JP2010286145A - Diffuser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce pressure loss while maintaining stability of flow rate split. <P>SOLUTION: This diffuser includes: a throat part 10 arranged between a diffuser chamber 8 and inner and outer passages 5, 6; and expanded flow passages 11, 12 expanded from the throat part 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a diffuser chamber that decelerates and pressurizes a supplied fluid, and the fluid boosted in the diffuser chamber is arranged with the combustion chamber interposed therebetween and branched into an inner passage and an outer passage that lead to the combustion chamber. It is related with the diffuser supplied.

  For example, a diffuser incorporated in a combustor of a turbojet engine is configured to increase the pressure of the air by reducing the flow rate of the introduced air and supply the air to the combustion chamber. Such a diffuser is configured to branch the introduced air into an inner passage and an outer passage by a cowl.

  The conventional diffuser includes a conventional diffuser that pressurizes air by an inner passage and an outer passage that smoothly increase the passage width, and upstream of the inner passage and the outer passage. There is a dump type diffuser that rapidly boosts air in an enlarged flow path that is installed and then guides the air to an inner passage and an outer passage (see Patent Document 1).

US Pat. No. 4,997,361

By the way, the conventional diffuser branches the introduced air into an inner passage and an outer passage by a cowl having an arc cross section, and gradually raises the air in the inner passage and the outer passage. For this reason, since pressure | voltage rise can be aimed at, suppressing peeling of air, a pressure loss (pressure loss) can be reduced, and this becomes a big advantage.
However, this conventional diffuser promotes and exacerbates the variation in the distribution of the inlet flow velocity of the supplied air. For this reason, there exists a fault that one side peeling is induced and the balance of the air supplied to an inner passage and an outer passage tends to collapse.

In the dump type diffuser, since the introduced air collides violently with the cowl, a pair of separation vortices are formed across the air inlet. If there is a variation in the inlet flow velocity distribution of the supplied air, the size of the separation vortex is deformed according to the variation. As a result, the pressure loss coefficient automatically adjusts the balance between the flow rate of air flowing into the inner passage and the flow rate of air flowing into the outer passage. In other words, the dump diffuser has a function of automatically equalizing the flow split, and has an advantage that the flow split is stabilized.
However, the dump diffuser has a disadvantage that the pressure loss increases because the above-described separation vortex is generated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a diffuser capable of reducing pressure loss while maintaining stabilization of a flow rate split.

  The present invention adopts the following configuration as means for solving the above-described problems.

  1st invention is equipped with the diffuser chamber which decelerates and pressurizes the supplied fluid, the inner channel | path and outer channel | path which are arrange | positioned on both sides of a combustion chamber and guide | inducing the said fluid pressure-rised in this diffuser chamber; A diffuser is provided that is branched and supplied, and includes a throat portion disposed between the diffuser chamber and the inner passage and the outer passage, and an enlarged flow path extending from the throat portion.

  According to a second invention, in the first invention, a front surface where the fluid supplied to the diffuser chamber collides, a side surface communicating with the inner passage or the outer passage, and a corner connecting the front surface and the side surface. A cowl having a portion is provided, and the throat portion is formed by a corner portion of the cowl and a casing that forms the outer shape of the diffuser chamber.

  According to a third aspect of the present invention, in the first or second aspect of the invention, when the pre-diffuser is provided to supply the fluid to the diffuser chamber, and the opening width of the inlet opening of the pre-diffuser is set to “1”, the throat A configuration is adopted in which the channel width of the portion is 1.28, the opening width of the outlet opening of the enlarged channel is 1.88, and the center length distance of the enlarged channel is 1.98.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, a configuration is adopted in which the inclination angle of the front face of the cowl is 82.9 ° with respect to an axis passing through the center of the supply port along the fluid flow direction. .

According to the present invention, the pressure drop can be reduced because the separation vortex generated in the diffuser chamber is prevented from entering the downstream side by the throat portion.
Further, according to the present invention, the flow rate of air supplied to the inner side and the flow rate of air supplied to the outer side can be automatically adjusted by the enlarged flow path, and the flow rate split can be stabilized.
Therefore, according to the present invention, it is possible to reduce pressure loss while maintaining stabilization of the flow split.

