STEAM TURBINE ROTOR

STEAM TURBINE ROTOR
A steam turbine converts thermal energy from fluid to mechanical energy. The steam turbine rotor is the most important component of the steam turbine, the principle is very simple, just like the pelton turbine rotor traps mechanical energy from a jet of water from a nozzle and creates rotation, so does the steam turbine traps mechanical energy from high pressure steam. The first designs of steam turbine rotors were similar to the pelton wheel having only one set of blade fins so couldn’t trap all the mechanical energy of the high pressure steam as they are immediately deflected by 90°
after hitting the blades. In other to trap all the energy of the steam, other line of blade fins had to be installed stationary to each other, redirecting the steam 90° to the next set of blades so all the mechanical energy of the steam can be utilized. The stationary blades are fixed and immovable so as to deflect the steam with more energy providing a large amount of speed RPM and torque. In steam turbine rotor design, the diameter of the blades increases as the steam travels, this is because the steam looses mechanical energy as it travels through the shaft so this change in pressure can be accommodated. The smaller blades are called ‘high pressure turbines’ while the larger diameter fins are called low pressure turbines. 

note: the fixed/ immovable blades are attached to the turbine casing but the movable blades are attached to the turbine shaft; this is why the turbine casing must be made of a very strong material to transfer this pressure and achieve amazing amounts of horsepower.

note: In a steam turbine, steam is the working fluid but other high pressure gasses can be used to drive this same rotor design giving birth to JET ENGINES, GAS TURBINES, etc, all that is needed is a high pressure gas compressor [usually axial compressor fitted on the same shaft] to pressurize the gas and possibly ignite it to combust and expand with high pressure producing even more kinetic energy than steam.

note: Even nuclear and coal power plants still use steam turbines to drive high performance GENERATORS producing large amounts of electricity, the main purpose of the coal or nuclear fuel rods is to heat up water to generate STEAM. [for more explanation on power plants, watch out for our next post].
steam turbine are also used in ships and heavy duty boats.

 

                                                A HAPPY NEW YEAR FROM THE MECHANIST