JP5427900B2 - Mixed flow turbine - Google Patents

Description

  The present invention relates to a mixed flow turbine used in a small gas turbine, a supercharger, an expander, and the like.

This type of mixed flow turbine is constantly required to improve efficiency.
The efficiency of the turbine is the ratio of the peripheral speed U at the blade inlet and the maximum speed at which the working fluid (gas) is accelerated at the turbine inlet temperature and pressure ratio, that is, the theoretical speed ratio (= U / C0).
There is an incident loss that deteriorates this efficiency. This is caused by the incidence that is the difference between the flow angle β of the gas flowing into the leading edge of the blade and the blade angle βk at the leading edge. That is, when the incidence increases, the inflowing gas is separated at the leading edge, so that the collision loss increases and the incidence loss occurs.

Since the cross-sectional shape of the blade of the mixed flow turbine when it is cut at a constant radius line is formed in a curved line (parabolic shape) including the vicinity of the leading edge, in the mixed flow turbine, the flow angle β and the blade angle βk Can be designed to approach. Thereby, for example, the incidence on the hub surface can be made close to zero, but the incidence occurs between the hub and the shroud.
That is, since the cross-sectional shape along the radial line is formed in a curved line (parabolic shape), the blade of the mixed flow turbine has a linear flow angle β109 between the hub and the shroud as shown in FIG. On the other hand, since the blade angle βk110 changes parabolically, the incidence of the central region of the blade height is maximized.
Thus, the incidence loss due to the increase in the incidence caused by the difference between the distribution of the flow angle β and the distribution of the blade angle βk leads to an increase in the loss of the mixed flow turbine, and the efficiency thereof decreases.

As what suppresses this reduction in efficiency, for example, one disclosed in Patent Document 1 has been proposed.
As shown in FIG. 18 or FIG. 19, the leading edge 103 of the moving blade 101 is formed to be convex toward the upstream side in the flow direction of the working fluid. As a result, the flow angle distribution 115 has a downward convex curve as shown in FIG.
As a result, the blade angle βk110 distribution and the flow angle β115 distribution are close to each other, particularly in the center of the hub and the shroud, resulting in an incidence Ina. That is, since the incidence is reduced by ΔIn, the incidence loss is reduced accordingly.

In addition, in the radial turbine, for example, as shown in Patent Document 2, the scroll is divided into two parts, and the supply amount of the working fluid is made variable by supplying from one side or from both sides simultaneously. It is used.
As shown in FIG. 21, this is because the scroll 120 uses a partition wall 121 to supply gas to the hub side of the leading edge 125 of the moving blade 124, and the second supply path 122 supplies gas to the shroud side. It is divided into an introduction path 123. When the amount of gas is small, for example, the gas is supplied only from the first introduction path 122, and when it is increased, the gas is supplied from the first introduction path 122 and the second introduction path 123.

JP 2004-92498 A Japanese Utility Model Publication No. 62-79938

By the way, what is shown in Patent Document 1 is the distribution of the flow angle β115 shown in FIG. 20 when the gas is supplied in an ideal state to the leading edge 103 of the moving blade 101. The product cannot be expected to supply gas in this ideal condition.
That is, when the flow path from the scroll 105 toward the moving blade 101 extends in the radial direction as shown in FIG. 18, or as shown in FIG. It is normal if it is tilted to extend its slope.
Further, there is a case where a nozzle 107 provided with a blade forming an airfoil is installed immediately upstream of the moving blade 101.

As shown in FIG. 18, when the gas is supplied to the moving blade 101 in the radial direction, the inclination angle δ of the flow on the hub side becomes small, and thus the effect that the leading edge 103 is formed to be convex toward the upstream side is obtained. The flow angle β on the hub side is halved and becomes larger as shown by the flow angle β distribution 102 in FIG.
For this reason, there is a problem that the incidence, which is the difference between the blade angle βk and the flow angle β, increases and the loss on the hub side increases.
As shown in FIG. 19, when the gas is supplied to the moving blade 101 with an inclination, since the inclination angle on the shroud side is large, the turning angle on the meridian plane of the flow flowing from the scroll 105 into the shroud becomes large. Thus, when the turning angle on the meridian surface increases, the boundary layer of the shroud surface expands at the leading edge of the moving blade 101, and thus the flow angle β on the shroud side decreases. That is, as shown by the flow angle β distribution 104 in FIG. 20, the incidence increases in the opposite direction, and the shroud side loss increases.

On the other hand, what is shown in Patent Document 2 is that the partition wall 121 exists as a plate having a finite thickness upstream from the front edge 125 of the rotor blade 124, and therefore the wake 128 is downstream of the rear edge of the partition wall 121. Develops and loss increases.
Further, since the gas from the first introduction path 122 and the second introduction path 123 is supplied to be inclined with respect to the front edge 125 of the moving blade 124, a boundary layer is formed between the shroud side wall surface and the hub side wall surface of the front edge 125. 127 develops and loss increases.

  In view of the above-mentioned problems, the present invention provides a mixed flow turbine capable of reducing the incidence loss by devising the supply of the working fluid on the hub side and the shroud side, effectively functioning the shape at the inlet side edge of the blade. The purpose is to provide.

In order to solve the above problems, the present invention employs the following means.
That is, according to one aspect of the present invention, a mixed flow turbine rotor blade in which a shape line of an inlet side edge located upstream is convex toward the upstream side, and an outer diameter side end of the mixed flow turbine blade. A scroll that is formed on the upstream side of the mixed flow turbine blade by a casing having a shroud portion that covers the edge, and is a space for supplying a working fluid toward the inlet side edge of the mixed flow turbine blade. The scroll is divided into a shroud side space and a hub side space by a scroll dividing wall, and the shroud side divided wall surface and the hub side divided wall surface on the trailing edge side of the scroll divided wall are respectively The shroud-side inflow passage in which the working fluid flows in a substantially radial direction and the inclined direction of the outer peripheral surface of the hub of the mixed-flow turbine rotor blade inlet flow in a direction substantially the same as the inclined direction of the hub. Forming a Bed-side inlet channel, the hub-side inlet channel provided with a hub-side blade-shaped nozzle, the said hub-side blade-shaped nozzle, when cut in a cylindrical surface centered on the rotational axis of the mixed flow turbine moving blades A mixed flow turbine is provided in which cutting lines on the upper surface and the lower surface forming the blade surface are substantially parallel to the rotation axis .

