JP2000018004A - Radial turbine with nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress loss caused by enlarging a nozzle flow-in angle in the vicinity of both wall surfaces of a hub side and a shroud side, in a radial turbine having a plurality of nozzles for forming a flow-in passage for a turbine moving blade of a fluid such as gas for rotatably driving a turbine moving blade. SOLUTION: The shape of a plurality of nozzles 3 for forming a flow-in passage for a fluid such as gas for rotatably driving a turbine moving blade, has larger blade angle 7a in the vicinity of a hub side wall surface 3a and a shroud side wall surface 3b part of a nozzle front edge than a blade angle 7b in the center passage. Accordingly, an incidence angle of flow formed in the vicinity of both wall surfaces of a hub side and a shroud side is reduced, and nozzle loss is also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radial turbine with a nozzle used for a small gas turbine, an expander, a turbocharger, a mixed flow turbine, a water turbine, and the like.

[0002]

2. Description of the Related Art As shown in FIG. 4, a nozzle 3 of a radial turbine has a flow angle from a scroll flow path 2 in a turbine casing 1 with respect to a moving blade 4 in both a circumferential direction and a width direction. Used to increase speed to be uniform. As shown in FIG. 5, the shape of the nozzle 3 of the conventional radial turbine with a nozzle has a uniform shape (blade angle 7) in the width direction.
Constant).

The flow flowing into the nozzle 3 is affected by the secondary flow due to the boundary layer developed inside the scroll on the upstream side of the nozzle, and is affected by the hub side wall surface 3a and the shroud side wall surface 3a.
In the vicinity of b, the centrifugal force is small because the flow velocity in the circumferential direction is small, and therefore, the flow velocity flowing inward in the radial direction is high.
This is shown in FIG.

As shown in FIG. 6, the radial flow velocity 51a near the hub side wall surface 3a and the shroud side wall surface 3b is higher than the radial flow velocity 51b at the flow path center B.
Therefore, as shown in FIG. 7A, the nozzle inflow angle 6a near both wall surfaces becomes larger than the nozzle inflow angle 6b at the center of the flow channel shown in FIG. 7B (6a> 6b).

Accordingly, the conventional nozzle shape has a problem that the blade angle 7 is constant in the nozzle width direction, so that the incident angle 8 is large near both wall surfaces, and the loss is large.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional radial turbine with a nozzle, the present invention provides a turbine rotor blade rotatably installed and a rotating blade for rotating the turbine rotor blade. In a radial turbine having a plurality of nozzles forming an inflow path of a fluid such as a gas to be driven into a turbine rotor blade, it is possible to suppress a loss caused by a large nozzle inflow angle near both a hub side wall and a shroud side wall surface. It is an object to provide a radial turbine with a nozzle that can be used.

[0007]

According to the present invention, there is provided a radial turbine having a nozzle.
Provided is a radial turbine with a nozzle that employs a nozzle having a blade angle in the vicinity of both a hub side wall and a shroud side wall surface of a nozzle front edge that is larger than a blade angle at the center of a flow path.

In the radial turbine of the present invention having the above-described configuration, the blade angles near both the hub side wall and the shroud side wall at the leading edge of the nozzle are larger than the blade angles at the center of the flow path. The incident angle in the vicinity of both side walls is reduced, and the nozzle loss is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radial turbine with a nozzle according to an embodiment of the present invention will be specifically described below with reference to FIGS. As described above, in the radial turbine with a nozzle, the radial flow velocity 51a near the hub side wall surface 3a and the shroud side wall surface 3b is affected by the secondary flow, as shown by the nozzle inflow speed shown by the curve 6 in FIG. 7, the velocity becomes higher than the radial flow velocity 51b at the center B of the flow path, and the velocity becomes a velocity triangle as shown in FIG.

Therefore, the nozzle inflow angle 6a near the hub and shroud side walls shown in FIG. 7A is larger than the nozzle inflow angle 6b at the center of the flow path shown in FIG. 7B. Therefore, the incident angle near both wall surfaces increases. As the incident angle increases, the nozzle loss increases as shown in FIG. In order to reduce this nozzle loss, it is necessary to reduce the incident angle 8 near both wall surfaces.

