JPS5859399A - Turbo-type fluid machine - Google Patents

Abstract

PURPOSE:To improve the performance of a turbo-type fluid machine, by reducing the area of flow separating regions in both of a diffuser passage and an impeller passage through provision of a conduit connecting these two passages to each other. CONSTITUTION:When a valve 12 is opened, fluid flow from a diffuser section 8 toward an impeller 3 is caused in a conduit 11 since pressure in the diffuser section 8 is higher than that in the region of the impeller 3. Here, since one end of the conduit 11 is opened on the side 7a of a guide vane 7 where the pressure is negative, i.e., in a region 14 where separation of fluid flow is caused, separated fluid is drawn into the conduit 11. Therefore, the area of the separation region 14 is reduced. On the other hand, since the other end of the conduit 11 is opened on the side 13 of the fluid passage in the casing 4, high-pressure fluid drawn into the conduit 11 from the diffuser 8 is ejected toward the impeller 3. Resultantly, energy is supplied to the fluid separated from the negative-pressure side of the impeller 3, so that the area of the separation region in the impeller 3 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbo fluid machine such as a centrifugal compressor or mixed flow blower.

As shown in FIG. 1, the employee's turbo 1 fluid machine has an impeller without side plates, which is composed of six plates 1 and a plurality of blades 2. A casing 4 is provided to face the impeller 3, and a pair of diffuser plates 5, 6 are arranged to face the outer circumferential side of the impeller 3.
A diffuser with guide vanes 8 in which guide vanes 7 are arranged in a circular row between the guide vanes. It is comprised of a scroll 91 that collects fluid discharged from the diffuser 8, a suction pipe 10, and the like. In the turbo fluid machine configured in this way, the flow angle α almost matches the blade angle β at the inlet of one impeller 3 and the diffuser 8 near the design flow point, so the performance of the turbo fluid is is expensive. However, when the flow rate decreases, at the inlet of the impeller 3, as shown in FIG.

Since the angle β1 of the blade 2 and the flow angle α, i are different, the flow causes separation on the suction side 2a of the blade 2.

Furthermore, as shown in FIG. 3 at the entrance of the diff user 80, separation occurs on the negative pressure side 7a due to the difference between the angle βd of the guide vane 7 and the flow angle αd. As a result, not only the performance of the turbo-type fluid machine deteriorates, but also the fluid machine enters surging at a flow point relatively close to the design flow point, resulting in a disadvantage that the operating range becomes narrower.

This invention was made based on the above-mentioned matters −′
□The purpose is to provide a turbo fluid machine that expands the operating range of the turbo fluid machine and improves performance in the low flow range (partial load) by reducing the separation area in the diffuser and impeller. That is.

The present invention is characterized in that it provides a turbo fluid machine including an impeller without side plates provided in a casing and a diffuser with guide vanes in which guide vanes are arranged in a circular row between a pair of opposing diffuser plates. , a conduit is provided with one end opening on the negative pressure side of the guide vane in the diffuser flow path and the other end opening on the flow path side of the casing provided opposite to the impeller, and a turbo type It is equipped with a valve that is operated in conjunction with the flow rate of the fluid machine.

With this configuration, the fluid in the negative pressure section in the diffuser can be blown out to the negative pressure section in the impeller flow path, thereby reducing the amount of separation in the diffuser and the separation area in the impeller. It is possible to expand the operating range of the machine and improve characteristics in the low flow range.

An embodiment in which the present invention is applied to a centrifugal fluid machine will be described below with reference to FIGS. 4 to 6. In each of these figures, buttons that are the same as those in the book shown in FIGS. 1 to 3 are given the same reference numerals.

In the figure, 11 is a conduit, and one end of this conduit 11 passes through the diffuser plate 5 and opens on the negative pressure side 7a of the guide vane 7 in the diffuser flow path (see FIG. 6), and the other end is It opens on the flow path surface side 13 of the casing 4 provided opposite the impeller 3. Further, as shown in FIG. 5, the angle Rr between the pipe line 11 on the flow path side 13 of the casing 4 and its normal line is positive.