In the mixed flow turbine blade of the mixed flow turbine, the line connecting the hub side and the shroud side of the inlet side end edge is usually located on the radially outer side on the shroud side.
According to this aspect, the inlet side edge of the mixed flow turbine blade is convex toward the upstream side, in other words, it is intermediate between the line connecting the hub side and the shroud side of the inlet side edge. Since the portion protrudes upstream, the shroud side portion of the inlet side edge is arranged so as to be along substantially the same radial position.
Since the working fluid supplied from the shroud side space through the shroud side inflow passage flows in a substantially radial direction, it flows in parallel to the shroud side wall surface and substantially perpendicular to the inlet side edge of the rotor blade. To do. Therefore, it is possible to prevent the wall surface boundary layer from increasing in the shroud portion of the mixed flow turbine blade inlet.
The working fluid supplied from the hub side space through the hub side inflow passage flows in a direction substantially equivalent to the inclined direction of the hub outer peripheral surface of the mixed flow turbine rotor blade inlet, and therefore flows in parallel to the hub outer peripheral surface. . Therefore, it is possible to prevent the wall boundary layer from increasing on the outer peripheral surface of the hub.

The working fluid flows in a substantially radial direction in the shroud-side inflow passage, and on the other hand, in the hub-side inflow passage, flows in a direction substantially equivalent to the inclined direction on the hub side of the mixed flow turbine blade inlet, so that the operation fluid that has passed through both inflow passages. The fluid flows into the inlet side edge of the mixed flow turbine rotor blade in an intersecting state.
In other words, when viewed from the inlet side edge of the mixed flow turbine blade, there is nothing to prevent the flow of the working fluid upstream.
Therefore, the development of the wake due to the scroll dividing wall can be suppressed.
In this case, the shroud-side divided wall surface and the hub-side divided wall surface on the trailing edge side of the scroll dividing wall form a shroud-side inflow passage and a hub-side inflow passage that intersect with each other, respectively. Therefore, the shroud side surface and the hub side surface are extended so as to intersect at the trailing edge side. Therefore, if it is configured such that the thickness of the scroll dividing wall is eliminated at the trailing edge, the occurrence of a wake can be prevented.

  In this way, it is possible to prevent an increase in the wall boundary layer on the outer peripheral surface of the hub and the shroud at the edge of the inlet side of the mixed flow turbine rotor blade, and to eliminate the influence of the wake due to the scroll dividing wall in the intermediate portion. In addition, the effect of reducing the incidence by the mixed flow turbine rotor blade whose inlet end edge is convex toward the upstream side can be reliably exhibited, and the incidence loss can be reduced.

Since the hub-side inflow passage is inclined with respect to the radial direction, the hub-side inflow passage is longer than the shroud-side inflow passage along the radial direction. Furthermore, since the radius decreases on the hub side, the flow velocity on the hub side increases due to the angular momentum conservation law. For this reason, the working fluid has increased friction loss on the side wall surface of the hub, and the boundary layer may expand in the vicinity of the entrance of the outer peripheral surface of the hub.
In this configuration, since the hub-side wing nozzle is provided, the circumferential speed of the flow flowing through the hub-side inflow passage can be increased. Thereby, the expansion of the boundary layer can be prevented and the efficiency of the mixed flow turbine can be improved.
Since the blade surface of the hub side airfoil nozzle is formed substantially parallel to the rotation axis, it can be easily manufactured by casting.

Further, in the above configuration, the hub side blade type nozzle is provided with a guide plate that is a substantially extended portion of the hub side blade type nozzle up to a position approaching the inlet side edge of the mixed flow turbine blade. Is preferred.

The hub-side inlet channel is inclined with respect to the radial direction, and the blade surface of the hub-side airfoil nozzle is formed substantially parallel to the rotation axis, so that the inlet-side end of the mixed flow turbine blade from the trailing edge of the hub-side airfoil nozzle A space having a long hub side wall surface to the edge is formed. Furthermore, since the radius decreases on the hub side, the flow velocity on the hub side increases due to the law of conservation of angular momentum, so the friction loss on the hub side wall surface increases and the boundary layer may expand near the hub outer peripheral surface. In other words, when a radially inward swirling flow flows on an inclined surface, the flow tends to flow back radially outward due to the centrifugal force caused by the swirling, so the boundary layer may expand beyond the flat boundary layer. is there.
Therefore, a guide plate, which is a substantially extended portion of the hub-side blade-shaped nozzle, so with the trailing edge of the hub-side blade-shaped nozzle to a position close to the inlet-side edges of the mixed flow turbine moving blades, the flow is radially outward The tendency to flow backward can be suppressed, and the expansion of the boundary layer can be prevented.

Further, in the above arrangement, the shroud-side inlet channel, shea shroud-side blade-shaped nozzle is provided, the shroud-side blade-shaped nozzle, blade when cut in a cylindrical surface centered on the rotational axis of the mixed flow turbine moving blades It is preferable that a cutting line between the upper surface and the lower surface forming the surface is substantially parallel to the rotation axis, and the throat width of the shroud side wing type nozzle is larger than the throat width of the hub side wing type nozzle.

The blade angle at the inlet side edge of the mixed flow turbine rotor blade is as large as 40 degrees on the hub side, for example, and the shroud side is as small as that of a radial turbine blade, for example. In other words, the turbine characteristic indicated by the shroud side flow is the reaction turbine characteristic, and the turbine characteristic indicated by the hub side flow is the impulse turbine characteristic.
Since the throat width of the shroud-side wing nozzle is made larger than the throat width of the hub-side wing-type nozzle, the blade of the shroud-side wing-type nozzle has a larger angle with respect to the circumference than that of the hub-side wing-type nozzle.
Therefore, the hub blade type nozzle can have an appropriate nozzle blade angle in the region having the impulse turbine characteristics on the hub side, and the shroud blade type nozzle can have an appropriate nozzle blade angle in the characteristics having the shroud side reaction turbine characteristics. .

  Further, in the above aspect, the inlet portion of the scroll is provided with an inlet dividing wall that divides into a shroud-side flow path communicating with the shroud-side space and a hub-side flow path communicating with the hub-side space. The dividing wall is attached at a position where a channel cross-sectional area of the shroud-side channel is larger than a channel cross-sectional area of the hub-side channel, and at least the shroud-side channel is located upstream of the inlet dividing wall. It is good also as a structure provided with the adjustment member which adjusts the inflow ratio of the said working fluid to the said shroud side flow path and the said hub side flow path while making can fully close.