It is sectional drawing of a combustor provided with the diffuser which concerns on one Embodiment of this invention. It is a figure which shows the result of having performed the fluid analysis with respect to the conventional dump type diffuser. It is a figure which shows a streamline when the air supplied to the diffuser which concerns on one Embodiment of this invention is biased to the outer side.

  Hereinafter, an embodiment of a diffuser according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a combustor C including a diffuser according to the present embodiment. In FIG. 1, a line XX that horizontally crosses the combustor C indicates an axial center line of the combustor C.

In this embodiment, the combustor C is assumed to be mounted on the jet engine. In FIG. 1, a line X0-X0 extending in parallel with the axial line XX below the combustor C is indicated by the jet engine. The axial center line is shown.
The jet engine has a combustor C and an axial compressor (not shown) on one end side (left end side in the illustrated example) of the combustor C, and has an annular and axisymmetric configuration. Presents.

  In the present embodiment, for the sake of convenience, the axial center line X0-X0 of the jet engine and the axial center line XX of the combustor C are shown in parallel, but they may intersect each other. In the following description, “upstream side” or “downstream side” corresponds to the flow of air in the direction of the axial line XX of the combustor C, and in the illustrated example, the axial line X The left side in the −X direction corresponds to the upstream side, and the right side corresponds to the downstream side. Therefore, the axial compressor (not shown) is located on the upstream side of the combustor C.

  Before describing the diffuser D of the present embodiment, the overall configuration of the combustor C will be described first. As shown in FIG. 1, the combustor C includes a diffuser D, a combustion chamber 1, and an injector 2. The combustor C mixes and burns the air (fluid) supplied through the diffuser D and the fuel supplied from the injector 2 in the combustion chamber 1 provided on the downstream side of the diffuser D. The combustion gas produced | generated as a result of is discharged | emitted.

Further, the combustor C includes an inner passage 5 and an outer passage 6 for guiding the air pressurized by the diffuser D to the combustion chamber 1.
These inner passage 5 and outer passage 6 are formed between a wall surface 3 that forms the outer shape of the combustion chamber 1 and a wall surface 4 a that is a part of the casing 4 that forms the combustor C and faces the wall surface 3. Which is disposed with the combustion chamber 1 in between. Among the flow paths, the flow path on the side of the jet engine axial line X0-X0 is the inner passage 5, and the flow path on the side away from the jet engine axial line X0-X0 is the outer path 6. ing.
In FIG. 1, the channel widths of the inner passage 5 and the outer passage 6 are reduced toward the downstream side. However, it is also possible to adopt a configuration in which the flow path widths of the inner passage 5 and the outer passage 6 do not change toward the downstream side, or increase toward the downstream side.

  Now, the diffuser D of this embodiment is the cowl 7, the diffuser chamber 8, the pre-diffuser 9, the throat part 10 (throat part), the inner expansion flow path 11 (expansion flow path), and the outer expansion flow path 12. (Enlarged flow path).

The cowl 7 divides the air ejected from the pre-diffuser 9 into the inner passage 5 side and the outer passage 6 side, and is placed in front of the pre-diffuser 9 so that the air ejected from the pre-diffuser 9 collides with it. Has been placed.
Actually, the cowl 7 is formed with one or a plurality of through holes or slits, and a part of the air injected from the pre-diffuser 9 is directly in the combustion chamber without passing through the inner flow path 5 and the outer flow path 6. 1 is supplied. However, in FIG. 1, the through hole is omitted.
In the present embodiment, the surface of the cowl 7 on the pre-diffuser 9 side (that is, the collision surface on which the air collides) has a small inclination with respect to the axis XX, whereas the conventional one has a small axis X-X. The inclination with respect to X is set to be large, and is arranged so as to be substantially perpendicular to the injection direction of the air injected from the pre-diffuser 9.
The cowl 7 has a front surface 7b where air supplied to the diffuser chamber 8 collides, a side surface 7c communicating with the inner passage 5 or the outer passage 6, and a corner portion 7a connecting the front surface 7b and the side surface 7c. is doing.

