CN103195487A

CN103195487A - Last stage blade design to reduce turndown vibration

Info

Publication number: CN103195487A
Application number: CN2013100007133A
Authority: CN
Inventors: A.D.马道斯
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2012-01-04
Filing date: 2013-01-04
Publication date: 2013-07-10
Also published as: GB2498259A; DE102012113129A1; RU2012158343A; GB201223075D0; US20130170984A1; JP2013139778A

Abstract

A turbine bucket includes a bucket airfoil having a cross-section in an airfoil shape. The bucket is twisted from a root end to a tip end. A degree of twist defines an accumulated angular offset of the tip end in a range of 10-15 DEG relative to a tangential direction, thereby reducing excess negative incidence by 15-20 DEG relative to the tangential direction.

Description

Be used for reducing to reduce the exhaust stage blade design of load vibration

Technical field

The present invention relates generally to turbine, and more specifically, relates to the exhaust stage blade of steamturbine.

Background technique

The exhaust stage blade of steamturbine or " movable vane " (LSB) design the end similar to flat board (tip) section are arranged.The orientation of end segments is alignd with tangent direction with radius ratio according to rotating speed more or less closedly, mates with the flow direction with externally thread radial position place.The accurate pointing of end segments is by determining at design point or near the flow analysis it.But steamturbine need turn round with very low flow and maximum discharge pressure with respect to design point, to adapt to load request and atmospheric conditions respectively.This causes the remarkable deviation in the flow direction of movable vane tail end and speed, thereby causes that stream causes vibration (FIV), in case the threshold value of negative incidence is exceeded, stream causes vibration just may damage and limit operating flexibility.

Fig. 2 shows the typical steamturbine final stage geometrical shape of locating endways with velocity vector, and Fig. 3 shows the more detailed view of the exhaust stage blade section of radially inwardly observing from end.Reducing under load (turndown) condition the obviously off-design point that is flowing on magnitude and the direction all in blade or movable vane tail end with the steamturbine of underload and/or maximum discharge pressure correlation.When direction changed from the designing optimal entering angle towards the tangential direction relative with the blade rotation, this magnitude increased and reaches the magnitude of impeller speed vector W in not having the limit that flows.If it is obvious to reduce load, then is defined as best entering angle and can surpasses 15 degree and cause with wing recessed side or the FIV of the raising that on the pressure side flow separation is relevant with stall with the mobile inclination angle of the difference of actual flow direction.

Fig. 4 is the plotted curve of the relation of the mean velocity (Van) in blade or movable vane terminal flow inclination angle and the outlet annular space.This plotted curve shows, under the inclination angles of about 15 degree, if structural damping is low, then FIV, flutter or more specifically stall flutter begin.Stall flutter can cause the short term failure of blade.The operating guidance that is used for avoiding taking place the minimizing load state of stall flutter is the standard convention of industry.The FIV behavior of milder to a certain extent, be also referred to as " accidental resonance response " vibration can with identical inclination angle threshold value take place and lost efficacy with blade in long operation time period and/or blade connect lost efficacy relevant.

Wish to make the FIV reducing under the loading condition to minimize, it can be realized by the Applicable scope of radius ratio and speed is revised tip designs.

Summary of the invention

A kind of turbine rotor blade comprises that the movable vane in the cross section with wing shape is wing.This movable vane reverses from butt to end.The degree of reversing limits end and departs from respect to the accumulation angle of tangential direction in 10-15 ° scope, with respect to tangential direction excessive negative incidence is reduced 15-20 ° thus.

In a further exemplary embodiment, a kind of turbine comprise rotor, with the rotatable shaft of rotor rotation and the turbine that connects with rotatable shaft and rotor.This turbine comprises a plurality of impeller of rotor that axially separate.A plurality of movable vanes connect with each impeller of rotor, and wherein each movable vane has the cross section of wing shape.Last stage movable vane reverses from butt to end, and reverses degree restriction end and depart from respect to the accumulation angle of tangential direction in 10-15 ° scope, with respect to tangential direction excessive negative incidence is reduced 15-20 ° thus.

In another exemplary embodiment, the method that a kind of stream that reduces in the final stage turbine rotor blade causes vibration may further comprise the steps: turbine rotor blade is reversed to limit the terminal degree that departs from respect to the accumulation angle of tangential direction in 10-15 ° scope, with respect to tangential direction excessive negative incidence is reduced 15-20 ° thus.

Description of drawings

Fig. 1 is the low pressure section of condensing steam turbine, namely has a biopsy cavity marker devices perspective view of the steamturbine section of subatmospheric discharge pressure;

Fig. 2 shows the typical steamturbine final stage geometrical shape of locating endways, has pointed out the terminal admission velocity of movable vane of design and off-design;

Fig. 3 shows the detail drawing of the exhaust stage blade section of radially inwardly observing from end;

Fig. 4 is the flow plotted curve of the relation between inclination angle and the mean velocity that exports in the annular space of blade end; And

Fig. 5 and Fig. 6 compare the last stage movable vane design (Fig. 6) of last stage movable vane prior art design (Fig. 5) with described embodiment.

