JPH07224794A - Moving blade of axial flow machine - Google Patents

Abstract

PURPOSE:To reduce any loss of a compressor efficiency due to the secondary crow, by decreasing the secondary flow strengtnened by the impulsive waves generated from the front end of a moving blade by control of the impulsion position of the impulsive waves to the adjacent moving blade. CONSTITUTION:An axial flow machine is provided with moving blades 41 protruded on the external periphery of a rotor and planted at the periphery of a roter hub 42 and a easing 45 so as to cover the roter containing the moving blades 41. In this case, the impulsion position on the back face of the adjacent moving blades 41 of the passage imulsive waves generated by the transonic or faster air stream flowing into the front edge 43 of the moving blade at a certain height, is defined so as not to be positioned behind the impulsive point on the back face of the adjacent moving blade 41 of the passage impulsion waves generated from the front edge 43 which is positioned at a lower height than that. That is, the front edge 43 positioned at a higher level of the moving blade 41 is arranged at a forward position than the front edge 43 in the lower position and the shape of the front edge 43 of the moving blade 41 is made to show a plane form inclined forward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a large industrial gas turbine, a fan of an aero fan engine, a front stage of an axial flow compressor of an aero jet engine, and the like. Or to a moving blade of an axial flow machine in which a working fluid of supersonic velocity flows in and is operated.

[0002]

2. Description of the Related Art A flow loss in an axial flow machine, for example, in a moving blade of a front stage of a compressor described above is roughly classified into a profile loss and a secondary flow loss. Conventionally, in a moving blade of a subsonic compressor in which a supersonic flow portion having a Mach number of more than 1 is not generated in the working fluid relatively flowing into the moving blade,
These two losses have been reduced. For example, in the former case, the profile loss is reduced by making a blade cross-sectional profile with less loss. In the latter case, the secondary flow loss is reduced by, for example, Japanese Patent Application No. Proposed in No. 274812 "Blade of axial machine",
The loss is reduced by adopting the forward skew blades.

Further, the working fluid having a velocity relatively flowing into the moving blade is transonic, that is, a velocity at which a supersonic portion having a Mach number exceeding 1 is generated in the working fluid flowing into the moving blade. In a transonic compressor or a supersonic compressor that is operated with, the problem of shock waves due to the compressibility of the working fluid arises.Therefore, when reducing the profile loss of the former, the profile including the shock wave loss is also included. This is achieved by using a blade cross-section profile that reduces loss. However, regarding the latter reduction of secondary flow loss, it seems that no measures have been taken so far.

Next, the secondary flow loss in the airfoil of the conventional transonic compressor or supersonic compressor will be described with reference to the drawings.

FIG. 3 is a side sectional view of a rotor hub of a rotor blade of a conventional axial flow compressor. In the figure, 01 is a rotor blade planted on the outer circumference of a rotor hub, 02 is a rotor hub protrudingly provided on the outer circumference of a rotor (not shown), and 03 is a rotor, a rotor hub 02, a rotor 01, etc. surrounding a movable body. The casing 05 provided is the center of rotation of the rotor. Rotor 01
A necessary and sufficient quantity is planted and held on the outer circumference of the rotor hub 02, and rotates about the rotation center 05 of the rotor. At this time, the average meridional streamline of the working fluid flowing is set to 04,0
4 ', 04 ". These streamlines as a whole form a substantially cylindrical or conical surface, which is hereinafter referred to as the flow surface.

FIG. 4 is a developed view of the flow surface 4, which is indicated by the arrow A--A, among the intersecting surfaces of the flow surfaces 04, 04 ', 04 "and the rotor blades 01. At 01
1, 011 'is the front edge of the profile of the rotor blades 01, 01' in this cross section, 012, 012 'is the back surface of the profile, and 013, 013' is the ventral surface. When a working fluid of transonic speed or more flows into the moving blade 01, the leading edge portion 011,0
A shock wave having an angle corresponding to the Mach number of the working fluid and the shape of the front edge portion 011 'is generated from the front of 11' or its very close vicinity. 016 of the shock wave that extends upstream
The shock wave indicated by 016 'is referred to below as the bow shock wave (bow s).
Hock wave), which extends downstream 015
The shock wave indicated by 015 'is hereinafter referred to as passage shock wave (pa
It is called a sage shock wave). In addition,
Although only two moving blades 01 are shown in this figure, as described above, a sufficient number of moving blades 01 are planted on the outer periphery of the rotor hub 02. Also, the same shock wave is generated.