According to this configuration, the working fluid is divided into the shroud-side flow path and the hub-side flow path at the inlet portion of the scroll by the inlet dividing wall.
The working fluid that has flowed into the shroud side flow path is supplied to the shroud side of the inlet side edge of the mixed flow turbine blade through the shroud side space and the shroud side inflow path.
On the other hand, the working fluid flowing into the hub side flow path is supplied to the hub side of the inlet side edge of the mixed flow turbine rotor blade through the hub side space and the hub side inflow path.
At this time, since the adjustment member can fully close the shroud side flow path, the working fluid can be allowed to flow only into the hub side flow path.
Further, when the shroud-side flow path is not fully closed, the working fluid flows into the shroud-side flow path and the hub-side flow path with an inflow amount along the inflow rate adjusted by the adjustment member.

For example, assuming that the condition of the working fluid flowing into the hub side of the mixed flow turbine blade is substantially constant, it flows into the shroud side channel and the hub side channel as it is when the fluid flows only in the hub side channel. In some cases, the flow rate of the working fluid is different. That is, the flow rate of the working fluid is determined by adding the cross-sectional area of the hub-side flow path when the former is fully closed and the cross-sectional area of the shroud-side flow path and the cross-sectional area of the hub-side flow path in the latter case. Therefore, this ratio becomes the flow rate change.
Since the inlet dividing wall is attached at a position where the channel cross-sectional area of the shroud-side channel is larger than the channel cross-sectional area of the hub-side channel, this change in flow rate can be increased.
Thereby, it is possible to cope with a larger fluctuation amount in the supply amount of the working fluid, and to improve the controllability of the mixed flow turbine.

The turbine characteristic indicated by the shroud side flow in the mixed flow turbine blade is a reaction turbine characteristic, and the turbine characteristic indicated by the hub side flow is an impulse turbine characteristic.
The reaction turbine is highly efficient when U / C0 is small, and the impulse turbine is highly efficient when U / C0 is large.
The adjustment member can fully close the shroud side flow path and can adjust the flow rate of the working fluid into the shroud side flow path and the hub side flow path, so that the shroud side can be adjusted in accordance with the U / C0 situation of the working fluid. The mixed flow turbine can be used in a highly efficient state by adjusting the flow rate of the working fluid into the flow path and the hub side flow path.
For example, when U / C0 is small, the shroud-side flow path is fully closed by the adjusting member, the working fluid is allowed to flow only into the hub-side flow path, and the working fluid is supplied to the hub on the inlet side edge of the mixed flow turbine blade. To supply to the side. As a result, high-efficiency operation is performed by the flow at the hub side with low U / C0 and high efficiency.

In the above configuration, it is preferable that the adjustment member includes a plate member that can swing around the upstream end of the inlet partition wall as an axis.
If it does in this way, the inflow rate of a working fluid can be easily adjusted by rocking a board member.
In addition, in order to perform adjustment reliably, it is preferable that a board member is made into the shape which follows the flow-path cross-sectional shape of the installed part.

  Moreover, in the said structure, the flow path cross section of the said inlet part of the said scroll of the part which the said plate member rock | fluctuates is made into the height along the said axis center substantially constant, and follows the said axis line center of the said plate member. The length is preferably substantially the same as the height.

If it does in this way, since the leakage of the working fluid from the edge part of the plate member orthogonal to the axis center can be substantially prevented, the accuracy of adjustment can be improved and the decrease in efficiency can be prevented.
For example, the cross section of the flow path and the plate member are preferably a rectangle, an oval having a straight portion, or the like.

  According to the present invention, the scroll is divided into the shroud-side space and the hub-side space by the scroll dividing wall, and the shroud-side divided wall surface and the hub-side divided wall surface on the rear edge side of the scroll dividing wall are respectively a portion facing them. Forming a shroud-side inflow passage in which the working fluid flows in a substantially radial direction and a hub-side inflow passage in which the working fluid flows in a direction substantially equivalent to the inclined direction on the hub side of the rotor blade inlet. Since the hub side blade type nozzle formed substantially parallel to the rotation axis is provided, it is possible to prevent the wall boundary layer from increasing on the outer peripheral surface of the hub and the shroud side wall surface at the inlet side edge of the moving blade, and in the middle The influence of the wake by the scroll dividing wall in the part can be eliminated. As a result, the effect of reducing the incidence by the moving blade whose inlet end edge is convex toward the upstream side can be reliably exhibited, and the incidence loss can be reduced. In addition, by providing the hub side blade type nozzle, the circumferential speed of the flow flowing through the hub side inflow passage can be increased, the expansion of the boundary layer can be prevented, and the efficiency of the mixed flow turbine can be improved.

It is a front view which shows the casing of the mixed flow turbine concerning 1st embodiment of this invention. It is XX sectional drawing of FIG. It is a fragmentary sectional view which expands and shows a part of FIG. It is a fragmentary sectional view which shows the same part as FIG. 3 of another embodiment of the mixed flow turbine concerning 1st embodiment of this invention. It is a fragmentary sectional view which longitudinally cuts the main body of the mixed flow turbine concerning 2nd embodiment of this invention, and shows the one part. It is the schematic which shows the shape of the wing | blade and guide plate of the hub side nozzle concerning 2nd embodiment of this invention. It is a fragmentary sectional view which longitudinally cuts the main body of the mixed flow turbine concerning 3rd embodiment of this invention, and shows the one part. It is YY sectional drawing of FIG. It is a longitudinal cross-sectional view of the mixed flow turbine concerning 4th embodiment of this invention. FIG. 10 is a Z view of FIG. 9. FIG. 10 is a W view of FIG. 9. It is a longitudinal cross-sectional view which shows the wing | blade and hub concerning 4th embodiment of this invention. It is a graph which shows the change of the channel area of the hub side, and the channel area of the shroud side by the position of the valve body concerning 4th embodiment of this invention. It is a graph which shows the incidence distribution concerning 4th embodiment of this invention. It is a schematic block diagram which shows the relationship between the hub side nozzle of 4th embodiment of this invention, and the hub side shape of a wing | blade. It is a schematic block diagram which shows the relationship between the shroud side nozzle of 4th embodiment of this invention, and the shroud side shape of a blade | wing. It is a graph which shows the dimensionless characteristic of the mixed flow turbine concerning 4th embodiment of this invention. It is a fragmentary sectional view which cuts along the main part of the conventional mixed flow turbine, and shows the one part. It is a fragmentary sectional view which cuts along the main part of the conventional mixed flow turbine, and shows the one part. It is a graph which shows the incidence distribution of the conventional mixed flow turbine. It is a fragmentary sectional view which cuts along the main part of another conventional mixed flow turbine, and shows the part.

