EP2294285A2

EP2294285A2 - Blade cascade for a flow engine and flow engine comprising said blade cascade

Info

Publication number: EP2294285A2
Application number: EP09771999A
Authority: EP
Inventors: Günter Neumann; Jörg GATZKE; Ulrich Harbecke; Marc Andre Schwarz
Original assignee: MAN Diesel and Turbo SE
Current assignee: MAN Energy Solutions SE
Priority date: 2008-07-04
Filing date: 2009-06-24
Publication date: 2011-03-16
Also published as: JP5478617B2; CN102084089B; CN102084089A; JP2011524490A; WO2010000229A3; WO2010000229A2; DE102008031781B4; DE102008031781A1

Abstract

The invention relates to a blade cascade for a flow engine, especially a steam turbine, comprising a plurality of profiled blades, especially profiled rotor blades (1), having an intake side (SS), a pressure side (DS), a median line (Sk) and a chord length (s) between a blade leading edge and a blade trailing edge. The invention is characterized in that a quotient of the chord length (s) for a maximum height (fSS) of the intake side (SS) is between 0.53 and 0.55, a maximum height (fDS) of the pressure side (DS) is between 0.19 and 0.21, a maximum height (fSk) of the median line (Sk) is between 0.36 and 0.38, a diameter (Dmax / s) of a maximum circle extending between the intake and the pressure side is between 0.34 and 0.36, its distance between centers (xDmax/ s) is between 0.37 and 0.39, its height in the center (fxDmax / s) is between 0.35 and 0.37, a diameter (De / s) of its leading edge circle (3) is between 0.025 and 0.045, a diameter (Da / s) of a trailing edge circle (4) is between 0.01 and 0.02, a radius of curvature of the intake side (SS) at a distance (XRkSS0.1) of 0.1 times the chord length (s) is between 0.39 and 0.41, a radius of curvature of the intake side (SS) at a distance (XRkSS0.75) of 0.75 times the chord length (s) is between 0.83 and 0.85, a radius of curvature of the pressure side (DS) at a distance (XRKD0.15) of 0.15 times the chord length (s) is between 0.74 and 0.76, and/or a radius of curvature of the pressure side (DS) at a distance (XRkDS0.80) of 0.80 times the chord length (s) is between 0.55 and 0.57.

Description

Blade grid for a turbomachine and turbomachine with such a blade grid

The invention relates to a blade grid for a turbomachine, in particular a steam turbine, with a plurality of profiled blades, in particular profiled blades, with a suction side, a pressure side, a skeleton line, a blade leading edge and a blade trailing edge, and a flow machine with such a blade grid.

In turbomachines, for example steam turbines, in particular compressible, fluid such as steam is deflected by one or more blade lattice and exerts forces on the blade grid. If this is movable, the fluid will drive this blade lattice while doing work. To redirect the fluid, in particular to downstream blades, it is also possible to provide fixed so-called guide blade grids.

In today's airfoils, in particular with blades of steam turbines, takes place in the flow channel, which is defined between a pressure side of a blade and a suction side of a circumferentially adjacent blade, a significant acceleration of the fluid, the static pressure is correspondingly significantly lower behind the deflecting blade grid, so that the fluid is expanded in the flow channel.

Currently used staking angles, ie the angles that include tangents to the blade leading and trailing edges with the circumferential direction, are in a range between 64 ° and 72 °. This chord lengths between Schaufelvorder- and trailing edge up to 63 mm and division ratios, ie quotients of a distance in the circumferential direction between axis-parallel tangents on suction sides of adjacent blades to the chord length in a range between 0.85 and 1.1 achieved. Depending on the area of use, optimum flow angles of an inflow of the blade leading edge to the circumferential direction are between 37 ° and 47 °, while outflow angles of the blade trailing edge are in one Range between 21 ° and 29 °, ie significantly different from the angle of attack.

Such known blade grids are suboptimal.

Object of the present invention is to improve a blade grid for a flow machine.