The passage shock wave 015 'generated from the front edge portion 011' of the moving blade 01 'adjacent to the back surface 012 side is
The point of collision with the back surface 012 is hereinafter referred to as a collision point 014. The dotted line 06 shown in FIG. 3 is the locus in the height direction of the collision point 014 of the passage shock wave 015 ′ generated from each front edge portion 011 ′ located in the height (radius) direction of the moving blade 01 on the back surface 012. Indicates. As shown in the figure, the dotted line 06, which is the locus of the collision point 014, moves backward in the axial direction as the height of the moving blade 01 increases.

FIG. 5 is a view for explaining in detail the locus of the above-mentioned collision point 014 in a conventional blade designed in a transonic or supersonic working fluid designed by a conventional design method. It is a figure. In the figure, in order to show the position of the collision point 014 of the passage shock wave 015 ', the side view of the moving blade 01 and the supersonic inflow portion XX, YY, Z are shown.
-Back surface 01 of rotor blades 01, 01 'in three horizontal sections of Z
2 (X), 012 (Y), 012 (Z), 012 '
(X), 012 '(Y), 012' (Z) and the leading edge portion 011 '(X), 011' of the moving blade 01 '.
Passage shock waves 015 '(X), 015' (Y), 015 '(Z) and bow shock waves 016' (X), 016 '(Y), 01 generated from the (Y), 011' (Z) portions.
6 '(Z) is shown. Incidentally, the above-mentioned symbols (X), (Y),
(Z) shows the thing in three horizontal cross sections of the arrow XX, YY, and ZZ, respectively.

As can be seen from this figure, the rotor blade 01 '
Leading edge portions 011 '(X), 011' (Y), 011 '
Passage shock wave 015 'generated from each of (Z)
(X), 015 ′ (Y), 015 ′ (Z) are the back surfaces 012 (X), 012 (Y), 012 of the adjoining blades 01.
Collision points 014 (X), 014 (Y), which collide with (Z),
The position of 014 (Z) is (1) so that the blade cross section shape of the moving blades 01, 01 'can be understood from the shape of the back surface.
The closer to the blade tip of 01, the larger the stagger angle becomes, and (2) the working fluid flowing into the leading edge of the blades 01 and 01 'is closer to the blade tips of blades 01 and 01'. The higher the velocity becomes, the higher the Mach number becomes, so ZZ → Y
-Y → XX It retreats as it goes to the cross section and the radial direction outer side (blade tip side). The locus of the collision point 014 on the dotted line 06 shown in FIG. 3 indicates this state.

The flow in the vicinity of the collision point 014 in FIG. 4 will be described by reproducing a part of FIG. 4 in FIG. As shown in FIG. 6, the thickness distribution 020 of the boundary layer 020 on the back surface 012 side of the moving blade 01 gradually increases from the leading edge portion 011 to the collision point 014 as it goes backward, but the passage shock wave Before and after the collision point 014 where 015 'collides, the thickness rapidly increases. That is, passage shock wave 01
Before and after 5 ', the static pressure increases remarkably discontinuously,
The thickness of the boundary layer 020 behind the passage shock wave 015 'increases sharply as shown.

By the way, the working fluid in the boundary layer 020 generated on the blade surface of the moving blade 01 adheres to the moving blade 01 as compared with the working fluid flowing outside the boundary layer 020 (hereinafter referred to as the mainstream fluid). Since the rotation speed around the rotor rotation center is faster than the mainstream fluid outside the boundary layer,
It receives a centrifugal force larger than that of the mainstream fluid and tends to be discharged outward in the radial direction of the moving blade 01 along the blade surface. This is shown in FIG.

