CN2766054Y

CN2766054Y - Wheel with L-type blades of mixed flow turbine

Info

Publication number: CN2766054Y
Application number: CNU2004200190629U
Authority: CN
Inventors: 覃大清; 纪兴英
Original assignee: Harbin Electric Machinery Co Ltd
Current assignee: Harbin Electric Machinery Co Ltd
Priority date: 2004-06-04
Filing date: 2004-06-04
Publication date: 2006-03-22
Anticipated expiration: 2014-06-04

Abstract

The utility model discloses an L-shaped blade rotating wheel of a mixed flow turbine. The part which the utility model relates to is a water outlet side of a blade, and the purpose of improving the water force performance can be reached by the change of the geometric shape and the dimension of the water outlet side of the blade. The utility model mainly comprises an upper canopy 1, a lower ring 2 and a plurality of curved-face blades 3 which are connected between the upper canopy 1 and the lower ring 2. The high pressure side of the rotating wheel, namely the side which water flow radially flows in, is a water inlet side of the blade 4. The lower pressure side of the rotating wheel, namely the side which the water flow axially flows out, is a water outlet side of the blade 5. The connecting point of the water outlet side of the blade 5 and the lower ring 2 is A, the connecting point of the water outlet side of the blade 5 and the upper canopy 1 is B, and the midpoint of a shape line of the water outlet side 5 is M. G is an arbitrary point between A and M on the shape line of the water outlet side 5, the rotating center of the rotating wheel is O, and the rotating direction is the direction n. The utility model is characterized in that at least one turning point exists between the shape line A of the water outlet side and the M on a rotating wheel top view.

Description

Francis turbine L type blade rotary wheel

Technical field:

The utility model relates to the runner of water turbine, and definite saying so relates to the improvement of each unit blade in the wheel commentaries on classics.

Technical background:

Through long-term technical development, Francis turbine finalizes the design almost, but the slight improvements of the vane airfoil profile of runner may produce considerable influence to turbine efficiency, seeking more reasonable airfoil structure remains the artificer and constantly pursues one's goal, and along with the raising of water turbine specific speed, the increase of head luffing, hydraulic turbine operation stability qualitative question becomes increasingly conspicuous, more domestic and international large-scale units over nearly 30 years, have a considerable amount of water turbine to occur in various degree vibration problem in succession, the stability problem of hydraulic turbine operation is a world-famous puzzle.Along with hydraulic generator unit single-machine capacity improves constantly, turbine size increases thereupon, the runner stiffness weakens relatively, Chinese patent ZL97195388.0 proposes the impeller of the not Lang Xi Si type water turbine after a kind of the improvement, its cavitation erosion and flow characteristics improve, but still not ideal with regard to above-mentioned several respects index.Existing Francis Turbine Blades goes out the waterside following two kinds of situations:

1. shown in Fig. 3 left side, 2 of A, M on the runner plan view and between any 1 G on same straight line, promptly go out the waterside and be positioned at same shaft section.

2. shown in Fig. 3 right side, on the runner plan view, for any 1 G between A and the M, in rotational direction G is positioned on the below or straight line AM of straight line AM.

In a word, overlook direction for existing blade at runner, straight line AM is always in vane region.

Summary of the invention:

The utility model purpose is to disclose a kind of Francis turbine L type blade rotary wheel.Related position is a blade outlet, by the variation of blade outlet geometrical shape and size, reaches the purpose of improving the water turbine hydraulic performance.

The utility model mainly comprises: crown 1, encircle 2 and the some crown 1 and following curved surface buckets 3 of 2 on ring of being connected down; The runner high pressure side, promptly water flow path is blade water inlet limit 4 to the inflow side, the runner low voltage side, promptly the axial outflow side of current is blade outlet 5; Blade outlet 5 is A with the tie point that encircles 2 down, blade outlet 5 is B with the tie point of crown 1, going out waterside 5 shape line mid points is M, G be on the 5 shape lines of waterside between the A and M more arbitrarily, the center of rotation of runner is O, sense of rotation be n to, it is characterized in that: on the runner plan view, have a flex point between blade outlet shape line A and the M at least.

The utility model is on the runner plan view, and for the point between A and the M, in rotational direction n always exists a G to be positioned at the top of straight line AM, and promptly straight line AM is not exclusively in blade (3) district.

It is less that the utility model goes out the angle (α) of waterside terminal A, B and center of rotation O, is not more than 20 degree.

The utility model straight line AG elongation line and this place angle (θ) of ring cutting line down are not less than 90 degree.

Greater than the bone line length of blade at the crown place, and its ratio is greater than 1.1 in the bone line length at following ring place for the utility model blade.

