JPH05149103A - Divided type radial turbine impeller - Google Patents

Abstract

PURPOSE:To integrate both divided turbine blades so as to prevent breakage caused by resonance of the turbine blades, and improve efficiency of a turbine by joining a large diameter turbine blade with a small diameter turbine blade by the combination of a projection part and a notch part. CONSTITUTION:Both divided turbine disks 2x, 2y are joined together with a pin 3. A projection part 5 is formed on one of divided turbine blades 4x, 4y, for example, in the vicinity of a bottom part of a divided surface on the large diameter turbine blade 4x of a trapezoidal cross section. On the other hand, a notch part 6 is formed on the other of the turbine blades 4x, 4y, for example, in the vicinity of a bottom part of a divided surface on the small diameter turbine blade 4y of a trapezoidal cross section. The notch part 6 and the projection part 5 are fit to each other by shrinkage-fitting so as to join both turbine blades 4x, 4y together. It is thus possible to increase the natural frequency of the turbine blade 4x, 4y so as to prevent breakage caused by resonance, and also to reduce the clearance between joining parts so as to improve efficiency of a turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split type radial turbine impeller of a radial turbine used for power recovery of a chemical plant or the like.

[0002]

2. Description of the Related Art For this type of radial turbine,
In order to reduce the plant operating cost and construction cost,
There is a great demand for high efficiency and miniaturization. On the other hand, the processing capacity required for a plant is increasing year by year, and in order to satisfy these contradictory needs, in recent years, a high specific speed of the turbine impeller has been required. Therefore, FIG.
Research and development of a high specific speed turbine impeller 12 shown in FIG. 14 in which the inlet diameter is suppressed and the outlet diameter is increased to increase the flow rate as compared with the conventional turbine impeller 11 shown in FIG. Where the inlet diameter of the turbine impeller 11 is D
io, outlet diameter is Doo, inlet diameter of turbine impeller 12 is Din, outlet diameter is Don, Dio> Din,
The relationship is Doo <Don. Further, in the case of a relatively large radial turbine, the high specific speed turbine impeller 12 is forced to be of a split type due to restrictions on processing accuracy. For this reason, the turbine impeller 15 in which the turbine disks 13x and 13y divided as shown in FIG. 15 are joined by the pin 14 or the turbine disks 16x and 16y divided as shown in FIG.
The turbine impeller 18 joined in 1. was used.

[0003]

In the conventional turbine impellers 15 and 18 described above, the joining surface is only the turbine disk portion, and therefore, due to the assembly structure, between the divided turbine blades 19x, 19y and 20x, 20y, There is a gap. If the diameter (height) on the inlet side of the turbine impellers 15 and 18 is about the diameter on the inlet side of the turbine impeller 11 shown in FIG. 13, the turbine blades 19x and 1
The natural frequencies of 9y, 20x, and 20y were higher than the rotational frequency component, and there was no problem in fatigue strength. However, in the case of the high specific speed type turbine impellers 15 and 18 as shown in FIGS. 15 and 16, the diameter on the inlet side is larger than that of the conventional turbine impeller 11 shown in FIG. 13, which results in the turbine blades 19x and 19y. In addition to the reduction of the natural frequencies of 20x and 20y and the reduction of the natural frequency due to the division of the turbine blade, the natural frequency and the rotation speed may overlap with each other, resulting in damage due to resonance. There is a problem that the possibility comes out.

On the other hand, in order to avoid this problem, turbine blades 19x, 19y and 20x, 2
It is possible to increase the thickness of 0y to increase the natural frequency. However, in this case, it is considered that the aerodynamic performance of the turbine impellers 15 and 18 is adversely affected, and the turbine blades 19x and 19y are also affected. And 20
Since the weight of x and 20y increases, the turbine blade 1
The stress due to the centrifugal force of 9x, 19y and 20x, 20y increases, which causes a problem in strength. Also, in FIG.
Turbine blades 19x, 19y and 20 shown in 16
x, 20y, turbine blades 19x, 19
There is a problem in that a gap is created in the y and 20x, 20y divisions, and gas leakage from this causes a decrease in the efficiency of the turbine impeller. The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a split type radial turbine impeller capable of avoiding damage due to resonance and improving the efficiency of the turbine impeller.

[0005]

In order to solve the above-mentioned problems, the present invention provides a large-diameter side turbine blade and a small-diameter side turbine blade with a protrusion and a notch having a concave-convex reverse shape. It is formed by joining by combining at least one of the combination or the combination of the notch and the pin fitted therein.

