US1861960A - Turbine blading - Google Patents

Description

June 7, 1932.

WITNESS H. J. HANZLIK 1,861,960

TURBINE BLADING Filed Nov. 28, 1930 i a I MIN ill m INVENTOR H. a), Hmmzum. a 2; BY

ATTORNEY Patented June 7, 1932 UNITED STATES PATENT OFFICE I HENRY J'. HANZLIK, OF SWABTHMORE, PENNSYLVANIA, ASSIGNOR T WESTINGHOUSE ELECTRIC 8:; MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA TURBINE BLADING Application filed November 28, 1930. Serial No. 498,830.

My invention relates to turbine blading, more particularly to end-tightened blading; that is, blading having axial clearance packing for restricting leakage over the tips of the blades, and it has for its object to avoid eddying of the motive fiuid'caused by discharge of leakage from the packing transversely into the path ofthe motive fluid.

A further object is to direct the leakage into the pathot the motive fluid in a direction parallel to said path.

End-tightened blading in elastic fluid turbines has the advantage that the clearances may readily bevaried -by endwise or axial movement of the rotor. Close working clearances may thus be provided during the normal operation of the turbine, by axial adjustment of the rotor. It is found, however,

. that the leakage through a given axial clearance has a greater detrimental effect on the turbine efiiciency than the same radial clearance. that the leakage from certain of the packing clearances is directed transversely into the path of the motive fluid, thereby causing eddying. I

In accordance with my invention, I make provision for directing the leakage, from those packing clearances discharging into 3'? the Path of the motive fluid, from a P transverse of the motive fluid path, the leakage being preferably directed parallel to said motive fluid path. Preferably, a deflector is carried by the blade shrouding and arranged to deflect the leakage into the path of the motive fluid. I

The above and other objects are efi'ected by my invention, as will be apparent from the following description and claims taken in connection with the accompanying draw;

ing, forming a part of this application, inv

which: I

Fig. 1 is a sectional View, taken longitudinally of the turbine, showing the end-tightened blading; and,

Fig. 2 is a similar view showing a modified form of end-tightened blading.

Referring nowto the drawing more in detail, at and 11, I show two blade-carrying members of a turbine. Either one of these This is believed to be due to the fact members may be rotatable and the other stationary, but for the purpose of the present description, the member 10 will be considered the stator or stationary member, and the member 11 will be'considered the rotor or rotatable 'member, rotating about a horizontal axis. The stator 10 carries annular rows of turbine blades 12, fixed thereto by mounting the root portions of the blades in annular grooves 13. The rotor 11 carries annular rows of In order to restrict the leakage of motive fluid around the tips or free ends of the blades, it is necessary'to provide suitable packing means. I employ end-tightenedor axial clearance packing means, in order to obtain close Working clearances by relative axial adjustment of the blade-carrying members. In order to eifect the adjustment just noted, it is necessary that all of the packing portions carried" on one member be on the same side of the packing clearances and that all of the packing portions carried by the other member be on the opposite side, so that relative axial adjustment will vary all the clearances in the same direction.

In the present embodiment, the rotatable packing portions are on the low pressure or right-hand side of the moving bladesl, and the stationary packing portions are-on the high pressure or left-hand side of the stationary blades 12. By moving the rotor 11 to the left, all of the clearances are increased, and by movingthe rotor to the right, all of the clearances are decreased. v j

The shrouding 16 of the stationary blades is extended to the left to form a thin'edge packing element 18. The element 18' packs against a part carried by the rotor which faces axially to the right. This part is preferably provided by separate pieces 19, which are fixed in the grooves in which the blades 14 are mounted and which extend circumferentially along the root portions of the moving blades. The right hand surface of the packing elements 19 opposing the packing element 18 is indicated by the reference numeral 21.

The packing elements 18 and 19 restrict leakage from the space between the blades 14 and 12 to the space between the shrouding 16 and the rotor 11. The leakage then flows through the latter space along the shrouding 16 to the space on the low pressure side of the stationary blades 12. As will be noted from the drawing, there is a wide clearance between the right-hand edge of the shroud 16 and the adjacent portion of the moving blades 14, so that the leakage flowing therethrough does not attain a high velocity, and'readily assumes a direction parallel to the path of the motive fluid which is flowing through the successive rows of blades.

