The document summarizes key concepts about steam turbines including: 1) Steam turbines are classified as impulse turbines, reaction turbines, or impulse-reaction turbines depending on how the steam's energy is converted. 2) Impulse turbines use nozzles to direct steam jets at the turbine blades to impart momentum change, while reaction turbines use stationary and rotating blades to impart a combined momentum and pressure change. 3) Example calculations are provided for determining blade angles, forces, power output, and efficiencies for impulse turbines operating under various conditions.

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Power Plant Lecture Notes - CHAPTER-4 STEAM TURBINE
Chapter · October 2014
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2. ‫المستنصرية‬ ‫الجامعة‬
–
‫الھندسة‬ ‫كلية‬
‫قس‬
‫ــــ‬
‫م‬
‫الھندســــــــة‬
‫الميك‬
‫ـــــ‬
‫انيك‬
‫يـــة‬
‫محط‬
‫ــــــــــــ‬
‫طاق‬ ‫ات‬
‫ــــــــــــــــــــــ‬
‫ة‬
CHAPTER (4)
Steam Turbine
.‫م‬.‫أ‬
‫عبد‬ ‫مشعل‬ .‫د‬
‫االمير‬
10‐Dec‐14

3. Chapter 4
Steam Turbine
Classification of Steam Turbines: Impulse turbines, Reaction turbines, The impulse
principle, The reaction principle, The impulse turbine, Compounding of impulse
turbine: Pressure compounding, Velocity compounding, Pressure-Velocity
compounding, The impulse-reaction turbine, Flow of Steam Through Impulse
Turbine, Tangential force, Axial force, Power produced, Blade efficiency, Example
(1), Home Work , Stage Efficiency, Degree of Reaction, Cumulative Heat Drop,
Reheat Factor, Overall Efficiency, Example (2), Losses in Steam Turbines: Internal
losses: Friction losses, Leakage losses, External losses, Turbine Governing and
Control: Throttle governing, Nozzle governing, By-pass governing, Tutorial Sheet
4.

42. Power Plant Engineering TUTORIAL SHEET ‐ 4 ‫المستنصرية‬ ‫الجامعة‬
–
‫الھندسة‬ ‫كلية‬
Steam Turbine ‫الميكانيك‬ ‫قسم‬
–
‫ط‬ ‫محطات‬
‫ــــــــ‬
‫اقة‬
77
1‐ The velocity of steam at inlet to a simple impulse turbine is (1000 m/s), and the nozzle angle
is (20 o
). The blade speed is (400 m/s), and the blades are symmetrical. Determine the blades
angle if the steam is to enter without shock. If the friction effects on the blade are negligible,
calculate the tangential force on the blades and the diagram power for a mass flow of (0.75
kg/s). What is the axial thrust and the diagram efficiency?
If the relative velocity at exit is reduced by friction to (80 %) of that at inlet, what is then the
diagram power and the axial thrust?
Calculate also the diagram efficiency in this case.
(Ans. 32.5; 810 N; 324 kW; 0; 86.2%; 291.5 kW; 51.29 N; 77.7%)
2‐ The steam from the nozzles of a single wheel impulse turbine discharges with a velocity of
(600 m/s) and at (20 o
) to the plane of the wheel. The blade wheel rotates at (3000 rpm) and
the mean blade radius is (590 mm). The axial velocity of the steam at exit from the blades is
(164 m/s) and the blades are symmetrical. Calculate:
a) The blade angles,
b) The diagram work per (1 kg/s) steam flow,
c) The diagram efficiency,
d) The blade velocity coefficient.
(Ans. 28o
28’
; 126.3 kj per kg/s; 70%; 0.799)
3‐ A reaction turbine is supplied with steam at (60 bar, 600 Co
). The condenser pressure is (0.07
bar). If the reheat factor can be assumed to be (1.04) and the stage efficiency is constant
throughout at (80%). Calculate the steam flow required in (ton/hr) for a diagram power of
(25 MW). (Ans. 75.6 ton/hr)
4‐ The steam consumption at full load for a (3 MW) turbine is (16.6 ton/hr). At half load the
steam consumption is (9.1 ton/hr). Applying Willan’s line, estimate the steam consumption
at no load, and the consumption at a load of (2.5 MW).
(Ans. 1.6 ton/hr; 14.1 ton/hr)
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