CN113864248A

CN113864248A - Streamline splitter ring matched with space guide vane type centrifugal pump

Info

Publication number: CN113864248A
Application number: CN202111168070.4A
Authority: CN
Inventors: 高波; 梅子逸; 张宁; 倪丹
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2021-12-31

Abstract

The invention relates to a streamline splitter ring matched with a space guide vane type centrifugal pump, and belongs to the field of fluid machinery. For a single stage centrifugal pump, the splitter ring is located from the inlet suction chamber to the impeller blade inlet, and from the impeller blade outlet to the space vane inlet. For a multistage centrifugal pump, the splitter ring is present at the outlet of the spatial guide vanes to the inlet of the impeller blades in addition to the two locations described above. The molded line of the shunt ring is the middle streamline of the fluid, and the shape is similar to a trumpet shape. All the splitter rings are connected and fixed on the stator, namely the space guide vane and the inlet suction chamber. The invention reduces the vortex and the secondary flow at the inlet and the outlet of the impeller and improves the flowing state of the fluid in the flow passage by adding the splitter ring in the flow passage of the space guide vane type centrifugal pump, so that the centrifugal pump can run more stably under the working condition of low flow, the efficiency is improved, the head of a dead point is reduced to match the designed system pressure, the system damage is avoided, and the economic benefit is improved.

Description

Streamline splitter ring matched with space guide vane type centrifugal pump

Technical Field

The invention relates to a streamline splitter ring matched with a space guide vane type centrifugal pump, and belongs to the field of fluid machinery.

Background

The space guide vane type centrifugal pump is used as a fluid machine and has wide application in various fields of national economy. In recent years, with the increasing demand for centrifugal pump performance, more attention has been paid to the problem of centrifugal pump dead center head. According to the hydraulic characteristic curve of the centrifugal pump, when the flow rate is reduced, the lift is increased, and when the flow rate is 0, the lift reaches the highest value, namely the dead point lift. The pressure grade setting of the whole pipeline system is influenced by the size of the head of the closed point, and if the head is too high, the pressure grade is improved, so that the accessories such as pipelines, valves and the like are designed according to higher pressure grade requirements, and the construction cost is greatly improved. For the designed centrifugal pump, when in operation, because the flow under the working condition of small flow is extremely unstable, a vortex is formed at an inlet, and the blades perform work on the fluid repeatedly. In addition, at the outlet of the impeller, because the flow lines of the front cover plate and the rear cover plate of the impeller are different in length and work-applying capacity, the flow line of the rear cover plate is long, and much work is applied, the fluid at the outlet forms secondary flow flowing from the rear cover plate to the front cover plate, and the blades apply work to the fluid repeatedly. The two phenomena can cause the lift of the centrifugal pump near a closed dead point to be increased and exceed a design value, so that the system pressure is increased and is damaged, and if the design pressure of the system is exceeded, the system is damaged and serious economic loss is caused. Therefore, there is a need for a method of controlling the head at the dead center by improving the flow conditions.

Disclosure of Invention

The invention provides a streamline splitter ring matched with a space guide vane type centrifugal pump, which aims to improve the flow of the space guide vane type centrifugal pump under low flow, inhibit the generation of vortex and secondary flow and reduce the lift of a dead point to prevent overhigh pressure. It is located from the inlet suction chamber to the inlet of the impeller blade, from the outlet of the impeller blade to the inlet of the space guide vane blade, and for the multi-stage pump, from the outlet of the space guide vane to the inlet of the next stage impeller blade. The method is characterized in that: the molded lines of each shunting ring are intermediate fluid lines of fluid, and the molded lines of each shunting ring are perpendicular to the inlet and outlet edges of the impeller blades and the inlet and outlet edges of the space guide vane blades; the thickness of each part of the shunting ring is equal, and the thickness is 10 percent of the length of the inlet edge of the space guide vane; a proper gap is reserved at the end part of the splitter ring close to the inlet and outlet of the impeller blade, and the distance can be 0.5-1.5 mm; the splitter ring is positioned from the inlet suction chamber to the inlet of the impeller blade, and is fixed on the inlet suction chamber by 4 uniformly arranged round pipes, the relative positions of the round pipes are positioned at the inlet end 1/3 of the splitter ring close to the inlet suction chamber, and the diameters of the round pipes are 1.1-1.3 times of the thickness of the splitter ring; the splitter rings located from the outlet of the impeller blade to the inlet of the space guide blade and from the outlet of the space guide blade to the inlet of the lower-stage impeller blade are fixed on the space guide blade, or fixed on the inner wall of the space guide blade by uniformly distributed circular tubes in the manner as described above, and the relative positions of the circular tubes are close to the outlet end 1/3 of the space guide blade at the splitter rings.