With this concept, in the turbine according to the present embodiment, the blade angle 7a near the hub side wall surface and near the shroud side wall surface of the nozzle is changed to the blade angle 7b at the center of the flow path.
Is larger. That is, as shown in FIG. 1B, the blade angle 7a in a cross section (broken line) along the line AA near the hub side wall surface 3a and the line CC near the shroud side wall surface 3b is determined by the flow path. The blade angle 7b is larger than a blade angle 7b in a cross section (solid line) along the center line BB. FIG. 2 shows the relationship between the blade angle of the nozzle of the conventional radial turbine and the blade angle of the nozzle in the present embodiment.

In the radial turbine with a nozzle according to this embodiment, the blade angle 7a near both the hub side wall and the shroud side wall surface at the front edge of the nozzle is made larger than the blade angle 7b at the center of the flow path, so that the incident angle 81 can be reduced. Is smaller than the incident angle 82, and the nozzle loss is reduced. However, if the flow outflow from the nozzle 3 is given an outflow angle in the width direction, an incident is made in the width direction by the moving blade and the loss increases, so that only the leading edge of the nozzle has a blade angle distribution in the width direction.

In the case of a scroll with nozzles, the cross-sectional area of the scroll is large because the circumferential flow velocity at the nozzle inlet is lower than that of a nozzleless scroll. Therefore, also in a scroll with a nozzle, by increasing the circumferential flow velocity, the scroll cross-sectional area can be reduced, and the manufacturing cost can be reduced.

However, if the circumferential flow velocity is increased, the nozzle inflow angle becomes smaller, making it difficult to increase the leading edge radius. That is, the nozzle loss is greatly affected by the incident.

Therefore, if the blade angle near both the hub side wall and the shroud side wall at the front edge of the nozzle is made larger than the blade angle at the center of the flow passage as in this embodiment, the nozzle loss when the scroll is downsized is reduced. Can be reduced. It is desirable that the incident angle of the nozzle be changed according to the present invention only within the chord length range of 0.15 to 0.2.

[0016]

As described above, the present invention relates to a turbine rotor blade rotatably provided and a plurality of fluid passages for forming a fluid such as gas for rotating the turbine rotor blade into the turbine rotor blade. In the radial turbine having the nozzle described above, the nozzle provides a radial turbine with a nozzle in which the blade angle near both the hub-side and shroud-side wall surfaces of the nozzle front edge is larger than the blade angle at the center of the flow path.

As described above, according to the present invention, with respect to the nozzle shape of the radial turbine with a nozzle, the blade angles near both the hub-side and shroud-side wall surfaces at the front edge of the nozzle are made larger than the blade angle at the center of the flow path. In addition, it is possible to improve the incident of the flow near both wall surfaces and reduce the nozzle loss.

[Brief description of the drawings]

FIG. 1 is a drawing showing a radial turbine with a nozzle according to an embodiment of the present invention, in which (a) is a sectional view in a radial direction,
(B) Drawing which shows the cross-sectional shape which follows the AA, BB, and CC line of the nozzle of (a).

FIG. 2 is a diagram showing a flow angle distribution in a nozzle width direction at a nozzle inlet in a radial turbine with a nozzle,
(A) shows the case of the nozzle in the conventional turbine, and (b) shows the case of the nozzle in the turbine of the present invention.

FIG. 3 is a diagram showing a relationship between an incident angle to a nozzle and a nozzle loss in a radial turbine with a nozzle.

FIG. 4 is a radial cross-sectional view showing the structure of a conventional radial turbine with a nozzle.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a diagram showing a velocity distribution in a nozzle width direction of a flow velocity at a nozzle inlet of a conventional radial turbine with a nozzle.

FIG. 7 is a drawing showing a velocity triangle at a nozzle inlet in a radial turbine with a nozzle, where (a) shows the vicinity of both wall surfaces,
(B) shows a velocity triangle at the center of the flow channel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine casing 2 Scroll flow path 3 Nozzle 3a Hub side wall surface 3b Shroud side wall surface 4 Moving blade 5a, 5b Absolute flow velocity 51a, 51b Radial flow velocity 52 Circumferential flow velocity 6 Nozzle inflow velocity 7 Blade angle 7a (A-A neighborhood) Blade angle in the vicinity 7b (near BB) Blade angle in the center of the channel 8 Incident angle

Claims (1)

[Claims] 1. A turbine blade rotatably installed,
A plurality of nozzles forming an inflow path of a fluid such as gas for rotating the turbine rotor blade into the turbine rotor blade, wherein the nozzle is located near the hub-side and shroud-side wall surfaces of the nozzle front edge. A radial turbine with a nozzle, characterized in that the blade angle is larger than the blade angle at the center of the flow path.