CN201255070Y

CN201255070Y - Reversing s-shaped runner for francis turbine

Info

Publication number: CN201255070Y
Application number: CNU2008200907536U
Authority: CN
Inventors: 刘万江; 魏显著; 覃大清
Original assignee: Harbin Electric Machinery Co Ltd
Current assignee: Harbin Electric Machinery Co Ltd
Priority date: 2008-08-28
Filing date: 2008-08-28
Publication date: 2009-06-10
Anticipated expiration: 2018-08-28

Abstract

The utility model relates to an inversed S type runner for a mixed-flow turbine, which comprises a runner crown, a runner band and a plurality of curved surface blades connected between the runner crown and the runner band. The water inlet side of the blades is in an inversed S type, and thus, the flow state of the inlet of the blades during low flow capacity and high flow capacity is improved; simultaneously, the head of the water inlet side is kept small and the highest optimum efficiency is achieved;the blades are lengthened, the wider running range with high efficiency is achieved; and i.e. an electric station always has high-efficiency performance indexes during the running work conditions, such as low flow capacity, high flow capacity and optimum work conditions. The shape of the molded line of the runner crown of the blades, and the shape of the molded line of the runner band of the special blades are slightly in an inversed S type; the inlet flow rate is reduced, the flow state in the runner is improved and the running stability of a machine group is enhanced.

Description

Reverse S type runner of mixed-flow turbine

Technical field: reverse S type runner of mixed-flow turbine belongs to water turbine and makes art.

Technical background: through long-term technical development, Francis turbine finalizes the design almost, but the slight improvements of the sheet aerofoil profile of runner may produce considerable influence to turbine efficiency and stability.In recent years, domestic large and medium-sized hydraulic generator unit requirement of invitation for bid francis turbine runner had proposed special requirement to energy indexes under the prerequisite that guarantees stability.Requirement all has high efficiency performance index in the operating conditions of small flow, big flow and optimum operating condition, promptly still keep high efficiency with changes in flow rate, realizes increasing unit output, makes the power station obtain bigger economic benefit.

Early stage achievement in research shows that bigger stator distribution circle hydrous water turbine blade water inlet end portion can improve the efficient of small flow and big flow operating conditions more greatly, but optimum efficiency is lower.Modern achievement in research shows that stator distribution circle and leaf head are less, can improve the efficient of hydraulic turbine model optimum operating condition and big flow operating conditions, but the efficient of small flow operating conditions is low.All having high efficiency performance index in the operating conditions of the small flow that the power station requires, big flow and optimum operating condition is contradiction on present understanding to water turbine.Existing francis turbine runner blade is generally common blade and negative incidence blade.The common blade plan view as shown in Figure 2, its water inlet limit 4 be straight line or parabola, have only a flex point at most.Negative incidence blade plan view as shown in Figure 3, its water inlet limit 4 be straight line or parabola, have only a flex point at most.

The content of invention: the purpose of this utility model is to disclose a kind of reverse S type runner of mixed-flow turbine.The main position that the utility model relates to is an inlet edge of runner blade, improves stability when water inlet limit shape realizes having broad more high-efficiency operation scope by changing; Secondly be the shape of the shape of crown molded lines (blade and crown intersection) of blade radial length, special blade and the following ring-like line of special blade (blade with encircle intersection down), the efficient and the stability of raising runner.The technical solution of the utility model is: a kind of reverse S type runner of mixed-flow turbine, ring and several are connected crown and the curved surface bucket between the ring down down to comprise a crown, one, each blade all has one in water turbine, the water inlet limit of upstream deflector and over against the waterside that goes out in downstream: the water inlet limit molded lines of blade has two flex points from the A point to the D point, the water inlet limit molded lines of blade has two flex points of P1, P2, and the water inlet limit molded lines of blade is reverse " S " type; The crown molded lines of blade is blade and crown intersection, to the C point two flex points is arranged from the D point, and the crown molded lines of blade has two flex points of S1, S2, and the crown molded lines presents oppositely " S " type; The following ring-like line of blade is blade and following ring intersection, and to two flex points are arranged the B point, the following ring-like line of blade has two flex points of X1, X2 from the A point, and following ring-like line presents oppositely " S " type.According to the utility model, water inlet limit anti-S type runner bucket reasonable in design can make Francis turbine benefit in the following areas.

1 turbine efficiency

Blade water inlet limit molded lines is instead " S " type, incoming flow when its middle and lower part adapts to small flow, and incoming flow when its middle and upper part adapts to big flow, thus improve small flow and the fluidised form of blade import during flow greatly simultaneously.Could keep water inlet end portion little like this, help improving the runner optimum hydraulic efficiency.

Axial plane water inlet limit A, D and the axial plane of blade goes out waterside B, C streamline arc length increases with the ratio of nominal diameter φ, be equivalent to add linear leaf, increase the acting area, improve energy transformation ratio, realization has broad more high-efficiency operation scope, realizes that promptly the power station all has high efficiency performance index in the operating conditions of small flow, big flow and optimum operating condition.Because lengthened vanes has reduced the blade surface flow velocity, therefore help to improve set steady simultaneously.

The shape of the crown molded lines of blade (blade and crown intersection), bigger to the influence of the turbine efficiency of big flow, increased near the pressure reduction of blade pressure surface and the suction surface crown, help the raising of runner efficiency.Simultaneously, reduce exit velocity, improve fluidised form in the runner.

