Gujarat Technological University 2010-5th Sem B.Tech Aeronautical Engineering - in - EMBER,Fundamentals of Turbo Machines - Question Paper
The 5th semester of the Gujarat Technological University in the stream of Aeronautical Engineering has 7 subjects. The paper trend are all the identical and 1 has the subsequent subjects Composite Materials and Smart Structures, Flight Mechanics, Fundamentals of Turbo M/cs, Management-II, Aircraft Structure-II, Computational Fluid Dynamics-1 and Operation & Maintenance of Aircraft. The paper has five ques. of 14 marks each, making the total marks of the paper 70. The ques. paper is to be answered within three hours.
beneath are attached Fundamentals of Turbo M/cs ques. paper.
Seat No. Enrolment No.
GUJARAT TECHNOLOGICAL UNIVERSITY
B.E. Sem-Vth Examination December 2010
Subject code: 150102 Subject Name: Fundamentals of Turbo Machines
Date: 15 /12 /2010 Time: 03.00 pm - 05.30 pm
Total Marks: 70
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) Determine the impeller diameters an the width at the impeller exit and the 07 power required to drive the compressor, from the following given data:
Speed 12500 rpm, mass flow 15 kg/s, pressure ratio 4:1, isentropic efficiency 75%, slip factor 0.9, flow coefficient at impeller exit 0.3, hub diameter of eye 15 cm, velocity of air at the entry to and the exit from the impeller 150m/s, stagnation temperature and stagnation pressure at inlet 295 K and 1bar. Assume equal pressure ratio in the impeller and diffuser.
(b) Define degree of reaction and derive the expression for the same. Define the 07 low reaction stage and high reaction stage.
Q.2 (a) Draw and explain the H-S diagram for the axial turbine stage. Also define the 07 performance coefficient for the same.
(b) A multistage gas turbine is to be designed with impulse stages, and is to 07 operate with an inlet pressure and temperature of 6 bar and 900 K and at outlet pressure of 1 bar. The isentropic efficiency of the turbine is 85%. All the stages are to have a nozzle outlet angle of 15 and equal outlet ad inlet blade angles. Mean blade speed of 250 m/s and equal inlet and outlet gas velocities. Estimate the number of stages required considering optimum blade to gas speed ratio.
OR
(b) Draw and explain zero percent, fifty percent and hundred percent reaction 07 axial turbine stages.
Q.3 (a) How the radial turbine differs than axial turbine? Show the entry and exit 07 velocity triangle for a general inward flow radial turbine stage.
(b) For a ninety percent IFR turbine stage derive the expressions for power, stage 07 loading coefficient and degree of reaction.
OR
Q.3 (a) How the spouting velocity is to be defined? Derive the expression for the 07 stage efficiency for the radial turbine stage in terms of pressure ratio and loading coefficient.
(b) An IFR turbine impulse stage with cantilever blades has a flow coefficient of 07
0.4 and develops 100KW with a total to total efficiency of 90% at 12000 rpm. If the flow rate is 2 kg/s at an entry temperature of 400 K determine the rotor diameters, blade angles at the entry and exit, the nozzle exit air angle and the stagnation pressure ratio across the stage. Take d3=0.8d2, zero swirl and constant meridional velocity.
(b) Air at temperature of 290K enters a ten stage axial flow compressor at the 07 rate of 3kg/s. the pressure ratio is 6.5 and the isentropic efficiency is 90%, the compression process being adiabatic. The compressor has symmetrical blades. The axial velocity of 110 m/s is uniform and the peripheral speed of each stage is 180 m/s. determines the rotor and stator blade angles and flow angles and also the power given to the air. Assume temperature change in each stage is constant.
OR
Q.4 (a) The conditions of air at entry of an axial compressor stage are 768 mm Hg 07 and 314 K. the air angles are Pi=51, p2= 9, a1=a3=7. The mean diameter and peripheral speed are 50 cm and 100 m/s. mass flow rate 25 kg/s, the work done factor 0.95 and mechanical efficiency is 92%. Assuming a stage efficiency 88% determine: air angle at the stator entry, blade height at entry and the hub tip diameter ratio, stage loading coefficient and stage pressure ratio.
(b) Draw and explain the sketch of two stage axial compressor with IGVs. 07
Q.5 (a) Explain the matching procedure for the compressors and turbines.
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(b) What is an equilibrium diagram? How to find out the equilibrium points from the characteristic curves?
OR
Q.5 (a) Classify and explain the turbo machines with respect to flow direction, types of fluid and degree of reaction.
(b) Derive the dimenless parameter for compressor pressure p2. where p2 = f(p1,D,m,N,p)
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| Earning: Approval pending. |