List of parts

10 low pressure (LP) steamturbine section

12 rotors

14

16 last stage movable vanes (LSB) row

18 impeller of rotor

20 movable vanes

22 stationary nozzle

24 steam

26 entrances

201 butts

202 ends.

Embodiment

Fig. 1 is the biopsy cavity marker devices perspective view that comprises rotor 12 and last stage movable vane (LSB) row's 16 low pressure (LP) steamturbine section 10, and this rotor 12 comprises axle 14.LP turbine 10 comprises a plurality of axially spaced impeller of rotor 18.A plurality of movable vanes 20 mechanically are connected on each impeller of rotor 18.More specifically, movable vane 20 is to put around each impeller of rotor 18 circumferential arranging of extending.A plurality of stationary nozzle 22 around rotor 12 circumferentially extend and axially locating between the adjacent row of movable vane 20.Nozzle 22 cooperates to form turbine stage and limits the vapor flow path of passing through turbine 10 with movable vane 20 a part.

In operation, steam 24 enters the entrance 26 of turbine 10 and is conducted through nozzle 22.Nozzle 22 guides steam 24 downstream facing to movable vane 20.Steam 24 passes remaining level, gives the power that makes rotor 12 rotations at movable vane 20.At least one end of turbine 10 can leave rotor 12 and extend axially and can be attached to load or mechanical (not shown) such as, but not limited to generator and/or another turbine.Therefore, in fact large-scale steamturbine unit can comprise the some low-pressure turbines that all are connected to coaxially on the same axle 14.This unit for example can comprise the high-pressure turbine that is connected on the middle pressure turbine, presses turbine to be connected on the low-pressure turbine in this.

The meaning that reduces load FIV zone is, under the condition of low discharge and maximum discharge pressure, the stream by the LSB path the hub place separate and radial height about 80% and 100% between be restricted to thread (wherein radial height is defined as at butt 201 places of movable vane and is 0% and is 100% at end 202 places of movable vane).Therefore, the mobile inclination angle of minimizing load FIV is mainly meaningful in this zone.The flowing angle of restriction is the peak of the flowing angle that can realize.For significant FIV to take place, often gets do radial height last 20% on terminal the best of LSB of mean value of distribution differences of entering angle (OEA) and 180 degree must surpass negative 15 degree.Therefore, have 165 or the LSB design of bigger terminal OEA should not experience and reduce load FIV.Be used for that 3600 rpm use 40 " LSB is very near this standard, and 33.5 ", 30 " and 26 " the excessive negative incidence with increase gradually has the possibility of the minimizing load FIV of increase under identical rotating speed.Prove to the data summing-up that use resistance strain gauge scene is obtained the vibration amplitude of 30 " the LSB vibration amplitude is similarly reducing under the load operation condition obviously greater than 33.5 ", thereby tended to confirm this theory.

About 40 "More than the radial height, for the 3600rpm design, be generally expected that for for the movable vane of prior art aerodynamic design method design, realizing 15 required degree negative incidences, because this type of LSB will have the terminal OEA greater than 165 degree.For having the full and half speed movable vane that can design the effective length of measuring based on speed from 3600rpm, be this situation equally.For example, under 3000rpm, have radial height=(3600/3000) * 35 "=42 "The minimizing load FIV possibility of movable vane also should be low.

Fig. 5 and Fig. 6 show prior art 30 "The design (Fig. 5) and reflected the design that proposes thought 30 "Design (Fig. 6).The design that proposes has increased reversing in the section of stator between 30% and 60% altitude range, departs from thereby the size that causes end segments is about the accumulation angles of 13 degree.This with excessive negative incidence reduce 17 the degree consistent, thereby greatly reduced the FIV possibility.The alternate ways that realization redirects terminal identical result can be near the section of root, add required reverse and endways near provide relatively little section that section is reversed.Performance evaluation can follow any final design to enter the best distribution of angle with the best that is identified for the design point performance, guarantees to be implemented in the target of the minimum excessive negative incidence of tail end simultaneously.Final result will be the LSB design with end on orientation as shown in Figure 6.Reduce the target to satisfy performance and FIV except optimization the best enters angular distribution, the leading edge of blade can be to be cut into (radiused) of fillet to reduce positive rake performance sensitive degree.

This design is applicable to and combines pin and finger shape plate, dovetails, bending or straight axially enter dovetails or tangential direction enters type dovetails (latter comprises that in impeller radial recess is to allow assembling) and pin block or grooving blade with the LSB design of complete filling impeller.This design be applicable to the LSB that belongs to " independence " type (that is, adjacent do not have between wing connect) and have in stride and/or LSB that terminal shroud connects.In addition, it is identical with the design with the LSB that reverses from root to terminal traditional section that the final stage nozzle can keep, and perhaps adjusted throat's opening in the position that reasonably removes from root (~ 25%) beginning is to keep low root reaction.This adjusting should guarantee that LSB enters flowing angle and preferably enters angle near LSB metal section as far as possible in all radial positions.Alternately, can adopt the nozzle of redesign fully.The nozzle of regulating or redesigning will be guaranteed the highest possible level performance.LSB design proposal described in the literary composition goes for tradition and maximum discharge pressure design, and the latter has the required higher discharge pressure limit of steamturbine that has the Air-cooled Condenser of operating in the power facility under the high ambient temperature condition.