In FIG. 7, reference numeral 030 indicates the back surface 0 of the moving blade 01.
12 shows a secondary flow generated by centrifugally pushing out the fluid inside the boundary layer 020 in a cross section below the moving blade 01, which has a small radial height above 12. Reference numeral 031 indicates a secondary flow above the rotor blade 01 and radially outward from the rear of the locus 06 by centrifugal force. Locus 06
, The boundary layer 0 on the back surface 012 of the rotor blade 01 is affected by the passage shock wave 015 ', as shown in FIG.
Since 20 is significantly enlarged and thickened, a large amount of fluid in the boundary layer tends to be pushed out by centrifugal force. This secondary flow 031 becomes extremely larger than the secondary flow at subsonic speed or the secondary flow 030 generated below the moving blade 01. In addition, the static pressure in front of the locus 06, that is, in front of the passage shock wave 015 ', is the locus 06 as described above.
, Which is smaller than the static pressure behind the passage shock wave 015 ', which promotes this tendency. That is, the average static pressure on the flow surface equilibrates in the radial direction and rises outward in the radial direction. However, the opposite phenomenon may occur locally in this way. In the case of the airfoils shown in FIGS. 3 and 7 which are operated by the transonic or supersonic working fluid of the conventional axial flow compressor, the centrifugal force accompanying the rotation of the rotor blades 01 is applied to the outside along the back surface 012. The generated secondary flow becomes extremely large, and this tendency is significantly accelerated by the static pressure difference before and after the trajectory 06.

Further, the boundary layer 020 located at a point 032 behind the trajectory 06 of the collision point 04 of the passage shock wave 015.
The working fluid inside moves to the blade tip side by the mechanism described above,
Point 033 in front of trajectory 06 of passage shock wave 015 '
, The boundary layer 020 at the point 033 on the upstream side of the trajectory 06 becomes enlarged and becomes disordered. in this way,
If the boundary layer 020 on the back surface 012 before the passage shock wave 015 'hits the back surface 012 is enlarged, the boundary layer 0
20 and the passage shock wave 015 'at the point of interference, the boundary layer 020 is further enlarged, or the flow is separated from the back surface 012, resulting in a boundary layer condition that is extremely inconvenient in terms of performance.

As described above, in the moving blade of the conventional airfoil axial flow machine in which the working fluid having a transonic speed or more is introduced to operate,
There is an unavoidable decrease in efficiency due to an increase in secondary flow, and improvements are required.

[0015]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the moving blade of the conventional axial flow machine, and the secondary flow strengthened by the shock wave generated from the front end portion of the moving blade causes the moving blade adjacent to the shock wave to move. By controlling the position of the collision point to
An object of the present invention is to provide a moving blade of an axial-flow machine that reduces the loss of compressor efficiency due to the next flow.

[0016]

The moving blades of the axial flow machine of the present invention are as follows. In the moving blades of the axial flow machine, which are installed so as to intersect with each other in the working fluid flowing in the flow path, and at least a part of the height direction of which the working fluid having a transonic speed or more relatively flows into the working fluid, A leading edge where the position of the collision point of the passage shock wave generated by the working fluid of transonic velocity or higher flowing into the leading edge of the blade at a certain height on the back surface of the adjacent blade is smaller than that The passage shock wave generated from the section is at least behind the position of the collision point on the back surface of the adjoining blade.

[0017]

