JP2010265761A - Inducer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inducer device suppressing the vibration caused by a reverse flow, secondary flow, cavitation and the like, and materializing high suction performances while improving the load balance of a blade whole body. <P>SOLUTION: The blade 9 of the inducer device 10 includes a blade root 9a joined with a rotary shaft 3a and the distal end 9b at an opposite side to the blade root 9a, and includes the leading edge 9c at the upstream end and the trailing edge 9d at the downstream end. When angles formed by the blade surface of blade 9 and relative velocity vector ω which is fluid velocity component vector of an axial direction of the rotary shaft 3a in a view from a rotating blade 9 and the blade surface of the blade 9 is defined as the approach angle α of fluid, (1) the approach angle α at the leading edge 9c is larger than the approach angle at the trailing edge 9d, (2) the difference between the approach angle at the blade root 9a and the approach angle at the distal end 9b is at least roughly same at the leading edge 9c and the trailing edge 9d, and (3) the difference between the approach angle at the leading edge 9c and the approach angle at the trailing edge 9d is at least roughly same at the blade root 9a and the distal end 9b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inducer device provided in a pump used in a rocket engine or the like.

  In a rocket engine or the like, a large suction capacity pump such as a turbo pump is used to pressurize a cryogenic fluid such as liquid hydrogen or liquid oxygen.

  Such a pump has, for example, the configuration shown in FIG. That is, the pump (turbo pump) 3 includes a rotating shaft 3a, a pump impeller 3b fixed to the rotating shaft 3a, and a turbine impeller 3c fixed to the rotating shaft 3a. The rotating shaft 3 a is rotatably supported by the casing 7 via the bearing 5.

The inducer device is provided to maintain the suction performance of the pump 3. That is, the inducer device is provided in front of the pump impeller 3b of the turbo pump 3, and assists the fluid suction of the pump impeller 3b by pressurizing the suction fluid. When the rocket is launched from the ground and ascends, the atmospheric pressure decreases as the altitude increases, so that sufficient pressure may not be obtained at the inlet of the pump 3. Therefore, the pressure of the cryogenic fluid is increased by the inducer device so that the turbo pump 3 can sufficiently suck the fluid.
As shown in FIG. 9, the inducer device has an impeller composed of a plurality of blades 9 fixed to the end 7a of the rotary shaft 3a on the upstream side of the pump impeller 3b. The rotating shaft 3a is rotationally driven by the turbine, whereby the plurality of blades 9 of the inducer device rotate at the same speed as the turbine impeller 3c and the pump impeller 3b. Its rotational speed is tens of thousands of revolutions / minute. As a result, the inducer device preloads the suction fluid and sends it to the pump impeller 3b.

  The inducer apparatus as described above is described in, for example, Patent Document 1 below. Other prior art documents in the technical field of the present invention include the following Patent Documents 2 and 3.

JP 2005-273621 A JP 11-294388 A JP 2005-330865 A

Conventionally, the shape of the trailing edge of the blade 9 has been designed in consideration of the fact that the fluid pressurization characteristic (lift characteristic) by the inducer device depends on the shape of the trailing edge of the blade 9 that is the downstream end of the blade 9. . Further, the shape of the leading edge of the blade 9 has been designed in consideration of the fact that the cavitation characteristics of the inducer device depend on the shape of the leading edge of the blade 9 that is the upstream end of the blade 9.
However, conventionally, it has been difficult to achieve high suction performance by suppressing rotation shaft vibration due to cavitation, reverse flow, or secondary flow while improving the load balance of the blade 9 as a whole.

  Cavitation is a phenomenon in which a low pressure region is generated in a liquid flowing at high speed, and a gas phase or a gas-liquid mixed phase is generated in this low pressure region. Cavitation occurs behind the leading edge of the blade 9 in the rotational direction. The secondary flow is a flow generated on a plane perpendicular to the main flow (the axial flow of the rotating shaft 3a).

  Accordingly, an object of the present invention is to provide an inducer device capable of realizing high suction performance by suppressing vibration due to cavitation, reverse flow, or secondary flow while improving the load balance of the entire blade.