The diffuser chamber 8 is a large-capacity space formed between the cowl 7 and the casing 4. The diffuser chamber 8 is disposed downstream of the pre-diffuser 9 and is connected to the inner enlarged flow path 11 and the outer enlarged flow path 12.
The diffuser chamber 8 decelerates the air ejected from the pre-diffuser 9 and rapidly raises the air.
More specifically, the diffuser chamber 8 includes a cowl 7, an upstream casing 4b provided on the upstream side of the casing 4 and in a direction orthogonal to the axis XX, and the upstream casing 4b. Is formed by a space surrounded by a connection casing 4c that connects the peripheral position of the cylinder and the upstream position of the combustor side casing 4a. The connection casing 4c can be formed of a plate material that connects the tip position of the upstream casing 4b and the upstream position of the combustor side casing 4a in a straight line. However, in the illustrated example, the mechanical strength and the air flow are connected. In consideration of the line state, it is formed on a slightly bent surface at one place in the middle.

The pre-diffuser 9 preliminarily boosts the air upstream of the diffuser chamber 8 and has an opening area that increases toward the downstream. An outlet opening 9 a (supply port) on the downstream side of the pre-diffuser 9 is provided so as to slightly protrude into the diffuser chamber 8. Then, air is supplied to the diffuser chamber 8 from the outlet opening 9a.
As shown in FIG. 1, the front surface 7 b of the cowl 7 is disposed so as to face the pre-diffuser 9.

The throat portion 10 is a joint portion between the diffuser chamber 8 and the inner enlarged passage 11 and the outer enlarged passage 12. The throat portion 10 is a flow path formed by communicating the diffuser chamber 8 with the inner enlarged passage 11 and the outer enlarged passage 12. It is formed to have the smallest flow path area.
That is, the distance from the connecting casing 4c to the “R” of the corner portion 7a of the cowl 7 is formed to be the shortest, and the area indicated by the straight line is the throat portion 10.
Thus, the throat portion 10 is configured to have a shape in which the passage is narrowed down at the corner portion 7 a of the cowl 7. The degree of this narrowing is determined in consideration of the streamline state of air.

The inner enlarged passage 11 is a flow passage that connects the throat portion 10 and the inner passage 5, and is a flow passage whose flow passage area is enlarged toward the downstream side.
Further, the outer enlarged passage 12 is a flow passage that connects the throat portion 10 and the outer passage 6 and is a flow passage whose flow passage area is enlarged toward the downstream side.
In these inner expansion passage 11 and outer expansion passage 12, the flow passage area increases as it goes downstream, so that when the flow velocity of the flowing air increases, the fluid is isolated from the wall surface to form a separation vortex. Is done. And this peeling vortex becomes large in proportion to the flow velocity of air.
That is, in the inner expansion passage 11 and the outer expansion passage 12, the pressure loss coefficient increases as the air flow rate increases.

  According to the diffuser D of the present embodiment having such a configuration, air flows along a streamline as shown in FIG. The streamline shown in FIG. 1 indicates that when the opening width L1 of the inlet opening of the pre-diffuser 9 is “1”, the opening width L2 of the outlet opening of the pre-diffuser 9 is 1.67, and the axial direction of the pre-diffuser 9 is The length distance L3 is 2.75, the separation distance L4 (dump gap) from the outlet opening of the pre-diffuser 9 to the front surface 7b of the cowl 7 is 1.26, the opening width L5 of the throat portion 10 (the flow width of the throat portion) 1.28, the opening width L6 of the outlet opening of the outer enlarged passage 12 and the inner enlarged passage 11 is 1.88, and the center length distance L7 of the outer enlarged passage 12 and the inner enlarged passage 11 is 1.98 (the enlarged flow passage Center length distance), the shortest length distance L8 of the outer enlarged flow path 12 and the inner enlarged flow path 11 is 1.74, the length distance L9 of the outer passage 6 and the inner passage 5 is 7.10, the outer passage 6 or the rear end width L10 of the inner passage 5 is 1.10, the width L11 of the combustion chamber 1 is 5.08, and from the tip position on the upstream side of the cowl 7 to the tip position on the downstream side of the corner portion 7a of the cowl 7. In the fluid analysis, the distance L12 is 0.80, and the inclination angle θ is 82.9 ° with respect to the axial center line XX of the front surface 7b of the cowl 7 (the axis passing through the center of the supply port along the fluid flow direction). It is a result.

