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speed; the cross-channel steamer Viper for Messrs. "G.' & Je Burns, of 315° ft. by 39 ft. 6 in. by 13 ft. and 213%4 knots speed; and another Clyde passenger steamer, the Atalanta, for the Glasgow & Southwestern Railway Co., of 210 ft. by 27 ft. by to ft. 6 in. and 17% knots speed. In addition to the above; the two Great Central railway steamers are nearing completion, and will, it is .an- ticipated, be put in service this year, and ENERGY OF STEAM AVAILABLE == FOR RECIPROCATING ENGINE EXHAUSTING INTO AVACUUM 150 AREA ENCLOSEO BY THICK LINES. 3S S$ 40 20 30 40 $0 60 70 (rcra4y - the yacht Mahroussa, which has been re- engined by Messrs A. & J. Inglis, has run her trials, when a speed of 17% knots was attained. : In addition to.the large number of war vessels that are now being built and fit- ted with turbine machinery by some eight of the Parsons Marine Co.'s licen- sees, and also in addition to the two ex- press Cunarders by Messrs. J. Brown & Co., and Messrs. Swan, Hunter & Wig- ham Richardson, Ltd., and the Wallsend Slipway & Engineering Co., the follow- ing mercantile orders are in hand: Two large ocean-going liners by the Fairfield Ship Building & Engineering Co.; two cross-channel steamers for the South- eastern & Chatham railway, similar to the Onward and Invicta; and a further steamer for the Union Steamship Co., of New Zealand, by Messrs. Denny; two large sets of turbine engines for ship- ment to Japan, by the Turbine Co. at Wallsend; and the royal yacht, building by Messrs. Inglis, the turbine engines for which are being manufactured at the Turbinia works, Wallsend, representing a total I. H. P. of work in hand of about 590,000. ; é Although the turbine itself has been described in various publications which are now being issued, it may be of in- terest to some of the members to briefly describe the principle of the Parsons turbine, and to mention a few points in- cidental to the application of the turbine system to different classes of vessels. In regard to the arrangement of tur- bines, this partly depends on the condi- tion of service, and the various classes of vessels require, more or less, to be taken upon their own merits. The ar- 60 "THE Marine. REVIEW rangement which has been almost uni- versally adopted in the mercantile ma- rine, is that of dividing the power equal- ly over three shafts, viz., a high-pressure on the center shaft, exhausting into two low-pressure turbines, one on each side of the vessel. In) such - a case the high-pressure. turbine is made suitable for an expansion ratio of about five, and the low-pressure for 25. The turbines are of the parallel flow Rig 8. = 250 HEAT UNITS PER LB. 25 that of the main drum. A large number of small grooves are turned in this dummy piston, into which fit corre- sponding fixed brass rings which are bedded into the dummy casing, forming steam baffles. The steam presses aft on the blades and on the annular part of the drum forming the step between the drum and the dummy piston, and the sum of these pressures bal- ances the thrust of the propeller. ENERGY OF STEAM THAT CAN BE UTILISED 4N A STEAM TURBINEAS COMPAREO WITH A RECIPROCATING ENGINE. iS OF 26. & AREA SHADED DOITIONAL ENERGY AVAILABLE 120 BLACK --__= FOR TURBINE EXHAUSTING INTO | ™ GO HSAT UNITS PER LB. & AVYACUUM OF 28° QR RS 100 3 ®» ¢0 5 8 g 60 S S 90 100 110 730 40 Cubic Fe. per Lb. 150 160 170 type, the general course of the steam through them being parallel to the axis. Each turbine consists of a number of rings of blades or vanes mounted on a drum or rotor. This rotor is enclosed within a cylindrical case, upon which rings of blades are also fitted. The rings of blades are alternately fixed and moving, that is to say, the blades in the cylinder are stationary or. guide blades, whilst the blades fitted on the drum are moving blades. The diameter of the drum is less than the cylindrical case, and thus an annulus is left between the two, which is occupied by the blades referred to. Steam, issuing from the boilers flows through the first row of fixed or guide blades on the cylinder, it then in jets of moderate velocity, im- pinges on the moving blades, and im- parts to them a rotary motion, this pro- cess being repeated on each successive ring of fixed and moving blades through- out the turbine.- _As the steam passes from ring to ring it falls in pressure and increases in vol- ume, and to meet this expansion the blades are increased in height by steps. The areas of the steam passages through the blades thus gradually increase from one end of the turbine to the other, to correspond to the expansion in volume of the steam for the range of pressures from beginning to the end of the tur--- bine. . The turbine shaft is coupled to the propeller shafting and the thrust of the propeller is steam borne by the follow- ing arrangement: Forward of the steam inlet a dummy piston is fitted of reduced diameter to 'on the center shaft only. 90, St $0, EXPANS SURE it 230 249 250 To meet any unbalanced thrust such as is set up when steam is turned on or off suddenly, and to maintain the true lon- gitudinal alignment of the rotors, a small thrust block is provided at the forward end of bearing. Where the turbine shaft passes through the casing, steam packed glands are fitted. These glands consist of a number of rings or strips arranged in series and designed to obtain a gradual rise or fall in pressure from the inner or steam end to the outer or at- mospheric end of the gland. Valves are fitted to these glands to regulate the pressures and to ensure against leakage of air inwards. All the main bearings are under oil pressures, and the oil is discharged from the pump at a pressure of from 8 to 1o lbs. or at such a pres- sure as to ensure the efficient lubrication of all bearings. oe In the exhaust casing of each of the low pressure turbines a reversing turbine is fitted. By means of suitable valves, when' maneuvering, the low-pressure and astern on each side of the vessel, are capable of being worked ahead or astern, as required, independently of the high-pressure turbine (the high-pressure turbine under such conditions running idly in a vacuum). By this arrange- ment, the vessel has all the maneuver- ing qualities of a twin screw vessel. In torpedo boats, a similar arrange- ment is adopted as in the Turbinia, viz., three in series, with one astern. This arrange- reduced weight ment. permits of a being obtained, as compared with the high-pressure and two low-pressures in parallel for equal efficiency.