US3047267A

US3047267A - Method and means for quieting the hydraulic operation of turbines

Info

Publication number: US3047267A
Application number: US715795A
Authority: US
Inventors: Peyrin Henri
Original assignee: Neyrpic SA
Current assignee: Neyrpic SA
Priority date: 1957-02-18
Filing date: 1958-02-17
Publication date: 1962-07-31
Anticipated expiration: 1979-07-31

Description

y 31, 1952 H. PEYRIN 3,047,267

METHOD AND MEANS FOR QUIETING THE HYDRAULIC.

OPERATION OF TURBINES 2 Sheets-Sheet -1 Filed Feb. 17, 1958 an s ATTORNEY wnvsu'rok Hevwi Pe r'm 87 44 MAW- July 31, 1962 H. PEYRIN 3,04 6

METHOD AND MEANS FOR QUIETING THE HYDRAULIC.

OPERATION OF TURBINES 2 Sheets-Sheet 2 Filed Feb. 17, 1958 FIG.4

\NVENTOR Ha k P\ v'\\ B ATTORNEY United States Patent It is a well known fact that reaction turbines such as those of the Francis or propeller type, and chiefly the larger sized turbines, are subjected under certain loads to cavitation phenomena due to the lack of stability of the central section of the stream of fluid passing out of the wheel and entering the aspirator. The violent disturbances in the pressure conditions produced by such phenomena are transmitted throughout the length of the stream starting from the suction end up to the high pressure pipe and through the turbine in which they produce transient and sudden deformations of'its parts.

With a view to reducing said phenomena, it has often been proposed to resort to the blowing of air into the central area, for instance through a central channel in the shaft carrying the turbine group or else through tubes entering the suction means and feeding air into the central section of the turbine immediately underneath the wheel or even into the insideof the terminal tip of the wheel or again, in the case of a Francis turbine, through the cover of the turbine whence the air enters the fluid stream through balancing ports either directly through the hubs of the wheel or through the tip of the latter. In this last case, it is necessary to provide a system of compressors with a view to introducing air into the turbine since the space available between the cover of the turbine and the hub of the wheel is normally subject to pressure.

The present invention has for its object a method for quieting the operation of hydraulic turbines, said method consisting in providing, simultaneously with the formation inside the turbine of a small throughput of air intimately admixed with water in the form of an emulsion, the introduction of said emulsion into the space comprised between the cover of the turbine and the hub of the wheel with a view to leaving in such a space a large volume of an air and water emulsion.

A further object of the invention consists in providing for the execution of the method a simple and particularly efficient apparatus adapted to produce a fine emulsion of.

air in water and to urge said emulsion into the space generally subjected to pressure extending between the cover of the turbine and the hub of the wheel.

A still further object of the invention is to provide an apparatus for the aeration of the turbine, adapted to operate a turbine without any substantial change in the design of the machine and without it being necessary to provide any auxiliary compressor group.

Another object of the invention consists in providing an apparatus for aerating the turbine during normal operation, While it is capable of supplying immediately the amount of air required for keeping out of water the turbine wheel of a hydroelectric group when the alternator serves as a compensator. I

The apparatus proposed for the execution of the abovementioned method is of the jet type. Apparatus of this type are adapted to inject fluid or to pump it out by re sorting to the kinetic energy of another fluid forming the driving fluid which is used in jet form.

It is a well known fact that, with such apparatus, the

pumping and the delivery of the fluid into an unwatering 1 thermore, the important volume of'emulsion underneath Patented July 31, 1962 equal to or even slightly lower than that of the driving fluid. In contradistinction, when it is desired to deliver or to inject a gas into a chamber subjected to a certain pressure through the agency of a liquid driving stream, the conventional apparatus are not operative. as a matter of fact by carrying along the gases in contact with a liquid jet after the manner of a conveyor belt. The gasiform stream is driven substantially at the same speed as the liquid, but the jets of gas and of liquid remain in practice independent over a substantial length of travel and it is found that the gas cannot enter a chamber sub jected to pressure, even if said pressure is low, because the mixture of the two fluids is very far from being complete and consequently the kinetic energy of the heavy driving fluid cannot be used to any extent by the gas.

The jet apparatus according to the present invention is characterized by the fact that it includes means for fractionating the jet of driving fluid for the dual purpose, on the one hand of multiplying the contact surfaces between the fluids with a View toincreasing the throughput of the gas carried along and on the other hand of furthering be- Under said conditions, the gas bubbles form a unit with the particles of liquid enclosing them and since they benefit by the kinetic energy of the latter, they enter readily inside the chamber subjected to pressure.