Embodiments according to the present invention will be described below with reference to the drawings.
[First embodiment]
Hereinafter, the mixed flow turbine 1 concerning 1st embodiment of this invention is demonstrated using FIGS. 1-3. This mixed flow turbine 1 is used for a turbocharger for a diesel engine of an automobile.
FIG. 1 is a front view showing a casing 3 of a mixed flow turbine 1 of the present embodiment. FIG. 2 is a sectional view taken along line XX in FIG. FIG. 3 is a partial cross-sectional view showing a part of FIG. 2 in an enlarged manner.

The mixed flow turbine 1 includes a casing 3, a hub 5, and a plurality of blades (mixed flow turbine blades) 7 provided on the outer peripheral surface 6 of the hub 5 at substantially equal intervals in the circumferential direction. ing.
A rotation shaft 9 is fixed to the central portion of the hub 5. The rotating shaft 9 is rotatably supported by a bearing (not shown) attached to the bearing housing 11, and the other end is connected to a turbo compressor (not shown).

The casing 3 includes a main body 13 having a substantially hollow cylindrical shape, a substantially hollow cylindrical shape introduction portion (scroll inlet portion) 15 connected to the main body 13 in the tangential direction, and a substantially coaxial line center from one surface of the main body 13. A discharge portion 17 having a substantially hollow cylindrical shape protruding so as to have C is provided.
The introduction part 15 is connected to an exhaust part of a diesel engine (not shown), and the discharge part 17 is connected to an exhaust part of an automobile (not shown).

The hollow portion of the main body 13, the introduction portion 15, and the discharge portion 17 communicate with each other, and exhaust gas (working fluid) exhausted from the diesel engine introduced from the introduction port 19 of the introduction portion 15 is sent to the blades 7 by the main body 13. The hub 5 is acted to rotate, and is exhausted from the discharge port 21 of the discharge unit 17.
The rotation of the hub 5 is transmitted to a turbo compressor (not shown) via the rotary shaft 9, and the turbo compressor is rotated. Air is compressed by the rotation of the turbo compressor and supplied to the diesel engine.

The inner space of the main body 13 constitutes a scroll 23 that accelerates exhaust gas and supplies it to the blades 7. As shown in FIG. 3, a shroud portion 27 that covers the outer diameter side edge 25 of the blade 7 is formed in the inner portion of the main body 13.
A scroll dividing wall 29 is provided on the inner side of the main body 13 so as to protrude in the radial direction from the outer side to the inner side. The scroll 23 is divided into a shroud side space 31 and a hub side space 33 by a scroll dividing wall 29.

The hub side on the inner periphery (rear edge) side of the scroll partition wall 29 forms a hub-side partition wall surface 35 that is inclined so as to taper toward the shroud side. A shroud side on the inner peripheral side of the scroll dividing wall 29 forms a shroud side dividing wall surface 37 extending in a substantially radial direction.
The hub side wall surface 39 facing the hub side divided wall surface 35 on the hub side of the casing 3 is substantially parallel to the hub side divided wall surface 35, and the hub side inflow passage 41 is between the hub side divided wall surface 35. Is forming.
The hub-side inflow passage 41 has an inclination direction substantially the same as the inclination direction at the upstream end of the outer peripheral portion 6 of the hub 5.

The shroud side wall surface 43 that faces the shroud side divided wall surface 37 on the shroud side of the casing 3 is substantially parallel to the shroud side divided wall surface 37. Is forming.
Since the shroud side divided wall surface 37 extends in a substantially radial direction, the shroud side inflow passage 45 extends in a substantially radial direction.

The wing 7 is a plate-like member, and is erected on the outer peripheral surface 6 of the hub 3 so that the surface portion extends in the axial direction.
The intersection of the front edge 47 and the outer diameter side edge 25 is located outside in the radial direction with respect to the intersection of the hub 5 and the front edge 45.
The blade 7 is provided with a leading edge (inlet side edge) 47 located on the upstream side in the exhaust gas flow direction. As shown in FIG. 3, the front edge 47 is formed of a curved line that bulges smoothly in a convex shape in the entire region toward the upstream side.
The shroud side portion of the front edge 47 has a shape along substantially the same radial position, in other words, substantially perpendicular to the radial direction.

The blade shape of the blade 7 has a parabolic shape that protrudes in the rotational direction from the leading edge 47 to the downstream side when projected onto a constant radius.
The blade angle βk of the front edge 47 is gradually reduced parabolically from the hub 5 side toward the outer diameter side edge 25 side, for example, in the same manner as the conventional one shown in FIG. The blade angle βk at the front edge 47 is, for example, 40 degrees on the hub 5 side and 0 degrees on the outer diameter side edge 25 side.
The hub 5 and the blades 7 are integrally formed by casting or cutting. The hub 5 and the blades 7 may be separated and firmly fixed by welding or the like.

The operation of the mixed flow turbine 1 according to this embodiment described above will be described.
Exhaust gas from the diesel engine flows from the inlet 19 into the inlet 15 and is supplied to the main body 13. The exhaust gas flowing into the main body 13 is divided by the scroll dividing wall 29 and flows into the shroud side space 31 and the hub side space 33, respectively.
The exhaust gas flowing into the shroud side space 31 is supplied to the leading edge 47 of the blade 7 through the shroud side inflow passage 45.

  At this time, since the shroud side inflow passage 45 extends in the substantially radial direction, the exhaust gas flows in the substantially radial direction. Since the shroud side of the front edge 47 is substantially orthogonal to the radial direction, the exhaust gas flows in substantially orthogonal thereto. For this reason, it is possible to prevent the wall surface boundary layer from increasing near the front edge 47 of the shroud portion 27.

On the other hand, the exhaust gas flowing into the hub side space 33 is supplied to the leading edge 47 of the blade 7 through the hub side inflow passage 41.
At this time, since the hub-side inflow passage 41 has an inclination direction substantially equal to the inclination direction at the upstream end of the outer peripheral portion 6 of the hub 5, the exhaust gas supplied to the front edge 47 through the hub-side inflow passage 41. Flows in parallel to the hub outer peripheral surface 6. Therefore, it is possible to prevent the wall surface boundary layer from increasing near the front edge 47 of the outer peripheral surface 6.

