JP3679875B2 - Radial turbine impeller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radial turbine employed in a gas turbine, a supercharger or the like.
[0002]
[Prior art]
A conventional device will be described with reference to FIGS. FIG. 4 shows a conventional radial turbine impeller 010 having a scallop 011 formed thereon.
[0003]
In the radial turbine, the center line of the blade 012 is substantially composed of a radial line, and the center line position of the blade 012 is extrapolated to the surface of the main plate 014 and indicated by a broken line 013.
[0004]
The impeller 010 of the radial turbine has a scallop 011 in which the main plate 014 is cut out in an arc shape in order to reduce the stress at the rotation center shaft 015 of the impeller 010.
[0005]
Further, the scallop 011 has a symmetric shape with the minimum radius portion being located at the center between the blades, that is, the center between the pressure surface 017 of one blade and the suction surface of the adjacent blade.
[0006]
[Problems to be solved by the invention]
In the conventional structure configured as described above, by providing the scallop 011, a gap 019 is formed between the blade 012 and the casing 016, and a leak 0110 is generated from the pressure surface 017 to the negative pressure surface 018 side, thereby reducing efficiency. There is a problem.
[0007]
It is an object of the present invention to solve such problems in the prior art and to provide a highly reliable device that reduces leakage and prevents efficiency reduction.
[0008]
[Means for Solving the Problems]
The present invention the problems mentioned above were solved all Kunasa, to form scallops by notching with the suction side of one blade pressure surface and the adjacent wing of the main plate, the minimum radius portion of the scallops biased from the center between one blade and the adjacent blade in the suction side of the blade of the next, to provide a radial turbine impeller and asymmetrical scalloped at the right and left wings, the minimum radius of the scallop Thus Leak from the pressure surface side to the suction surface by making the scallop shape asymmetric by biasing the part from the center between one adjacent blade and the adjacent blade to the suction surface side of the adjacent blade flow, in which case, the easier to form a shape that resists its inlet to flow into the prior SL gap flowing into the gap between the blade and the casing.
[0009]
The present invention also provides a radial turbine impeller having an acute angle of 45 degrees or less between the pressure surface of the blade and the main plate surface, and the blade forming the same inlet at the inlet portion between the blade and the casing By making the angle formed between the pressure surface and the main plate surface an acute angle, the loss coefficient at the inlet is increased 3 to 5 times compared to the case where the angle is a right angle, thereby reducing the leakage amount by about 1 / √. The efficiency is reduced by 3 to 1 / √5 to prevent a decrease in efficiency due to leakage.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0011]
Reference numeral 10 denotes an impeller, and a plurality of scallops 11 are formed in the circumferential direction corresponding to the wings 12 on the main plate 14 constituting the main part thereof. Reference numeral 16 denotes a casing, and a gap 19 is formed between the casing and the impeller 10.
[0012]
Reference numeral 17 denotes a pressure surface of the blade 12, and 18 denotes a suction surface. The impeller 10 has an axis 15, and a line obtained by extrapolating the center line of the blade 12 to the main plate 14 is indicated by a broken line 13. The shape of the scallop 11 is asymmetrical with respect to the broken line 13 so that the minimum radius portion 111 is biased toward the suction surface 18 from the center between the blades.
[0013]
As shown in FIG. 2 as a sectional view taken along line II-II in FIG. 1, in this embodiment, as described above, the shape of the scallop 11 that is asymmetrical is formed between the pressure surface 17 of the blade 12 and the surface of the main plate 14. The angle 112 easily and surely becomes an acute angle, and the resistance (loss factor) of the flow 110 leaking from the gap 19 between the casing 16 and the blade 12 is 3 as compared with the conventional one having an angle of approximately 90 °. Increase by -5 times.
[0014]
That is, when the angle between the pressure surface of the blade and the main plate surface is approximately 90 ° as in the conventional case, the loss factor is approximately 0.5, but if this is 45 °, the loss factor is If the degree of acute angle at the same angle becomes sharper, the loss factor increases further. Therefore, in the present embodiment, at least 3 to 5 compared to the case where the angle is approximately 90 °. This is a loss factor twice as large.
[0015]
And there is the following relationship between each physical quantity in this part.
(Loss) ∝ (Leakage flow rate) ∝ (Gap area) × (Leakage flow rate).
(Leakage flow rate) ∝√ [(pressure difference between pressure surface and suction surface) / (loss factor)].
Therefore, according to the present embodiment, when the loss factor is 3 to 5 times, the leakage flow rate is reduced to 1 / √3 to 1 / √5, and the efficiency reduction due to leakage can be prevented.
[0016]
Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to this embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention. Absent.
[0017]
【The invention's effect】
As described above, according to the present invention, the leakage flow rate between the blade and the casing is greatly reduced as compared with the conventional one, and the reduction in efficiency due to this leakage is prevented, providing an efficient and highly reliable one. It was something that could be done.
[Brief description of the drawings]
FIG. 1 is a front view of an impeller according to an embodiment of the present invention viewed from a main plate side.
2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is an enlarged view of a portion X in FIG.
FIG. 4 is a front view of a conventional impeller viewed from the main plate side.
5 is a VV cross-sectional view of FIG.
6 is an enlarged view of a Y part in FIG. 5;
[Explanation of symbols]
10 Impeller 11 Scallop 12 Blade 14 Main plate 16 Casing 17 Pressure surface 18 Negative pressure surface 19 Clearance 112 (Blade pressure surface and main plate) angle

Claims (2)

The main plate is notched between the pressure surface of one wing and the suction surface of the adjacent wing to form a scallop, and the minimum radius of the scallop is from the center between the one wing and the adjacent wing to the adjacent A radial turbine impeller characterized in that the scalloped shape is asymmetrical on the left and right sides of the blades by biasing toward the suction surface side of the blades. The radial turbine impeller according to claim 1, wherein an angle formed between the pressure surface of the blade and the main plate surface is an acute angle of 45 degrees or less .

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