In the case of the improved method disclosed, the airin-water emulsion is urged into the space extending between the cover of the turbine and the hub of the wheel whence it reaches the central area of the stream at the output end of the blades of the wheel through the compensating openings or the like passages provided particulary for this purpose. Now, the space extending between the cover of the turbine and the hub. of the wheel corresponds to the points where the pressure is always higher than atmospheric pressure; in other words, the conditions are such that an injector of the conventional type could be of a magnitude of. about 1 to 2% of the water throughput of the turbine, but it may reach sometimes a value which is substantially higher and this may be estimated by the intense noise produced by the air entering at almost sonic speed the outer air input ports. In addition to the fact that the noise arising is highly objectionable, such an amount of-air entering the stream passing through the turbine results in a reduction in the efliciency. without however ensuring a fully satisfactory quieting of .the operation ofthe turbine at critical speeds.

The improved method according to the invention pro.- vides; on the contrary with a much lower input of air of a magnitude of about 0.5% and much less in most cases, a remarkable quieting effect on the-operation ,of the turbine while remaining perfectly silent.

This remarkable result is ascribable chiefly to the fact that the emulsion is introduced according to my inven tion. through the cover of the turbine. fact, the annular space comprised between the cover of the turbine and the hub of the wheel is filled with an emulsion under pressure and it forms a cylindrical collector arranged coaxially with the turbine, which allows a perfectly symmetrical distribution through the ports and/or passages provided in the hub of the wheel. Fur- They operate" As a matter of the cover of the turbine exerts through its presence a particularly eflicient damping action on the .jarring produced by the pressure pulses arising as a result of the hydraulic operation of the turbine.

A preferred embodiment of the apparatus according to the invention will now be described, reference being made to the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view of the improved apparatus.

FIG. 2 is a sectional view through line IIII of FIG. 1.

FIG. 3 is a developed cylindrical sectional view through line III-III of FIG. 1.

FIG. 4 is a diagrammatic view on a smaller scale of a hydraulic reaction turbine incorporating an emulsifying apparatus according to the invention.

The apparatus illustrated in FIG. 1 is constituted by a cylindrical body 10, the upper end of which is provided-with a ball valve 11, while its lower end is provided with a convergent nozzle 12 opening into a cylindrical pipe 13, terminating with a connecting flange 14. A bent pipe 15 enters transversely inside the body and its output end extending along the axis 16 of the apparatus is provided with a nozzle 17. Radial partitions 18 of a suitable thickness and the downstream ends of which are not shaped into a tapering outline but which may be formed with blunt transverse end surfaces, FIG. 3, are arranged inside the inner nozzle 17, in the vicinity of its output end. A central pipe 19 coaxial with the nozzle 17 passes through the wall of the bent pipe and its rear end opens into the upper end of the cylindrical body 10.

The apparatus according to the invention is secured as a whole through the flange 14 to the cover 21 which forms part of the casing of the turbine T (FIGS. 1 and 4).

The operation of the apparatus is as follows: a stream of water under pressure illustrated by the arrow e and tapped off for instance from the water feeding the turbine is sent into the pipe 15 whence it passes out through the nozzle 17 in the shape of a plurality of jets 22, five in the case illustrated. At the output end of the inner nozzle 17 said jets are separated from one another by the radial gaps shown at 23 in FIGS. 2 and 3 and by the central free space 24 corresponding respectively to the partitions 18 and to the wall of the central pipe 19.

Furthermore, the inner diameter of the output end of the inner nozzle 17 is selected preferably so as to be slightly smaller than the inner diameter of the terminal pipe 13, so that at the input of the latter there is formed a small free annular space 25 between the water jets Z2 and the inner wall of the pipe 13.

Under the action of the reduced pressure prevailing at the output end of the nozzle 17, air is sucked in through the ball valve 11 into the body 10, as illustrated by the arrows a and it enters then through the pipe '19 and the annular passage 26 between the inner nozzle 17 and the outer nozzle 12 inside the above-defined central free space 24, the radial gaps 23 and the annular space 25.

The air is then carried along by its numerous surfaces of contact with the water, which surfaces are provided according to the invention by the fractionation of the stream of driving fluid. There is rapidly obtained, as a consequence of the turbulent condition arising along the contact surfaces between air and water, an intimate mixture at 27 between the two fluids inside the terminal mixing pipe 13 which has for its primary result to allow an easy introduction of the light fluid together with the driving fluid through the agency of the apparatus described which is extremely simple.