This object is achieved by a blade grid with the features of claim 1, 5 and 6, respectively. Claim 10 provides a turbomachine with such a blade grid under protection, the dependent claims relate to advantageous developments. A vane grille for a turbomachine, for example, a steam or gas turbine, a compressor or the like, has a plurality of profiled vanes with a suction side, a pressure side, a skeleton line and a chord length, which are arranged side by side in the circumferential direction.

Directional details such as "circumferential direction", "radial" and "axial" direction refer to a rotor of a turbomachine in a customary manner.As a skeleton line or (profile) center line or curvature line is in the usual way, preferably in the axial and curved or curved line, which has the same distance from the suction and pressure sides, ie lies exactly in the cross section between the pressure and suction sides Skeleton line The connecting line of the circle centers inscribed in a profile Suction or pressure side are defined by the two circumferentially spaced outer surfaces of a blade cross-section, which is normal to the radial direction.

The blade grid can form, for example as a blade grid, a stage of a steam turbine. In this case, the suction and pressure sides are preferably curved convexly in the direction of rotation of the turbine rotor, the suction side being in the direction of rotation in front of the pressure side, so that the fluid flowing through the turbine rotates the blade grid and thus the turbine rotor carrying it in the direction of rotation to do, for example, to drive a generator coupled to the turbine rotor. The tendon of a blade, in particular a tangent to its front and rear edge circle, may be inclined with respect to the axial direction. Height and distance indications therefore refer to a bit tangent system whose one axis is parallel to the chord of the blade and whose other axis is tangential to the blade leading edge, unless otherwise stated, so that, for example, a height in cross section is defined as the distance from the chord. The chord length accordingly denotes the distance between a downstream upstream blade edge in the flow direction of the fluid flowing through the fluid machine and a downstream blade trailing edge along the chord.

The invention is based on the finding that a blade lattice can be improved if the ratio of very specific blade heights, blade circles and / or blade curvatures to this chord length lies in specific, predetermined ranges. In this case, already advantageous blade grids result if one or more blade heights, one or more blade circles or one or more blade curvatures, based on the chord length, lie in the ranges indicated below. Particularly advantageous blade grids can be realized if one or more blade heights and blade circles, one or more blade heights and blade curvatures, one or more blade circles and blade curvatures, and in particular one or more blade heights, blade circles and blade curvatures lie in these regions.

In this case, information on blade heights, blade circles or blade curvatures subsequently always refers to at least one cross section normal to the radial direction. If the pressure and suction sides of the blades extend parallel to the radial direction, that is to say that each blade cross section is obtained by purely translational displacement of a cross section at the radially inner blade root in the radial direction, the data apply correspondingly to all cross sections. Equally, however, the pressure and / or suction side can also be curved in the radial direction, in which case one or more blade heights, blade circles and / or blade cambers in at least one cross section, for example at the blade root, at the blade head and / or in the radial blade center. relative to the chord length, should be in the ranges indicated below.

Accordingly, according to a first aspect of the present invention, it is proposed that the suction side in cross section has a maximum height whose quotient with the chord length is in a range between 0.52 and 0.56, in particular between 0.53 and 0.55. Additionally or alternatively, the pressure side in cross section has a maximum height whose quotient with the chord length is in a range between 0.18 and 0.22, in particular between 0.19 and 0.21. Additionally or alternatively, it is proposed that the skeleton line in cross section has a maximum height whose quotient with the chord length is in a range between 0.35 and 0.39, in particular between 0.36 and 0.38. Advantageously, the maximum heights of at least two of the suction side, the pressure side and the skeleton line are each in the specified ranges, more preferably from the suction side, pressure side and skeleton line.

As described above, in particular a shortest distance of the side or skeleton line from a connecting path between the axial beginning and end of the skeleton line, in particular from a tangent to a front and -kantenkreis, referred to in cross section.

