ME-603-A Turbo Machinery - May 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWhich is called Euler's equation for reaction turbine? What is Euler's energy equation?
   How to answer

   • State Euler's turbine equation for energy transfer
   • Write equation for reaction turbine with inlet and outlet velocity triangles
   • Explain terms: whirl components, blade speed, head/work
2. 7 Marks
   bDefine and derive specific speed of pump.
   How to answer

   • Define specific speed of pump
   • State assumptions for similarity
   • Derive expression Ns = N*sqrt(Q)/H^(3/4)
   • Explain significance
3. 7 Marks
   aWhat is degree of reaction in turbomachinery? What is a 50% reaction turbine?
   How to answer

   • Define degree of reaction as rotor enthalpy drop / total stage drop
   • Give formula using velocity components
   • Define 50% reaction turbine
   • Mention symmetric velocity triangles
4. 7 Marks
   bDescribe velocity and pressure compounding of steam turbine.
   How to answer

   • Define velocity compounding (Curtis) with diagram
   • Define pressure compounding (Rateau) with diagram
   • Explain variation of velocity and pressure in stages
   • Compare purpose and losses
5. 7 Marks
   aExplain various losses in turbine.
   How to answer

   • List internal losses: friction, leakage, windage, residual velocity
   • List external losses: mechanical, radiation
   • Briefly explain each loss mechanism
   • Mention effect on efficiency
6. 7 Marks
   bWhat are the factors that affect the performance of steam turbines? What is the condition of maximum efficiency of turbine?
   How to answer

   • List factors: steam pressure, temperature, mass flow, blade condition, vacuum
   • Explain influence on output and efficiency
   • Derive condition for maximum efficiency (blade speed ratio)
   • State rho = cos alpha /2 for impulse
7. 7 Marks
   aDry saturated steam is expanded in a nozzle from $1.3\ \text{MPa}$ to $0.1\ \text{MPa}$. Assume friction loss in the nozzle is equal to $10\%$ of the total enthalpy drop; calculate the mass of steam discharged when the nozzle exit diameter is $10\ \text{mm}$.
   How to answer

   • Determine inlet enthalpy of dry saturated steam at 1.3 MPa from steam tables
   • Apply 10% friction loss to isentropic enthalpy drop to 0.1 MPa
   • Find exit velocity and specific volume at exit
   • Calculate mass flow using m = A*V/v
8. 7 Marks
   bWhat is positive displacement machines?
   How to answer

   • Define positive displacement machine
   • Explain trapping and displacing fluid volume
   • Give examples: reciprocating pump, gear pump
9. 14 Marks
   The velocity of steam leaving a nozzle is $925\ \text{m/s}$ and the nozzle angle is $208$. The blade speed is $250\ \text{m/s}$. The mass flow through the turbine nozzles and blading is $0.182\ \text{kg/s}$ and the blade velocity coefficient is $0.7$. Calculate the following:

   1. i)Velocity of whirl.
   2. ii)Tangential force on blades.
   3. iii)Axial force on blades.
   4. iv)Work done on blades.
   5. v)Efficiency of blading.
   6. vi)Inlet angle of blades for shockless inflow of steam. Assume that the inlet and outlet blade angles are equal.
   How to answer

   • Draw inlet and outlet velocity triangles with given data
   • Calculate whirl components Vw1, Vw2 using blade speed and velocity coefficient
   • Compute tangential and axial forces, work and blading efficiency
   • Determine inlet blade angle for shockless entry assuming symmetric angles
10. 14 Marks
    In one stage of an impulse turbine the velocity of steam at the exit from the nozzle is $460\ \text{m/s}$, the nozzle angle is $22^\circ$ and the blade angle is $33^\circ$. Find the blade speed so that the steam shall pass on without shock. Also find the stage efficiency and end thrust on the shaft, assuming velocity coefficient $= 0.75$, and blades are symmetrical.
    How to answer

    • Draw velocity triangle for shockless entry to get blade speed
    • Calculate relative velocities using velocity coefficient and symmetrical blades
    • Compute stage efficiency = work / kinetic energy supplied
    • Compute axial/end thrust = mass * change in flow velocity
11. 7 Marks
    aDraw a neat sketch of Torque convertor.
    How to answer

    • Show pump, turbine and stator arrangement
    • Label flow direction and components
    • Explain torque multiplication principle
12. 7 Marks
    bDefine various efficiency of a hydraulic turbine.
    How to answer

    • Define hydraulic, mechanical, volumetric and overall efficiencies
    • Give formulas for each
    • Explain power flow in hydraulic turbine
13. 14 Marks
    Write short notes on any three of the following:

    1. a)Degree of reaction of turbomachine
    2. b)Governing of steam turbine
    3. c)Vector diagram of Axial flow compressor
    4. d)Slip and efficiency of fluid coupling
    How to answer

    • For each chosen topic give definition and formula
    • Draw relevant velocity triangle / schematic where applicable
    • Explain working and significance
    • Mention applications