In order to achieve the above object, according to the present invention, there is provided an inducer device provided in a pump having a pump impeller for sucking fluid, and a rotary shaft on which the pump impeller is fixed and rotationally driven.
A blade fixed to the rotary shaft on the upstream side of the pump impeller,
The blade has a root coupled to the rotating shaft and a tip opposite to the root, and has a leading edge that is an upstream end and a trailing edge that is a downstream end,
The fluid velocity component vector (U) in the axial direction of the rotating shaft is defined as an angle formed by the relative velocity vector (ω) viewed from the blade and the blade surface of the blade as the fluid entrance angle (α).
(1) The approach angle is larger at the trailing edge than at the leading edge,
(2) The magnitude of the difference between the entry angle at the root and the entry angle at the tip is at least approximately the same at the front edge and the rear edge,
(3) The inducer device is characterized in that the magnitude of the difference between the approach angle at the leading edge and the approach angle at the trailing edge is at least substantially the same between the root and the tip. Provided.

In the above-described configuration, (1) the approach angle is larger at the trailing edge than at the leading edge, so that the load acting on the blade can be distributed to the trailing edge side without being concentrated on the leading edge side. (2) Since the magnitude of the difference between the approach angle at the root and the approach angle at the tip is at least approximately the same at the leading edge and the trailing edge, the wing is at the root at the leading edge. The difference between the amount of work done at the tip and the amount of work done at the tip and the difference between the amount of work done at the root of the blade and the amount of work done at the tip can be made the same, so that the load balance and rotation of the blade The balance can be improved. (3) Further, since the magnitude of the difference between the approach angle at the leading edge and the approach angle at the trailing edge is at least substantially the same at the root and the tip, the wing is at the leading edge at the root. The difference between the amount of work done at the trailing edge and the amount of work done at the trailing edge, and the difference between the amount of work done at the leading edge of the blade at the leading edge and the amount of work done at the trailing edge can be made comparable, and this makes the load balance of the blade In addition, the rotation balance can be improved.
Thus, as described in (1) above, the load acting on the wing can be distributed to the trailing edge without being concentrated on the leading edge, and further, as in (2) and (3) above, The load balance and the rotation balance are improved, and these combine to improve the load balance of the entire blade, while suppressing vibration due to cavitation, reverse flow, secondary flow, etc., and realizing high suction performance.

  According to a preferred embodiment of the present invention, the approach angle gradually changes as it moves from the leading edge to the trailing edge, and gradually changes as it moves from the root to the tip.

  In the above configuration, the approach angle gradually changes as it moves from the leading edge to the trailing edge, and also gradually changes as it moves from the root to the tip, thereby further improving the load balance and rotation balance of the blade. be able to.

According to a preferred embodiment of the present invention,
(1) The approach angle is 1 degree or more larger at the rear edge than at the front edge at the root and the tip,
(2) Assuming that the difference between the approach angle at the base and the approach angle at the tip is ΔT at the trailing edge and ΔL at the leading edge, ΔT / ΔL is 0.9 or more. 1.1 or less,
(3) Assuming that the difference between the approach angle at the leading edge and the approach angle at the trailing edge is Δh at the root and Δt at the tip, Δh / Δt is 0.9 or more. 1.1 or less,
(4) At the front edge and the rear edge, the difference between the entry angle at the root and the entry angle at the tip is 4.0 degrees or less.

In the above configuration, (1) the approach angle is larger at the root and the tip at the trailing edge by 1 degree or more than the leading edge, so that the load acting on the wing is not concentrated on the leading edge side. Can be effectively dispersed. (2) Further, assuming that the magnitude of the difference between the approach angle at the root and the approach angle at the tip is ΔT at the trailing edge and ΔL at the leading edge, ΔT / ΔL is set to 0. By setting it to 9 or more and 1.1 or less, the difference between the amount of work performed at the base of the blade at the leading edge and the amount of work performed at the tip, and the amount of work performed at the root and the tip of the blade at the trailing edge The difference can be made substantially the same, thereby improving the load balance and rotation balance of the blade. (3) Further, assuming that the difference between the approach angle at the leading edge and the approach angle at the trailing edge is Δh at the root and Δt at the tip, Δh / Δt is set to 0. By setting it to 9 or more and 1.1 or less, the difference between the work done at the leading edge and the work done at the trailing edge at the root of the blade, and the work done at the leading edge and the trailing edge at the tip of the blade Can be made the same level, so that the load balance and rotation balance of the blades can be improved. (4) In addition, at the leading edge and the trailing edge, the difference between the approach angle at the root and the approach angle at the tip is 4.0 degrees or less, so that the wings are at the leading edge and the trailing edge. The difference between the amount of work at the root and the amount of work at the tip can be kept small, thereby improving the load balance and rotation balance of the blades.
Thus, as described in (1) above, the load acting on the blade can be distributed to the trailing edge side without being concentrated on the leading edge side. Further, as described in (2) to (4) above, The load balance and the rotation balance are improved, and these combine to improve the load balance of the entire blade, while suppressing vibration due to cavitation, reverse flow, secondary flow, etc., and realizing high suction performance.