The suction side preferably reaches its maximum height in a range between 0.39 and 0.43, in particular between 0.40 and 0.42, measured from the blade leading edge in the bit tangent system of the blade and with respect to the chord length. In other words, a maximum extent in the cross section of a blade according to the invention is preferably about 0.40 to 0.42 times the chord length measured from the axially foremost point of the blade contour along the chord.

Correspondingly, the pressure side preferably reaches its maximum height in a range between 0.50 and 0.54, in particular between 0.51 and 0.53, measured from the blade leading edge in the bit tangent system of the blade and with respect to the chord length. The skeleton line preferably assumes its maximum height in a range between 0.41 and 0.45, in particular between 0.42 and 0.44, measured from the leading edge of the blade in the bit tangent system of the blade and relative to the chord length.

According to a second aspect of the present invention, in addition to or as an alternative to the first aspect explained above, it is proposed that a maximum circle between the suction and pressure sides, referred to the chord length, has a diameter in a range between 0.33 and 0.36 , in particular between 0.34 and 0.36, and / or a center distance, measured from the blade leading edge in the bit tangent system of the blade, in a range between 0.36 and 0.40, in particular between 0.37 and 0.39 and / or a height in cross section, measured from the chord, in a range between 0.34 and 0.38, in particular between 0.35 and 0.37, that a leading edge circle, in relation to the chord length, has a diameter in a range between 0.024 and 0.046, in particular between 0.025 and 0.045, and / or that a trailing edge circle, based on the chord length, has a diameter in a range between 0.099 and 0.021, in particular between 0, 01 and 0.02.

Circles can be inscribed between the pressure and suction sides, the centers of which lie on the skeleton line and which touch the pressure or suction side from inside. The largest of these circles forms the inscribed maximum circle. The leading or trailing edge circle preferably define the leading or trailing edge of the blade such that the blade contour has a radius of curvature in the transition from the pressure and suction side, which corresponds to the radius of the leading or trailing edge circle.

According to a third aspect of the present invention, additionally or alternatively to the above-described first and / or second aspect, it is proposed that the suction side be at a distance 0.1 times the chord length, measured from the blade leading edge in the bit tangent system of the blade Radius of curvature whose quotient with the chord length is in a range between 0.38 and 0.42, in particular between 0.39 and 0.41, and / or at an axial distance of 0.75 times the chord length has a radius of curvature, its quotient with the chord length in a rich between 0.82 and 0.86, in particular between 0.83 and 0.85, and / or that the pressure side at an axial distance of 0.15 times the chord length, measured from the blade leading edge in the bit tangent system of the blade, a Radius of curvature whose quotient with the chord length is in a range between 0.73 and 0.77, in particular between 0.74 and 0.76, and / or at an axial distance of 0.80 times the chord length has a radius of curvature, whose quotient with the chord length is in a range between 0.54 and 0.58, in particular between 0.55 and 0.57.

In the case of a blade grid according to the first, second and / or third aspect, the medium is advantageously deflected substantially only without being accelerated significantly, so that the pressure before and after the blade grid is only reduced to a lesser extent. Advantageously, a low-separation boundary layer flow along the pressure and suction side and / or a greater flow deflection can be achieved, i. the impulse transferred from the fluid to the blade grid is increased. Thus, the efficiency of the flow grid can be increased. Especially with often only partially applied control stages of steam turbines, the deflection can be advantageous without significant pressure reduction. Another advantage may be that a blade grid according to the invention is easier to produce, in particular can be milled without obstructive transfer operations.

Preferably, the chord or a tangent to the blade leading and trailing edges encloses a so-called stagger angle with the circumferential direction, which is in a range between 73 ° and 83 °, in particular between 74 ° and 82 °, which also differs from conventional stagger angles advantageous effect on the efficiency.

Preferably, in a blade grid according to the present invention, a pitch ratio of a distance to the axial direction of parallel tangents on suction sides in the circumferential direction of adjacent blades to the chord length may be in a range of 0.70 to 0.79, more preferably 0.71 to 0.78 height. If the circumferential extent of the profile is smaller than the pitch, no rhomboid foot shapes or platforms are required, resulting in especially advantageous in terms of vorzuhaltendem tool and material inventory.