The exhaust gas flows in a substantially radial direction in the shroud-side inflow passage 45, and on the other hand, in the hub-side inflow passage 41, the exhaust gas flows in a direction substantially equivalent to the inclination direction of the hub outer peripheral surface 6 of the front edge 47. Since the shroud-side divided wall surface 37 and the hub-side divided wall surface 35 are joined at the rear edge of the scroll-divided wall 29, the exhaust gas flowing through the shroud-side inlet channel 45 and the hub-side inlet channel 41 is the rear edge of the scroll-divided wall 29. Will join. Thereby, the development of the wake generated at the rear edge of the scroll dividing wall 29 can be suppressed.
This means that when viewed from the front edge 47, there is nothing upstream that prevents the flow of exhaust gas.

  Thus, the increase in the wall boundary layer at the outer peripheral surface 6 of the hub 5 and the shroud portion 27 at the leading edge 47 of the blade 7 can be prevented, and the influence of the wake by the scroll dividing wall 29 at the intermediate portion can be eliminated. Therefore, the effect of reducing the incidence by the blade 7 having the leading edge 47 convex toward the upstream side can be surely exhibited, and the incidence loss can be reduced.

As shown in FIG. 4, an airfoil nozzle 49 in which the blade surface is formed substantially parallel to the rotation axis may be provided between the scroll dividing wall 29 and the blade 7.
When the airfoil nozzle 49 is provided in this manner, the circumferential speed of the flow can be increased, and the efficiency of the mixed flow turbine 1 can be improved.
Since the blade surface of the airfoil nozzle 49 is formed substantially parallel to the rotation axis, it can be easily manufactured by casting.

Thus, the exhaust gas flowing into the blades 7 passes between the blades 7. At this time, the exhaust gas pushes the pressure surface of the blade 7 and moves the blade 7 in the rotation direction.
Thereby, the hub 5 integral with the blade 7 rotates in the rotation direction. The turbo compressor is rotated via the rotating shaft 9 by the rotational force of the hub 5. A turbo compressor compresses air and supplies it to a diesel engine as compressed air.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
The mixed flow turbine 1 in the present embodiment is different from that in the first embodiment in the configuration of the hub-side inflow passage 41. Since other components are the same as those of the first embodiment described above, a duplicate description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment mentioned above.
FIG. 5 is a partial cross-sectional view illustrating a part of the main body 13 cut vertically. FIG. 6 is a schematic view showing the shapes of the blades 53 and the guide plate 55 of the hub side nozzle 51.

In the present embodiment, the hub-side inflow passage 41 is provided with a hub-side blade-type nozzle 51 composed of a plurality of blades 53 whose blade surfaces are formed substantially parallel to the rotation axis C.
As shown in FIG. 6, the blades 53 of the hub-side blade-type nozzle 51 are attached so as to be inclined at a predetermined angle with respect to the circumference.
The blades 53 are attached between the nozzle inlet radius NI and the nozzle outlet radius NO.
Since the blade surface of the hub-side airfoil nozzle 51 is formed substantially parallel to the rotation axis, it can be easily manufactured by casting.

A guide plate 55 is attached to the downstream side of the hub-side blade-type nozzle 51 corresponding to each blade 53.
The guide plate 55 has a logarithmic spiral cross-sectional shape and is attached so as to be a substantially extended portion of the wing 53.
The downstream end G of the guide plate 55 extends to the vicinity of the front edge 47 and has a shape that substantially follows the hub-side shape of the front edge 47.

Since the operation of the mixed flow turbine 1 according to the present embodiment configured as described above is basically the same as that of the first embodiment described above, a duplicate description will be omitted, and different parts will be described.
Since the hub-side inflow passage 41 is inclined with respect to the radial direction, the hub-side inflow passage 41 is longer than the shroud-side inflow passage 45 along the radial direction. Furthermore, since the radius decreases on the hub side, the flow velocity on the hub side increases due to the angular momentum conservation law. For this reason, the exhaust gas has increased friction loss on the hub side wall surface 39, and the boundary layer may expand in the vicinity of the front edge 47 of the outer peripheral surface 6 of the hub 5.

In the present embodiment, since the hub-side wing nozzle 51 is provided in the hub-side inflow passage 41, the circumferential speed of the flow flowing through the hub-side inflow passage 41 can be increased.
Thereby, the expansion of the boundary layer can be prevented and the efficiency of the mixed flow turbine can be improved.

  Further, since the hub-side inflow passage 41 is inclined with respect to the radial direction and the blade surface of the hub-side airfoil nozzle 51 is formed substantially parallel to the rotation axis, the hub-side airfoil nozzle 51 and the front side of the blade 7 are formed. A space in which the length of the hub side wall surface 39 up to the edge 47 is long is formed. Further, since the radius decreases on the hub side, the flow velocity on the hub side increases due to the law of conservation of angular momentum, so the friction loss on the hub side wall surface 39 increases, and the boundary layer may expand near the outer peripheral surface 6 of the hub 5. . In other words, when a radially inward swirling flow flows on an inclined surface, the flow tends to flow back radially outward due to the centrifugal force caused by the swirling, so the boundary layer may expand beyond the flat boundary layer. is there.

In the present embodiment, the flow exiting the blade 53 of the hub-side blade-type nozzle 51 is guided to the vicinity of the front edge 47 by the guide plate 55.
Since the flow exiting the hub-side airfoil nozzle 51 flows according to the law of conservation of angular momentum, it is ideally a logarithmic spiral flow.
Since the guide plate 55 has a logarithmic spiral cross-sectional shape, this ideal flow can be maintained.
Since the guide plate 55 is used as necessary, it may be omitted depending on conditions.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
The mixed flow turbine 1 in the present embodiment is different from that in the second embodiment described above in the configuration of the shroud side inflow passage 45. Since other components are the same as those of the second embodiment (first embodiment) described above, redundant description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment mentioned above and 2nd embodiment.
FIG. 7 is a partial cross-sectional view illustrating a part of the main body 13 cut vertically. 8 is a cross-sectional view taken along line YY of FIG.

In the present embodiment, the shroud-side inflow passage 45 is provided with a shroud-side blade-type nozzle 59 composed of a plurality of blades 57 whose blade surfaces are formed substantially parallel to the rotation axis C. Since the blade surface of the shroud side blade type nozzle 59 is formed substantially parallel to the rotation axis, it can be easily manufactured by casting.
As shown in FIG. 8, the wings 57 are attached so as to be inclined so as to have a predetermined angle (blade angle) with respect to the circumference.
The blade angle of the blades 57 is larger than the blade angle of the blades 53 as shown in FIG. As a result, the throat width δs of the shroud-side wing nozzle 59 (width at the portion where the flow is most restricted) becomes larger than the throat width δh of the hub-side wing nozzle 51. For this reason, the shroud side blade type nozzle 59 has a larger flow rate than the hub side blade type nozzle 51.

