US1491907A - Water-turbine draft tube - Google Patents

Description

MATER TURBNE DRAFT TUBE Filed OCt. 18, 1922 2 Sheets-Sheet lv IM/@W06 asc/ar @$0 @HL wwf/w Ami 29 w24, www? Q. C. GOERIZ WATER TURBINE DRAFT TUBE Filed OCT'. 18. 1922 2 SjlgeietsfSheet 2 arrasar OSCAR C. GOEIRIIZ,r 0F OAKLAND, CALIFORNIA.

WATER-TURBINE DRAFT TU BE.

Applicationr filed October 18, 1922.

To all whom t may concern:

Be it known that I, OSCAR C. Gonnrz, a

citizen of Germany, residing at Oakland, in

the county of Alameda, State of California, have invented a new and useful 1Water-Turbine Draft Tube, of which the following is a specification in such full and clear terms as will enable those skilled in the art to construct and use the same.

This invention relates to draft tubes used in connection with reaction turbine wheels and its object is to reducethe discharge velocity of the water and to avoid the necessity of making the deep excavations necessary with the ordinary form of straight draft tubes.

The ymodernhigh speed turbine discharges the water with such a high residual velocity that the most eflicient draft tube design is required to reduce that velocity to as low a velocity as possible to give the mostefficient results for a given quantity of water used. This design would cause the straight drafttube to become so long as to produce excavations of prohibitive depths.

The present invention provides a downward flow draft tube combined with an air tight water sealed chamber above the tail water level. The chamber is arranged so it will receive part of the water issuing from the tube, but all of the water will eventually be discharged at or below thel tail water level.

Another object of thel invention is to pro-V f vide the draft tube with a surrounding chamber which will be of such extent as to allow in the water smooth flow lines of considerable radius to most eiiiciently let the water How, partly above and partly below the tail water level while it is in the discharge chamber.

4Another object of the invention is to provide the discharge chamber with' an additional cross-section above the tail water level to pass the water issuing from the upstream rThe depth of the draft tube is ordinarilyv dependent upon the diierence in elevation between the base of thet-urbine and the con- Since any water that can bey Serial No. 595,435.

venient depth below the tail water level up to a limit of the depth requiredto balance the atmospheric pressure and the angle of the draft tube due to its increasing area downwardly and then upwardly is that angle which will give as slow a discharge move` ment to the water as possible without danger `of breaking the vacuunreither in the vacuum chamber or in the draft tube 3.

`Other objects of the invention will appear as the description proceeds. K

An embodiment of the invention is shown in the accompanying drawings in which the same reference numeral is applied to the same portion throughout, but I am aware that there may be modifications thereof.

Figure l is a vertical lsectional view of a turbine with a thin walled draft tube discharging into the vacuum chamber.

Figure 2 is a vertical section at right angles toV Figure l, 'the turbine being omitted.

Figure 3 is a horizontal cross-section on line 3-3, Figure l.

Figure 4 is a vertical section at a slightly different form of draft tube and vacuum chamber. y

Figure 5 is a vertical section of the tube and chamber at right angles to Figure 4.

Figure 6 is a sectional plan view of a portion of the draft tube and vacuum chamber yof Figure 4 on the line 6-6.

Figure 7 is a vertical sectional viewfof a turbine draft tube and discharge chamber of a slightly dierent form.

Figure 8 is a vertical sectional view of a portion of the draft tube and discharge chamber of FigureV 7 looking toward the outlet, and Figure 9 is a plan on the sec tion line 9-9, Figure 7.

In Figure l the numeral l indicates the turbine. 2 the penstock wall and 3 the draft tube, which tube is small where it leaves the turbine and larger at its lower end, the exact angle of the cone being determined by well known conditions of hydraulics unnecessary to consider here. The draft tube discharges into a large chamber V', open for its full width at the front to the tail race and which has a curtain wall 5 extending below the level of the surface of the tail race water. As the tube 3 is made of a conr ypara-tively thin material the cross-sectional area of the water passages increase constantly downwardly from the turbine and then upwardly from the bottom of the draft y curved through'mitV and .has v its dischargey tube3. As the height ofthe waterdischarge chamber VV is considerable'that portion of the chamber above the level of the tail water will always be subjected to a pressurerbelow atmospheric, andto prevent the accumulation of air from the water in'thechamber there is a vacuum pipe 6 leading from the chamber to' a suitable vacuum pump which walls are made thinner andfthe shoulders 8, 9.are produced onV thesides onf the draft tube. The vacuum chamber V2 `is smoothly opening 10 inclining downwardly `so Ythe wall 11 vis belowY the water surface of the tail race. v L v VIn the form of the inventionshown` 1n Figure 7 the turbine VVis `indicated at 20,.the tube V21 is east in concrete. The discharge or vacuum chamber V3 is formed on a `fiat surface v22 which extends to the tail race with the curtain wall 23 below the surfaceV of the Vwaterin the tail race. In this form ofthe invention the draft tube hasV its 'f sideV walls thinned to produce shoulders'Q/l 25 to in crease'theV discharge areas. 'Y Y A Y' Both of he latter lforms of the invention may be provided with the vacuum pipe 6 to remove any air collecting .in the vacuum chamber.y

vThe vacuum pipe 6 must ofl necessity be operated at the Vstarting of the turbine to produce the desired vacuum inthel vacuum chamber, but thereafter it need only be 0perated occasionally as air may collect therein; 4What I claimis as follows, but various modifications maybe made in the construction shown in the Vdrawings and above particularly described form, withinthe purview of my invention: Y

1. The combination with aturbine of a ydownward flow draft tube and a water sealed vacuum chamber into which the draft y tube discharges.Y Y Y Y Q ,The combination with a turbine having a downward How Ydraft tube of a chamber larger'in area than the draft tube, said chamber having a curtain wall below the level of the water in the'tail race.

3. The combination with a turbine having a 'downward How drafttube of a vacuum chamber into which said tube extends, the

discharge area of Vsaid chamber increasing upwardly for a portion of its height.

ll. The combination with a turbine having a downwardly rextending draft tube of Va vacuum chamber, and means to Vexhaust the air from said'chamber whenever necessary.

5.V The combinationwith a turbine having a downwardly extending draft tube increasing inV diameter downwardly of a vacuumY chamber havinga curtainwall extending below the leveljof the water in thetail race into which the draft tube extends, and means to exhaust the air from the vacuumy chamber whenever necessary.V

6. The combination withv a turbineand its draft tube of a vacuum chamber extending above the level of the bottom of the draft tube. w Y

7. The combination with a turbine having a downwardly extending draft tubeof a vacuum chamber extendingabov'e the level of thev bottom of the draft tube', thedischarge area of said chamber being greater at an intermediatepoint than at the bottom.

8. The combination with afturbine and a downwardly extendingv draft tube of a vacuv um chamber, said chamberextendirig upwardly from the bottom of the draft tube andV being of increasing cross-sectional area from its lower portion to an intermediate portion thereof, and means to exhaust the air from said chamber when necessary.

VIn testimony whereof I have hereunto sesy . os'oaa c. GoERiz.

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