JPS61187502A - Blade construction of axial flow turbo-machine - Google Patents

Abstract

PURPOSE:To reduce a loss due to a secondary flow in a machine and improve its performance, by providing an inflow hole in the leading edge of a blade section in the vicinity of an end wall in the axial flow turbomachine and allowing the inflow of an air stream to flow out from a discharge hole, provided in the vicinity of the trailing edge of a blade, through a flow path in the blade section. CONSTITUTION:A blade 1 is constructed such low energy fluid flowing along an end wall of the blade 1 is inducted from an inflow hole 10, provided in a blade leading edge 1c, and discharged from a discharge hole 11, provided in the rear of a blade belly surface, through inside a blade section. In this way, the growth of a horseshoe-shaped volute generated from the blade leading edge 1c can be suppressed. While the growth of a flow path volute generated between blade paths can be prevented by an outflow of fluid from the discharge hole 11 in the trailing edge side. Accordingly, the improvement of performance can be attained by concurrently reducing a loss.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in the technical field of reducing losses due to secondary flow in axial flow turbomachinery and improving performance.

A conventional axial flow turbomachine, for example, as shown in FIG. 3, has a boss 03 fixed to a rotating shaft within a casing 03a.
The rotor blades 01 and stationary blades 02 attached to b are alternately arranged.

When this axial flow turbomachine is in operation, as shown in FIG. 4, an example of the rotor blade 01, the horseshoe-shaped cylinder 06 is moved along its end wall, that is, along the surfaces of the casing 03a and the boss 03b in FIG. A secondary flow is generated due to the flow path vortex 05.

That is, as shown in Fig. 5, if the curvature of the streamlines in the wall boundary layer that develops on the end wall is equal to the curvature of the main stream 08 of the interblade passage, the flow in the end wall boundary layer will be smaller than the main stream 08. The flow velocity is low and the centrifugal force is low.

Therefore, the pressure gradient in the pitch direction of the blade row is smaller than that of the main flow 08 in the boundary layer, and the fluid moves along the end wall surface toward the blade ventral surface 08.
It flows from 1a to the back side 01b. This is called a flow path vortex 05.

On the other hand, on the front wall surface, as shown in Fig. 6, the boundary layer 08
has developed, and when it hits the wing leading edge 01c,
Because the dynamic pressure due to the velocity at the blade height position separated by the wall is greater than the dynamic pressure near the wall where the velocity is lower, the fluid flows toward the wall where the dynamic pressure is lower, and the fluid hits the wall.
A so-called horseshoe-shaped tube 0 that goes around the wing leading edge 01c on the end wall
yields 6.

These vortices constitute the so-called secondary flow, and the seventh
As shown in the figure, casing 03a and boss 031]
Low-energy fluid accumulates on the side, which is the main cause of degrading the performance of axial flow turbomachinery.

As a countermeasure against this, for example, as shown in FIG. 8, there is an idea to provide fins 09 of a certain height in the wall passage of the casing 03a or the boss 03b to prevent losses due to the flow passage vortices 05. However, this has no effect on the growth of the horseshoe-shaped vortex 06, which is considered to be the dominant cause of loss, and results in a significant drop in performance.

Problems to be Solved by the Invention The present invention provides a flow path from the leading edge of the blade to the trailing force of the blade in the cross section of the blade near the end wall so that the working fluid flows in from the leading edge of the blade and exits near the trailing edge. By providing the passage, the purpose is to suppress the growth of the horseshoe-shaped vortex that develops from the front of the blade on the end wall and the flow path vortex that occurs between the blade row passages, thereby improving performance.

Means for Solving the Problems The present invention employs the following means to solve the above-mentioned problems. That is, an inflow hole is provided at the leading edge of the wall section near the end wall of the axial flow turbomachine, and the incoming airflow passes through a flow path in the blade section and exits from the exhaust hole provided near the trailing edge of the blade.

Effect: According to the means described above, a portion of the flow along the end wall enters from the leading edge of the wing and flows out toward the ventral surface of the wing, thereby suppressing the development of a horseshoe-shaped vortex.

Embodiment Next, an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

As shown in the sectional view of the vicinity of the end wall of the blade 1 in FIG. 2, the low-energy fluid flowing along the end wall is sucked through the inlet hole 10 provided at the leading edge IC of the blade, passes through the cross section of the blade, and flows into the ventral surface of the blade. The structure is such that a passage is provided for exiting from a discharge hole 11 provided at the rear. In this embodiment, the discharge hole 11 is provided on the rear side of the ventral surface, but it may be provided on the back side 16 and both surfaces la and lb. In general,
It is preferable to provide the discharge hole 11 in the blade vent surface 1a.

Moreover, the inflow port 10 and the discharge hole 11 may be one or more and may be slit-shaped. Furthermore, it is also possible to use the fin 09 shown in FIG. 8, which is a conventional technique, in combination.

A part of the flow along the end wall enters from the leading edge of the blade and flows out to the ventral surface of the blade.

Effects of the Invention By employing the blade structure of a turbomachine according to the present invention, the following effects can be achieved.

a. By suppressing the development of horseshoe-shaped vortices that grow from the leading edge of the blade, which is the main cause of loss, loss can be reduced and performance can be improved.

b. The fluid flowing out from the discharge hole on the trailing edge side does not grow between the blade passages and prevents the growth of stone passage vortices, reducing loss and improving performance.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a perspective view of a wing, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIGS. , Fig. 3 is a cross-sectional view of the casing showing the rotor blades and stationary blades, Fig. 4 is a perspective view showing vortex generation, Fig. 5 is a cross-sectional view showing streamlines in the wall boundary layer, and Fig. 6 is a secondary cross-sectional view. FIG. 3 is a perspective view showing the generation of flow. FIG. 7 is a diagram showing a case where low-energy fluid accumulates and performance deteriorates, and FIG. 8 is a sectional view of another example of a fin provided with a fin. 1... wing, 1a... wing ventral surface, lb... back side, 1c...
Blade leading edge, 10...inflow hole, 11...discharge hole. Sub-agent Masami Kimura, :゛〕]. (and 7 others)'' Figure 1 Figure 2 Cross-sectional view of II-II Figure 3 Figure 5 Figure 6 Figure 7 Figure 6 Procedure Iff official document (spontaneous) May 21, 1985 Commissioner of the Japan Patent Office Manabu Shiga l・l< Display of patent application No. 26541 of 1986 2
Title of the invention Axial flow turbomachinery blade structure 3, hli
Person making the correction Relationship to the case Name of applicant Mitsubishi Heavy Industries, Ltd. 4 Sub-agent 8-1-chome, Yurakucho, Chiyoda-ku, Tokyo 100゛ 5 Subject of amendment The column of “Detailed description of the invention” in the specification and The details of drawing [Δ] will be corrected as follows. (1) In the 2nd Ll, the 6th line "curvature" was corrected to "J" and the 13th line "08" was corrected to "04". (2) Delete “Therefore,” on page 4, line 6. [13] In Figure 6 of the drawings, the code “08” has been corrected to “04” as shown in red on the attached copy.

Claims (1)

[Claims] Axial flow is an axial flow system in which an inflow hole is provided at the leading edge of the wall cross section near the end wall of an axial flow turbomachine, and the incoming airflow passes through a flow path within the blade cross section and exits through a discharge hole provided near the trailing edge of the blade. Turbomachinery wing structure.