US 1708402 A
Description (OCR text may contain errors)
April 9, 1929. R. scHlLLlNG TURBINE BLADE Filed sept. 4, 1925 TML Gl m Mms RL H Ou. N T# R mc O Ww m l. w V| @Bm Patented Apr. 9, 1929.
UNITED STATES 1,708,402 PATENT OFFICE.
'RUDOLPH sCHILLINa/OF wooDsIDE, CALIFORNIA, AssIGNOR 'ro HOLzWAR'rII GAs TUBBINE co., or SAN FRANCISCO, CALIFORNIA, A CORPORATION or DELAWARE.
lApplication led September 4, 1926. Serial No. 133,566.
-My present invention relates to turbine blades, and particularly to constructions in which such blades are in contact with a hotdriving medium, such as combustion gases under pressure, and also wlth a cooling medium. My invention is` applicable to turbines having partitioned blades whereby there arev produced an inner path andan Outer path, one of which is used for the combustion gases or other hot driving medium, and the other. for the cooling medium, for instance steam. As regards the absorption of heat by the blades vfrom the hot driving medium,
this depends chiefiy upon the area of the surface with which such medium comes in contact. The removal yor dissipation of the heat thus absorbed, however, is determined largely by the cross section of the blades, since this is a measure of the path afforded for such dissipation. Since it is possible to increase the cross section of the blades without materially increasing their surface, I am enabled to obtain a higher rate of heat dis sipation without altering the rate of heat absorption, and as a result, a more eiiicient cooling of the blades.
I have found it desirable to employ a relatively large diameter for the rotor body to which' the inner ends of the rotor blades are fastened and to use a relatively low number of revolutions. The cooled portions of the rotor blades are preferably made of' approximately the same length as the blade portions in contact with the hot combustion gases, and the exit angle at the cooled blade portion is preferably smaller than the exit angle at the hot blade portions. By causing the hot combustion gases to travel through the inner blade path, and the cooling medium through the outer blade path, I secure a double cooling effect, since the outer portions of the blades are in contact with a cooling medium, while their inner ends are secured to a rotor drum or body which dissipates the heat, particularly if this drum is cooled Vby passing steam or some other suitable AThe rotor of the turbine has a body or drum 10 to which are secured the inner ends or feet of the rotor'blades 11. 'lhe latter are preferably made of greater thickness at their inner portions than toward their ends, so as to facilitate the conduction and transfer of heat from the rotor blades to the drum, which is preferably cooled internally, as set forth hereinafter. About midway between their ends, the blades are provid-ed with partitions 12 bridging the spaces between adjacent blades and forming part of a cylindrical wall which subdivides the blade channels into an inner path and an outer path further removed from the center of the rotor than said inner path. The driving medium, preferably hot combustion gases under pressure, obtained by the-explosion of a mixture of air and fuel, is discharged against the inner portions of the rotor blades 11 from stationary nozzles 13. In the particular embodiment shown, the rotor has two sets of blades 11 acted upon successively by the driving medium, and in this case stationary so-called, reversing blades 14 are projected inwardly from the casing 15 between the two sets of rotor blades, and these reversing stator blades 14 are provided with partitions 16 in line with the partitions 12 of the rotor blades and in as close proximity thereto as possible, so as to obtain a practically tight joint between the rotating partitions 12 and the stationary partitions 1G and keep the driving medium traveling through the inner path separate from the cooling medium which passes in contact with the outer portions of the blades 11, 14. This cooling medium, which may be steam (the temperature of such steam being lower than that of the combustion gases) is discharged against the outer portions of the rotor blades 11' of the first set, from nozzles 17 receiving their supply through a pipe 18. After passing in Contact with the outer portions of the rotor blades of both sets and of the reversing blades 14, and thus cooling all the blades, such steam, as it issues from the last set of rotor blades, may be conducted, in full or in part as by a pipe 19, to the interior of the rotor vdrum 10 so as to cool the latter and the inner rotor blade portions which are in contact therewith; the steam finally passes out at 20. The balance of the steam may leave at exit pipe 21. The radial length of the outer rotor blade portions is approximately the same as the radial length of the inner blade portions. The blade portions which come in contact with the hot combustion gases are preferably made with a greater exit angle than the blade portions `which come in contact with the steam or othcrcooling medium as shown in Figs. 3 and 4. The purpose of this arrangement is to cause the cooling medium' to come in contact With a heat-absorbing surface which is about as large as the heat-absorbing surface in contact with the combustion gases.
While li have referred to the iiuid medium ot' lower temperature as a cooling medium (i. e. the steam) it will be obvious that such cooling medium, While of. a lower temperature than the combustion gases, may yet be ot such pressure as to be capable of performing Work in the turbine, the steam, or its equivalent, beingsuperheated by the coinbustion gases through the medium of the blades, the gases thus acting as a superheating medium.-
Various changes in the specific forms shown and described may be made Within the scope of the claims Without departing from the spirit of my invention.
1. A turbine comprising a rotor having blades partitioned to form an inner path and an outer pat-h beyond said inner path, in combination with devices for Adirecting a cooling medium into one 'of said paths and a hot driving medium into the other path, and with a rotor body to which said blades are attached at one end, the thickness of the blades increasingv toward their lattached ends.
2. A turbine comprising a rotor having blades partitioned to form an inner path and an outer path beyond said inner path,
in combination with devices for directing a cooling medium into one of said paths and a hot driving medunn into the other path,
the exit angle of the blades being greater at one of said paths than at the other.
3. turbine comprising rotor blades partitioned to form an inner path and an outer path, a hollow rotor body to which the inner ends of said blades are secured, devices for directing a cooling medium into one of said paths and a hot driving medium in the other path, and a connection for leading the cooling medium after its passage in reversing blades arranged between said sets of rotorblades and artitioned correspondingly thereto, and evices for' directing a cooling medium into one of said paths and the hot driving medium into the other path.
5. ln a turbine, a hollow rotor body, rotor blades each having its inner end secured to said rotor body, said blades being arranged in two sets and partitioned to form an inner path and an outer path beyond said inner path, the thickness of said blades increasing toward said rotor body, stationary reversing blades arranged between said sets of rotor blades and partitioned correspondingly thereto, devices for directing a cooling medium into one of said paths and the hot driving medium into the other path, and a connection for conveying the cooling medium after it has passed in contact with the said blades, into the said hollow rotor body to cool the same internally.
In testimony whereof I have hereunto set my hand.