Centrifugal compressor annular combustor and diffuser arrangement for a gas turbine

[Detailed Description of the Invention]

(Technical field of an invention) The present invention relates to diffuser, especially the diffuser for gas turbine engines which rations the gas stream from the impeller (impeller) of a centrifugal compressor in very little pressure loss at the entrance of a burner. (The background of an invention) Generally, a centrifugal compressor has a rotation impeller (impeller), and this impeller accelerates the gas stream which passes through this, and it is arranged so that this may increase the kinetic energy of a gas stream. Diffuser will be To enclose annular space about an impeller, if a definition is generally given. Diffuser falls the speed of the fluid style which comes out from an impeller, and makes the operation which heightens the Static pressure by this. This diffuser can be made also into the Behn type and a juxtaductal type. It has the diffuser passage which generally converges both types on tangential adjusting to the annular space surrounding an impeller and which was estranged in two or more directions of the circumference. these passages -- the lower stream of an impeller -- the Suehiro shape -- the gas stream from an intermediary impeller is diffused. In the Behn type diffuser, this passage is formed using the vane member estranged in two or more directions of the circumference. This is indicated by U.S. Pat. No. 3460748 and U.S. Pat. No. 3369737, for example. Or the above-mentioned passage may be formed as a pipe member between countering plates again. This is indicated by U.S. Pat. No. 3719430, for example. In this specification, the Behn type and juxtaductal type diffuser name generically the field arranged downstream from the diffuser passage in order to fit the channel of diffuser to the geometrical shape of a burner, and they are called a "transition field." In a transition field, a whirlpool elimination means is provided in the upper position of the entrance to a burner, and the direction fault style of the circumference is removed from the flow which comes out from a diffuser passage. In the diffuser of above-mentioned U.S. Pat. No. 3719430, the diffuser passage estranged in two or more directions of the circumference advances to the transition field which consists of an annular manifold gradually, ranks second to it, and comes out from here. Behn (guidance wings) who is the whirlpool elimination means estranged by the manifold in two or more directions of the circumference is provided. These Behn makes the operation which negates the direction velocity component of the remains circumference of the flow which comes out from a diffuser passage. The flow which passed whirlpool removal Behn is guided in a combustion chamber. As for this structure, the room of improvement in the field of the performance of diffuser mentioned above although remarkably improved compared with the performance of the conventional centrifugal compressor for gas turbine engines, especially the pressure loss of a system is I have left. In such conventional diffuser, the flow which comes out from a diffuser passage is in a comparatively high speed state, when whirlpool removal is done by whirlpool removal Behn. The whirlpool removal with a high Mach number becomes the cause of falling the pressure of the flow included in a burner remarkably. The flow in a high Mach number requires the passage on the smooth surface of a wall where ring quantity (the inlet section of a transition field is annular-shaped, and says this population width) is small, And manufacture common difference (common difference of a burner entrance and a diffuser exit) comparatively severe at the time of manufacture of a transition field must be maintained, Other conventional diffusers which perform whirlpool removal with the diffuser and the comparatively high Mach number of the type indicated by the above-mentioned U.S. Pat. No. 3719430 specification as a result which stations whirlpool removal Behn become much more complicated, and a manufacturing cost goes up. (The object of an invention) Therefore, there is a primary aim of the present invention in providing the centrifugal compressor diffuser constituted so that pressure loss, complexity, and a manufacturing cost might be low-Limit(ed). (Constitution of an invention) The invention in this application adopts the next composition. the inside of the annular housing which surrounds a centrifugal compressor, and the annular housing -- the circumference -- Along -- estrangement -- it being arranged and carrying out penetration extension of the inside of the annular housing Two or more diffuser passages which diffuse the gas stream which comes out from the above-mentioned centrifugal compressor, The plenum zone which is arranged downstream from the diffuser passage, expands the gas stream discharged, and decreases the speed of the gas stream, the lower stream of the plenum zone -- the near