CN100427753C - A Francis turbine with H-shaped channel runner - Google Patents

Abstract

The invention relates to a Francis water turbine with an H-shaped channel runner, and relates to a structural design of the Francis water turbine. The technical feature of the present invention is that a guide blade is added horizontally between two runner blades to form an H-shaped runner runner. The guide vane is placed in the middle of the flow channel, and its length is the same as that of the runner blade. Taking the streamline in the middle of the flow channel as the bone line in the optimal working condition, the thin airfoil thickness distribution rule is adopted, and the maximum thickness is the largest of the runner blade. 2/3～1/2 of the thickness. Under the action of the water turbine of the present invention, the cross flow in the runner channel can be effectively suppressed, the flow condition can be improved, the high-efficiency operation area of the water turbine can be expanded, and the hydraulic vibration can be reduced; meanwhile, the water turbine has the advantages of simple structure, convenient loading and unloading, and low processing cost. Low and wide application range, it can meet the stable operation under the conditions of large flow and small flow.

Description

A Francis turbine with H-shaped channel runner

technical field

The invention relates to a Francis water turbine, in particular to a Francis water turbine with an H-shaped channel runner, belonging to the technical field of fluid machinery and engineering equipment.

Background technique

The Francis turbine is currently the most widely used water turbine. The water flows radially into the runner blades, pushes the runner to do work, and changes the flow direction to flow out axially. Francis turbines are generally suitable for water heads ranging from 50 to 700 meters, and outputs ranging from tens of thousands of kilowatts to several million kilowatts.

The Francis turbine is a fixed blade turbine, and the blades are fixed between the upper crown and the lower ring. When the Francis turbine operates in a deviation from the design condition, impact will occur at the blade inlet of the runner, and the blade outlet will form an outlet with a ring. Especially in the case of small flow rate, a wide range of cross flow is formed on the pressure surface of the runner blade, that is, the water flow does not flow from the inlet to the outlet, but flows from the upper crown to the lower ring, and concentrates at the outlet of the lower ring of the runner. Outflow. As a result, the flow is unstable, the efficiency of the water turbine is reduced, the hydraulic vibration is increased, and the operation of the water turbine is limited, which brings great harm to the safe operation of the unit.

Contents of the invention

The object of the present invention is to propose a Francis turbine with an H-shaped channel runner, which can suppress the cross flow in the runner channel, expand the high-efficiency operating area of the turbine, and reduce hydraulic vibration, thereby improving the efficiency of the Francis turbine and increasing the operating efficiency. stability.

Technical scheme of the present invention is as follows:

A Francis turbine with an H-shaped channel runner, which sequentially includes a volute, a fixed guide vane, a movable guide vane, a runner and a draft tube according to the direction of water flow. The runner includes an upper crown, a lower ring and a The runner blade between the crown and the lower ring is characterized in that: a guide vane is added horizontally between every two adjacent runner blades to form an H-shaped flow channel, and the guide vane is placed in the middle of the flow channel. Its length is the same as that of the runner blade, and the streamline in the middle of the flow channel under the optimal working condition is taken as the bone line. The thin airfoil thickness distribution rule is adopted, and the maximum thickness is 2/3 to 1/2 of the maximum thickness of the runner blade.

Compared with the prior art, the present invention has the following advantages and outstanding effects: the present invention forms a runner with an H-shaped flow channel due to the addition of a guide vane between every two adjacent runner blades. Effectively suppress the cross flow in the runner channel, improve the flow condition, expand the high-efficiency operation area of the turbine, and reduce the hydraulic vibration; at the same time, the turbine has the characteristics of simple structure, convenient loading and unloading, low processing cost and wide application range, which can meet the needs of large Stable operation under flow conditions and small flow conditions.

Description of drawings

FIG. 1 is a schematic structural view of a Francis turbine with an H-type channel runner provided by the present invention.

Fig. 2 is a schematic diagram of the three-dimensional structure of the H-shaped channel runner of the present invention.

FIG. 3 is a longitudinal sectional view of FIG. 2 .

Fig. 4 is a schematic diagram of a guide vane.

Figure 5 is a diagram of the thickness of the airfoil of the guide vane.

In the figure: 1-volute; 2-fixed guide vane; 3-movable guide vane; 4-H type runner; 5-draft tube; 6-lower ring; 7-runner blade; 8-guide vane ; 9- crown.

Detailed ways

The principle and structure of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a schematic structural diagram of a Francis turbine with an H-shaped channel runner provided by the present invention. The Francis turbine includes a volute 1, a fixed guide vane 2, a movable guide vane 3, an H-shaped runner 4 and a draft tube 5 according to the direction of water flow; the H-shaped runner 4 consists of an upper crown 9, a lower ring 6. The rotor blade 7 and the guide vane 8 fixed between the upper crown and the lower ring are composed, and the guide vane 8 is installed between every two adjacent runner blades 7 (as shown in Fig. 2 and Fig. 3 ) , forming an H-shaped channel; the guide vanes 8 are placed in the middle of the channel, and the length is the same as that of the runner blades. The streamline in the middle of the channel in the optimal working condition is the bone line, and the thickness distribution of the thin airfoil is adopted. The maximum The thickness is 2/3～1/2 of the maximum thickness of the runner blade (as shown in Figures 4 and 5). The number of runner blades is the same as the number of guide blades, generally 9 to 21 pieces.

When the Francis turbine with the H-type channel runner is working, when it is running in the optimal working condition, since the guide vanes are placed along the streamline, the water flows along the blades, which has no effect on the flow in the runner, and does not affect this When the water turbine is running at a low flow rate condition, due to the existence of the guide vane 8, the cross flow from the upper crown 9 is guided by the guide vane, and the flow in the middle of the flow channel begins to flow along the optimal working condition. Linear flow, the intensity and range of cross flow are greatly reduced, therefore, the hydraulic efficiency of the Francis turbine is improved and the hydraulic vibration is reduced; when operating in a large flow condition, due to the existence of guide vanes, the flow in the middle of the flow channel is still Flow along the streamline of the optimal working condition; therefore, the application of the H-shaped runner can effectively suppress the cross flow in the runner runner, improve the flow condition, expand the high-efficiency operating area of the turbine, and reduce hydraulic vibration.

Claims (1)

1. A Francis turbine with an H-shaped channel runner, comprising a volute (1), a fixed guide vane (2), a movable guide vane (3), a runner (4) and a draft tube (5) in sequence according to the flow direction ), the runner includes an upper crown (9), a lower ring (6) and a runner blade (7) fixed between the upper crown and the lower ring, and it is characterized in that: each adjacent two runners A guide vane (8) is added horizontally between the blades (7) to form an H-shaped flow channel. The guide vane is placed in the middle of the flow channel and has the same length as the runner blade. The streamline is the bone line, and the thickness distribution of the thin airfoil is adopted, and the maximum thickness is 2/3 to 1/2 of the maximum thickness of the runner blade.

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