JPS5818600A - Blower compressor - Google Patents

Abstract

PURPOSE:To prevent the surging by providing an impeller entrance casing, at its inside and at a position facing the blade leading edge of an impeller, with a recessed circular groove whose width includes the blade leading edge. CONSTITUTION:An impeller 1 equipped with a blade 2 is rotated by a rotating shaft 3. At the impeller entrance part 7, a circular groove 17, which is extended up to the leading edge 6 of the blade 2, is provided. With this constitution, eddies occur only in the circular groove without disturbing the main stream line for an adequate flow rate. Even when the flow rate is decreased, the angle of the stream line situated upstream against the circular groove 17 becomes smaller than the blade fitting angle. When the fluid inlet speed to the blade 2 is reduced, the eddies are pushed away from the main stream casing 5. It results in an apparent increase in the flow rate to the leading edge 6 of the blade 2, and a separation of flow can be prevented.

Description

[Detailed description of the invention] The present invention relates to a blower compressor.

Known blower compressors include an axial flow type as shown in Fig. 1;
There are diagonal flow type as shown in Fig. 2 and centrifugal type as shown in Fig. 3, but the flow of fluid in the lower wing of each is shown in Fig. 4.

As shown in FIGS. 5 and 6, l is an impeller, 2 is a blade, 3 is a rotating shaft, 5 is a casing, 6 is a blade leading edge, lla, and 12a.

13a, llb, 12b, and 13b are velocity vectors, 11 is a circumferential velocity vector of the rotation of blade 2, 12 is a meridional velocity vector at which the flow flows into blade 2, and 13 is a relative velocity vector of the flow as seen from the blade. .

In Fig. 5, the flow angle βa and the blade installation angle β are the same, so the flows 14a and 15a flow smoothly along the concave and convex surfaces of the blade 2, but if the flow rate decreases, as shown in Fig. 6. As shown in , the meridional velocity vector 12 becomes shorter and the flow angle βb becomes smaller than β, so the flow '14
b, 15b will come into contact with the ventral surface 9 of the wing 2, so
Flow 15b is no longer able to flow along the back surface;
A delamination 16 occurs.

As described above, in conventional blowers and compressors, separation 16 occurs on the back surface 10 of the blades as the flow rate ' decreases, resulting in a disadvantage that the operating range of the blowers and compressors is narrowed.
The present invention was proposed in view of these circumstances.
In order to prevent the occurrence of surging and provide a blower compressor with a wide operating range, an annular groove spanning the front line of the blade is provided in the portion of the casing at the impeller inlet facing the directly leading edge of the impeller. It is characterized by:

An embodiment in which the present invention is applied to a mixed-flow type blower will be explained with reference to the drawings. Fig. 7 is a partial longitudinal sectional side view of the same, and Figs. 8 and 9 respectively show the impeller inlet when the flow rate is appropriate in Fig. 7. flow diagrams in the meridional plane and in the rotational plane,
Figures 10 and 11 are flow diagrams in the meridian plane and rotational flow plane at the impeller inlet when the flow rate is low in Figure 7, respectively. Figure 12 is an enlarged view between the blades in Figure 11, and Figures 13 and 14 are the points PI in Figure 12, respectively.
.

A velocity triangle diagram at P2, FIG. 15 is a partially enlarged view of FIG. 7, and FIGS. 16 to 23 are partial longitudinal sectional views showing annular grooves different from those in FIG. 7.

First, in FIG. 7, the same symbols as in FIG. 3 indicate the same members as in FIG. 3, respectively.

Reference numeral 17 denotes an annular groove provided in the casing 5 of the lower rain root wheel, spanning the leading edge 6 of the impeller blade.

In such a blower, when the flow rate is appropriate, as shown in FIGS. 8 and 9, the flow angle βC and the mounting angle β of the blades 2 coincide with each other. A vortex 18 is generated, and the flow of the main stream 8 is the same as the velocity vector diagrams shown in FIGS. 4 and 5.

However, when the flow rate decreases slightly, the
As shown in FIG. 1, the angle β of the flow upstream of the annular groove 17
d becomes smaller than the blade attachment angle β. When the inflow velocity into the blade 2 becomes small, the centrifugal force exerted on the fluid by the blade increases, so the mainstream 8 is pushed downward, and the apparent The flow rate flowing into the blade leading edge 6 increases, and the flow angle βd' at the blade leading edge 6 becomes larger than the upstream βd, so that separation 16 as shown in FIG. 6 is prevented from occurring.

To further supplement this point, the velocity triangle at points PI and P2 on the center line between the blades shown in Fig. 12 is as shown in Figs. 13 and 14, and the solid line indicates an appropriate flow rate and a flow angle β
1 (see FIG. 13) is y-coinciding with the blade attachment angle βbl (see FIG. 13), and the broken line shows the velocity triangle when the flow rate decreases.

When the flow rate decreases, as shown in Fig. 14, the meridional velocity - decreases to CIrL2', and the flow at point P2 tends to flow along the blade, so βb2JFβ2kiβ2', and the relative Velocity W2 decreases to W2'.

However, since the peripheral speed U2 is constant, the absolute speed C
2 changes its flow direction and size to C2', and accordingly, the circumferential component Cu2 of the absolute velocity C2 increases to Cu·2'.

