CN105782121A - Axial flow pump - Google Patents

Abstract

The invention discloses an axial flow pump, which comprises a pump casing (1) and an impeller (2) placed in the pump casing, and also includes a plurality of baffles (3), and the plurality of baffles (3) are uniform along the circumferential direction. Arranged on the inner wall of the pump casing (1) at the inlet end of the impeller, the front end of the baffle (3) is streamlined. The axial flow pump of the present invention can still run efficiently and stably under the condition of small flow.

Description

axial flow pump

technical field

The invention belongs to the technical field of fluid machinery, in particular to an axial flow pump capable of running efficiently and stably under the condition of small flow.

Background technique

The stall problem is one of the outstanding problems faced by large axial flow pump units. Under the condition of small flow rate, the flow-head of the axial flow pump is unstable, and there is a backflow zone at the inlet and outlet of the impeller, and the unit vibrates violently, which seriously affects the safe operation of the pump. The stalling of the pump unit may cause resonance, and the high-efficiency zone of the pump will also become narrow. In recent years, with the continuous increase of the flow rate of the single unit and the size of the pump unit, the reliability and stability of the pump operation have become increasingly prominent. In the pump Accidents of cracks or even breakage of blades are often found during station operation.

Therefore, the problem existing in the prior art is that the axial flow pump cannot run efficiently and stably under the condition of small flow.

Contents of the invention

The purpose of the present invention is to provide an axial flow pump, which can still run efficiently and stably under the condition of small flow.

The technical solution that realizes the object of the present invention is:

An axial flow pump, including a pump casing and an impeller placed in the pump casing, and also includes a plurality of baffles, the plurality of baffles are evenly arranged on the inner wall of the pump casing at the inlet end of the impeller along the circumferential direction, and the front ends of the baffles Streamlined.

Compared with the prior art, the present invention has significant advantages:

It can still run efficiently and stably under low flow conditions. Experiments have shown that when the impeller inlet is equipped with a baffle, it has basically no effect on the lift in the high-efficiency zone. Under the condition of small flow, the lift continues to increase with the decrease of the flow rate, effectively eliminating the saddle area of the original flow-lift curve. Stablize. At the same time, in the case of small flow rate, the efficiency of the water pump is higher than that of the water pump without the baffle, which increases by about 2%-4%.

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a structural schematic diagram of an axial flow pump of the present invention.

Fig. 2 is an outline view of the baffle in Fig. 1 . Wherein, Fig. 2a is the main view, Fig. 2b is the A-A view, and Fig. 2c is the B-B view.

Fig. 3 is a sectional view of the inlet section of the pump casing in Fig. 1 . Among them, Fig. 3a is the main view, and Fig. 3b is the C-C view.

Figure 4 is a diagram of the verification experiment setup.

Fig. 5 is a comparison chart of Q-H curves between the present invention and the prior art.

Fig. 6 is the Q-η curve comparison figure of the present invention and prior art.

In the figure, 1 pump casing, 2 impeller, 3 baffle, 4 wheel hub, 5 pump shaft, 6 rear guide vane

detailed description

As shown in Figure 1, the axial flow pump of the present invention includes a pump casing 1 and an impeller 2 placed in the pump casing, and also includes a plurality of baffles 3, and the plurality of baffles 3 are evenly arranged on the inlet end of the impeller along the circumferential direction. On the inner wall of the pump casing 1, the front end of the baffle plate 3 is streamlined.

As prior art, the figure also includes a hub 4 , a pump shaft 5 and a rear guide vane 6 .

Here, the baffles 3 are evenly arranged in the circumferential direction on the inner wall of the pump casing 1 at the impeller inlet end, including two meanings: one is that a plurality of baffles 3 are evenly arranged in a ring shape on the inner wall of the pump casing 1 at the impeller inlet end, and the other is the baffles 3 is perpendicular to the inner wall of the pump casing 1 where it is connected.

Preferably, the baffle 3 is a 1/4 elliptic curve whose major axis is the intersection line between the baffle 3 and the inner wall of the pump housing 1, and the curve faces the direction of water flow. Specifically, the streamlined baffle 3 can be a part of an elliptic curve. The major axis of the ellipse is along the intersection line between the baffle 3 and the inner wall of the pump casing 1, and its short axis is perpendicular to the inner wall of the pump casing 1. The front end of the baffle 3 is a streamline , along the water flow direction, the rear end is a straight line perpendicular to the inner wall of the pump casing 1.