By small division ratios can higher blade numbers at the same chord length, which is preferably at most 70 mm, in particular at most 63 mm represent, which not only advantageous improves the strength, but due to the improved strength also allows higher mass flows. Thus, in one embodiment of the present invention, the number of blades at the same chord length can be increased by about 20%.

In a turbomachine according to the present invention, advantageously steeper inflow and outflow angles of an inflow of the blade leading edge to the axial direction can be realized, which in particular can lie in a range between 26 ° and 38 °, preferably between 27 ° and 37 °. Thus, advantageously flows with a larger swirl can be processed before the blading. With a blade grid according to the invention, in particular the pressure peaks in the leading edge region can be reduced.

Further advantages and features emerge from the subclaims and the exemplary embodiments. This shows, partially schematized:

Fig. 1: a blade of a blade grid according to an embodiment of the present invention in a perspective view;

Fig. 2: the blade of Figure 1 in a cross section H-Il normal to the radial direction with characteristic blade heights and - circles in Bitangentensystem.

Fig. 3: the blade of Figure 1 in Figure 2 corresponding representation with characteristic blade curvatures. and

Fig. 4: two circumferentially adjacent blades of the blade blade of FIG. 1 in a corresponding cross-sectional view.

Fig. 1 shows a profiled blade 1 of a blade grid according to an embodiment of the present invention with a three-lobated plug foot. For orientation tion are the radial direction r, the circumferential direction U and the axial direction a drawn.

2 shows this blade in a cross section U-II normal to the radial direction r (see Fig. 1) with characteristic blade heights and circles in Bitangen- tensystem whose axes with the axial or circumferential direction in each case explained in more detail below staggering angle ß _s include. In this case, a first axis (from left to right in FIG. 2) of the bitangent system, to which the following dimensions refer, is parallel to a chord 5 of the blade 1, ie tangential to a leading and trailing edge circle 3, 4, a second axis / from bottom to top in Fig. 2) tangential to the leading edge. The other, not shown blades are identical in their dimensions.

The blade 1 has a front suction side SS (upper in Fig. 1) in the rotational direction, a pressure side DS in the rotational direction DS, and a skeleton line Sk having the same distance at each point from the suction and pressure sides, i.e., the same distance. lies in cross section exactly between the pressure and suction side.

A chord length s of the chord 5 between a blade leading edge and a blade trailing edge is 60 mm. Since the excellent blade circles, heights and curves explained below have according to the invention predetermined conditions with this chord length, the chord length s in FIGS. 2 and 3 is normalized to "1".

The suction side SS has in cross section a maximum height fss from the chord 5, measured in the bit tangent system, whose quotient fss / s with the chord length s is 0.54. The pressure side DS has in cross-section a maximum height füs whose quotient f _D s / s with the chord s length is 0.20. The skeleton line Sk has in cross-section a maximum height fsk whose ratio fs _k / s with the chord length s is 0.37:

f _ss / s = 0.54,

f _Sk / s = 0.37,

f _DS / s = 0.20. The suction side of SS has its maximum height f _S s at a position X _f ss, which, based on the chord length of s, is 0.41, measured along the chord tangent system 5 in the Bi- (from left to right in Fig. 2) from the blade leading edge. In other words, the ratio x _fS s / s is 0.41. The pressure side DS reaches its maximum height fσs in an axial position Xros, which, based on the chord length s, is 0.52. The skeleton line Sk has its maximum height fs _k in an axial position x _f s _k , which is 0.43 with respect to the chord length s.

X _f ss / s 0.41,

X _fSk Z s = 0.43,

XfDs / s = 0.52.