According to the moving blade of the axial flow machine of the present invention, for example, the leading edge portion in the moving blade cross section has a radial height from the cross-sectional profile near the root portion having a small radial height. The blade is a blade profile that is forwardly inclined or advanced as it is reflected in the axial direction toward the large tip cross-section profile, and as a result, (1) at the same axial position, the blade on the back surface of the blade is static. Pressure
As the position of the blade cross section in the height direction increases, the height increases,
The boundary layer secondary flow is not strengthened by the centrifugal force due to the rotation of the rotor blades, and conversely, because the static pressure is higher at the outside where the blade cross section height is higher, the back boundary layer secondary flow is Suppressed. (2) In this way, by suppressing the secondary flow in the boundary layer, the enlargement of the blade back surface boundary layer before the interference with the shock wave is avoided.
In the interference between it and the shock wave, further significant deterioration of the boundary layer (large enlargement or peeling) can be avoided.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a moving blade of an axial flow machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an embodiment of a moving blade of an axial flow machine according to the present invention. In the figure, reference numeral 41 is a rotor blade that is provided on the outer periphery of a rotor (not shown) and is planted on the peripheral edge of a rotor hub 42. The rotor blade 41 has a horizontal cross-section as shown in FIGS.
The necessary number is provided on the outer circumference of the work fluid to accelerate and compress the inflowing working fluid. A front edge portion 43 and a rear edge portion 44 are formed at the front end and the rear end of the moving blade 41, respectively, and a ventral surface and a back surface are formed on the side surfaces as in FIGS. 4 and 6.

Reference numeral 45 designates the rotor, the rotor hub 42, and the rotor blades 4.
It is a casing that surrounds a rotating body composed of 1 or the like and forms a flow path 46 for a working fluid together with the rotating body. Channel 46
The working fluid flows therein to form cylindrical or conical flow surfaces 47, 47 ', 47 ".
The rotor blades 41 disposed so as to intersect 7'and 47 "rotate about the rotor rotation center 48. The working fluid flowing into the rotor blades 41 is at least in the radial direction (height direction) of the rotor blades 41. In one part, the part that becomes supersonic flow is included in the flow,
Since the velocity is higher than the transonic speed, the bow shock wave and the passage shock wave as described with reference to FIG. 4 are generated from the front edge portion 43 of the moving blade 41 or from the front extremely close to the front edge portion 43 to both sides of the moving blade 41. .

In 49, the passage shock wave generated at the front edge portion 43 is adjacent to the moving blade 41 as shown in FIGS.
Is the trajectory of the collision point that collided with the back surface of the. That is, as can be understood from the locus 49, the front edge portion 43 having a low height is
The collision point of the passage shock wave generated from is not ahead of the collision point of the passage shock wave generated from the front edge portion 43 located at a higher position, and is a straight line drawn on the rotor rotation center 48 and the trajectory 49 of the collision point. The angle θ formed with is 90 °
Is the lower limit. As shown in FIG. 1, the shape of the leading edge portion 43 of the moving blade 41 is set such that the leading edge portion 43 at the higher position of the moving blade 41 is arranged in front of the leading edge portion 43 at the lower position. This can be achieved by making the blade plane shape inclined forward.

This will be described in detail with reference to the drawings. Figure 2
Shows a side view of the embodiment shown in FIG. 1 in the lower part, and in the upper part, the moving blade 41 and a moving blade 41 ′ adjacent to the moving blade 41.
Supersonic inflow portions X'-X ', Y'-Y', Z'-Z '
Backsides 12 (X '), 12 (Y') in three horizontal sections,
12 (Z '), 12' (X), 12 '(Y), 12'
(Z) shape and leading edge 11 '(X'), 1 of the blade 41 '
Passage shock waves 15 '(X'), 15 '(Y'), 15 'generated from the 1' (Y ') and 11' (Z ') portions.
(Z '), Bow shock wave 16' (X '), 16'
(Y ') and 16' (Z ') are shown. Also, passage shock waves 15 '(X'), 15 '(Y'), 15 '
The collision point of (Z ′) on the back surface of the adjacent moving blade 41 is set to 14
(X '), 14 (Y'), 14 (Z ').

As shown, the leading edge 11 'of the blade 41' is shown.
Since the flow velocity (Mach number) of the working fluid flowing into (X '), 11' (Y '), 11' (Z ') is specified when designing the axial flow machine, the shapes of the moving blades 41, 41' are Back 12
As can be understood from the shapes of (X ') to 12' (Z '), the leading edge is moved forward toward the wing tip, and
Due to the raised shape, the collision points 14 (X '), 14 (Y') of the passage shock waves 15 '(X'), 15 '(Y'), 15 '(Z') on the back surface of the moving blade 41 are formed. ),
The locus 49 connecting 14 (Z ') can be made to lie in a plane perpendicular to the rotor rotation axis (θ = 90 when viewed in the meridional section).
°). The angle θ formed by the center line 48 of the rotation axis of the locus 49 can be set to θ> 90 ° in the same manner as described above.