The end parts of the splitter ring except the end parts fixedly connected to the space guide vane blades are all in arc transition, and the diameter of the arc is equal to the thickness of the splitter ring.

The invention has the advantages that:

1. starting from controlling the poor flow under the working condition of small flow in the centrifugal pump, the method of additionally arranging the splitter ring in the flow channel blocks the vortex and the secondary flow, prevents the impeller from doing work on the fluid for many times, improves the flow condition and reduces the head of the closed dead point to match the designed system pressure.

2. The invention has simple and reasonable structure, convenient processing and good economical efficiency.

Drawings

The invention will be further explained with reference to the drawings.

Fig. 1 is a schematic diagram of a multi-stage space guide vane centrifugal pump without a flow divider ring.

Fig. 2 is a schematic diagram of a multistage space guide vane type centrifugal pump additionally provided with a splitter ring.

FIG. 3 is a right side view schematic of a multistage space guide vane centrifugal pump with an additional splitter ring. Mainly indicates the shape of the shunting ring and the fixing method.

Fig. 4 is a schematic view of the profile of the splitter ring from the suction chamber to the vane inlet section.

FIG. 5 is a schematic view of the splitter ring profile from the impeller blade exit to the inducer section of the spatial guide vanes.

FIG. 6 is a schematic view of a splitter ring profile from the outlet of a spatial guide vane to the inducer of an impeller blade.

Fig. 7 is a schematic diagram of the vortex and secondary flow generation at small flow rates of the centrifugal pump.

Fig. 8 is a graph of expected external characteristics of the water pump.

Fig. 9 is a bezier curve plotting process.

Detailed Description

In order to achieve the purposes of improving the flow condition of the centrifugal pump under small flow and controlling the lift of a dead point, the flow divider is designed according to the following principles for each part according to the fluid mechanical principle:

1. to ensure constant flow conditions of the fluid before and after the separation, the profile of the diverter ring should be an extension of the intermediate flow lines 7 through which the fluid flows in the impeller. The molded line of the splitter ring is perpendicular to the inlet and outlet edges of the blades of the impeller 2 and the inlet and outlet edges of the blades of the space guide vane 3.

2. In order to ensure that the flowing conditions of the fluid before and after separation are unchanged, the thickness of the shunt ring is equal everywhere. The thickness is designed according to the nominal size, and the inlet width of the space guide vane 3 can be selected as the nominal thickness. The diverter ring thickness is 10% of the nominal thickness. The thickness of the shunt rings at different positions is uniform.

3. The whole shunting ring is in a horn shape and is fixedly connected on the stators such as the space guide vane 3 or the inlet suction chamber 1 and the like. For the splitter ring fixed on the inlet suction chamber 1, in order to ensure that the fluid flow angle is unchanged, the splitter ring is fixedly connected by a circular tube 6 in consideration of small influence of cylindrical streaming on the fluid flow, and the circular tube is uniformly distributed in the circumferential direction of the splitter ring. The diameter of the round pipe is 1.1-1.3 times of the thickness of the shunt ring. The pipe 6 is positioned relative to the diverter ring at the inlet end 1/3 of the inlet suction chamber 1.

4. The end parts of the splitter ring except the end parts fixedly connected to the blades of the space guide vane 3 are all in arc transition, and the diameter of the arc is equal to the thickness of the splitter ring. A gap is reserved at one end of the splitter ring close to the inlet and the outlet of the blade of the impeller 2, and the distance is 0.5-1.5 mm.