A maximum circle 2 inscribed between the suction side and the pressure side has, in relation to the chord length s, a diameter D _ma χ / s of 0.35, its center from the blade leading edge along the chord 5 in the bitmap system a distance Xomax / s of 0.38, of the tendon 5 a height fxomax ts of 0.36. The leading edge circle 3 has, with respect to the chord length s, the diameter D ₀ / s 0.035, a trailing edge circle 4 a diameter D ₉ / s of 0.015:

D _max / S = 0.35; Xomax / S = 0.38; fxomax / S = 0.36,

D _β / s = 0.035,

D _a / s = 0.015.

As shown in Fig. 3, the suction side SS at an axial distance XRRSSO.I 0.1 times the chord length s, measured from the blade leading edge along the chord 5, a radius of curvature RRSSO.I, the quotient R _κ sso, i / s with chord length s is 0.40. At a distance XRKSSOJS of 0.75 times the chord length s, a quotient RKSSOJS / s with the chord length s of a radius of curvature Rkssojs is 0.84.

XRkSso.i / s = 0.1; Rksso.i / s = 0.40, XRkSSO.75 / S = 0.75; RkSS0.75 / S = 0.84.

On the pressure side, the quotient RRDSO.IS / s, the one radius of curvature Rk _D so.tä in a distance X _R koso.iδ of 0.15 times the chord length s, measured from the blade leading edge along the chord 5, with the chord length s, 0.75, is a quotient RkDso.βo / s of a radius of curvature RKDSO.BO at an axial distance XRKDSO.8O of 0.80 times the chord length s 0.56.

XROSO.15 / S = 0.15; RRDSO.IS / s = 0.75,

XRkDso, 80 / s = 0.80; RkDso.βo / s = 0.56.

The chord 5 and a tangent to Schaufelvorder- and trailing edge closes with the circumferential direction U a staggering angle ßs, which is registered in Fig. 4 and 78 °. A division ratio t / s of a distance t (see Fig. 4) of axially parallel tangents on suction sides SS in the circumferential direction of adjacent blades to the chord length s is 0.74.

An angle of incidence ßi in Fig. 4 indicated by an arrow flow of the blade leading edge to the circumferential direction is 32 °, a corresponding outflow angle ß≤ 25 °.

LIST OF REFERENCE NUMBERS

1 blade

2 maximum inscribed circle

3 leading edge circle 4 trailing edge circle

5 tendon

SS suction side

DS print page

Sk skeleton line

Claims

claims

A blade grid for a turbomachine, in particular a steam turbine, with a plurality of profiled blades, in particular profiled rotor blades (1), with a suction side (SS), a pressure side (DS), a Skelettli- (Sk) and a chord length (s ) between a blade leading edge and a blade trailing edge, characterized in that the suction side (SS) has a maximum height (fss) in cross-section whose quotient (fss / s) with the chord length (s) is in a range between 0.52 and 0, 56, in particular between 0.53 and 0.55, and / or that the pressure side (DS) in cross-section has a maximum height (f _D s) whose quotient (fos / s) with the

Chord length (s) is in a range between 0.18 and 0.22, in particular between 0.19 and 0.21, and / or that the skeleton line (Sk) has in cross-section a maximum height (f _Sk ) whose quotient ( fsk / s) with the chord length (s) is in a range between 0.35 and 0.39, in particular between 0.36 and 0.38.

Second blade grid according to claim 1, characterized in that the suction side (SS) their maximum height (fss) in a range (x _fS s / s) between 0.39 and 0.43, in particular between 0.40 and 0.42 measured from the leading edge of the blade and with respect to the tendon length (s).

3. Blade grate according to one of the preceding claims, characterized in that the pressure side (DS) their maximum height (füs) in a range (XfDs / s) between 0.50 and 0.54, in particular between 0.51 and 0.53 measured from the blade leading edge and relative to the chord length (s).

4. Blade grate according to one of the preceding claims, characterized in that the skeleton line (Sk) its maximum height (fsk) in a range (XfS _K / s) between 0.41 and 0.45, in particular between 0.42 and 0, 44, measured from the blade leading edge and relative to the chord length (s).

