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Home ‣ Mechanical Engineering ‣ Steam Nozzles and Turbines Comments
  • Question

  • The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and ? = Nozzle angle)


  • Options
  • A. Vb = 0.5 V cos ?
  • B. Vb = V cos ?
  • C. Vb = 0.5 V2 cos ?
  • D. Vb = V2 cos?

  • Correct Answer
  • Vb = 0.5 V cos ? 

    • Steam Nozzles and Turbines problems

    Search Results

    • 1. When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.

    • Options
    • A. increases
    • B. decreases
      • Discuss
    • 2. For a Parson's reaction turbine, if ?1 and ?2 are fixed blade angles at inlet and exit respectively and ?1 and ?2 are the moving blade angles at entrance and exit respectively, then

    • Options
    • A. ?1 = ?2 and ?1 = ?2
    • B. ?1 = ?1 and ?2 = ?2
    • C. ?1 < ?1 and ?2 > ?2
    • D. ?1 = ?2 and ?1 = ?2
      • Discuss
    • 3. In a nozzle, the effect of supersaturation is to

    • Options
    • A. decrease dryness fraction of steam
    • B. decrease specific volume of steam
    • C. increase the entropy
    • D. increase the heat drop
      • Discuss
    • 4. In a nozzle, the effect of supersaturation is to increase the dryness fraction of steam.

    • Options
    • A. Yes
    • B. No
      • Discuss
    • 5. Steam turbines may be classified according to

    • Options
    • A. direction of steam flow
    • B. number of stages
    • C. mode of steam action
    • D. all of these
      • Discuss
    • 6. The expansion of steam in a nozzle follows

    • Options
    • A. Carnot cycle
    • B. Rankine cycle
    • C. Joule cycle
    • D. Stirling cycle
      • Discuss
    • 7. In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be

    • Options
    • A. 260 kW
    • B. 282 kW
    • C. 296 kW
    • D. 302 kW
      • Discuss
    • 8. The stage efficiency is the ratio of energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam.

    • Options
    • A. True
    • B. False
      • Discuss
    • 9. The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages.

    • Options
    • A. same
    • B. less
    • C. more
      • Discuss
    • 10. When the inlet pressure of steam is equal to the exit pressure, then

    • Options
    • A. there is a pressure drop in the nozzle
    • B. fluid flows through the nozzle
    • C. pressure drops and fluid flows through the nozzle
    • D. there is no pressure drop and fluid does not flow through the nozzle
      • Discuss

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