STEAM NOZZLES AND

TURBINESG M LIONUS LEO

METHODS OF REDUCING WHEEL OR ROTOR SPEED

VELOCITY COMPOUNDING

METHODS OF REDUCING WHEEL OR ROTOR SPEED

PRESSURE COMPOUNDING

METHODS OF REDUCING WHEEL OR ROTOR SPEED

PRESSURE VELOCITY COMPOUNDING

METHODS OF REDUCING WHEEL OR ROTOR SPEED

REACTION TURBINE

PROBLEM 5The first stage of an impulse turbine is compounded for velocity and has two rows of moving blades and one ring of fixed blades. The nozzle angle is 15o and the leaving angle of blades are respectively, first moving 30o, fixed 20o; second moving 30o. The velocity of steam leaving the nozzle is 540 m/s. The friction loss in each blade row is 10% of the relative velocity. Steam leaves the second row of moving blades axially. Find : 1. Blade velocity 2. Blade efficiency

ANSWER PROBLEM 5𝐶𝑟𝑜

𝐶𝑟𝑖

=𝐶 ′

𝑟𝑜

𝐶 ′𝑟𝑖

=𝐶1′.

𝐶𝑜

=0.9

𝐶𝑏𝑙=117.3m /s

Blade Efficiency

𝜂𝑏𝑙=2𝐶𝑏𝑙 (𝐶𝑤+𝐶′

𝑤 )𝐶1

2

78.6 %

PROBLEM 6The following data refer to a particular stage of a Parson’s reaction turbine: Speed of the Turbine = 1500 rpmMean diameter of the rotor = 1 metreStage efficiency = 80%Blade outlet angle = 20o

Speed ratio = 0.7Determine the available enthalpy drop in the stage.

ANSWER PROBLEM 6𝐶𝑏𝑙=

𝜋𝐷𝑁60

𝜌=𝑐𝑏𝑙𝐶𝑖

𝜂𝑠𝑡𝑎𝑔𝑒=𝐶𝑏𝑙(𝐶𝑤𝑖−𝐶𝑤𝑜)

h𝑑