ME-603-A Turbomachinery - Dec 2024 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
   aExplain the application of the first law of thermodynamics to the turbo machines.
   How to answer

   • State steady flow energy equation / first law for control volume
   • Apply to turbomachine with heat, work, kinetic and potential terms
   • Explain application to turbines, pumps, compressors with simplifications
2. 7 Marks
   bDerive the general Euler's equation for turbo machines.
   How to answer

   • Define control volume and velocity triangles
   • Apply momentum moment principle
   • Derive $T = \dot{m}(r_2V_{w2}-r_1V_{w1})$ and Euler head
   • State assumptions and general form
3. 14 Marks
   The following data relates to a single stage impulse turbine: Steam velocity $= 600$ m/s, Blade speed $= 250$ m/s, Nozzle angle $= 20^{\circ}$, Blade outlet angle $= 25^{\circ}$. Neglecting the effect of friction, calculate work developed by the turbine for the steam flow rate of $20$ kg/s; also calculate the axial thrust on the bearings.
   How to answer

   • Draw inlet/outlet velocity triangles with $V_1=600$ m/s, $U=250$ m/s, $\alpha_1=20^\circ$, $\beta_2=25^\circ$
   • Apply $V_w$ change for work $W=\dot{m}U\Delta V_w$
   • Calculate axial components for axial thrust $F_a=\dot{m}\Delta V_f$
   • Compute numerical values for 20 kg/s
4. 7 Marks
   aDerive the maximum blade efficiency of the Parson's reaction steam turbine.
   How to answer

   • Define Parson's 50% reaction stage with symmetric triangles
   • Write blade efficiency expression in terms of $\rho=U/V_1$ and $\alpha_1$
   • Maximize w.r.t. blade speed ratio
   • Obtain maximum efficiency condition and value
5. 7 Marks
   bDiscuss reheat factor in steam turbines with the help of a neat diagram.
   How to answer

   • Define reheat factor as ratio of cumulative to overall drop
   • Explain with h-s diagram for multi-stage expansion
   • Give formula $RF > 1$ and reasons
   • Discuss effect on efficiency
6. 14 Marks
   A Pelton wheel is to be designed for a head of $60$ m when running at $200$ r.p.m. The Pelton wheel develops $95.6475$ kW shaft power. The velocity of the buckets $= 0.45$ times the velocity of the jet, overall efficiency $= 0.85$ and coefficient of the velocity is equal to $0.98$.
   How to answer

   • Calculate jet velocity from $V=C_v\sqrt{2gH}$
   • Use $U=0.45V$ and $N$ to get wheel diameter
   • Use overall efficiency to get discharge and jet diameter
   • Summarize design dimensions and power
7. 7 Marks
   aHow the hydraulic turbines are classified?
   How to answer

   • List classification bases: action, flow direction, head, specific speed
   • Give impulse vs reaction examples
   • Mention Pelton, Francis, Kaplan placement
8. 7 Marks
   bA turbine is to operate under a head of $25$ m at $200$ r.p.m. The discharge is $9$ cumec. If the efficiency is $90\%$ determine:

   1. i)Specific speed of the turbine
   2. ii)Power generated
   3. iii)Types of turbine
   How to answer

   • Compute power $P=\eta \rho g Q H$
   • Compute specific speed $N_s = N\sqrt{P}/H^{5/4}$
   • Decide turbine type from $N_s$ range
   • State results with units
9. 7 Marks
   aDerive an expression for the degree of reaction for an axial flow compressor.
   How to answer

   • Define degree of reaction for compressor stage
   • Use velocity triangles and enthalpy rise
   • Derive $R$ in terms of flow angles / $C_a/U$
   • Simplify for symmetric / 50% case
10. 7 Marks
    bDraw and explain characteristic curves of fans.
    How to answer

    • Draw head-discharge, power, efficiency vs discharge curves
    • Explain stable operating region and effects of speed
    • Label shut-off, best efficiency point
    • Interpret fan selection use
11. 7 Marks
    aWhat is Hydraulic coupling? Explain with a neat sketch the working of a hydraulic coupling.
    How to answer

    • Define hydraulic coupling and its elements
    • Sketch pump-turbine impeller circuit
    • Explain torque transmission via fluid
    • List applications and slip
12. 7 Marks
    bExplain with the help of neat sketch the working principle of hydraulic accumulator.
    How to answer

    • Define hydraulic accumulator function
    • Sketch accumulator with cylinder, piston/weight
    • Explain storage and supply of pressurized fluid
    • Mention types and uses
13. 14 Marks
    Write short notes on any three of the following.

    1. a)Degree of reaction in steam turbines
    2. b)Working of centrifugal pumps
    3. c)Surging and choking in compressor
    4. d)Hydraulic press.
    How to answer

    • Define degree of reaction, centrifugal pump action
    • Explain surging vs choking phenomena
    • Describe hydraulic press principle
    • Give diagrams, formulas and applications for chosen three