FIG. 2 shows the result of a similar fluid analysis performed on a dump type diffuser (conventional diffuser) under the same conditions for the supplied air.
As can be seen by comparing FIG. 1 and FIG. 2, in the diffuser D of the present embodiment, the throat portion 10 prevents the separation vortex generated in the diffuser chamber 8 from entering the downstream side. The contact area between the main air flow and the separation vortex generated in the diffuser chamber 8 is reduced. Therefore, in the diffuser D of this embodiment, it is possible to reduce a pressure loss rather than the conventional dump type diffuser.

FIG. 3 shows streamlines in the diffuser D of the present embodiment when the supplied air is biased toward the outer side (when the inlet flow velocity distribution varies).
As shown in this figure, when the supplied air is biased toward the outer side, the separation vortex of the outer expansion passage 11 having a high flow velocity is increased, and the separation vortex of the inner expansion passage 12 having a low flow velocity is decreased. That is, the pressure loss coefficient on the outer side where the flow rate is relatively increased is increased, and the pressure loss coefficient on the inner side where the flow rate is relatively decreased is decreased. As a result, even if the supplied air is biased toward the outer side, the flow rate of air supplied to the inner side and the flow rate of air supplied to the outer side are automatically adjusted to stabilize the flow split. To do.

According to the diffuser D of the present embodiment as described above, the throat portion 10 prevents the separation vortex generated in the diffuser chamber 8 from entering the downstream side, so that pressure loss can be reduced.
Further, according to the diffuser D of the present embodiment, the flow rate of air supplied to the inner side and the flow rate of air supplied to the outer side are automatically adjusted by the inner enlarged flow channel 11 and the outer enlarged flow channel 12. And the flow split can be stabilized.
Therefore, according to the diffuser D of this embodiment, pressure loss can be reduced while maintaining the stabilization of the flow split.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, the numerical value used for the fluid analysis in the above embodiment is an example, and this numerical value can be changed.

C ... combustor, D ... diffuser, 1 ... combustion chamber, 2 ... injector, 3 ... wall surface, 4 ... casing, 4a ... combustor side casing, 4b ... upstream casing, 4c ... connection casing, 5 ... inner passage, 6 ... outer passage, 7 ... cowl, 7a ... corner, 7b ... front, 7c ... side, 8 ... diffuser chamber, 9 ... pre-diffuser, 9a ... outlet opening (supply port), 10 ... throat part (throat part) ), 11 ... Inner enlarged channel (enlarged channel), 12 ... Outer enlarged channel (enlarged channel)

Claims (4)

A diffuser chamber that decelerates and pressurizes the supplied fluid is provided, and the fluid that has been pressurized in the diffuser chamber is branched and supplied to an inner passage and an outer passage that are disposed across the combustion chamber and lead to the combustion chamber. A diffuser,
A diffuser comprising: a throat portion disposed between the diffuser chamber and the inner passage and the outer passage, and an enlarged flow path extending from the throat portion.   A cowl having a front surface where the fluid supplied to the diffuser chamber collides, a side surface communicating with the inner passage or the outer passage, and a corner portion connecting the front surface and the side surface, the throat portion, The diffuser according to claim 1, wherein the diffuser is formed by a corner portion of the cowl and a casing forming an outer shape of the diffuser chamber.   A pre-diffuser for supplying the fluid to the diffuser chamber, and when the opening width of the inlet opening of the pre-diffuser is set to “1”, the flow width of the throat portion is 1.28, and the outlet of the enlarged flow path The diffuser according to claim 1 or 2, wherein an opening width of the opening is 1.88, and a center length distance of the enlarged flow path is 1.98.   The diffuser according to claim 2, wherein an inclination angle of a front surface of the cowl is 82.9 ° with respect to an axis passing through a center of the supply port along a fluid flow direction.

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