US 2000741 A
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May 7, li935- 0 B. o. BUCKLAND 2,000,741
FLUID JET PUMP Filed Oct. 26, 1933 Inventor: Bruc vOrBuc Iad, by
Patented May 1935 UNITED STATES PATENTA OFFICE FLUID JET PUMP Bruce 0. Buckland, Schenectady, N. Y., alsignor to General Electric Company, a corporation o! New York The present invention relates to uid iet pumps or injectors for conveying a uid by means oi a fast-moving stream of the same or another iluid and converting the velocity en- '5 ergy of the mixture into pressure energy in a the formation of a boundary layer of slowly moving iluid within the diiluser.
One object of the present invention is to provide an improved construction for pumps of the type above referred to in which the boundary layer is readily removed or substantially minimized in thickness.
For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accom-v drawing.
In the single ligure of the drawing I -have shown a sectional view of a iet pump embodying my invention. The pump comprises a casing defining a suction chamber III having an inlet II for receiving uid to be conveyed and a diifuser or discharge conduit I2 having a diverging or diiluser portion in which the diilusion takes place. A nozzle Il fastened to the casing by means o! bolts Il opens into the chamber in the direction o! the axis of the diffuser. The arrangement so far described is generally known in the art. During operation a iiuid under pressure is discharged through the nozzle I3 into the suction chamber III, where the jet or jets from the nozzle I3 entrain and increase the velocity of the fluid entering the inlet II. The resulting mixture suilers a reduction in velocity and an increase in pressure in its passage through the diffuser I2.
A typical application oi pumps oi this kind is their use for conveying feed-water to a boiler y by means oi elastic fluid received from the boiler and discharged through the nozzle I3 into the suction chamber. In this particular case steam discharged from the nozzle I3 mixes with the water supplied through the inlet II whereby the steam condenses and creates a vacuum. As pointed out above, the mixture of iluid in the diffuser forms a boundary layer which moves very slowly or not at all and thereby renders the pump unstable and reduces its efllciency. In accordance with my invention this boundary layer is eilectively removed by the provision of recesses or slots in the wall surface ofthe difiuser or discharge conduit and connecting these recesses to a point or points of lower pressure.
In the present instance I have shown two annular slots or recesses I5 axially spaced apart 5 and provided in the wall oi the diffuser. The diil'user wall deilning these slots has bulges I6. The slots are connected to the suction chamber Il by means oi' conduits I1. During operation the slowly moving boundary4 layer, being under l0 a pressure higher than the pressure existing in the suction chamber I0, is discharged through the conduits Il into the suction chamber. It is noted that the slots or recesses I5 are provided in the diverging or diiluser portion oi the conl5 duit I2 where the diiiusion takes place. The withdrawal of the boundary layer in the diiiuser renders the operation of the jet pump more stable in that itreduces the tendency of backilow of the boundary layer at certain points oi 20l the diiluser. Backiiow oi the boundary layer leads to whirling which reduces the eiliciency of a Jet pump.
In addition to the means just described vfor removing the boundary layer I may provide an 25 auxiliary nozzle arrangement for injecting impelling fluid in tangential direction along the walls of the diiiuser. To this end anged portions Il uniting the suction chamber with the diiiuser are recessed to dene an annular chan- 30 nel I 9 connected to a conduit 20 for receiving impelling iiuid and discharging through one or a plurality oi nozzles 22 into the diffuser. The impelling iluid discharged from the annular channel I9 accelerates the slowly moving bound- 35 ary layer and thus aids in removing the boundary layer. The arrangement of the auxiliary slots-forms a part o! and is more fully disclosed in the application of Hans Krait, Serial No. 695,299, iiled on the same date with the present 40 application.
It will be readily understood that my invention which comprises the provision of a plurality of grooves or slots in the diiluser wall and means for discharging the boundary layer 45 through the slot or slots to a point or points of lower pressure may be used singly or together with the auxiliary nozzle arrangement.
With my invention I have accomplished an improved construction oi fluid jet pumps or 50 injectors which are stable during operation and in addition have a higher eiliciency than ordinary jet pumps.
Having described the method of operation oi my invention, together with -the apparatus 55.
which I now consider to reprent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.
WhatIclaimasnew anddesiretosecureby Letters Patent of the United States is:
1. In a l1et pump, a casing defining a. suction chamber with an inlet ioriluid to be conveyed and a dischargeconduit having a daring diffuser portion, a nozzle for discharging a iet of impelling iluid into the chamber in the direction of the axis of the conduit, and conduit means connected to the flaring portion for removing a slowly moving boundary layer of fluid in said flaring portion to maintain stability during operation.
2. In a jet pump, a casing denning' a suction chamber with an inlet for iluid-to be conveyed and a discharge conduit having a flaring diifuser portion, a nozzle for discharging a jet of impelling fluid into the chamber in the direction oi the axis of the conduit, and means for removing a slowly moving boundary layer oi' iluid in the conduit comprising at least one circumierentlally extending slot in the flaring portion of the discharge conduit connected to a point o! lower pressure.
3. In a jet pump. a casing defining a suction chamber with an inlet for iluid to be conveyed and a discharge conduit having a naringdiiiuscr portion, a nozzle for discharging a iet of impelling iluid into the chamber in the direction o! the axis of the conduit, and means for removing a slowly moving boundary layer of iluid in the ilaring portion oi.' the conduit comprising a plurality of axially spaced apart circumferentially extending recesses in the flaring portion of the discharge conduit and conduits connecting the recesses to points of lower pressure.
4. In a jet pump, a casing deilning a suction chamber with an inlet for iluid to be conveyed and a discharge conduit having a ilaring dinuser portion, a nozzle for discharging a jet oi impeiling uid into the chamber in the direction ot the axis of the conduit, and means for removing a boundary layer of iluidin the flaring portion of the conduit comprising a plurality oi concentric axially spaced apart annular slots in the flaring portion of the discharge conduit and conduits connecting chamber. r
said slots to the suctionV BRUCE O. BUCKLAND. 25