Through a large number of experiments as shown in Figure 4, it is found that the geometric dimensions of the baffle 3 shown in Figures 2 and 3 have a better flow stabilization effect: the thickness of the baffle 3 is 0.01-0.03D, and the length is 0.70-0.90D , the width is 0.15 ~ 0.25D, where D is the diameter of the impeller.

Through a large number of experiments shown in Figure 4, it was found that the geometric dimensions of the baffle 3 shown in Figures 2 and 3 have the best flow stabilization effect: the thickness of the baffle 3 is 0.02D, the length is 0.80D, and the width is 0.20 D, where D is the impeller diameter.

Experiments show that the distance between the rear end of the baffle plate 3 and the inlet end of the impeller 2 is 0.10-0.15D, where D is the diameter of the impeller. The steady flow effect is better at this distance. When the distance between the rear end of the baffle plate 3 and the inlet end of the impeller 2 is 0.12D, where D is the diameter of the impeller, the flow stabilization effect is the best.

In comprehensive consideration of the flow stabilization effect and processing cost, the number of uniformly arranged baffles 3 is 3 to 5.

Optimally, the number of uniformly arranged baffles 3 is four.

The invention is verified on the transparent test bench of the vertical axial flow pump of the Key Laboratory of Water Conservancy and Power Engineering in Jiangsu Province. The pipeline system is shown in Figure 4. The ZM60 axial flow pump model used in the experiment is made of stainless steel, with four blades, impeller diameter D=150mm, hub ratio d=0.467, and the test speed is 2900r/min.

Figures 5 and 6 are comparison diagrams of the Q-H and Q-η curves of the two pumps. It can be seen from the figure that when there is no baffle at the impeller inlet, when the pump runs to the 20L/S working condition area, the head will drop obviously, and present a typical saddle shape; There is basically no effect. Under the condition of small flow, the head continues to increase with the decrease of flow, effectively eliminating the saddle area of the original Q-H curve. It can be seen from the Q-η curve that after the baffle is installed at the impeller inlet, the efficiency of the high-efficiency zone decreases slightly, but the magnitude is not obvious. Under small flow rate, the efficiency of the water pump is higher than that of the water pump without baffle, which increases by about 2%-4%.

The case shows that the invention can effectively weaken the axial and radial development of the inlet return flow of the impeller under the small flow condition, block the continuity of the inlet return flow, expand the effective flow area of the water flow, and effectively eliminate the saddle area of the performance curve under the small flow condition , to make the Q-H curve change smoothly, improve the operating efficiency of the axial flow pump under small flow rate, and find a simple method of "expanding stability and increasing efficiency". At the same time, the special streamlined structure of the baffle proposed in this scheme can reduce the resistance of the baffle itself to the water flow, and can eliminate the blocking of impurities and dirt in the water by the baffle to a certain extent.

Claims (8)

1. An axial flow pump, comprising a pump casing (1) and an impeller (2) placed in the pump casing, characterized in that: it also includes a plurality of baffles (3), and the plurality of baffles (3) are along the The circumferential direction is evenly arranged on the inner wall of the pump casing (1) at the inlet end of the impeller, and the front end of the baffle (3) is streamlined. 2. The axial flow pump according to claim 1, characterized in that: the baffle (3) is a 1/4 elliptic curve whose major axis is the intersection line between the baffle (3) and the inner wall of the pump casing (1), The curve faces the direction of the water flow. 3. The axial flow pump according to claim 2, characterized in that: the thickness of the baffle (3) is 0.01-0.03D, the length is 0.70-0.90D, and the width is 0.15-0.25D, where D is the impeller diameter. 4. The axial flow pump according to claim 3, characterized in that: the thickness of the baffle (3) is 0.02D, the length is 0.80D, and the width is 0.20D, wherein D is the diameter of the impeller. 5. The axial flow pump according to claim 2, characterized in that: the distance between the rear end of the baffle (3) and the inlet end of the impeller (2) is 0.10-0.15D, where D is the diameter of the impeller. 6. The axial flow pump according to claim 5, characterized in that the distance between the rear end of the baffle (3) and the inlet end of the impeller (2) is 0.12D, where D is the diameter of the impeller. 7. The axial flow pump according to claim 1, characterized in that: the number of uniformly arranged baffles (3) is 3-5. 8. The axial flow pump according to claim 7, characterized in that: the number of uniformly arranged baffles (3) is four.