Description of drawings

Fig. 1 is the utility model embodiment stereogram;

Fig. 2 is another angle stereogram of the utility model embodiment;

The runner depression angle transition figure of the existing blade plane figure of Fig. 3;

The angle transition figure of Fig. 4 the utility model embodiment blade plane figure;

Fig. 5 is the utility model embodiment blade plan view;

The ring place goes out the waterside stress pattern under Fig. 6 common blade;

The ring place goes out the waterside stress pattern under Fig. 7 the utility model embodiment blade;

The runner of the existing blade plane figure of Fig. 8 is overlooked round transition figure;

The round transition figure of Fig. 9 the utility model embodiment blade plane figure.

Embodiment

Finalize the design almost through the long-run development Francis turbine, rotaring wheel structure mainly comprises: crown, following ring and some curved surface buckets that is connected crown and following interannular, as shown in Figure 1.The runner high pressure side, promptly water flow path is blade water inlet limit to the inflow side, the runner low voltage side, promptly the axial outflow side of current is a blade outlet.As shown in Figure 3, it is A with the tie point that encircles down that Francis Turbine Blades goes out the waterside, going out waterside shape line mid point is M, G be on the shape line of waterside between the A and M more arbitrarily, the distinguishing feature of this patent runner bucket is: for the point that goes out between waterside shape line A and M, total exist some G in rotational direction n be positioned at the top of straight line AM, promptly overlook direction at runner, straight line AM is not fully in vane region, as shown in Figure 4.

Go out the L type blade of waterside according to ring place under the reasonable abduction of model utility, Francis turbine is benefited in the following areas.

1. turbine efficiency

Near the runner aerofoil profile of ring down has considerable influence to turbine efficiency, encircle out the local abduction in waterside under the blade, both having reduced has increased the pressure reduction of near blade pressure surface of time ring and suction surface again because of going out the hydraulic friction loss that the whole abduction in waterside causes, and is beneficial to the raising of runner efficiency.Model test of hydraulic turbine also shows: reasonably encircle out the L type blade of the local abduction in waterside down, can make optimum (2-5) ‰ of raising of water turbine.

2. water turbine stability

Along with the raising of water turbine specific speed, the increase of head luffing, the hydraulic turbine operation stability problem becomes increasingly conspicuous.Domestic and international some large-scale units over nearly 30 years have a considerable amount of water turbine to occur in various degree vibration problem in succession, and the operation stability problem of water turbine is a global difficult problem.

Practice shows: the pressure pulsation during sub load is the main root that causes the water wheels unit vibration.Outlet of rotary wheel circular rector and Pressure Fluctuation in Draft Tube, this is an important indicator of weighing water turbine stability, and direct contact is arranged.Encircle out the local abduction in waterside under the blade, the circular rector that can change outlet edge of runner blade distributes, and reduces the outlet of rotary wheel circular rector, thereby reduces the amplitude of pressure fluctuation in the draft tube, improves hydraulic turbine operation stability.

3. runner intensity

Modern Hydroelectric Generators group single-machine capacity improves constantly, and turbine size increases thereupon, and the runner stiffness weakens relatively.L type blade can also improve the runner stiffness when improving the water turbine hydraulic performance, reduce blade stress, improves water wheels unit operational reliability.

The stress numerical result of calculation of comparison diagram 6 and Fig. 7, after the ring place went out the local abduction in waterside under the blade, the stress value at ring place was reduced to 68.4MPa from 105MPa under the blade, and maximum stress value also descends to some extent.L type blade has improved the runner stiffness largely.

As seen through the above analysis: L type blade rotary wheel, can improve not only that the water turbine hydraulic performance is raised the efficiency and hydraulic turbine operation stability, can also improve the runner stiffness, on engineering, have higher use value.

Claims

1. a Francis turbine L type blade rotary wheel mainly comprises: crown (1), following ring (2) and some curved surface buckets (3) that is connected between crown (1) and following ring (2); The runner high pressure side, promptly water flow path is blade water inlet limit (4) to the inflow side, the runner low voltage side, promptly the axial outflow side of current is blade outlet (5); Blade outlet (5) is A with the tie point that encircles (2) down, blade outlet (5) is B with the tie point of crown (1), going out waterside (5) shape line mid point is M, G be on the shape line of waterside (5) between the A and M more arbitrarily, the center of rotation of runner is O, sense of rotation be n to, it is characterized in that: between outlet edge of runner blade shape line A and M, have a flex point at least.

2. by the described Francis turbine L of claim 1 type blade rotary wheel, it is characterized in that: for the point between A and the M, in rotational direction n always exists a G to be positioned at the top of straight line AM, and promptly straight line AM is not exclusively in blade (3) district.

3. by the described Francis turbine L of claim 1 type blade rotary wheel, it is characterized in that: the angle α that goes out waterside terminal A, B and center of rotation O is less, is not more than 20 degree.

4. by the described Francis turbine L of claim 1 type blade rotary wheel, it is characterized in that: straight line AG elongation line and this place angle theta of ring cutting line down are not less than 90 degree.

5. by the described Francis turbine L of claim 1 type blade rotary wheel, it is characterized in that: greater than the bone line length of blade at the crown place, and its ratio is greater than 1.1 in the bone line length at ring place down for blade.