The case where the locus 49 is a straight line has been described above, but within the range not departing from the gist of the present invention,
14 (Y ') located on the blade tip side from point 14 (Z')
It is also within the scope of the present invention that the point and the point 14 (X ') are sequentially on the upstream side in the axial direction and the locus connecting them shows an arc-shaped curve. Such 14 (X ') ~ 14
Each point of (Z ') can be obtained experimentally, or by using simple aerodynamic calculation or computational fluid dynamics.

In the above embodiment, the portion of the moving blade 41 near the root of the blade shown in FIG. 1 is inclined rearward. This is because the velocity of the working fluid in this portion is transonic. Since it did not reach the above, and the problem of secondary flow due to passage shock waves did not occur, we made such a shape, but of course,
In the case where the working fluid at a speed higher than the transonic speed flows into the entire surface of the moving blade 41, the entire front edge portion 43 is tilted forward so that the entire locus 49 generated in the height direction of the moving blade 41 is tilted forward. Just do it.

The angle of the shock wave generated from the front edge portion is the angle formed by the inflowing working fluid and the front edge portion, in other words, the thickness of the front edge portion, the inclination angle, or the inflow of the working fluid. Since it also changes depending on the installation angle with respect to the direction, if the blade profile is formed in consideration of these in accordance with the selection of the forward inclination angle of the above-mentioned blade leading edge, it will be possible to make the blade more aerodynamically superior. I can do it.

[0026]

EFFECTS OF THE INVENTION According to the moving blade of the axial flow machine of the present invention, (1) at the same axial position, the static pressure on the back surface of the moving blade has a large moving blade height. It becomes higher as it becomes higher, and the secondary flow in the boundary layer due to the centrifugal force accompanying the rotation of the moving blade can be reduced. (2) Further, by suppressing the secondary flow of the boundary layer, it is possible to avoid the back boundary layer from expanding before the interference with the shock wave. Peeling) can be avoided.

As described above, it is possible to suppress the increase of the two-letter flow loss and to prevent the increase of the profile loss, and by the total effect of these, it is possible to significantly improve the aerodynamic performance.

[Brief description of drawings]

FIG. 1 is a side view of a rotor blade of an axial compressor according to a first embodiment of the present invention,

FIG. 2 is an explanatory view of a collision point locus of a passage shock wave in the embodiment of FIG.

FIG. 3 is a side view of a rotor blade of a conventional axial flow compressor,

4 is a cross-sectional view showing one flow surface in a moving blade portion of the axial compressor of FIG.

5 is an explanatory view of a collision point locus of passage shock waves in the moving blade of FIG. 3,

FIG. 6 is a diagram showing a state of a boundary layer on the back surface of the moving blade on the flow surface of FIG. 4;

7 is a diagram showing a secondary flow of a boundary layer generated on the back surface of the moving blade in FIG.

[Explanation of symbols]

11, 11 'Leading edge (of moving blade) 12, 12' Rear surface in horizontal section (of moving blade) 14 Collision point of passage shock wave 15 'Passage shock wave 16' Bow shock wave 41 Rotor hub 43 Leading edge portion 44 Trailing edge Part 45 Casing 46 Flow path 47, 47 ', 47 "Flow surface 48 Rotor rotation center 49 Trajectory of shock wave collision point (X'), (Y '), (Z') Arrow view X'- of moving blade
The state in the X ', Y'-Y', Z'-Z 'cross section is shown.

Claims (1)

[Claims] 1. A moving blade of an axial-flow machine, which is installed in a flow path and in which a working fluid having a transonic speed or more relatively flows into at least a part in a height direction, the moving blade has a height at which the moving blade exists. The collision point of the passage shock wave generated from the leading edge of the above to the back surface of the adjacent moving blade should be at least behind the collision point of the passage shock wave generated from the leading edge lower than the leading edge. A blade of an axial-flow machine characterized by the above.