. Tech. (Turbo machines) Semester - II (YEAR: MARCH-2012) End semester Examination
Sub: Hydro Turbo machines
Time: 2 hr.
Marks: 50
Instructions:
(1) Attempt all questions
(2) Figure to the right indicate full marks
(3) Use of turbo machines data book and calculator is permitted
(4) Make suitable assumptions if required
Q-l Attempt any two
(a) Explain the dimensional and nondimesional performance characteristics of pelton wheel (5)
(b) Prove that for given values of <j),and Kthe optimal bucket outlet angle is given by: (8)
and ks=4.216 * C v5/2 * <J>3/2* m'1 * nj1/2
Q-2 A radial flow turbine with a degree of reaction as 0.5 works under a head of 90 m.It is to be sized () to develop a power of 75 MW with a targeted efficiency of 92% and non dimensional specific speed of 0.7.Determine the basic dimensions including vane angles of this machine. Make suitable assumptions if required.
An axial flow hydraulic turbine has a net head of 23m across it and when running at a speed of 150 () rpm, develops 23 MW.The blade tip and hub diameters are 4.75 m and 2.0 m, respectively. If the hydraulic efficiency of this machine is 93% and the overall efficiency is 85%, calculate the vane angles at the tip and hub. Comment on the data and the results.
Q-4
(A) Attempt any two 6)
(a) Explain the significance of dimensionless parameters which are based in centrifugal pumps.
(b) Explain ,with neat sketches .characteristics of centrifugal pumps of (i) low specific speed (ii) medium specific speed and (iii) high specific speed
(c)
(i) Efficiency of a hydrodynamic pump is generally lower than that of a hydraulic turbine. Comment upon the truth of this statement
(ii) In the light of circulatory flow, friction losses, shock losses and other hydraulic losses discuss the probable head discharge characteristics of a centrifugal pump.
() A centrifugal pump, in which water enters radially,delivers the water at the head of 165 m.The impeller has a diameter of 360 mm and width 180 mm at inlet and the corresponding dimensions at the outlet are 720 mm and 90 mm respectively. Its rotational speed is 1200 r.p.m.The blade angle measured from the radial flow direction is 60at exit and the discharge is 0.389 m1/s.Determine
(iv) Pressure rise across the impeller assuming losses equal to 12 percent of velocity head at exit.
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| Earning: Approval pending. |