entrance of the above-mentioned annular combustor -- the circumference -- Along -- estrangement -- two or more whirlpool removal Behn stationed is included Diffuser which acts also as a transition field for Then and the above-mentioned plenum zone to fit the above-mentioned diffuser passage to the shape of the above-mentioned annular combustor entrance by the diffuser which diffuses the gas stream accelerated from the centrifugal compressor to the annular combustor. The above-mentioned composition is adopted, the air style which comes out from a centrifugal compressor is diffused in the passage of tangential adjusting to a compressor impeller, and a Mach number is decreased. These passages are made into shape which guarantees efficient pressure recovery and is approximated to continuation slot discharge. From the low diffuser exit Mach number (for example, <0.3) by the passage where exit area is not decreasing, since an air style is emitted to a plenum zone at a stretch, a Mach number further decreases, and pressure loss becomes small as a result. The flow of the Mach number which decreased is To be guided to whirlpool removal Behn estranged in two or more directions of the circumference arranged at the passage which carried out the fluid free passage with the entrance of the burner. If whirlpool removal is performed in the gas stream of the Mach number which decreased to about 0.15, pressure loss will decrease remarkably by diffuser. Since the gas stream to pass is a low Mach number, whirlpool removal Behn's manufacture common difference and the manufacture common difference of the channel between the exit of a tangential adjusting passage and the entrance to a burner are remarkably eased compared with each manufacture common difference about the transition field of the conventional diffuser. As a result of easing common difference, the manufacturing cost and complexity of diffuser of the present invention decrease according to this. Since other advantages of the diffuser of the present invention is [ the flow of a plenum zone ] a low Mach number, even if it arranges here the drawing-in pipe (pipe used for the Lubricating oil circulation to the engine bearing in a central frame part, etc.) of a central frame, they do not cause degradation to a gas turbine engine. It is custom to arrange this drawing-in pipe conventionally near the entrance to the combustion chamber which touches downstream from whirlpool removal Behn, and it is Oh. Arranging this pipe upstream of whirlpool removal Behn was forbidden. This is because the Mach number of the flow in this upper point is comparatively high and excessive Wake is generated with the flow which goes into a burner by central frame supply conduct arrangement. However, as a result of arranging a supply conduct near the burner, the disorder which is not desirable is produced in the temperature distribution of the gas which comes out from a burner, and a local high temperature part is produced to Ciel metal by disorder of Konkotenko at Ciel of a burner. Although the composition which arranges a supply conduct near the burner for the reason these losses to bring about are smaller than the loss which arises when the drawing-in pipe to a central frame has been arranged in the upper stream although it has this operation that is not desirable has been adopted conventionally, However, since the Mach number of the flow in a plenum zone is low, even if the diffuser of the present invention arranges the supply conduct to a central frame upstream of whirlpool removal Behn, it does not produce the loss resulting from an excessive turbulent flow or this. As a result, the comprehensive performance of the gas turbine engine which the bad influence which it has on the outlet temperature distribution of a burner and Ciel temperature which conventional technology had was reduced sharply, therefore incorporated the diffuser of the present invention is improved. (Statement of an example) In order to clarify the present invention further, a conventional example and the example of the present invention are described, referring to drawings below. Drawing 1 is a sectional view of the conventional diffuser used for the centrifugal compressor of a gas turbine engine. In this annular compressor, the surroundings of the engine center axis (not shown) are equipped with impeller 1 at rotation self-Existence. Impeller 1 has two or more braids 3 which kept the interval mutually by the web (not shown) and were supported in the direction of the circumference. 