  According to the above-described present invention, it is possible to improve the load balance of the entire blade, suppress vibration due to cavitation, reverse flow, secondary flow, and the like, and realize high suction performance.

FIG. 10 is an AA arrow view of FIG. 9, showing an inducer device according to an embodiment of the present invention. FIG. 10 is a partially enlarged view of FIG. 9 showing an inducer device according to an embodiment of the present invention. It is a perspective view which shows an example of the inducer apparatus by this embodiment. FIG. 10 is a plan view in which the blades of the inducer device of FIG. 9 are developed in the rotational direction and are shown in a plan view. It is the elements on larger scale of Drawing 4, and is a figure for explaining an approach angle. FIG. 5 is a partially enlarged view of FIG. 4, (A) shows the tip of the leading edge, and (B) shows the root of the leading edge. FIG. 5 is a partially enlarged view of FIG. 4, (A) shows the tip of the trailing edge, and (B) shows the root of the trailing edge. It is a table | surface which shows the simulation result about the several blade shape of an inducer apparatus. It is a structural example of the turbo pump provided with the inducer apparatus.

  The best mode for carrying out the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to a common or corresponding part, and the overlapping description is abbreviate | omitted.

  1 is an AA arrow view of FIG. 9, showing an inducer device according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of FIG. 9, but shows an inducer device according to an embodiment of the present invention. FIG. 3 is a perspective view showing an example of the inducer device according to the present embodiment.

  The inducer device 10 according to the present embodiment is provided in the turbo pump 3 shown in FIG. The configuration of the turbo pump 3 may be the same as that described with reference to FIG. That is, as shown in FIG. 9, the turbo pump 3 includes a rotating shaft 3a, a pump impeller 3b fixed to the rotating shaft 3a, and a turbine impeller 3c fixed to the rotating shaft 3a. The rotating shaft 3 a is rotatably supported by the casing 7 via the bearing 5.

  As shown in FIG. 1, the inducer device 10 according to the present embodiment includes blades 9 fixed to the rotary shaft 3a on the upstream side of the pump impeller 3b.

In the present embodiment, a plurality of wings 9 (three in the example of FIG. 1) are provided. The plurality of blades 9 are fixed to the rotating shaft 3a on the upstream side of the pump impeller 3b, and are arranged in the rotating direction of the rotating shaft 3a (hereinafter simply referred to as the rotating direction). Each wing 9 has the same size and shape. The plurality of blades 9 are shifted from each other by equal intervals in the rotation direction. In FIG. 1, the inner wall surface 7 a of the casing 7 extends in the rotational direction so as to surround the plurality of blades 9 on the outer side in the radial direction (hereinafter simply referred to as “radial direction”) of the rotary shaft 3 a.
The blade 9 has a root 9a coupled to the rotating shaft 3a, a tip 9b on the casing 7 side opposite to the root 9a, a leading edge 9c as an upstream end, and a downstream end. And a trailing edge 9d. The radial direction is a direction from the root 9a toward the tip 9b.

  FIG. 4 is a diagram showing the blade 9 in a plan view with the blade 9 of FIG. 9 deployed in the rotation direction, and shows a case according to the present embodiment. That is, FIG. 4 is a view of the blade 9 as viewed from the outside in the radial direction in FIG. 9, but shows the blade 9 developed in the rotational direction. The blades 9 extend perpendicular to the axial direction of the rotating shaft 3a (hereinafter simply referred to as the axial direction) at each rotational direction position.

    The shape of the blade 9 according to the present embodiment will be described using the approach angle α shown in FIG. FIG. 5 is a partially enlarged view of FIG. The approach angle α is an angle formed by the relative velocity vector ω and the blade surface (on the ventral side) of the blade 9. The relative velocity vector ω is a velocity vector viewed from the blade 9 rotating the fluid velocity component vector Ca in the axial direction (entering the blade 9). In FIG. 5, U represents the rotational speed vector of the wing 9, and β represents the angle formed by the (velocity) blade surface of the wing 9 and the rotational speed vector U.