The shrouding 17 of the moving blades is extended on the right-hand edge to form packing elements 22 and 23, both of which pack against the left-hand side of packing elements 24,-which are similar to the packingelements 19. The packing elements 24 and the root portions of the stationary blades 12 are formed with axially-extending ducts 25, which open into the left-hand surface of the packing elements 2 1 between the packing elements 22 and 23. i

The clearance formed by the. packing element 23 restricts the leakage of fluid from the space between the shrouding 17 V and the stator 10. The clearance directs the leakage downwardly at right angles to the path of the motive fluid, and ifthe leakage were permitted to so project into the path, it would cause eddying of the motive fluid resulting in decreased efliciency of the turbine. T18

leakage is deflected from its downward path,

however, by the packing element 22, and flows through the ducts 25 to the right-hand side of the stationary blades 12. The packing element 22 also restricts the escape of fluid from the space on the right hand side of the moving blades 1% to the space between the packing elements 22 and 23.

Referring to Fig. 2, I show two relatively rotatable blade carrying members 30 and 31. For the purpose of the present description, the member 30 will be considered as the stationary member or stator and the member 31 will be considered as the rotatable member or rotor. The rotor 31 rotates about a horizontal axis. The stator 30 carries a row of blades 32, and the rotorcarries a row of cooperating blades 33, the flow of fluid being in the axial direction from left to right. The blades 32 and 33 are again of the reaction type, providing a pressure drop across each row. The blades 33 carry shrouding 34 having a thin edge packing element 35. The latter packs against the right hand side of pack ing elements 36 and forms a packing clearance for restricting leakage from the space between the blades 32 and 33 to the space between the shrouding 34 and the stator 30.

The stationaryblades 32 haveqshrouding 37 fixed on the free ends thereof. The right hand edge of the shrouding 37 is formed with a packing element 38 having a thin edge extending axially to the right and packing against the left-hand side of packing elements 39 which are disposed on the left-hand side of the moving blades 33. The shrouding 37 is also formed on its right hand edgewith a deflector 41, which extends axially to the right beyond the left-hand side of the packing element 39 against which the element 38 packs. The deflector 41 extends in overlapping relationwith the axially extending surface 42, formed by the packing element 39 and the root portions of the blades 33, and forms therewith a passage which conveys the leakage into the path of the motive fluid. The surface 42, for-the major part thereof, forms a boundary of the motive fluid path, so that the leakage discharged through said passage joinsthe motive fluid. p

The clearance formed by the packing elements 38 and 39 restricts leakage of fluid from thespace between the shrouding 37 and the rotor 31 to the space on the right hand side of the blades 32. The leakage is directed by said clearance radially outwardly or at right angles to the path of motive fluid. The leakage is deflected, however, by the deflector 41, which deflects it in a direction axially to theright. The leakage thus joins the motive fluid flowing parallel therewith and disturbance of the flow of the motive fluid is avoided.

From the above description, it will be seen that I have provided a construction in which the leakage from the axial clearance packing is directed in a path parallel to theflow of motive fluid, and that its projection transversely into the path of the motive fluid is avoided. The efficiency of the turbine is thereby increased.

While I have shown my invention in two forms, it will be obvious to thoseskilled. in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically setforth in the appended claims.

WVhat I claim is:

1. In an axial flow turbinepthe combinadecreased in flowing through thefirst row, shrouding fixed on the free ends of the blades in the first row, packing means for restricting leakage of motive fluid from the outer side of the shrouding to the space between the blade rows and means for deflecting the fluid leaking through the packing means into and parallel to the path of the motivefluid.

2. In an axial flow turbine, the combination of two relatively rotatable blade-carrying members, a row of blades carried by one of said members, the pressure of the motive fluid being decreased in flowing through the blade passages of said row, a second row of cooperating blades carried by the other member and disposed on the low pressure side of the first row, shrouding carried by the blades of the first row, packing means for restricting leakage around said shrouding comprising a packing portion facing axially in the lowpressure direction carried by said shrouding and a cooperating packing portion carried by the other member and opposing the firstmentioned packing portion to provide a close packing clearance, and means for deflecting leakage through said clearance into and parallel to the path of the motive fluid.