Of course, the invention is by no means limited to the embodiment described and illustrated and it covers all the modifications thereof falling with the scope of the accompanying claims. In particulan'and as examples which should not be construed in a limiting sense, the

central pipe 19 may be omitted, the driving fluid may be fed along the axis of the apparatus at the location provided in the embodiment disclosed for the input of the light fluid for which one or more openings are then provided in the side wall of the cylindrical body 10; the inner nozzle 17 may be constituted by a cylindrical section and many other modifications may be provided.

Furthermore, any other suitable arrangements adapted to produce an emulsion of air in water and to urge it through the cover of the turbine may be used.

Lastly, the hydraulic emulsifying and compressing apparatus disclosed with reference to the accompanying drawings for the application of the method described can also be used in many other fields, whenever it is desired to urge a gas into a chamber subjected to pressure through the agency of a liquid jet.

What I claim is:

1. Apparatus for quieting the operation of a reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a straight mixing pipe of substantial uniform diameter adapted to be connected at its discharge end with a chamber formed in the turbine between the casing and the upstream side of the wheel thereof, and means for feeding air and Water to said mixing pipe so as to cause the creation therein of an emulsion thereof, said feeding means including a water feeding pipe extending towards said mixing pipe to terminate at a place adjacently spaced from the entry end of said mixing pipe, means connected to the entry end of said mixing pipe and forming an air chamber, the discharge end of said water feeding pipe projecting into said means forming the air chamber and being directed toward the entry end of said mixing pipe so that it discharges through the air chamber between such discharge end and said entry end directly into the latter, means at the discharge end of said water feeding pipe for fractionating the Water fed therethrough before its entry into said mixing pipe, and means for feeding air to the fractionated water in the air chamber adjacent to the entry end of the mixing pipe so that the water and air will enter the mixing pipe in such turbulent condition as to cause the creation therein of an emulsion thereof.

2. Apparatus for quieting the operation of a reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a mixing pipe adapted to be connected at its discharge end with a chamber formed in the turbine between the casing and the upstream side of the wheel thereof, and means for feeding air and water to said mixing pipe so as to cause the creation therein of an emulsion thereof, said feeding means including a body forming a closed chamber having a discharge opening in communication with the entry end of said mixing pipe and having a supply opening in communication with a source of air, the major portion of the chamber in said body having a cross-sectional area substantially greater than the cross-sectional area of the opening in said pipe and said body having a convergent section provided at its discharge end with said opening in communication with the entry end of said mixing pipe, means connected to said body for providing a controlled feed of air through said supply opening into said body chamber and through said convergent section into said mixing pipe, a water-feeding pipe entering into said body and having at its discharge end a nozzle located within said body chamber in coaxial relation with said convergent section so that said nozzle and section provide an annular convergent air passage to the entry end of said mixing pipe, said nozzle having its discharge end directed toward the entry end of said mixing pipe and terminating short of the latter to provide therebetween an open area in communication with said. annular passage and the interior of said mixing pipe, and means within said nozzle for fractionating the water fed to said nozzle before its entry into said mixing pipe, the air passing through said annular passage from the main portion of said chamber combining with the fractionated water in said open area to cause the mixture thereof to enter the mixing pipe in such turbulent condition as to cause the creation therein of an emulsion thereof.

3. Apparatus for quieting the operation of a reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a mixing pipe adapted to be connected at its discharge end with a chamber formed in the turbine between the casing and the upstream side of the wheel thereof, and means for feeding air and water to said mixing pipe so as to cause the creation therein of an emulsion thereof, said feeding means including a body forming a closed chamber having a discharge opening in communication with the entry end of said mixing pipe and having a supply opening in communication with a source of air, means connected to said body for providing a controlled feed of air through said supply opening into said body chamber from which it passes through said discharge opening thereof into said mixing pipe, a water-feeding pipe entering into said body and extending toward said mixing pipe to terminate at a place adjacently spaced from the entry end of said mixing pipe to provide an open area in said. chamber between said water feeding pipe and the discharge opening of said chamber, said end of said water-feeding pipe being in axial alignment with said mixing pipe and having a crosssectional area at the discharge opening thereof less than the cross-sectional areas of said intermediate open area and the opening in said mixing pipe, and means Within said pipe end for fractionating the Water feed thereto before its entry into said mixing pipe, the air passing from the main portion of said closed chamber into said intermediate open area thereof combining with the fractionated Water in said intermediate open area to cause the mixture thereof to enter the mixing pipe in such turbulent condition as to cause the creation therein of an emulsion thereof.