4 shows the whole diffuser, this diffuser has annular housing 5, two or more passages 6 are arranged in the housing, and entrance 7 of each passage 6 surrounds the outer edge of impeller braid 3. The cross-sectional area of passage 6 is gradually expanded to the method of the outside of a radial direction, diffuses the gas which flows through this, and it is constituted so that this may convert the high kinetic energy of gas into Static pressure energy. In order to make pressure loss of a plenum zone low, it is preferred to coincide the shape of the exit passage of diffuser with the shape indicated by U.S. Pat. No. 4027997. In order to fit diffuser to the geometrical shape of burner 10 in engine casing 11, the "transition field" shown by 12 is provided near the exit of diffuser passage 6. Two or more whirlpool removal Behn 14 who removes the whirlpool which is not desirable from the flow to burner 10 is provided in transition field 12. It arranges near the entrance of burner 10 which connects drawing-in pipe 16 to two or more engine central frames of an engine bearing which are lubricous and make a channeling-back operation downstream from diffuser passage 6. As mentioned above, this type of diffuser has left some faults. One of the faults is that the small size, the smooth wall surface, and the severe manufacture common difference (common difference of diffuser and a burner entrance) of diffuser passage 6 are required, and manufacture of this diffuser is comparatively expensive. Since the Mach number is comparatively high when the flow from diffuser exit passage 6 collides with whirlpool removal Behn 14, big pressure loss arises. Another fault is that drawing-in pipe 16 of a central frame is located near the entrance of burner 10 in whirlpool removal Behn's 14 part. If central frame drawing-in pipe 16 is located in this zone, a turbulent flow will arise with the flow included in a burner, outlet temperature distribution of burner 10 will become uneven by this, and Ciel temperature will become high locally. The improved type discharge diffuser of the present invention is shown in Drawing 2. The same Numbers as Drawing 1 shows the same parts as the above. While arranging transition field 12 including the plenum zone (high-pressure zone) named generically by 20 to the exit of diffuser passage 6 and also expanding the flow in diffuser so that clearly from a drawing, it may be made to make it the Mach number decrease. since it further decreases plenum zone 20 -- the speed of a flow -- 1, it enables it to remove the direction whirlpool of the circumference from the flow which carries out the termination of the plenum zone 20 by neck 21 which carried out the fluid free passage with burner 10, stations two or more whirlpool removal Behn 15 into this portion, and goes into burner 10 Plenum zone 20 can be penetrated and drawing-in pipe 16 to a central frame can be transferred to the upper stream from whirlpool removal Behn 14. As a result of constituting in this way, the Mach number of the flow which passes whirlpool removal Behn becomes comparatively low, therefore pressure loss decreases. if the comparative examination of this method is carried out to the conventional system of Drawing 1 -- a system -- it turns out that the whole pressure loss may be decreased only by 1.5%. 1.5% of this reduction is equal to the increase in about 15 shaft horsepower in a turbo shaft gas turbine engine. This is illustrated in Drawing 3 showing the relation of the pressure loss from a diffuser throat part [ as opposed to the Mach number (entrance flow coefficient of 3rd / The / figure horizontal axis) of an entrance flow for the performance of the conventional diffuser and the diffuser of the present invention ] to a burner plenum part. The common difference of plenum zone 20, neck 21, and whirlpool removal Behn's 14 geometrical shape is eased by performing whirlpool removal with a comparatively low Mach number. In plenum zone 20, when a flow is a low speed comparatively, drawing-in pipe 16 of a central frame can be arranged in the upper stream from whirlpool removal Behn 14, The flow which goes into a burner as a result becomes much more uniform, and the bad influence to the outlet temperature distribution of a flow and the Ciel temperature of a burner which come out of a burner according to this decreases. Although the suitable example of the present invention was illustrated and described, it is clear that various change can be added within limits which do not deviate from the gist of the present invention. Although the example which applied the present invention to the diffuser of the juxtaductal type was explained, it is equally [ to all the conventional diffusers of the Behn type and a juxtaductal type ] applicable.

[Brief Description of the Drawings]

The sectional view showing the conventional diffuser which built Drawing 1 into the centrifugal compressor of a gas turbine engine, the sectional view in which Drawing 2 shows the diffuser of the present invention, and Drawing 3 are graphs which show the performance of the diffuser of the former and the present invention. 1 ...... An impeller, 3 ...... A braid, 4 ...... A A tap user, 5 ...... An annular housing, 6 [ ...... A transition field 14 / ...... Whirlpool removal Behn 16 / ...... The drawing-in pipe of a central frame, 20 / ...... A plenum zone 21 / ...... Neck. ] ...... A diffuser passage, 7 ...... An entrance, 10 ...... A burner, 12