[0006]

By configuring as in the above invention, the natural frequency of the turbine blade is increased and the gap between the divided turbine blades is reduced.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 show a split type radial turbine impeller 1 according to a first embodiment of the present invention, in which split turbine disks 2x and 2y are joined by a pin 3. In addition, one of the divided turbine blades 4x and 4y, in the present embodiment, the protrusion 5 is provided in the vicinity of the root of the divided surface of the large-diameter side turbine blade 4x having a substantially trapezoidal cross section. On the other hand, in this embodiment, the notch 6 is formed in the vicinity of the root of the split surface of the small diameter turbine blade 4y having a substantially trapezoidal cross section. Then, by fitting the protrusion 5 and the notch 6 by shrink fitting,
The turbine blades 4x and 4y are joined together. Thus, by joining the turbine blades 4x and 4y together, the natural frequency of the entire turbine blades 4x and 4y is increased, the difference from the rotational speed of the turbine impeller 1 is opened, and the turbine impeller 1 is damaged due to resonance. It can be avoided. Further, the gap between the divided turbine blades 4x and 4y is also reduced, and the efficiency of the turbine impeller is improved.

FIG. 4 shows the relationship between the number of revolutions of the turbine impeller and the maximum frequency at which the turbine blade can cause a non-negligible resonance at this number of revolutions, that is, the maximum excitation curve I. The horizontal axis represents the turbine. The rotational speed of the impeller (for example, rpm) is shown, and the vertical axis shows the vibration frequency of the turbine blade (for example, Hz). Therefore, the resonance occurs below the maximum excitation curve I, and the resonance occurs above the maximum excitation curve I, or only negligible resonance occurs. In the case of the turbine impeller 1 according to the present invention, the turbine blade 4
The natural frequencies of the entire x and 4y are located above the maximum excitation curve I as shown by the point A in FIG. 4 so that resonance does not occur. On the other hand, in the case of the conventional turbine impellers 15 and 18 shown in FIGS. 15 and 16, the natural frequencies of the turbine blades 19x and 19y or 20x and 20y are the maximum excitation curves as shown by the point B in FIG. It is located below I and is in a state where resonance can occur. By the way, if the high-specific-speed turbine impeller is integrated, the natural frequency of the turbine blade is calculated and located higher than the point A as shown by the point C in FIG. It becomes more difficult to cause resonance.

By the way, in the turbine impeller 1, the projections 5 and the notches 6 are formed near the roots of the turbine blades 4x and 4y. The reason is turbine blade 4
This is because x and 4y have a substantially trapezoidal cross section, and the wall thickness is larger in the vicinity of the root portion than in the tip portion, and a sufficient wall thickness can be obtained in terms of processing and strength. FIG. 5 shows a split type radial turbine impeller 1a according to a second embodiment of the present invention, and the split type radial turbine impeller 1 according to the first embodiment.
Means that the turbine blades 4x and 4y (however, the turbine blade 4x is not shown in FIG. 5) are different in the shape of the cross section perpendicular to the axis, and are substantially similar to each other, The same numbers are assigned and the description thereof is omitted (the same applies to each of the following embodiments.
The same numbers are given and explanations are omitted). In the case of this turbine impeller 1a, the turbine blade 4y (not shown in the drawing, but the same applies to the turbine blade 4x) is not trapezoidal in cross section, and both sides of the tip end are parallel to each other. Since the wall thickness becomes insufficient, only the root portion is formed so that the wall thickness increases toward the shaft core portion as shown in FIG. In this way, by increasing the wall thickness of only the root portions of the turbine blades 4x, 4y, it is possible to suppress an increase in centrifugal force due to the increase in the wall thickness of the turbine blades 4x, 4y. Therefore, it is considered that the natural frequency of the turbine blades 4x and 4y can be increased without causing a problem in strength and aerodynamics.

FIG. 6 shows a split type radial turbine impeller 1b according to a third embodiment of the present invention, in which a tapered portion 7 and a rounded portion 8 are provided at the corners of the split surfaces of the turbine blades 4x and 4y.
Is provided. If the turbine blades 4x, 4y have a sufficient thickness in terms of processing and strength, the protrusions 5 and the cutouts 6 are provided up to the tips of the turbine blades 4x, 4y,
Further, by providing the taper portion 7 and the rounded portion 8, the dividing surface, that is, the joining portion, particularly the turbine blade 4
It is possible to reduce the energy loss due to the turbulence of the gas flow at the step at the joint near the tips of x and 4y. Note that FIG. 6 exemplarily shows the tapered portion 7 and the rounded portion 8.
The turbine blade 4x may be provided with a rounded portion 8 and the turbine blade 4y may be provided with a tapered portion 7, and both the turbine blades 4x and 4y may be provided with a tapered portion 7.
Alternatively, the rounded portion 8 may be provided.