Described embodiment is used for reducing to cause the stream of the vibration of off-design to endeavour by wing redesign.Wing end segments is designed so that significantly to have relaxed stalled flow under the minimizing loading condition.Particularly, this is by specifying the end segments with respect to tangential direction to tilt to finish with predetermined angular.As a result, increased the safety operation scope, for the client provides more freedom and to the response of load request, especially in hot weather.In addition, especially the client turbine is exceeded under the situation of manufacturer recommendation limit running and improved the last stage movable vane reliability.

Although in conjunction be considered to the most practical at present and preferred embodiment invention has been described, but it should be understood that, the present invention is not limited to the disclosed embodiments, but is intended to contain various modification and equivalent arrangements in the spiritual scope that is included in claims on the contrary.

Claims

1. wing turbine rotor blade of movable vane that comprises the cross section with wing shape, described turbine rotor blade reverses from butt to end, wherein, the degree of reversing defines described end and departs from respect to the accumulation angle of tangential direction in 10-15 ° scope, with respect to described tangential direction excessive negative incidence is reduced 15-20 ° thus.

2. turbine rotor blade according to claim 1 is characterized in that, describedly reverses 13 ° the accumulation angle that degree limits described end and departs from, and thus excessive negative incidence is reduced 17 °.

3. turbine rotor blade according to claim 1 is characterized in that, described turbine rotor blade comprises leading edge, described leading edge be cut into fillet to reduce positive rake performance sensitive degree.

4. turbine rotor blade according to claim 1, it is characterized in that, height dimension is defined as at described butt place to be 0% height and to be 100% height in described tail end, and wherein, the degree with other section of being higher than described turbine rotor blade is reversed in the section of described turbine rotor blade between the 30-60% height.

5. turbine rotor blade according to claim 1 is characterized in that, described turbine rotor blade is sentenced the degree that is higher than at other section of described turbine rotor blade at described butt and reversed.

6. turbine rotor blade according to claim 1 is characterized in that, described turbine rotor blade is the last stage movable vane of turbine.

7. turbine rotor blade according to claim 6 is characterized in that, under the running speed of 3,600 RPM, the maximum height of described turbine rotor blade is 35 inches.

8. turbine rotor blade according to claim 6 is characterized in that, under the running speed of X RPM, the maximum height of described turbine rotor blade is 3600/X*35.

9. turbine comprises:

Rotor;

Running shaft, it rotates with described rotor; And

The turbine that connects with described rotatable shaft and described rotor, described turbine comprises a plurality of axially spaced impeller of rotor, wherein, a plurality of movable vanes connect with each impeller of rotor, and each in the described movable vane all has the cross section of wing shape, wherein, last stage movable vane reverses from butt to end, and wherein, the degree of reversing limits described end and departs from respect to the accumulation angle of described tangential direction in 10-15 ° scope, with respect to described tangential direction excessive negative incidence is reduced 15-20 ° thus.

10. turbine according to claim 9 is characterized in that, depart from the described 13 ° terminal accumulation angle of degree restriction of reversing, and thus excessive negative incidence is reduced 17 °.

11. turbine according to claim 9 is characterized in that, described last stage movable vane comprises leading edge, and described leading edge is cut into fillet to reduce positive rake performance sensitive degree.

12. turbine according to claim 9, it is characterized in that, the height dimension of described last stage movable vane is defined as at described butt place to be 0% height and to be 100% height in described tail end, and wherein, the degree with other section of being higher than described movable vane is reversed in the section of described last stage movable vane between the 30-60% height.

13. turbine according to claim 9 is characterized in that, described last stage movable vane reverses in the degree that described butt is sentenced other section that is higher than described movable vane.

14. turbine according to claim 9 is characterized in that, under the running speed of 3,600 RPM, the maximum height of described last stage movable vane is 35 inches.

15. turbine according to claim 9 is characterized in that, under the running speed of X RPM, the maximum height of described last stage movable vane is 3600/X*35.

16. a stream that reduces in the final stage turbine rotor blade causes the method for vibration, described turbine rotor blade reverses from butt to end, described method comprises makes described turbine rotor blade be torqued into following degree, namely depart from respect to the accumulation angle of tangential direction in 10-15 ° scope to limit described end, with respect to described tangential direction excessive negative incidence is reduced 15-20 ° thus.

17. method according to claim 16 is characterized in that, implements the described step of reversing and makes and describedly reverse 13 ° the accumulation angle that degree limits described end and depart from, and thus excessive negative incidence is reduced 17 °.

18. method according to claim 16 is characterized in that, described method comprises makes the leading edge of described turbine rotor blade be cut into fillet, to reduce positive rake performance sensitive degree.