CN103511008A

CN103511008A - Diffuser for turbomachines

Info

Publication number: CN103511008A
Application number: CN201310240850.4A
Authority: CN
Inventors: C.普福斯特; T.莫库伊斯; M.塞尔; H-L.博斯海梅; S.加夫纳; B.格佐德滋伊
Original assignee: Alstom Technology AG
Current assignee: General Electric Technology GmbH
Priority date: 2012-06-18
Filing date: 2013-06-18
Publication date: 2014-01-15
Anticipated expiration: 2033-06-18
Also published as: EP2677123B2; JP5726236B2; EP2677123B1; US20130336783A1; CN103511008B; EP2677123A1; JP2014001735A

Abstract

The invention relates to a diffuser for turbomachines. The diffuser is described with an entry section close to the last stage of a turbine having an outer wall including several subsequent straight wall parts at an angle to each other followed by a curved wall part with the curved wall part connecting the straight wall parts to a diffuser lip or exit and having as vertical cross-section a non-circular 2 nd order curve, preferably part of an elliptic curve.

Description

Diffuser for turbo machine

Technical field

The present invention relates to the improvement to the diffuser for turbo machine.It in particular but do not relate to exclusively the diffuser after the final stage of low pressure (LP) steamturbine.

Background technique

The diffuser of setting up in large-scale steamturbine is for for example guiding to condenser by steam from the final stage of turbine.So diffuser has the wall of two or more essentially concentrics of arranging with the rotor axis around turbine of axial orientation at least at first.

As for example U. S. Patent the 6th, 602, described in No. 046, the diffuser after final stage has following task: make flowing medium slow down, increase available pressure drop or enthalpy drop across turbine, a certain proportion of kinetic energy is converted to pressure energy and reduces the flow losses towards the diffuser outlet port of condenser group.Therefore clear, the design of diffuser contributes to the total efficiency of turbo machine, and has made the layout that diffuser is optimized in many effort for this reason.

In American Society of Mechanical Engineers (ASME) turbine fair (Turbo Expo) GT2011 of 2011 o'clock that June 6 in 2011, Vancouver city, Zhi10Yu Columbia Province of Britain, Canada held by Ch. Musch, H, the title of Stuer and G. Hermle issue is in the document of " OPTIMIZATION STRATEGY FOR A COUPLED DESIGN OF THE LAST STAGE AND THE SUCCESSIVE DIFFUSER IN A LOW PRESSURE ENVIRONMENT ", author has shown a kind of diffuser design, it is with the external wall cross-section by following two angled straight lines of camber line and another straight sections in radial direction outlet port below and forming.

Described in ' 046 patent, straight line may form a series of kinks (kinks) in the wall of diffuser, thereby has a mind to cause and wall flow separation.This structure is allowed the pulsation that suppresses shock-induced boundary layer.Yet this measure can be associated with the very big minimizing of diffuser efficiency.

Consider prior art, further optimize existing diffuser design and thereby improve the low-voltage module of the especially steam-powered power equipment of turbo machine or the efficiency of turbine can be regarded as object of the present invention.

Summary of the invention

According to an aspect of the present invention, a kind of diffuser with outer wall is provided, outer wall has the entrance part section of close turbine final stage, it comprises some continuous linear portion sections in a certain angle each other, after it, follow curve part section, wherein, curve part section has the vertical cross section as the curve of order 2, this curve of order 2 is preferably oval sections, but except circular segment.

The curve of order 2 except circle can be described according to the algebraic equation of the rectangular coordinates of for example following form:

Figure 2013102408504100002DEST_PATH_IMAGE001

Wherein, at least one mixing coefficient is not 0.

Have been found that by using the diffuser lip of elliptical shape, with regard to aerodynamic force and performance, may obtain a kind of better diffuser design.Especially on inflow direction, in curve part Duan first portion, may there is higher curvature, and towards diffuser outlet, there is the curvature of minimizing.Because spray on the top of exhaust stage blade, thereby also may optimize the subtended angle (or open angle) of diffuser and Area Ratio and more approach ideal value than camber line, thereby can in the straight sections of the first angle or kink, realize the mobile more multi-steering in diffuser.

These and other aspect of the present invention will become clear from following detailed description and the accompanying drawing listed below.

Accompanying drawing explanation

Now with reference to accompanying drawing, exemplary embodiments of the present invention is described, in the accompanying drawings:

Fig. 1 has shown the schematically vertical cross section for the known diffuser with potential Optimal Parameters of low pressure steam turbine stage;

Fig. 2 shown known diffuser based on Fig. 1 according to the schematically vertical cross section of the diffuser of example of the present invention; And

Fig. 3 is the plotted curve of the segmentation diffuser recovery rate, and it has shown the potential efficiency gain that surmounts known diffuser according to diffuser of the present invention.

Embodiment

The aspect of example of the present invention and details are described the example that is used for the diffuser of low pressure steam turbine by use in the following description in further detail.