The operation of the mixed flow turbine 1 according to the present embodiment configured as described above is basically the same as that of the first embodiment and the second embodiment described above. Will be described.
The blade angle at the leading edge 47 of the blade 7 is as large as, for example, 40 degrees on the hub side, and the shroud side is as small as, for example, a moving blade of a radial turbine. In other words, the turbine characteristic indicated by the shroud side flow is the reaction turbine characteristic, and the turbine characteristic indicated by the hub side flow is the impulse turbine characteristic.

The exhaust gas flowing through the shroud side inflow passage 45 is guided to a relatively small blade angle of the shroud side blade type nozzle 59 and smoothly flows into the shroud side of the leading edge 47 having a relatively small blade angle. On the other hand, the exhaust gas flowing through the hub-side inflow passage 41 is guided to a relatively large blade angle of the hub-side blade-type nozzle 51 and smoothly flows into the hub side of the leading edge 47 having a relatively large blade angle.
In this way, by making the throat width δs of the shroud side blade type nozzle 59 larger than the throat width δh of the hub side blade type nozzle 51, the hub side blade type nozzle 51 has a nozzle blade suitable for the region having the impulse turbine characteristics on the hub side. The shroud side blade type nozzle 59 can have a nozzle blade angle suitable for the characteristics of the shroud side reaction turbine characteristics.
Since the guide plate 55 is used as necessary, it may be omitted depending on conditions.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
The mixed flow turbine 1 in the present embodiment has the same basic configuration as that of the second embodiment described above, but the configuration of the introduction unit 15 is different. Therefore, here, this different point will be mainly described, and the redundant description of other components will be omitted.
In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment mentioned above-2nd embodiment.
FIG. 9 is a longitudinal sectional view of the mixed flow turbine 1. FIG. 10 is a Z view of FIG. FIG. 11 is a W view of FIG. FIG. 12 is a longitudinal sectional view showing the wing 7 and the hub 5.

The mixed flow turbine 1 according to the present embodiment is a variable capacity type in which the capacity can be varied in a wide range.
When the pressure ratio between the turbine inlet and outlet is constant, when a turbocharger to which this mixed flow turbine 1 is applied is mounted on a passenger car or truck, the minimum flow rate and maximum flow rate of the mixed flow turbine 1 are The flow rate ratio is required to vary in the range of 1: 3 to 1: 5.

The introduction part 15 has a substantially rectangular cross section. The internal space of the introducing portion 15 is divided into a hub-side flow path 63 that communicates with the hub-side space 31 and a shroud-side flow path 65 that communicates with the shroud-side space 31 by the inlet dividing wall 61.
The entrance dividing wall 61 is installed substantially parallel to one side of the rectangular internal space. The inlet dividing wall 61 is installed at a position shifted from an intermediate position CL on a side substantially orthogonal to the hub side flow path 63 so that the cross sectional area of the hub side flow path 63 is smaller than the cross sectional area of the shroud side flow path 65.

The amount of deviation is set as appropriate. Here, the cross-sectional area of the hub-side flow path 63 is set to be approximately half of the cross-sectional area of the shroud-side flow path 65.
That is, since the widths are approximately the same, the height Ah of the hub side channel 63 is approximately half the height As of the shroud side channel 65, in other words, Ah: As≈1: 2.

A flow rate variable valve (adjustment member) 67 is provided at the upstream end, which is the upstream portion of the inlet dividing wall 61.
The variable flow valve 67 has a swinging shaft 69 rotatably attached to the upstream end of the introduction portion 15 and the inlet dividing wall 61 and a substantially rectangular shape, and one side of the swinging shaft 69 is fixedly attached to the swinging shaft 69. Further, a valve body (plate member) 71 and a hydraulic cylinder 73 that rotates the swing shaft 69 around the axis center thereof are provided.
The rectangular internal space of the introduction portion 15 has a substantially constant height along the swing shaft 69, and the length of the valve body 71 along the swing shaft 69 is substantially the same as this height.

  Thereby, when the valve body 71 moves, the clearance gap between the inner wall surface of the introducing | transducing part 15 and the valve body 71 can be maintained constant in all opening. Further, the flow flowing through the shroud side of the valve body 71 becomes a substantially uniform flow in the height direction and flows into the shroud side flow path 65, and the flow flowing through the hub side of the valve body 71 flows almost uniformly in the height direction. And can flow into the scroll.

In addition, the cross-sectional shape of the internal space of the introduction part 15 and the shape of the valve body 71 are not limited to a rectangular shape, and can be appropriately formed.
At this time, the flow path cross section of the internal space of the introduction portion 15 where the valve body 71 swings has a substantially constant height along the swing shaft 69, and the length along the swing shaft 69 of the valve body 71. Is preferably substantially the same as this height. As this shape, it is good also as an ellipse which has a linear part, for example.
In this way, leakage of the working fluid from the end of the valve body 71 orthogonal to the swing shaft 69 can be substantially prevented, so that adjustment accuracy can be improved and efficiency reduction can be prevented.

The minimum length of the valve body 71 and the expansion / contraction range of the hydraulic cylinder 73 are such that the valve body 71 can fully close the shroud-side flow path 65.
Further, when the valve angle when the valve element 71 is set so as to narrow the hub-side flow path 63 is defined as minus, the maximum angle to the minus side is −20 to −30. Limited to be degrees.
The maximum length of the valve body 71 is set so that the area formed by the tip portion and the area of the hub-side flow path 63 is a ratio of 1: 2.5 or less when the maximum angle is toward the minus side. Yes. This is because the flow path formed by the valve body 71 and the scroll wall serves as a diffuser, so that the pressure loss increases rapidly when the area ratio exceeds 2.5.

FIG. 12 shows the shape of the leading edge 47 of the wing 7. A straight line having an intermediate angle between the radial line K and the vertical line V perpendicular to the outer peripheral surface of the hub 5 is defined as a straight line H, and a straight line S having a constant radius near the shroud. As for the shape of the front edge 47, the hub side is along the straight line H, the shroud side is substantially along the straight line S, and the middle part is formed by an arc connecting these two straight lines.
With this shape, the distance between the rear edge of the shroud-side nozzle 59 and the front edge 47 and the distance between the rear edge of the guide plate 55 provided on the downstream side of the hub-side nozzle 51 and the front edge 47 are kept substantially constant. I can do it.