A valve 12 is provided in the middle of the conduit 11 and is connected to a flow control valve (not shown) of a centrifugal fluid machine.
2 is operated in conjunction with the flow rate of the centrifugal fluid machine. One conduit 11 having such a valve 12 is provided for each pitch of the guide vanes 7 in the diffuser 8, that is, the same number as the guide vanes 7. The valve 12 is closed when the operating state of the turbo fluid machine is near the design flow rate point, but is configured to open when the opening of the flow control valve becomes less than a certain value, that is, the flow rate becomes less than a certain value.

The operation of one embodiment configured as described above will be described below. Since the valve 12 is closed near the design flow point of the centrifugal fluid machine, the centrifugal fluid machine operates in the same manner as a conventional centrifugal fluid machine, thus providing high performance.

By throttling the flow control valves of the centrifugal fluid machine, when the flow rate falls below a certain value, 12 valves are opened. In general, the pressure in the diffuser 8 section is higher than the pressure in the impeller 3, so when the valve 12 is opened, the pressure difference causes the pressure in the diffuser 8 section to move from the impeller to the impeller in the pipe line 11, as shown by the arrow in FIG. A flow toward 3 occurs. One end of this pipe 11 is connected to the sixth
As shown in the figure, guide vanes 7 in the diffuser flow path
Since it is open to the negative pressure side 7a of the diffuser 8, that is, the flow separation region 14, the fluid separated within the diffuser 8 is sucked into the pipe line 11. As a result, as shown in the figure, the separation area 14 in the diffuser 8 in the present invention is significantly reduced compared to the separation area 15 in the conventional centrifugal fluid machine, and the diffuser performance is significantly improved. worn,
The other end of the pipe line 11 is open to the flow path side 13 of the casing 4 provided opposite to the first impeller 3, so the pipe line 1
The high-pressure fluid in the diffuser 8 that has been sucked into the diffuser 1 is blown out toward the impeller 3 . As a result, energy is given to the separated fluid on the suction side of the blades 2 within the impeller 3, so the separated area within the impeller 3 can also be reduced, and the performance of the impeller is improved. Furthermore, due to the reduction in the separation area within the impeller 3 and the diffuser 8, the surging point of the turbo-fluid machine will be at a flow rate considerably lower than the design flow point, and the operating range will therefore be expanded.

In the above-described embodiment, one pipe is provided for each pitch of the blade row in the diffuser, but the invention is not limited to this. It is also possible to provide a path. In addition, although this example describes the case where it is applied to a centrifugal fluid machine,
It is also applicable to mixed flow type fluid machines.

As described above, in the turbo fluid machine of the present invention, a pipe is provided that communicates the negative pressure side of the guide vane in the diffuser with the flow path side of the casing provided opposite to the impeller. Not only can the separation area in the impeller be reduced and therefore the performance in the low flow region of turbo-type fluid machinery can be improved.

This has the effect that the operating range can also be expanded.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing a conventional turbo-type fluid machine;
The figure is an explanatory diagram showing the flow at partial load in the impeller of Figure 1, Figure 3 is an explanatory diagram showing the flow at partial load in the diffuser of Figure 1, and Figure 4 is an explanatory diagram showing the flow at partial load in the impeller of the present invention. A vertical cross-sectional view showing one embodiment of the fluid machine, FIG. 5 is an enlarged view of the main part of FIG. 4, and FIG. 6 is! FIG. 2 is an explanatory diagram showing the flow at partial load in the diffuser of FIG. 1; 3... Impeller, 4... Casing, 5.6... Diffuser plate, 7... Guide vane, 7a... Negative pressure side, 8... Diffuser, 11... Conduit, 12...
Valve t13...flow path side of the casing. fil prisoner; f2 figure, +3121 years 4 days

Claims (1)

[Claims] In a turbo fluid machine equipped with an impeller without side plates provided in a casing and a diffuser with guide vanes in which guide vanes are arranged in a circular row between a pair of opposing diffuser plates, one end is connected to the diffuser flow path. a conduit opening on the negative pressure side of the guide vane, the other end of which is provided opposite the vane, and opening on the flow path side of the casing;
A turbo-type fluid machine characterized in that a valve operated in conjunction with the flow rate of the turbo-type fluid machine is provided in the middle of the conduit.