The Francis turbine that has eddy suppressor
Technical field
The present invention relates to a kind of Francis turbine, relate in particular to a kind of Francis turbine that has eddy suppressor, belong to the Fluid Machinery and Engineering equipment technical field.
Background technique
Francis turbine is present most widely used water turbine, and current radial inflow runner bucket promotes the runner acting, and changes flow direction, flows out vertically.Francis turbine generally is suitable for head from 50~700 meters, exerts oneself from several ten thousand kilowatts to millions of kilowatts.
Francis turbine is fixed blade hydraulic turbine, and vanes fixed is at crown with between encircling down, and when Francis turbine operated in the off-design operating mode, will produce in the runner bucket import did not have bump, and blade exit forms band and measures mouth.Produce the whirlpool band in the draft tube below runner, simultaneously because the jacking effect of the backflow of draft tube centre area, complexity at centrifugal unstability and shearing instability interacts, and adds viscous effect, and draft tube whirlpool band will develop into highly time-dependent screw type whirlpool band.And the pulsation of draft tube internal pressure is strengthened.Unit is under partial load condition, whirlpool band curl is swung in draft tube and is circled round, it is moving to form low frequency whirlpool dai channel, whirlpool dai channel kinetic pressure reaches that each flow passage components can cause unit vibration, macro-axis periodic wobble, hydraulic pressure fluctuations etc. in exert oneself swing and the pipeline, and the large-scale Hydraulic Power Unit of lot of domestic and international is owing to the strong pressure pulsation that draft tube whirlpool band causes causes tremendous loss.Because draft tube whirlpool band is one of key factor that influences water turbine stability, the pressure pulsation size that it causes is to estimate the important indicator of water turbine performance, is obligato necessary index in the Hydraulic Power Unit bid.Because draft tube whirlpool band is the intrinsic characteristic of water turbine, as long as, will exist in the operation of off-design operating mode.Therefore, suppressing draft tube whirlpool band is the present technical issues that need to address.
Summary of the invention
The objective of the invention is to propose a kind of Francis turbine that has eddy suppressor, this eddy suppressor can strengthen draft tube center flow velocity, weaken the draft tube recirculating zone, the intensity that suppresses draft tube whirlpool band, reduce Pressure Fluctuation in Draft Tube, thereby further improved the operation stability of mixed-flow wheel unit.
Technological scheme of the present invention
A kind of Francis turbine with eddy suppressor, comprise spiral case, fixed guide vane, movable guide vane, runner successively and be installed in the draft tube of runner bottom by water (flow) direction, it is characterized in that: described Francis turbine also comprises an eddy suppressor that is arranged between draft tube and the web and is fixed on the web bottom, this eddy suppressor adopts the axial--flow blading structure, and its blade import laying angle is identical with runner bucket outlet laying angle; Subtended angle of blade is 150~180 degree, and length is 0.5-1.0 times of runner inlet diameter.
The number of blade of eddy suppressor of the present invention is preferably 4~8.
The present invention compared with prior art, have the following advantages and the high-lighting effect: under the effect of this eddy suppressor, this eddy suppressor can strengthen draft tube center flow velocity, weaken the draft tube recirculating zone, the intensity that suppresses draft tube whirlpool band, reduce Pressure Fluctuation in Draft Tube, the draft tube whirlpool band of Francis turbine is effectively suppressed, thereby further improved the operation stability of mixed-flow wheel unit.The while eddy suppressor has simple in structure, easy to loading and unloading, and processing cost is low, and advantage of wide range of application can satisfy the stable operation at big flow operating mode and low flow rate condition.
Description of drawings
Fig. 1 is the Francis turbine structural representation of band eddy suppressor provided by the invention.
Fig. 2 is the structural representation of eddy suppressor of the present invention.
Fig. 3 is the sectional arrangement drawing of Fig. 2.
Fig. 4 a, 4b, 4c, 4d are respectively plan view, A-A sectional view, B-B sectional view and the C-C sectional view of Fig. 2.
Among the figure: the 1-spiral case; The 2-movable guide vane; The 3-fixed guide vane; The 4-runner bucket; The 5-runner; The 6-eddy suppressor; The 7-draft tube; The 8-axial blade.
Embodiment
Below in conjunction with accompanying drawing principle of the present invention, structure are further described.
Fig. 1 is the Francis turbine structural representation of band eddy suppressor provided by the invention.Comprise spiral case 1 successively by water (flow) direction, movable guide vane 2, fixed guide vane 3, runner 5 and be installed in the draft tube 7 and the eddy suppressor 6 of runner bottom; This eddy suppressor is arranged between draft tube and the runner, by being bolted to the web bottom.This eddy suppressor 6 adopts the axial--flow blading structure, and the import laying angle of its axial blade 8 is identical with the outlet laying angle of runner bucket 4; The cornerite of axial blade 8 is 150~180 degree, and length is 0.5-1.0 times of runner inlet diameter.4~8 of the general employings of axial blade are advisable, and it turns to identical with rotary wheel of water turbine, rotates with runner.
After eddy suppressor is installed on the Francis turbine, when flow during less than design conditions, because outlet of rotary wheel is the forward circular rector, current flow along eddy suppressor, continue acting, impact the concave surface of axial blade, the forward circular rector will reduce, and weakens the forward vortex flow of outlet of rotary wheel centre area; When flow during greater than design conditions, circular rector is reverse circular rector because outlet of rotary wheel flows, and under the effect of the axial blade that is rotated in the forward, oppositely circular rector will be suppressed, and weakens the reverse vortex flow of outlet of rotary wheel centre area.Simultaneously, because the effect of the pump operating mode of axial blade, eddy suppressor will strengthen the flow of outlet of rotary wheel centre area, significantly reduce the backflow of draft tube centre area, reduce the jacking effect, reduce the precession radius of spiral whirlpool band, reduce the pressure pulsation of draft tube.