4. Apparatus for quieting the operation of a reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a mixing pipe adapted to be. connected at its discharge end with a chamber formed in the turbine between the casing and the upstream side of the wheel thereof, and means for feeding air and Water to said mixing pipe so as to cause the creation therein of an emulsion thereof, said feeding means including a body forming a closed chamber having a discharge opening in communication with the entry end of said mixing pipe and having a supply opening in communication with a source of air, means connected to said body for providing a controlled feed of air through said supply opening into said body chamber from which it passes through said discharge opening thereof into said mixing pipe, a waterfeeding pipe entering into said body and having at its discharge end a nozzle located within said body chamber in axial alignment with said mixing pipe and having its discharge end directed toward the entry end of said mixing pipe and terminating short of the latter to provide therebetween an open area in said chamber, a short pipe wholly contained in said closed chamber and extending coaxially through said nozzle to locate its entry end in communication with the main portion of said chamber adjacent to said supply opening thereof and having its outlet opening substantially in registry with the discharge opening of said nozzle and in communication with said open area, whereby a supply of air is by-passed from the main portion of said closed chamber to said open area to supplement the air fed directly to the latter from said main portion, and means positioned inside the discharge end of said nozzle and dividing the annular passage between the discharge end of said nozzle and said coaxial pipe, whereby water discharged through said annular passage is subdivided into a plurality of independent jets and is then admixed in said open area with the air discharged at the outlet opening of said coaxial pipe and with the air fed directly to said open area from the main portion of said chamber to cause the mixture thereof to enter the mixing pipe in such turbulent condition as to cause the creation therein of an emulsion there- 5. A reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a casing, a wheel supported for rotation within said casing, said casing and the upstream side of said wheel forming a chamber subjected to pressure above atmospheric by the main flow of water through the turbine, a mixing station adjacent to said casing chamber, means for feeding a stream of water under pressure toward said mixing station, means for feeding air to said mixing station, means at said mixing station for intimately mixing air with the stream of water to form a finely divided homogeneous emulsion and introducing such emulsion into said casing chamber, said feeding and mixing means coacting to inject such emulsion into the casing chamber at a higher pressure than the pressure of such casing chamber andat such rate that such chamber is maintained with a sufiicient volume of such emulsion to damp the action of the pressure pulses created by the operating turbine, and means for feeding the emulsion from such casing chamber into the central portion of the main flow of water through the turbine at the downstream side of the blades thereof.

6. A reaction type hydraulic turbine in which the wheel thereof turns in water, comprising a casing, a wheel supported for rotation Within said casing, said casing and the upstream side of said wheel forming a chamber subjected to pressure above atmospheric by the main flow of water through the turbine, means exteriorly of said casing chamber providing a mixing chamber in communication with said casing chamber, means for feeding a stream of water under pressure toward said mixing chamber, means for feeding air to said mixing chamber, said water feeding means including means at the discharge end thereof for fractionating the'stream of water prior to its admixture with the air, such fractionated water and the air being fed into said mixing chamber so as to be intimately mixed therein to form a finely divided homogeneous emulsion that as it is formed passes into the communicating casing chamber, said feeding and mixing means coacting to inject such emulsion into the casing chamber at a higher pressure than the pressure of such casing chamber and at such rate that such chamber is' maintained with a sufiicient volume of such emulsion to damp the action of the pressure pulses created by the operating turbine, and means for feeding the emulsion from such casing chamber into the central portion of the main flow of water through the turbine at the downstream side of the blades thereof.

7. A reaction type hydraulic turbine such as defined in claim 6, in whichsaid water feeding and fractionating means is so positioned with relation to the entry end of said mixing means that a driving stream of fractionatedwater is directed at the entry end of the mixing chamber and is so mixed with the air thereat as to place the fractionated water and air in a turbulent condition as they pass into the mixing chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,183,066 Felthousen May 16, 1916 1,529,634 Nagler Mar. 10, 1925 1,823,624 Nagler Sept. 15, 1931 1,936,246 Carter, et al. Nov. 21, 1933 2,079,258 Kerr May 4, 1937 2,695,265 Degnen Nov. 23, 1954 2,803,428 Garnett -QAug. 20, 1957 2,828,104 Fontaine Mar. 25, 1958 FOREIGN PATENTS 7 85,305 Norway Apr. 4, 1955 1,148,422 France June 24, I957