According to the present embodiment, the shape of the wing 9 is as follows.
(1) The approach angle α is greater at the trailing edge 9d than at the leading edge 9c (at each radial position).
(2) The magnitude of the difference between the entry angle α at the root 9a and the entry angle α at the tip 9b is at least substantially the same between the front edge 9c and the rear edge 9d.
(3) The magnitude of the difference between the approach angle α at the front edge 9c and the approach angle α at the rear edge 9d is at least substantially the same between the root 9a and the tip 9b.
(4) Preferably, at the front edge 9c and the rear edge 9d (that is, at each radial position), the difference between the entry angle α at the root 9a and the entry angle α at the tip 9a. Is 4.0 degrees or less.

Based on FIGS. 6 and 7, the above-mentioned conditions (1) to (4) will be described in detail.
FIG. 6 is a partially enlarged view of FIG. 4 and shows a leading edge 9c. 6A shows the tip 9b of the leading edge 9c, and FIG. 6B shows the root 9a of the leading edge 9c. FIG. 7 is a partially enlarged view of FIG. 4 and shows a trailing edge 9d. FIG. 7A shows the tip 9b of the trailing edge 9d, and FIG. 7B shows the root 9a of the trailing edge 9d.

Each symbol in FIG. 6 (A) is as follows.
α1t: The approach angle α at the leading edge 9c and the tip 9b.
ω1t: Relative velocity vector viewed from the blade 9 that rotates the fluid velocity component vector Ca1 in the axial direction at the leading edge 9c and the tip 9b.
Ca1: A fluid velocity component vector in the axial direction of the fluid at the leading edge 9c and the tip 9b.
U1t: rotational speed vector of the wing 9 at the leading edge 9c and the tip 9b.
β1t: An angle formed by the blade surface of the blade 9 on the leading edge 9c and the tip 9b with the rotational speed vector U1t.
Each symbol in FIG. 6B is as follows.
α1h: The approach angle α at the leading edge 9c and the root 9a.
ω1h: a relative velocity vector viewed from the blade 9 that rotates the fluid velocity component vector Ca1 in the axial direction at the leading edge 9c and the root 9a.
Ca1: A fluid velocity component vector in the axial direction of the fluid at the leading edge 9c and the root 9a.
U1h: Rotational speed vector of the wing 9 at the leading edge 9c and the root 9a.
β1h: an angle formed by the rotational speed vector U1h of the blade surface (on the ventral side) of the blade 9 at the leading edge 9c and the root 9a.
Each symbol in FIG. 7A is as follows.
α2t: The approach angle α at the trailing edge 9d and the tip 9b.
ω2t: A relative velocity vector viewed from the blade 9 that rotates the fluid velocity component vector Ca2 in the axial direction at the trailing edge 9d and the tip 9b.
Ca2: A fluid velocity component vector in the axial direction of the fluid at the trailing edge 9d and the tip 9b.
U2t: Rotational speed vector of the wing 9 at the trailing edge 9d and the tip 9b.
β2t: an angle formed by the rotational speed vector U2t of the blade surface (abdominal side) of the blade 9 at the trailing edge 9d and the tip 9b.
Each symbol in FIG. 7B is as follows.
α2h: The approach angle α at the trailing edge 9d and the root 9a.
ω2h: A relative velocity vector viewed from the blade 9 that rotates the fluid velocity component vector Ca2 in the axial direction at the trailing edge 9d and the root 9a.
Ca2: A fluid velocity component vector in the axial direction of the fluid at the trailing edge 9d and the root 9a.
U2h: Rotational speed vector of the wing 9 at the trailing edge 9d and the root 9a.
β2h: an angle formed by the blade surface (on the ventral side) of the blade 9 and the rotational speed vector U2h at the trailing edge 9d and the root 9a.

Condition (1) The condition (1) is that α2−α1> 0 at each radial position of the blade 9. Preferably, α2−α1 ≧ 1.0 [degrees] at each radial position of the blade 9.
Therefore, preferably, the condition (1) is that α2t−α1t satisfies the following expressions (a) and (b).

α2t−α1t ≧ 1.0 [degree] (a)
α2h−α1h ≧ 1.0 [degree] (b)

Condition (2) Condition (2) is that the magnitude of the difference between the approach angle α at the root 9a and the approach angle α at the tip 9b is ΔT at the trailing edge 9d, and the leading edge Assuming that ΔL is 9c, ΔT / ΔL is 1 or a value close to 1. That is, since ΔT = α2h−α2t and ΔL = α1h−α1t, (α2h−α2t) / (α1h−α1t) is a value close to 1 or 1. Preferably, the condition (2) is to satisfy the following formula (c).