In addition, the relationship between the representative length bh on the hub side of the front edge 47 and the representative length bs on the shroud side is set to bh: bs≈2: 3.
The throat width δh of the hub side wing type nozzle 51 and the throat width δs of the shroud side wing type nozzle 59 are set to δh: δs≈3: 4.
As a result, the relationship between the throat area Sh of the hub-side airfoil nozzle 51 and the throat area St of the shroud-side airfoil nozzle 59 is 2 × 3: 3 × 4≈1: 2.
That is, the area ratio between the hub-side channel 63 and the shroud-side channel 65 that is the inlet and the throat area ratio that is the outlet are set to be substantially the same.

  The operation of the mixed flow turbine 1 according to the present embodiment configured as described above is basically the same as that of the first embodiment, the second embodiment, and the third embodiment described above. Omitted and different parts will be described.

According to the present embodiment, the exhaust gas flowing into the introduction portion 15 is divided into the shroud side flow path 65 and the hub side flow path 63 by the inlet dividing wall 61.
The exhaust gas flowing into the shroud side flow path 65 is supplied to the shroud side of the leading edge 47 of the blade 7 through the shroud side space 31 and the shroud side inflow path 45.
On the other hand, the exhaust gas flowing into the hub side flow path 63 is supplied to the hub side of the leading edge 47 of the blade 7 through the hub side space 33 and the hub side inflow path 41.

At this time, since the shroud side flow path 65 and the hub side flow path 63 can be fully closed, the working fluid can be allowed to flow only into the hub side flow path.
In addition, when the shroud side flow path 65 is not fully closed, the exhaust gas flows into the shroud side flow path 65 and the hub side flow path 63 with an inflow amount along the inflow rate adjusted by the valve body 71.

FIG. 13 shows the relationship between the flow path area AhS on the hub side and the flow path area AsS on the shroud side at each flow path position depending on the position of the valve body 71.
The flow path positions of the knots that change include the position SI of the inlet 19 that is the inlet of the scroll, the position BI that is the tip of the valve body 71, the position DI that is the upstream end of the inlet dividing wall 61, the nozzle inlet radius NI position, and the nozzle. This is the exit radius NO position.
When the valve body 71 is located at the extended position of the inlet dividing wall 61, so-called fully open, the hub-side channel area AhS and the shroud-side channel area AsS at the positions SI, BI, and DI are the lines Zos and Constant and unchanged as shown in Zoh.

  When the valve body 71 completely closes the shroud side flow path, that is, the so-called fully closed state, the shroud side flow path area AsS is 0 at the position BI as shown by the line Zss, and when the valve body 71 is fully opened toward the position DI. It increases so as to become the flow path area. On the other hand, the flow path area AhS on the hub side decreases so as to be the flow path area when fully opened toward the position DI at the position BI as shown by the line Zsh.

  When the valve element 71 is positioned at a negative angle, the shroud-side channel area AsS increases by an amount corresponding to the upstream end position of the valve element 71 at the position BI as shown by the line Mks, and moves toward the position DI. To reduce the flow area to the fully open position. On the other hand, the flow area AhS on the hub side decreases by an amount corresponding to the increase in the flow area AsS on the shroud side at the position BI as indicated by the line Mkh, and becomes the flow area when fully opened toward the position DI. So as to increase.

Since the hub-side flow path 63, the hub-side space 33, and the hub-side inflow path 41 are gradually reduced in area, the hub-side flow path area is gradually reduced from the position DI to the position NO.
Since the area of the shroud side flow path 65, the shroud side space 31, and the shroud side inflow path 45 is gradually reduced, the flow area on the shroud side is gradually reduced from the position DI to the position NO.

When fully closed, the exhaust gas flows only through the hub-side channel 63, and when fully opened, flows through the hub-side channel 63 and the shroud-side passage 65.
The cross-sectional area of the hub-side flow path 63, that is, the flow path area, is approximately the half of the cross-sectional area of the shroud-side flow path 65, that is, the flow path area. The ratio is 1: 3.
For example, if the condition of the working fluid flowing into the hub side of the front edge 47 is substantially constant, the flow rate ratio between the fully closed state and the fully opened state is 1: 3.

In this way, the inlet dividing wall 61 is attached at a position where the flow passage cross-sectional area of the shroud-side flow passage 65 is twice the flow passage cross-sectional area of the hub-side flow passage 63. The flow rate ratio can be increased. Thereby, the controllability of the mixed flow turbine 1 and the response | compatibility to an engine side request | requirement can be improved.
Furthermore, when the valve is fully opened, an amount corresponding to the area ratio flows through the hub-side channel 63 and the shroud-side channel 65, so that the flow rates of the exhaust gas flowing through the hub-side channel 63 and the shroud-side channel 65 become substantially equal. The pressure loss of the hub side flow path 63 and the shroud side flow path 65 can be substantially equal and minimized.

The exhaust gas flowing into the shroud side flow path 65 and the hub side flow path 63 flows into the shroud side space 31 and the hub side space 33.
The exhaust gas flowing into the shroud side space 31 is supplied to the leading edge 47 of the blade 7 through the shroud side inflow passage 45. The exhaust gas flowing into the hub side space 33 is supplied to the leading edge 47 of the blade 7 through the hub side inflow passage 41.

  At this time, as described in the first embodiment, an increase in the wall boundary layer at the outer peripheral surface 6 of the hub 5 and the shroud portion 27 at the leading edge 47 of the blade 7 can be prevented, and the scroll dividing wall at the intermediate portion 29 can eliminate the influence of the wake, so that it is possible to reliably exhibit the effect of reducing the incidence by the blade 7 having the leading edge 47 convex toward the upstream side, and the occurrence loss can be reduced.

That is, as shown in FIG. 14, in the conventional mixed flow turbine that does not have the characteristics of Patent Document 1, the leading edge 47 of the blade 7 has a flow angle β71 linearly between the hub 5 and the shroud portion 27. Change. On the other hand, since the blade angle βk73 changes parabolically, the incidence of the central region of the blade height increases to the maximum.
In the present embodiment, since the leading edge 47 of the blade 7 is formed to be convex toward the upstream side, the flow angle β75 becomes smaller and changes in a curvilinear manner as shown in FIG.
As a result, the blade angle βk73 distribution and the flow angle β75 distribution are close to each other, particularly in the center portion of the hub 5 and the shroud portion 27, and an incidence Ina is obtained. That is, since the incidence is reduced by ΔIn, the incidence loss is reduced accordingly.