The schematically vertical cross section that has shown the diffuser for low pressure steam turbine stage proposing in above mentioned GT2011 publication in Fig. 1.The figure illustrates the cross section of upper half part of substantially rotational symmetric diffuser.It has also shown a part for rotor 10 and inner casing 11.Rotation blade and stator vane lay respectively between rotor and inner casing and are attached to rotor or inner casing.The final stage of turbine comprises the stator vane 111 of the circumferential arrangement that is attached to shell 11 and is attached to the rotor blade 101 of the circumferential arrangement of rotor 10.

After final stage 111,101, it is diffuser 12.It has outer wall 121 and the inwall 122 of the inside radius that forms diffuser, the common ring duct that forms of this outer wall 121 and inwall 122, thereby steam is guided to condenser (not shown), and all extend to diffuser lip 124, it has formed diffuser outlet 123 jointly.The detail drawing that Fig. 1 amplifies has shown a part for the outer wall 121 of diffuser, and has shown the parameter that can be used for optimizing diffuser for given turbine and vapor stream.Along the direction of vapor stream, wall has the first straight length part l1, follows the second straight length part l2 after it.The second straight section is with respect to the i.e. angulation δ 1 in axial direction of horizontal line.After these two straight sectioies, follow curved portion.Curved portion Qi ingress has angle δ 2 and radius R with respect to horizontal line, and Qi outlet port has angle δ 3 with respect to horizontal line.After camber line, follow another basic straight sections, its direction along outlet 123 is with length l 3.As described in GT2011 reference, all parameters shown in can changing, with the diffuser 12 of constitution optimization.

The diffuser that has shown the modification of the diffuser based on Fig. 1 (as shown in dotted line 121) according to example of the present invention in Fig. 2.This novel diffuser has more the straight section of big figure (3/4ths) and the curve 21 of high-order more after straight section.Curve 21 is essentially elliptic curve.

As shown in Figure 2, with circular curve 121 (shown in dotted line), compare, elliptical shape 21 has higher curvature in beginning or ingress, and towards the more smooth part of outlet 123 outside stretching one-tenth.When representing same or similar element, other label in Fig. 2 is identical with Fig. 1.

In Fig. 3, shown the comparison of efficiency of two kinds of designs of Fig. 2, it has shown the recovery rate of segmentation diffuser.This figure is that recovery rate Chi between diffusor entry (exhaust stage blade outlet) and diffuser outlet (2R plane) is with respect to the medium velocity C of the Yim/sWei unit in axial direction at diffusor entry place _{z ω}plotted curve.Line has more above shown the recovery rate of novel diffuser.This recovery rate is at least high by 3% than the known diffuser shown in Fig. 1.According to this relatively, obviously utilized hybrid diffuser of the present invention to there are the potentiality of improving the diffuser recovery rate in very big mode.With 4 or more hybrid diffusers of following below oval straight section, can be regarded as than the diffuser of the prior art of Fig. 1 with the better diffuser that improves potentiality.

When by this novel diffuser when utilizing a plurality of for example seven or designs that more multi straight part is omitted any curved portion simultaneously to compare for outer wall, can manifest similar improvement.

With the more straight section of big figure and the diffuser of respective length angulation between it thereof, after follow the curve of following general shape,

Wherein, at least one mixing coefficient is non-vanishing, and this diffuser has the potentiality of higher further improvement than the more limited design of following prior art.

So optimize can by use any known instrument for example other method described in ANSYS CFX or above mentioned GT2011 publication realize.

Only by example, describe the present invention above, and can make modification within the scope of the invention.The present invention also can comprise shown in described herein or implicit or accompanying drawing or implicit any independent feature, or any combination of any so feature, or any so feature or combination, and it extends to its equivalent.Therefore, range of the present invention and scope should not limited by any above-mentioned exemplary embodiments.

Unless clearly, outside statement, otherwise disclosed each feature of specification (comprising accompanying drawing) can be used to, alternative features identical, equivalent or similarly object substitutes.

Unless outside clearly stating herein, in specification, any discussion of prior art does not admit that so prior art is well-known all the time, or has formed a part for general knowledge known in the art.

Symbol list

Rotor 10

Inner casing 11

Stator vane 111

Rotor blade 101

Diffuser 12

Straight section length l 1

Straight section length l 2

Straight section length l 3

Angle δ 2, δ 3

The radius R of circular segment

Outlet 123

Antelabium 124

Curve 21

Claims

1. a diffuser (12), its final stage at turbine (101,111) below, there is outer wall (121), described outer wall (121) extends to diffuser lip (124), described diffuser lip (124) forms diffuser outlet (123), described outer wall (121) comprises some direct wall parts that connect continuously, described direct wall part is each other in a certain angle, after follow curved wall part, wherein, described curve part section is positioned between described straight section (3) and described diffuser lip (124), and has the vertical cross section of the formation curve of order 2 (21).

2. diffuser according to claim 1 (12), is characterized in that, the described curve of order 2 (21) is not circular segment.

3. diffuser according to claim 1 (12), is characterized in that, the described curve of order 2 (21) is the sections of elliptic curve (21).

4. diffuser according to claim 1 (12), is characterized in that, the number of straight section (3) is four or more.

5. diffuser according to claim 1 (12), is characterized in that, the described curve of order 2 (21) is substituted by the straight section of big figure (3) more.