0.9 ≦ (α2h−α2t) / (α1h−α1t) ≦ 1.1 (c)

Condition (3) Condition (3) is that the difference between the approach angle α at the leading edge 9c and the approach angle α at the trailing edge 9d is Δh at the root 9a, and the tip Assuming that Δt is 9b, Δh / Δt is 1 or a value close to 1. That is, since Δh = α2h−α1h and Δt = α2t−α1t, (α2h−α1h) / (α2t−α1t) is 1 or a value close to 1. Preferably, the condition (3) is to satisfy the following formula (d).

0.9 ≦ (α2h−α1h) / (α2t−α1t) ≦ 1.1 (d)

-Condition (4) This condition (4) is to satisfy the following expressions (e) and (f).

| Α1h−α1t | ≦ 4.0 [degrees] (e)
| Α2h−α2t | ≦ 4.0 [degrees] (f)

Preferably, the approach angle α gradually changes (in the example of FIG. 4) as it moves from the leading edge 9 c to the trailing edge 9 d at each radial position of the blade 9. As described above, in the example of FIG. 4, β gradually changes (in the example of FIG. 4) as it moves from the root 9 a to the tip 9 b at each rotational direction position of the blade 9.
Further, the approach angle α gradually changes (in the example of FIG. 4) as it moves from the root 9 a to the tip 9 b at each radial position of the blade 9.

  FIG. 8 is a table showing simulation results for a plurality of blade shapes of the inducer device. That is, as shown in FIG. 8, whether or not swirl cavitation, asymmetric cavitation, and cavitation surge are generated for each of the blades 9 to 9 is examined by simulation.

Note that swirl cavitation is a phenomenon in which cavitation sequentially moves through the blades 9 as the rotational position of the blades 9 changes due to rotation. That is, a phenomenon in which cavitation propagates in the rotational direction. Asymmetric cavitation is a phenomenon in which the size of cavitation generated in each blade 9 is non-uniform. Cavitation surge is a phenomenon in which fluid vibrates in an axial direction.

In FIG. 8, each frame in the same column as the frame in which the mathematical formula is entered is as follows. A box with a circle (that is, “◯”) indicates that the expression in the left frame in the same row (that is, any one of the above expressions (a) to (f)) is satisfied. . On the other hand, a box with a cross mark (that is, “×”) is written in any of the formulas in the left frame of the same row (that is, any of the above formulas (a), (b), (e), (f)). )) Is not satisfied. A box in which “small” is entered indicates that the value of the expression in the left frame in the same column (that is, one of the above expressions (c) and (d)) is less than 0.9. . Similarly, a frame in which “Large” is entered indicates that the value of the expression in the left frame of the same column (that is, any one of the above formulas (c) and (d)) is greater than 1.1. Show.
In FIG. 8, each frame in the same row as the frame in which the phenomenon name of “swivel cavitation”, “asymmetric cavitation” or “cavitation surge” is entered is as follows. A frame in which a circle (that is, “◯”) is written indicates that the phenomenon written in the left frame in the same row does not occur. A frame in which a cross mark (that is, “x”) is written indicates that the phenomenon written in the left frame in the same column occurs.
For example, in the case of A, the above formulas (a) to (f) are all satisfied. That is, in the case of A, all of the conditions (1) to (4) are satisfied. On the other hand, in the case of B to P, at least one of the above formulas (a) to (f) is not satisfied. That is, in the case of B to P, at least one of the conditions (1) to (4) is not satisfied.
As can be seen from FIG. 8, in the case of A where all the above formulas (a) to (f) are satisfied (that is, when the conditions (1) to (4) are satisfied), swirl cavitation, asymmetric Neither cavitation nor cavitation surge occurs. On the other hand, in the case of B to P where at least one of the above formulas (a) to (f) is not satisfied (that is, when at least one of the conditions (1) to (4) is not satisfied), turning At least one of cavitation, asymmetric cavitation, and cavitation surge occurs.

