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March, 1910 The New Westinghouse Marine Steam Turbine Drive. In designing a steam turbine to be used in connection with the Melville and Macalpine reduction gear' for marine propulsion, I have avoided the introduc- tion of any untried or experimental features. While the machine as a whole is novel, it will be. found on analysis that it is made up of elements that have thoroughly proven their practicability and reliability. It is not necessary for me to touch on the question of steam economy; this is purely a matter of the right propor- tioning of the blades, nozzles and other steam passages. I am sure that no one who has a reasonable acquaintance with the turbine work carried out by the Westinghouse Machine Co. over a period of 15 years, will question the ability of the engineering staff at my disposal, to care for this detail in a thoroughly satisfactory manner. 'The inherent econ- omic possibilities of the turbine I pro- pose are, by reason of its higher rotative speed, markedly greater than those of a turbine limited in its speed on account of being directly coupled to the propel- ler, and these possibilities will be util- ized to the fullest extent. The features I wish to emphasize at present are not based on theoretical con- siderations, but are purely mechanical features which have to do with the simplicity and adaptability, the accessibil- ity, and the method of control. Simplicity and Adaptability. Each turbine is a complete independ- ent unit, with the high pressure and low pressure ahead and astern turbines in one casing. There is no complicated tangle of piping; a single pipe brings the high pressure steam to the turbine, and a single direct exhaust connection to the condenser suffices for the astern as well as the ahead turbine, the exhaust from both sections communicating with each other through the hollow rotor. The comparatively high rotative speed reduces the number of rows of blades necessary to efficiently utilize the energy in the steam, and the number is still further reduced by making the first and largest pressure drop through a single impulse wheel, instead of through a number of rows of blades of the reac- tion or "Parsons" type. When the steam has expanded to a considerable volume it is handled more efficiently by blading of the latter type, but in the earlier stages of the expansion, when the pres- sures are high and the volumes com- paratively small, the energy is extracted with a properly designed impulse wheel just. as efficiently as it could be with a "TAE MarRINE. REVIEW many rows of "Parsons" type blades. The greater compactness, due to the use of the impulse wheel, is a most valuable feature in a turbine for installation on board ship. With this construction, the distance between the bearings becomes short, and the rotor is consequently very stiff, and has practically no tendency to set up vibrations which are not only annoying, but which necessitate wasteful clearances in order to avoid injury to the blading due to contact with the cyl- inder or the rotor. Another advantage of using the im- pulse wheel for the earlier stages of the expansion is that the high pressure steam at high temperature is confined to the nozzle chambers, so that the range of temperature and pressure to which the casing of the turbine is sub- jected, is much reduced' and consequent- ly there is less tendency for the casing to distort. The ahead and astern turbines have impulse elements of the same size, but in the latter the complement of reaction blading is less. The power, available for going. astern is, however, unusually lib- eral, and the economy is sacrificed in a much smaller degree than is usual in marine turbine installations. Further- more, all of the propellers are available for going astern, which is a decided 3600 4000 4400 4800 5200 BRAKE HORSE POWER Fic. 9, 5600 INLET PRESSURE POUNDS ABSOLUTE PER SQUARE INCH advantage not commonly met with in existing turbine-propelled ships. The impulse wheels have' two sets of blade passages arranged concentrically, the outer annulus being- considerably narrower than the inner one. When the turbine is working at low power, one or two nozzles may be opened which . discharge on the outer or smaller blade ring. For ereater power one or two 109 larger nozzles may be opened to dis- charge against the inner or larger blade -- ring. . For maximum power, all of the nozzles and both blade rings are brought into action. The nozzles are so propor- tioned, and can-be operatéd in so many different combinations that the entire range from minimum to maximum pow- er may be covered in convenient steps without throttling the pressure in the nozzle chamber. In other words, the full expansive energy of the steam is available even when the vessel is run- ning at the most moderate cruising speed. Accessibility. 7 In a marine turbine installation there is probably no single feature worthy of more serious consideration than that of accessibility. Space on shipboard is so valuable that the engine room must be confined within the smallest possible limits, and it is consequently important that every precaution should be taken to design the machinery with especial refer- ence to convenience in dismantling and 'opening for inspection and repair. The design which I submit is novel in that all pipe connections are made to the lower half of the casing. The cover may therefore be lifted or swung back on hinges, without breaking a sin- -- gle pipe joint. The most valuable improvement, how- ever, is in the design of the cylinder blading. In all other turbines of the Parsons type, it is necessary to remove the rotor in order that access may be had to the blades of the lower half of the cylinder. The removal of the rotor of a large turbine is at best a laborious and tedious undertaking and is attended with considerable risk of damage to the blading. On board ship, by reason of the congestion that exists even in the most liberally proportioned engine rooms, the difficulties are multiplied. Further- more, the time required for making in- spections and repairs is often a factor, the importance of which it is difficult to overestimate. I have perfected a design of cylinder blading in which the blades are mounted en flexible bronze strips instead of being calked into grooves in the cylinder. The cylinder grooves are made much wider and deeper than usual, and are slightly undercut, leaving overhanging shoulders near the top. These blade strips may be slipped into the grooves where they cut 'through into the cylinder flanges, and light springs underneath hold them up Fic, 10,