thermal engineering unit iii
DESCRIPTION
Thermal Engg Unit IIITRANSCRIPT
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 5πΆππ
πΆππ
=πΆ β²
ππ
πΆ β²ππ
=πΆ1β².
πΆπ
=0.9
πΆππ=117.3m /s
Blade Efficiency
πππ=2πΆππ (πΆπ€+πΆβ²
π€ )πΆ1
2
78.6 %
PROBLEM 6The following data refer to a particular stage of a Parsonβs 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 6πΆππ=
ππ·π60
π=ππππΆπ
ππ π‘πππ=πΆππ(πΆπ€πβπΆπ€π)
hπ