7 and 8 show a split type radial turbine impeller 1c according to a fourth embodiment of the present invention. One of the split turbine blades 4x and 4y, in this embodiment, a large diameter with a substantially trapezoidal cross section. In the vicinity of the root portion of the split surface of the side turbine blade 4x, the protrusion 5a is provided on the other side of the turbine blades 4x, 4y so that the side surface on the front side in the rotation direction indicated by the arrow D is flush with the other side. In the vicinity of the root of the split surface of the small-diameter turbine blade 4y having a substantially trapezoidal cross section, a projection 5a and a recessed portion 6a having an inverted concavo-convex shape are formed on the rear side in the rotation direction. And the notch 6a
The turbine blades 4x and 4y are joined together by positioning the protrusion 5a therein. Thus, the protrusion 5a and the cut 6a are formed on one surface of the turbine blades 4x and 4y.
By forming the, the processing becomes easy.

9 and 10 show a split type radial turbine impeller 1d according to a fifth embodiment of the present invention, in which a cut portion 6b is provided in the turbine blades 4x and 4y, and a pin 9 is fitted into the cut portion 6b. By doing so, the turbine blades 4x and 4y are joined together. And by forming in this way, processing becomes easy.

11 and 12 show a split type radial turbine impeller 1e according to a sixth embodiment of the present invention. One of the split turbine blades 4x and 4y, in this embodiment, a large diameter with a substantially trapezoidal cross section. Projection 5 having a cross-sectional cross-section that is tapered near the root of the split surface of the side turbine blade 4x
c is the other of the turbine blades 4x and 4y, and in the present embodiment, in the vicinity of the root of the split surface of the small-diameter side turbine blade 4y having a substantially trapezoidal cross section, the protrusion 5c and the notch 6c having an uneven shape are formed. I am doing it. Then, by positioning the protrusion 5c in the cut portion 6c, the turbine blade 4
The x and 4y comrades are joined. As described above, the protrusion 5c has a tapered cross-sectional shape, and the notch 6c has a concave-convex shape reverse to that of the protrusion 5c, which facilitates assembly.

The present invention is not limited to the above-mentioned embodiment, and contrary to the above-mentioned embodiments except the fifth embodiment, the projections 5, 5a, 5c are formed in the turbine blade 4y, and the notch 6, You may make it provide in 6a, 6c turbine blade 4x. Further, the present invention is directed to turbine disks 2x, 2
The joint structure of y is not limited in any way, and may be the pin joint shown in each of the above embodiments, or the above-mentioned tooth coupling.

[0015]

As is apparent from the above description, according to the present invention, the large-diameter side turbine blade and the small-diameter side turbine blade are provided with a projection and a combination of the projection and a notch having an inverted concavo-convex shape. They are joined to each other or formed by joining at least one of the combination of the cut portion and the pin fitted therein. For this reason, the divided turbine blades are integrated, the natural frequency of the turbine blades increases, damage due to resonance of the turbine blades can be avoided, and the gap between the divided turbine blades also becomes small, so the efficiency of the turbine impeller is reduced. There is an effect such as an improvement.

[Brief description of drawings]

FIG. 1 is an axially parallel half sectional view of a radial turbine impeller according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a diagram showing a relationship between a maximum excitation curve and a natural frequency of a radial turbine impeller.

FIG. 5 is a cross-sectional view of a turbine blade portion of a radial turbine impeller according to a second embodiment of the present invention, taken along a plane perpendicular to the axis.

FIG. 6 is an axially parallel sectional view of a turbine blade portion of a radial turbine impeller according to a third embodiment of the present invention.

FIG. 7 is an axially parallel half sectional view of a radial turbine impeller according to a fourth embodiment of the present invention.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is an axially parallel half sectional view of a radial turbine impeller according to a fifth embodiment of the present invention.

10 is a cross-sectional view taken along line XX of FIG.

FIG. 11 is an axially parallel half sectional view of a radial turbine impeller according to a sixth embodiment of the present invention.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is an axially parallel half-section of a conventional turbine impeller.

FIG. 14 is a half parallel sectional view of a high specific speed type turbine impeller.

FIG. 15 is an axially parallel half cross-sectional view of a conventional high specific speed type pin joint turbine impeller.

FIG. 16 is an axially parallel half cross-sectional view of a turbine impeller using a conventional high specific speed tooth coupling.

[Explanation of symbols]

1,1a, 1b, 1c, 1d, 1e, 1f Turbine impeller 4x, 4y Turbine blade 5,5a, 5c Projection 6,6a, 6b, 6c Cut 9 pin

Claims (1)

[Claims] 1. A large-diameter side turbine blade and a small-diameter side turbine blade are combined with a protrusion and a notch having a concave-convex shape, or a notch and a pin fitted therein. A split type radial turbine impeller characterized by being joined by a combination of at least one of the combinations.