The centrifugal force at point P2 is given by the radius R1 and the density ρ.

As a result of the decrease in flow rate, the centrifugal force F acting on point P2 becomes large as shown in FIG. The centrifugal force that generates the vortex increases due to the decrease in vortices, which causes the vortices to become larger.

Since the occurrence of peeling is the main cause of surging in blowers and compressors, the present invention prevents this by using an annular groove provided in the casing, thereby making it possible to obtain blowers and compressors with a wide operating range. can.

The shape of the annular groove may be the shape shown in FIG. 7 or the shapes shown in FIGS. 16 to 24.

In the case shown in FIG. 16, the upstream edge 22 and downstream edge 23 of the groove 17 are formed at acute angles, so that the vortex 18 generated in the groove 17 smoothly follows the wall of the groove.

The design shown in FIG. 17 is designed by creating a difference 27 between the casing radius on the upstream side and the casing radius on the downstream side of the groove 17, so that the flow 250 force that generates the vortex 18 is weakened by the flow 26 from upstream. It is possible to prevent performance deterioration due to flow rate.

The one shown in FIG. 18 can smoothly guide the flow 26 from upstream into the groove 17, and can have substantially the same effect as in FIG. 17. As shown in FIGS. 19 to 23, The groove can be constructed from arbitrary curves and straight lines.

In short, according to the present invention, an annular groove extending over the leading edge of the blade is provided in the portion of the casing at the impeller inlet facing the leading edge of the blade of the impeller, thereby preventing surging and compressing air over a wide operating range. Therefore, the present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are partial longitudinal sectional side views of known axial flow type, mixed flow type, and centrifugal type blowers, and FIGS. 4 and 5, respectively.
Figure 6 shows the flow on the meridian plane of Figures 1, 2, and 3, respectively.2 The flow is on a cylindrical surface (hereinafter referred to as a rotating flow surface) centered on the rotation axis, and when the flow rate is appropriate, Flow velocity triangle diagram when the flow rate decreases on a rotating flow surface, No. 7
The figure is a partial longitudinal sectional side view showing an embodiment in which the present invention is applied to a mixed flow type blower, and Figures 8 and 9 respectively show the flow in the meridian plane at the impeller inlet when the flow rate is appropriate in Figure 7. Figures 10 and 11 are flow diagrams in the meridian plane of the impeller inlet and flow diagrams in the rotating flow plane when the flow rate is small in Figure 7, respectively, and Figure 12 is a flow diagram in the rotating flow plane. The enlarged views between the blades in the figure, FIGS. 13 and 14, respectively correspond to point Pl in FIG. 12. A velocity triangle diagram at P2, FIG. 15 is a partially enlarged view of FIG. 7, and FIGS. 16 to 23 are partial longitudinal sectional views showing annular grooves different from those in FIG. 7. ■... Impeller, 2... Blade, 3... Rotating shaft, 5... Casing, 6... Blade leading edge, 7... Impeller inlet, 8... Main stream,
9. Ventral surface, 10. Back surface, 11. Peripheral velocity vector, 12
...Meridional velocity vector, 13.. Relative velocity vector, 14a, 15a, 14b, 15b.. Flow velocity vector, 16.. Separation, 17.. Annular groove, 18.. Vortex, Sub-Agent Patent Attorney Tsuka Masafumi Hon (and 1 other person) Shima Figure 12 Bird IL'E3 Figure Height 74 Figure Procedural Amendment Document Showa RTR February 1, 2017 Patent Commissioner 1, Indication of Case 1982 Patent Application No. 114432 2 , Title of the invention Air compressor 3, Address of applicant related to the case of the person making the amendment Name: 5-1 Marunouchi 2-chome, Chiyoda-ku, Tokyo (6
20”) Mitsubishi Heavy Industries, Ltd. 4, Sub-Agent 6, Contents of the amendment (1) Amend the claims as per the attached sheet. (2) Page 1, lines 3, 10, 11, and 2nd page 1st
Correct "blow compressor" in line 8 and line 12 of page 7 to "blower, compressor" respectively. (3) On page 2, lines 13-14, ``1 occurs,'' should be corrected to ``This occurs, and this is the main cause of surging in the blower and compressor.'' (4) Correct the second line of page 3 to "1 centrifugation for the slanted parrot." (5) After page 4, line 12, A, “Because it gets bigger,” it is corrected to “The flow that enters the impeller from near the tip of the impeller is pushed upwards and flows into the concave part, expanding the vortices that occur in the four parts.” do. (6) On page 7, line 16, "1 blower" is corrected to "blower. compressor". (Correct 1 diagonal flow 1 in the 2nd line of page 8 to "centrifugal". (8) Correct each figure J2.3 as shown in the attached sheet. In front of the blade of the above impeller in the casing at the impeller inlet. A blower characterized in that an annular groove spanning the leading edge of the blade is provided in a portion facing the edge.A compressor.

Claims (1)

[Claims] A blower compressor 0 characterized in that an annular groove spanning the leading edge of the blade is provided in a portion of the casing at the impeller inlet facing the leading edge of the blade of the impeller.