The shape of the following ring-like line of blade (blade with down ring intersection), bigger to the turbine efficiency influence, increased near the pressure reduction of blade pressure surface and suction surface time ring, help the raising of runner efficiency.Simultaneously, reduce exit velocity, improve fluidised form in the runner.

Model test of hydraulic turbine shows: the anti-S type blade with the crown molded lines (blade and crown intersection) of blade water inlet limit molded lines, blade of Reasonable Shape and following ring-like line of blade (blade with time encircle intersection), can make the water turbine optimum efficiency improve 5～10 ‰, and small flow and big flow turbine efficiency are increased substantially.

2 water turbine stability

Practice shows: outlet of rotary wheel circular rector and Pressure Fluctuation in Draft Tube, direct relation is arranged, and be the important indicator of weighing water turbine stability.The alteration of form of the following ring-like line of the shape of the crown molded lines of blade (blade and crown intersection) and special blade (blade and following ring intersection), use the waterside shape changes thereupon, thereby the circular rector that is controlled at outlet of rotary wheel when departing from optimum operating condition distributes, fundamentally avoid energy accumulating, realize reducing the pressure pulsation in the draft tube, improve the stability of unit operation.

Description of drawings:

The anti-S type of Fig. 1 Francis turbine runner erection drawing

The conventional runner bucket plan view of Fig. 2 Francis turbine

Fig. 3 Francis turbine negative incidence runner bucket plan view

The anti-S type of Fig. 4 Francis turbine runner bucket axial plane schematic representation

The anti-S type of Fig. 5 Francis turbine runner bucket plan view

The anti-S type of Fig. 6 Francis turbine runner bucket stereogram

Embodiment:

As shown in Figure 1, the utility model comprise a crown 1, one down ring 3 and several be connected crown 1 and the three-dimensional twisted blade 2 between the ring 3 down, each blade has one in water turbine, the water inlet limit 4 of upstream deflector and go out waterside 5 over against the downstream.ABCD is the axial plane of blade among Fig. 4, and φ is the diameter (being called nominal diameter again) that A is ordered, and P represents influent side, and O represents water outlet side, and Z represents the water turbine center of rotation.The definition of blade related point, line: some A is blade water inlet limit 4 and the intersection point that encircles 3 down, point B is blade outlet 5 and the intersection point that encircles 3 down, point C is the intersection point of blade outlet 5 and crown 1, point D is the intersection point of blade water inlet limit 4 and crown 1, line AD is the water inlet limit 4 of blade, line BC be blade go out waterside 5.

The water inlet limit molded lines 4 of blade 2 has two flex points from the A point to the D point.Two flex points lay respectively at the both sides of straight line AD among Fig. 5, are starting point with the A point, along molded lines 4 operations of water inlet limit, earlier through a flex point on straight line AD right side, pass through a flex point in straight line AD left side then from the A point, arrive the D point at last.The water inlet limit molded lines 4 that shows blade 2 in Fig. 6 has two flex points of P1, P2, and is significantly anti-" S " type;

The crown molded lines 6 of blade 2 (blade and crown intersection) has two flex points from the D point to the C point.Two flex points lay respectively at the both sides of straight line DC among Fig. 5, are starting point with D, from the D point along vacuum side of blade and 6 operations of crown intersection, earlier through a flex point on straight line DC right side, pass through a flex point in straight line DC left side then, arrive the C point at last.The crown molded lines 6 that shows blade 2 in Fig. 6 has two flex points of S1, S2, and slightly is anti-" S " type;

The following ring-like line 7 of blade 2 (blade and following ring intersection) has two flex points from the A point to the B point.Two flex points lay respectively at the both sides of straight line AB among Fig. 5, are starting point with A, from the A point along front side of vane or the back side and ring intersection 7 operations down, earlier through a flex point on straight line AB right side, pass through a flex point in straight line AB left side then, arrive the B point at last.The following ring-like line 7 that shows blade 2 in Fig. 6 has two flex points of X1, X2, and slightly is anti-" S " type.

The quantitative range of the utility model blade: 15～17.

Claims

1, a kind of reverse S type runner of mixed-flow turbine, ring (3) and several are connected crown (1) and time encircle curved surface bucket (2) between (3) down to comprise a crown (1), one, each blade all has one in water turbine, the water inlet limit (4) of upstream deflector and go out waterside (5) over against the downstream, it is characterized in that: the water inlet limit molded lines (4) of blade (2) has two flex points from the A point to the D point, the water inlet limit molded lines (4) of blade (2) has two flex points of P1, P2, and the water inlet limit molded lines (4) of blade (2) is reverse " S " type; The crown molded lines (6) of blade (2) is blade and crown intersection, to the C point two flex points is arranged from the D point, and the crown molded lines (6) of blade (2) has two flex points of S1, S2, and crown molded lines (6) presents oppositely " S " type; The following ring-like line (7) of blade (2) is blade and following ring intersection, and to two flex points are arranged the B point, the following ring-like line (7) of blade (2) has two flex points of X1, X2 from the A point, and following ring-like line (7) presents oppositely " S " type.

2, a kind of reverse S type runner of mixed-flow turbine according to claim 1 is characterized in that: the quantitative range of described blade: 15～17.