5. Blade grid for a turbomachine, in particular a steam turbine, with a plurality of profiled blades, in particular profiled blades (1), with a suction side (SS), a pressure side (DS), a skeleton line (Sk) and a chord length (s) between a blade leading edge and a blade trailing edge, in particular according to one of the preceding claims, characterized in that a inscribed between suction and pressure side maximum circle, based on the chord length (s), a diameter (D _max / s) in a range between 0.33 and 0.36, in particular between 0.34 and 0.36, and / or a center distance (xomax / s), measured from the blade leading edge, in a range between 0.36 and

0.40, in particular between 0.37 and 0.39, and / or has a midpoint height in cross section (fxomax / s) in a range between 0.34 and 0.38, in particular between 0.35 and 0.37, and or that a leading edge circle (3), with respect to the chord length (s), has a diameter (D _θ / s) in a range between 0.024 and 0.046, in particular between 0.025 and 0.045, and / or that a trailing edge circle (4), relative to the chord length (s), has a diameter (D _a / s) in a range between 0.099 and 0.021, in particular between 0.01 and 0.02.

6. Blade grid for a turbomachine, in particular a steam turbine, with a plurality of profiled blades, in particular profiled blades (1), with a suction side (SS), a pressure side (DS) _{1 of} a skeleton line (Sk) and a chord length (s) between a blade leading edge and a blade trailing edge, in particular according to one of the preceding claims, characterized in that the suction side (SS) at a distance (XRksso.1) of 0.1 times the chord length (s), measured from the blade leading edge, a radius of curvature ( R _k sso.i), the quotient (Rksso.i / s) with the chord length (s) in a range 0.38 to 0.42, in particular 0.39 to 0.41 is located, and / or in a distance (XRksso, 75) of 0.75 times the chord length (s), measured from the blade leading edge, has a radius of curvature (Rkssojs) whose quotient

(Rksso, 75 / s) with the chord length (s) is in a range between 0.82 and 0.86, in particular between 0.83 and 0.85, and / or that the pressure side te (DS) at a distance (XRKD .IS _O) of 0.15 times the chord length (s), measured from the blade leading edge, a radius of curvature (RRD _SO. _IS), the quotient (RKDSO.I _S / s) with chord length (s) is in a range between 0.73 and 0.77, more preferably between 0.74 and 0.76, and / or at a distance (XRKD _SO .B _O ) of 0.80 times the chord length (s), measured from the blade leading edge, has a radius of curvature (RkDso.βo) whose quotient (R _k oso.βo / s) with the chord length (s) is in a range between 0.54 and 0.58, in particular between 0 , 55 and 0.57.

7. Blade grate according to one of the preceding claims, characterized in that a chord (5) of the rotor blades (1) with the circumferential direction

(U) includes a stagger angle (β _s ) which is in a range between 73 ^* and 83 °, in particular between 74 ° and 82 °.

8. Blade grate according to one of the preceding claims, characterized in that the chord length (s) is less than or equal to 70 mm, in particular less than or equal to 63 mm.

9. Blade grate according to one of the preceding claims, characterized in that a division ratio (t / s) of a distance (t) of axially parallel tangents on suction sides (SS) in the circumferential direction (U) of adjacent blades to the chord length (s) in a range between 0 , 70 and 0.79, in particular between 0.71 and 0.78.

10. turbomachine, in particular steam turbine, with at least one blade grid according to at least one of the preceding claims.

11. turbomachine according to claim 10, characterized in that an angle of attack (ßi) an inflow of the blade leading edge to the circumferential direction in a range between 26 ° and 38 °, in particular between

27 ° and 37 °.

12. Turbomachine according to one of claims 10 to 11, characterized in that an outflow angle (p ₂ ) an outflow from the blade Hin- edge to the circumferential direction in a range between 20 ° and 30 °, in particular between 21 ° and 29 °.