In the inducer device 10 according to the embodiment of the present invention described above, (1) the approach angle α is larger at the root 9a and the tip 9b at the rear edge 9d (at least 1 degree) than the front edge 9c. The load acting on the blade 9 can be effectively dispersed on the trailing edge 9d side without being concentrated on the leading edge 9c side. (2) Further, the magnitude of the difference between the approach angle α at the root 9a and the approach angle α at the tip 9b is ΔT at the rear edge 9d and ΔL at the front edge 9c. By making ΔT and ΔL at least substantially the same (ΔT / ΔL is 0.9 or more and 1.1 or less), the difference between the work amount of the blade 9 at the root 9a and the work amount of the tip 9b at the leading edge 9c. The difference between the work amount of the blade 9 at the root 9a and the work amount of the tip 9b at the trailing edge 9d can be made substantially the same, thereby improving the load balance and rotation balance of the blade 9. (3) Further, the magnitude of the difference between the approach angle α at the leading edge 9c and the approach angle α at the trailing edge 9d is Δh at the root 9a and Δt at the tip 9b. By making Δh and Δt at least substantially the same (Δh / Δt being 0.9 or more and 1.1 or less), the work amount of the blade 9 at the root 9a at the leading edge 9c and the work amount at the trailing edge 9d The difference between the amount of work performed by the leading edge 9c and the amount of work performed by the trailing edge 9d at the tip 9b of the blade 9 can be the same or similar, thereby improving the load balance and rotation balance of the blade 9 Can do. (4) In addition, preferably, at the front edge 9c and the rear edge 9d, the difference between the entry angle α at the root 9a and the entry angle α at the tip 9b is 4.0 degrees or less. Thus, the difference between the amount of work performed by the base 9a and the amount of work performed by the tip 9b of the blade 9 at the leading edge 9c and the trailing edge 9d can be reduced, thereby further improving the load balance and rotation balance of the blade 9. Can be made.
Thus, as described in (1) above, the load acting on the blade 9 can be dispersed on the rear edge 9d side without being concentrated on the front edge 9c side, and the above (2) to (3) or As described in the above (2) to (4), the rotational balance of the blade 9 is improved, and these combine to improve the load balance of the entire blade 9 and to vibrate due to backflow, secondary flow, cavitation and the like. It can be suppressed and high suction performance can be realized.

  Further, the approach angle α gradually changes as the transition from the leading edge 9c to the trailing edge 9d (in FIG. 4 increases), and gradually changes as the transition from the root 9a to the tip 9b. The load balance and rotation balance of 9 can be further improved.

  The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the inducer device of the present invention improves the load balance of not only the turbo pump of the rocket engine but also the entire wing, and suppresses vibrations due to cavitation, reverse flow, secondary flow, etc., and realizes high suction performance. It is also applicable to other pumps where it is desired.

3 ... turbo pump, 3a ... rotating shaft, 3b ... pump impeller, 3c ... turbine impeller, 5 ... bearing, 7 ... casing, 7a ... inner wall surface, 9 ... Wings, 9a ... Root, 9b ... Tip, 9c ... Front edge, 9d ... Rear edge, 10 ... Inducer device

Claims (3)

An inducer device provided in a pump having a pump impeller for sucking fluid, and a rotary shaft on which the pump impeller is fixed and driven to rotate,
A blade fixed to the rotary shaft on the upstream side of the pump impeller,
The blade has a root coupled to the rotating shaft and a tip opposite to the root, and has a leading edge that is an upstream end and a trailing edge that is a downstream end,
The fluid velocity component vector (U) in the axial direction of the rotating shaft is defined as an angle formed by the relative velocity vector (ω) viewed from the blade and the blade surface of the blade as the fluid entrance angle (α).
(1) The approach angle is larger at the trailing edge than at the leading edge,
(2) The magnitude of the difference between the entry angle at the root and the entry angle at the tip is at least approximately the same at the front edge and the rear edge,
(3) The inducer device characterized in that the difference between the approach angle at the leading edge and the approach angle at the trailing edge is at least substantially the same between the root and the tip.   The inducer device according to claim 1, wherein the approach angle gradually changes as the transition from the front edge to the rear edge and gradually changes as the transition from the root to the tip. (1) The approach angle is 1 degree or more larger at the rear edge than at the front edge at the root and the tip,
(2) Assuming that the difference between the approach angle at the base and the approach angle at the tip is ΔT at the trailing edge and ΔL at the leading edge, ΔT / ΔL is 0.9 or more. 1.1 or less,
(3) Assuming that the difference between the approach angle at the leading edge and the approach angle at the trailing edge is Δh at the root and Δt at the tip, Δh / Δt is 0.9 or more. 1.1 or less,
(4) In the front edge and the rear edge, the difference between the approach angle at the root and the approach angle at the tip is 4.0 degrees or less. The inducer described in 1.

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