5. As mentioned above, the profile of the splitter ring should be perpendicular to the inlet and outlet edges of the blades of the impeller 2 and the inlet and outlet edges of the blades of the spatial guide vane 3, and at the same time, the profile should be the middle streamline of the fluid in the flow channel. However, the flow channel is complex, and the shape of the molded line cannot be accurately obtained, so that the molded line is drawn by using a bezier curve. The Bezier curve has the advantages that the control line of the curve is constrained, the curve is smooth and is easy to draw, and the Bezier curve is suitable for drawing the molded line of the shunt ring. The specific method comprises the following steps:

a) and drawing control lines at two end points of the molded line, wherein the control curve is vertical to the inlet and outlet edges of the blades of the impeller 2 and the inlet and outlet edges of the blades of the space guide vane (3). The two control lines intersect at one point;

b) the two control lines are divided equally, the more the number of copies is, the more accurate. And taking ten equal points in consideration of the actual drawing difficulty.

Connecting the equal division points pairwise to obtain ten new control lines;

c) dividing the new control line into ten equal parts, respectively taking equal division points with the same sequence as the equal division points of the control line,

and are connected by a smooth curve, namely a Bezier curve.

Fig. 9 is a bezier curve plotting process.

As shown in fig. 4, 5 and 6, the profile of the shunt ring designed according to the above principle is shown. In fig. 6, if the centrifugal pump has a large design flow and a large overall size, the centrifugal pump can be fixedly connected to the inner wall of the space guide vane 3 by uniformly distributed circular pipes according to the principle 3.

The centrifugal pump can generate vortex and secondary flow as shown in figure 7 under the working condition of small flow, the splitter rings are respectively arranged at the corresponding parts, the flow condition can be effectively improved, the generation of the vortex and the secondary flow is inhibited, and the purposes of improving the flow condition, improving the efficiency and controlling the dead point lift to match the design pressure of the system are achieved as shown in figure 8. The risk of system damage is avoided, and the economic benefit is improved.

Claims

1. A streamline splitter ring matched with a space guide vane type centrifugal pump is characterized in that the streamline splitter ring is positioned from an inlet suction chamber to an inlet of an impeller blade, from an outlet of the impeller blade to the inlet of the space guide vane blade, and for a multi-stage pump, from the outlet of the space guide vane to the inlet of a next-stage impeller blade; the molded lines of each shunting ring are intermediate fluid lines of fluid, and the molded lines of each shunting ring are perpendicular to the inlet and outlet edges of the impeller blades and the inlet and outlet edges of the space guide vane blades; the splitter rings are fixed on the space guide vane blades by uniformly distributed circular pipes, and the splitter rings are fixed on the space guide vane blades from the outlets of the impeller blades to the inlets of the space guide vane blades and from the outlets of the space guide vane blades to the inlets of the next-stage impeller blades.

2. A streamlined flow splitter ring for a matched space vane centrifugal pump according to claim 1 wherein the thickness of the splitter ring is about 10% of the length of the inlet edge of the space vane.

3. The streamline flow divider ring of the matched space guide vane type centrifugal pump as claimed in claim 1, wherein the clearance is 0.5-1.5 mm.

4. The streamline flow divider of the matched space guide vane centrifugal pump as claimed in claim 1, wherein the number of the round tubes is 4, the number of the round tubes is uniformly distributed in the circumferential direction of the flow divider, the diameter of the round tube is 1.1-1.3 times of the thickness of the flow divider, and the relative position of the round tubes is that the flow divider is close to the inlet end 1/3 of the inlet suction chamber 1.

5. The streamline splitter ring of the matched space guide vane centrifugal pump as claimed in claim 1, wherein the splitter ring located from the outlet of the impeller blade to the inlet of the space guide vane blade and from the outlet of the space guide vane to the inlet of the impeller blade of the next stage is fixed on the inner wall of the space guide vane by a uniform circular tube, and the relative position of the circular tube is that the splitter ring is close to the outlet end 1/3 of the space guide vane.

6. The streamlined flow divider of a matched space guide vane centrifugal pump as claimed in claim 1, wherein the end portion of the flow divider, except the end portion fixedly connected to the space guide vane blade, is made of circular arc transition, and the diameter of the circular arc is equal to the thickness of the flow divider.