How it Works / Dealing in simple language with steam, electricity, light, heat, sound, hydraulics, optics, etc., and with their applications to apparatus in common use

by Archibald Williams

Fig. 38.—Blades or vanes of a Parsons turbine.

One of the low-pressure turbines of the Carmania, in casing. Its size will be inferred from comparison with the man standing near the end of the casing.

THE EXPANSIVE ACTION OF STEAM IN A TURBINE.

On reaching the end of D¹ it enters the second, or intermediate, set of vanes. The drum here is of a greater diameter, and the blades are longer and set somewhat farther apart, to give a freer passage to the now partly expanded steam, which has lost pressure but gained velocity. The process of movement is repeated through this stage; and again in D³, the low-pressure drum. The steam then escapes to the condenser through B, having by this time expanded very many times; and it is found advisable, for reasons explained in connection with compound steam-engines, to have a separate turbine in an independent casing for the extreme stages of expansion.

The vanes are made of brass. In the turbines of the Carmania, the huge Cunard liner, 1,115,000 vanes are used. The largest diameter of the drums is 11 feet, and each low-pressure turbine weighs 350 tons.