3. In an elastic fluid turbine, the combination of two relatively rotatable bladecarrying members, a row of blades each fixed at one end to one of said members, a second row of blades each fixed at one end to the other member, the free ends of the first row of blades being adjacent the fixed ends of the second row of blades, shrouding attached to the blades of the first row at the free ends thereof, the flow of motive fluid being from the first row of blades to the second row and the pressure of the motive fluid being decreased in the blade passages of the first row,

axial clearance packing means for restricting the escape of fluid from the space between said shrouding and said other member, and means for deflecting the leakage from said axial clearance into and parallel to the path of the motive fluid.

4. In an elastic fluid turbine, the combination of two relatively rotatable blade-carrying members, a row of blades each fixed at one end to one of said members, a second row of blades each fixed at one end to the other member, the free ends of the first row of blades being adjacent the fixed ends of the second row of blades,shrouding attached to the blades of the first row at the free ends thereof, the flow of motive fluid being from the first row of blades to the second and the pressure of the motive fluid being decreased in the blade passages of the first row, a packing element carried by the shroudingon the low-pressure side of the first row for restricting leakage from the space between the shrouding and the other rotatable member, and a deflector element carried by said shrouding for deflecting the leakage from the sively, the pressure of the motive fluid being decreased in flowing through the first row,

shrouding fixed on the free ends of the blades in the first row, packing meansfor restricting leakage around said shrouding comp-rising a packingportion facing axially in. the lowpressure direction and carried by said shrouding on the low pressure side thereof and a cooperating packing portion carried by the other member and opposing the first-mentioned packing portion to provide a close packing clearance, and. a deflector carried by said shrouding on the low pressure side thereor" and extending therefrom in overlapping relation with the second-mentioned packing portion so as to deflect leakage from said packing clearance in a direction parallel to the flow of motive fluid.

6. In an axial flow turbine, the combination of two relatively rotatable blade'carry-' .ly, the pressure of the 'motivefluid being decreased in flowing through the first row,

shrouding fixed on the free ends of the blades in the first row, axial clearance packing means for restricting leakage around. said'shrouding, saidpacking clearance being arranged in radial alignment with the space between said blade rows so that the leakage therefrom is directed toward said space,and a deflector carried by said shrouding on the low pressure side thereof and extending therefrom across the path in which the leakage is discharged and in overlapping relation with a substantially axially extending surface carried by the member carrying the second row of blades, said deflector forming with said surface a passage through which the leakage is directed into the path of the motive fluid in a direction parallel to that in which the motive fluid is flowing.

7. In an axial flow turbine, the combination of two relatively rotatable blade-carrying 7 members, two rows of cooperating blades carried by said members, respectively, and through which motive fluid flows successively, the pressure of the motive fluid being decreased in flowing through the first row, shrouding attached'to the blades of the first row at thefree ends thereof, packing means for restricting leakage around said shrouding, the member carryingthe second row of blades also carrying a surface extending substantially parallel to the directionof the motive fluid path and the maj or portion of which defines a boundary of the motive fluid path,

and a deflector carried by said shrouding on the low pressure side-thereof and extending therefrom in overlapping relation with said axially-extending surface and deflecting the leakage from said packing means axially into the motive fluid path.

8. In an axial flow turbine, the combination of two relatively rotatable blade-carrying members, two rows of cooperating blades carr1edby said members, respectively, and

through which motive fluid flows successively, the pressure of the motive fluid being decreased in flowing through the first row, shrouding attached to the blades of the first row at the free ends thereof, packing means for restrictin leakage around said shrouding, the member carrying the second row of blades also carrying a surface extending substantially parallel to the direction of the m0- tive fluid path and the major portion of which defines a boundary of the motive fluid path, a deflector carried by said shrouding on the low pressure side thereof and extending therefrom in overlapping relation with said axially-extending surface and deflecting the leakage from said packing means axially into the motive fluid path, shrouding attached to the blades of the second row at the free ends thereof, and axial clearance packing means for restricting leakage around the second-mentioned shrouding and comprising packing portions carried by the low pres- I sure side of the first row and the high pressure side of the second row.

7 In testimony whereof, I have hereunto subscribed my name this 25th day of November,

f HENRY J. HANZLIK.

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