JP3040601B2 - Radial turbine blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial turbine blade, and can be applied to a radial turbine such as a supercharger, a gas turbine, a gas expander, and the like.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional radial turbine. FIG. 4 is a cross-sectional view including a cross section including the rotation axis of the radial turbine. In the drawing, 1 is a scroll which is a spiral flow path, 2 is a moving blade, 3 is a scroll outlet, 4 is a scroll outlet wall, and 5 is a dynamic The leading edge hub 6, the leading edge center 7, and the leading edge shroud side 8 of the blade 2 are shown.

The gas flowing into the radial turbine is given a radial velocity while flowing in the scroll 1 in the circumferential direction (perpendicular to the direction of the drawing), flows into the moving blade 2, and rotates the moving blade 2 around its rotation axis. Act to make it.

[0004]

FIG. 5 shows a speed triangle at the blade entrance of a conventional radial turbine. 5A shows a speed triangle at the center of the blade entrance, and FIG. 5B shows a speed triangle at the blade inlet hub side or shroud side, respectively.

The conventional blade leading edge 5 has a radius r _{hub of} the leading edge _hub 6, a radius r _{mid of the} leading edge center 7 and a leading edge shroud side 8.
_Is constant, that is, r _hub = r _mid = r _shroud , so that the peripheral speed corresponding to each position is also U _hub = U _mid = U _shroud .

On the other hand, the absolute inflow speed depends on the scroll outlet 3
As shown in FIG. 5, the leading edge hub side 6 and the leading edge shroud side 8 of the bucket leading edge 5 have the center 7 The standing flow has a smaller circumferential component and a larger radial component than the vicinity. As a result, the incident angle i _3, which is the collision angle of the flow when flowing relatively into the bucket, is i ₃ , _mid > i ₃ , _hub > i ₃ , _shroud . Therefore, in the conventional radial turbine rotor blade, as shown by a solid line in FIG. 3, when the incident angle i ₃ , _{mid at the} leading edge center 7 is the optimum incident angle i ₃ , _opt , the leading edge hub side 6 and the leading edge incidence angle i ₃ edge shroud side 8, _hub, i _{3, shroud} is deviated from the optimum value, as a result, increased incidence loss is, the efficiency of the turbine is disadvantageously decreases.

In FIG. 5, the speed triangles of the leading edge hub side 6 and the leading edge shroud side 8 are the same.
The degree of deviation of the two speed triangles from the leading edge center 7 varies depending on the shapes of the scroll 1 and the moving blade 2, the operating conditions, and the like. In general, the two do not coincide with each other. An example in which both are the same is shown below.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a radial turbine rotor blade capable of reducing incident loss and improving turbine performance in order to solve the above problems.

[0009]

According to the present invention, the shape of the leading edge of the moving blade on the inlet gas inlet side is large at the center of the leading edge, the leading edge hub side and the leading edge shroud side. Provides a radial turbine blade characterized by being formed by a continuous curve having a smaller radius.

[0010]

According to the above means, since the radii on the leading edge hub side and the leading edge shroud side are smaller than the radius of the leading edge center, the moving blade peripheral speed is also the peripheral speed on the leading edge hub side and the leading edge shroud side. The peripheral speed is lower than the peripheral speed at the center of the leading edge, the deviation of the incident angle on the leading edge hub side and the leading edge shroud side is reduced, the incident loss is reduced, and the decrease in turbine efficiency is reduced.

[0011]

FIG. 1 illustrates a radial turbine rotor blade according to the present invention. In FIG. 1, the same parts as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. Omitted.

According to FIG. 1, the shape of the blade leading edge of the blade 2 is such that the radius r _mid at the leading edge center 7 is large, the radius r _hub at the leading edge hub side 6 and the leading edge shroud side 8, It is formed by a continuous curve such that r _shroud is smaller.

More specifically, the relationship among the design average radius r _design , the radius r _hub of the leading edge hub side 6, the radius r _mid of the leading edge center 7, and the radius r shroud of the leading edge shroud side 8 is _represented by r _design <r decided _{to mid r design <r shroud <r} mid r hub <r design (r hub + r mid + r shroud) / 3 = r design the relationship is satisfied, the radius r _hub, r _mid and r
_{The shroud} is connected by a quadratic curve to form the bucket leading edge 5.

The relationship between these four members is that
According to the shape of the turbine and the operating conditions of the turbine design, for example, FIG.
As shown by the dashed line in FIG. 2, the incident angle distribution at the blade entrance is selected so as to be as optimal as possible.

Accordingly, since the radius r _hub and r _shroud are smaller than the radius r _mid , as shown in FIG. 2, the rotor blade peripheral speed is also the peripheral speed U _hub of the leading edge hub side 6 and the leading edge shroud side 8.
_Is smaller than the peripheral speed U _{mid at the} center 7 of the leading edge, and the deviation of the incident angle between the leading edge hub side 6 and the leading edge shroud side 8 is reduced as shown by the broken line in FIG. Thereby, the incident loss is reduced.

[0016]

As described above, according to the present invention, an inappropriate incident angle distribution caused by non-uniformity of the blade inlet flow is corrected, and the incident loss is reduced, thereby improving the turbine performance. Can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a radial turbine blade according to the present invention.

FIG. 2 is a view showing a moving blade entrance speed triangle for explaining the operation of the radial turbine moving blade according to the present invention.

FIG. 3 is an incident angle distribution comparison diagram for comparing the action of the radial turbine rotor blade according to the present invention with that of a conventional one.

FIG. 4 is a cross-sectional view illustrating a conventional radial turbine.

FIG. 5 is a diagram showing a moving blade inlet speed triangle of a conventional radial turbine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 scroll 2 rotor blade 3 scroll outlet 4 scroll outlet wall 5 rotor blade leading edge 6 leading edge hub side 7 leading edge center 8 leading edge shroud side

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F01D 1/08 F02C 3/05 F02B 33/00-39/16

Claims (1)

(57) [Claims] The shape of the leading edge of the blade on the inlet gas inlet side is formed as a continuous curve having a large radius at the center of the leading edge, and a smaller radius at the leading edge hub side and the leading edge shroud side. Radial turbine blade.