5g BULLETIN 173, U. S. NATIONAL MUSEUM 



In this turbine steam expands from boiler pressure to exhaust 

 pressure in three steps or stages, in the nozzles of a nozzle plate, the 

 first diaphragm and a second diaphragm. Following both the nozzle 

 plate and the first diaphragm are three rows of blades or buckets 

 consisting of two movable rows attached to the rotor of the turbine 

 and one row of intermediate buckets attached to the turbine casing. 

 Only one row of movable blades is provided after the second nozzle 

 diaphragm. The steam expands in the nozzles in each stage with a 

 resulting increase in the velocity of the steam. As the steam issues 

 with great velocity from the nozzles it impinges on moving blades, 

 which are curved in the direction of the path of the steam flow. 

 Through the interaction of the forces necessary to change the direc- 

 tion of the path of the steam, energy is imparted to the movable 

 blades causing the rotor to turn as well as reducing the velocity of 

 the steam. This process is repeated in each stage until the pressure 

 of the steam is reduced to the exhaust pressure. 



Steam is admitted to the first nozzle through a set of conical lift 

 valves, so arranged that they open in sequence as the load on the 

 turbine increases. This method permits the sensitive control of the 

 steam flow with a much smaller throttling loss than would occur 

 with a single large valve. The valves are operated by oil-driven 

 pistons and are controlled by a centrifugal governor, a small syn- 

 chronous governor, and a hand speed-control adjustment. The speed 

 regulation of the turbine is very close. The turbine is equipped with 

 emergency steam valve, oil pump, cooler, and filter. 



VACUUM VAPOR POWER PLANT, 1933 



U.S.N.M. no. 310651 ; original, gift of the Cochrane Corporation ; not illustrated. 



The miniature vapor turbine power plant, designed by G. H. 

 Gibson, utilizes the difference in temperature generall}^ existing be- 

 tween that indicated by an ordinary (dry bulb) thermometer and 

 that by a thermometer the bulb of which is kept wetted by a wick dip- 

 ping into water (wet bulb). The "plant" is made of glass and con- 

 sists of a boiler, which is a spiral of bare glass tubing in which vapor 

 is generated by the heat in the surrounding atmosphere, a nozzle 

 through which the vapor jets upon the buckets of a tiny turbine wheel 

 mounted on jeweled bearings, and a condenser, which is also a spiral 

 of glass tubing covered and cooled by wetted wicking. The conden- 

 sate return^- to the boiler by gravity. In an ordinary atmosphere the 

 turbine will spin indefinitely as long as the wick is kept moist. 