FIG. 15 shows the relationship between the hub side nozzle 51 and the hub side shape of the blade 7. The throat width δh of the hub side nozzle 51 is narrow, and the inclination angle of the blade 53 is small. On the other hand, the blade angle βkh of the leading edge 47 of the blade 7 is increased. Such a turbine is called an “impulsive turbine” and has high efficiency when U / C0 is small.
FIG. 16 shows the relationship between the shroud side nozzle 59 and the shroud side shape of the blade 7. The throat width δs of the shroud side nozzle 59 is wide, and the inclination angle of the blades 57 is large. On the other hand, the blade angle βks of the leading edge 47 of the blade 7 is made small. Such a turbine is called a “reaction turbine” and has high efficiency when U / C0 is large.

When the mixed flow turbine 1 is used as a variable capacity turbocharger for a passenger car or truck, U / C0 is reduced to 0.5 to 0.6 during acceleration, while U / C0 is increased to 0.7 to 0.8 at maximum output. Get higher. The common area UA is used when U / C0 is in the range of 0.6 to 0.7.
FIG. 17 shows the dimensionless characteristics of the mixed flow turbine 1.
When the valve body 71 is fully closed, the exhaust gas flows only through the hub side flow path 63 and is supplied to the hub side of the front edge 47 through the hub side inflow path 41. Therefore, low U / C0 is efficient. The fully closed characteristic 75 is shown.

On the other hand, when fully opened, the exhaust gas flows through the hub-side channel 63 and the shroud-side channel 65 and is supplied to the hub side and the shroud side of the front edge 47. At this time, since the amount of exhaust gas supplied to the shroud side is approximately twice the amount of exhaust gas supplied to the hub side, the flow characteristics on the shroud side are the main components. Therefore, the fully open characteristic 77 which is efficient at high U / C0 is shown.
When the valve body 71 is in an intermediate position between fully open and fully closed, an intermediate characteristic 79 is shown that is positioned between the fully closed characteristic 75 and the fully open characteristic 77.

The fully closed characteristic 75 shows the maximum efficiency in the vicinity of the acceleration operating point A, and the fully open characteristic 77 shows the maximum efficiency in the vicinity of the maximum output operating point M. Further, the characteristics at the time of the intermediate opening may show high efficiency in the normal range UA.
In this way, by adjusting the opening degree of the valve body 71, it is possible to continuously perform highly efficient operation from the time of acceleration to the time of maximum output.
When larger U / C0 characteristics are required depending on the operating point of the engine, the angle of the valve body 71 is controlled to the minus side, and the ratio of the characteristics on the shroud side to the characteristics on the hub side is controlled mainly on the characteristics on the shroud side. can do.

  In this embodiment, the shroud side blade type nozzle 59, the hub side blade type nozzle 51, and the guide plate 55 are used. However, these are used as necessary, and may be omitted depending on conditions. That is, you may make it combine the structure of the introduction path 15 concerning this embodiment with the structure of 1st embodiment and 2nd embodiment.

  In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

DESCRIPTION OF SYMBOLS 1 Mixed flow turbine 3 Casing 5 Hub 6 Outer peripheral part 7 Blade | blade 15 Introducing part 23 Scroll 25 Outer side edge 27 Shroud part 29 Scroll dividing wall 31 Shroud side space 33 Hub side space 35 Hub side dividing wall surface 37 Shroud side dividing wall surface 41 Hub side inflow path 45 Shroud side inflow path 47 Leading edge 49 Airfoil nozzle 51 Hub side airfoil nozzle 55 Guide plate 59 Shroud side airfoil nozzle 61 Inlet partition wall 63 Hub side flow path 65 Shroud side flow path 67 Flow rate variable valve 71 Valve body

Claims (6)

A mixed flow turbine rotor blade in which the shape line of the inlet side edge located on the upstream side is convex toward the upstream side;
Formed upstream of the mixed flow turbine blade by a casing having a shroud portion covering the outer diameter side edge of the mixed flow turbine blade, and working fluid toward the inlet side edge of the mixed flow turbine blade A scroll turbine that is a space for supplying
The scroll is divided into a shroud side space and a hub side space by a scroll dividing wall,
The shroud-side divided wall surface and the hub-side divided wall surface on the trailing edge side of the scroll dividing wall have a shroud-side inlet passage through which the working fluid flows in a substantially radial direction and a mixed flow turbine rotor blade inlet, respectively. forming a hub-side inlet channel flows in the inclination direction substantially equal to the direction of hub outer circumference, provided with a hub-side blade-shaped nozzle to the hub-side inlet channel, the hub-side blade-shaped nozzle, the mixed flow turbine moving blades A mixed flow turbine in which the cutting lines of the upper surface and the lower surface that form the blade surface when cut by a cylindrical surface centered on the rotation axis are substantially parallel to the rotation axis . 2. The guide plate according to claim 1, wherein a guide plate that is a substantially extended portion of the hub side airfoil nozzle is provided to the hub side airfoil nozzle up to a position approaching an inlet side edge of the mixed flow turbine blade. Mixed flow turbine. The downstream portion of the shroud-side inlet channel, provided with a sheet shroud-side blade-shaped nozzle, the shroud-side blade-shaped nozzle, forming a blade surface when cut in a cylindrical surface centered on the rotational axis of the mixed flow turbine moving blades The cutting line of the upper surface and lower surface to perform is substantially parallel to the said rotating shaft, The throat width of this shroud side blade type nozzle is made larger than the throat width of the said hub side blade type nozzle. Mixed flow turbine. The inlet portion of the scroll is provided with an inlet dividing wall that divides into a shroud-side channel communicating with the shroud-side space and a hub-side channel communicating with the hub-side space,
The inlet dividing wall is attached at a position where a flow passage cross-sectional area of the shroud-side flow passage is larger than a flow passage cross-sectional area of the hub-side flow passage,
An adjustment member is provided on the upstream side of the inlet dividing wall so that at least the shroud-side flow path can be fully closed and the flow rate of the working fluid into the shroud-side flow path and the hub-side flow path is adjusted. The mixed flow turbine according to claim 1, wherein the mixed flow turbine is provided.   The mixed flow turbine according to claim 4, wherein the adjustment member includes a plate member that is swingable about an upstream end of the inlet partition wall as an axis.   The flow passage cross section of the inlet portion of the scroll at least the portion where the plate member swings has a substantially constant height along the axis center, and the length along the axis center of the plate member is the height. 6. A mixed flow turbine according to claim 5, wherein the mixed flow turbine is substantially identical.

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