DE102008031781B4 - Blade grille for a turbomachine and turbomachine with such a blade grille - Google Patents

Abstract

Blade grille 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 skeleton line (Sk) and a chord length (s) between a blade front edge and a blade trailing edge, characterized in that the suction side (SS) has a maximum height (fss) in cross section, the quotient (fss / s) with the chord length (s) in a range between 0.52 and 0.56, in particular between 0.53 and 0.55, and / or that the pressure side (DS) has a maximum height (f) in cross-section, the quotient (f / s) with the chord length (s) in a range between 0.18 and 0 , 22, in particular between 0.19 and 0.21, and / or that the cross section of the skeleton line (Sk) has a maximum height (f) 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.

Description

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

In turbomachines, for example steam turbines, in particular compressible, fluid such as steam is deflected through one or more vane grilles and exerts forces on the vane grille. If this is movable, the fluid drives this blade grille and does work in the process. Fixed so-called guide vane grids can also be provided for deflecting the fluid, in particular onto downstream rotor blades.

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

According to the applicant's internal knowledge, the currently used graduation angles, i. e. the angles, which include tangents at the front and rear edge of the blade with the circumferential direction, lie in a range between 64 ° and 72 °. The chord lengths between the front and rear edge of the blade are up to 63 mm and the division ratios, i. e. Quotients of a distance in the circumferential direction between axially parallel tangents on suction sides of adjacent blades to the chord length in a range between 0.85 and 1.1 are reached. For this purpose, optimal inflow angles of an inflow of the leading edge of the blade to the circumferential direction lie between 37 ° and 47 °, depending on the area of use, while outflow angles from the trailing edge of the blade lie in a range between 21 ° and 29 °, that is to say differ significantly from the inflow angle.

With regard to specially profiled blade grille, reference is made to the DE 30 29 082 A1 and the US 2003 0 231 961 A1 referred.

Such known blade grids are suboptimal.

The object of the present invention is to improve a vane grille for a turbomachine.

This object is achieved by a vane grille with the features of claims 1, 5 and 6, respectively. Claim 10 provides a turbomachine with such a vane grille under protection, the subclaims relate to advantageous developments.

A blade grille for a turbomachine, for example a steam or gas turbine, a compressor or the like, has a plurality of profiled blades with a suction side, a pressure side, a skeleton line and a chord length, which are arranged next to one another in the circumferential direction.

Directional information such as "circumferential direction", "radial" and "axial" direction relate to a rotor of a turbomachine in the usual way. The skeleton line or (profile) center line or curvature line is commonly used to refer to the line, preferably curved in the axial and / or radial direction, which has the same distance from the suction and pressure side, i. e. in cross section lies exactly between the pressure and suction side. The profile contour of the blade is therefore symmetrical about its skeleton line. In other words, the skeleton line is the connecting line of the circle center points inscribed in a profile. The suction or pressure side is defined by the two outer surfaces of a rotor blade cross-section which are spaced apart in the circumferential direction and are normal to the radial direction.

The blade grille can form a stage of a steam turbine, for example, as a rotor blade grille. In this case, the suction and pressure sides are preferably convexly curved in the direction of rotation of the turbine rotor, the suction side lying in front of the pressure side in the direction of rotation, so that the fluid flowing through the turbine rotates the vane grille and thus the turbine rotor that carries it in the direction of rotation for work to do, for example, to drive a generator coupled to the turbine rotor.

The chord of a blade, in particular a tangent to its front and rear edge circle, can be inclined with respect to the axial direction. Unless otherwise stated, height and distance information therefore relate to a bitangent system, one axis parallel to the chord of the blade and the other axis tangential to the front edge of the blade, 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 an upstream, in the flow direction of the fluid flowing through the turbomachine, Blade leading edge and a downstream blade trailing edge along the chord.

The invention is based on the finding that a vane grille can be improved if the ratio of very specific vane heights, vane circles and / or vane curvatures to this chord length is in specific, predetermined ranges. Advantageous vane grids already result if one or more vane heights, one or more vane circles or one or more vane curvatures, based on the chord length, are in the ranges specified below. Particularly advantageous vane grids can be realized if one or more vane heights and vane circles, one or more vane heights and vane curvatures, one or more vane circles and vane curvatures, and in particular one or more vane heights, vane circles and vane curvatures are located in these areas.

In this context, details relating to blade heights, blade circles or blade curvatures always refer 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, i.e. if each blade cross-section results from a purely translational displacement of a cross-section on the radially inner blade root along the radial direction, the information applies accordingly 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 curvatures, based on that, in at least one cross section, for example on the blade root, on the blade head and / or in the radial blade center Chord length should be in the ranges given below.

Accordingly, it is proposed according to a first aspect of the present invention that the suction side has a maximum height in cross section, the quotient of which is with the chord length in a range between 0.52 and 0.56, in particular between 0.53 and 0.55. Additionally or alternatively, the pressure side has a maximum height in cross section, the quotient of the chord length being 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 cross-section of the skeleton line have a maximum height, the quotient of which is with the chord length in a range between 0.35 and 0.39, in particular between 0.36 and 0.38. The maximum heights of at least two of the suction side, the pressure side and the skeleton line are each advantageously in the specified ranges, particularly preferably of the suction side, pressure side and skeleton line.

As stated above, the height is in particular a shortest cross-section of the side or skeleton line from a connecting section between the axial beginning and end of the skeleton line, in particular from a tangent to a front and edge circle.

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 front edge of the blade in the bitangent system of the blade and in relation to the chord length. In other words, the greatest extent in the cross section of a blade according to the invention is preferably approximately 0.40 to 0.42 times the chord length, measured from the axially foremost point of the blade contour along the chord.

In a corresponding manner, 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 leading edge of the blade in the bitangent system of the blade and in relation to the chord length. The skeletal line preferably takes 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 bitangent system of the blade and in relation to the chord length.

According to a second aspect of the present invention, in addition or as an alternative to the first aspect explained above, it is proposed that a maximum circle inscribed between the suction and pressure sides, based on the chord length, have a diameter in a range between 0.33 and 0.36, in particular between 0.34 and 0.36, and / or a center-to-center distance, measured from the blade leading edge in the bitangent 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, based on 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 has.

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

According to a third aspect of the present invention, in addition or as an alternative to the first and / or second aspect explained above, it is proposed that the suction side have a radius of curvature at a distance of 0.1 times the chord length, measured from the leading edge of the blade in the bit-tangent system of the blade , 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, the quotient with the chord length in a range between 0.82 and 0.86, in particular between 0.83 and 0.85, and / or that the pressure side is at an axial distance of 0.15 times the chord length, measured from the front edge of the blade in Bitangent system of the blade, has a radius of curvature, the quotient of the chord length is in a range between 0.73 and 0.77, in particular between 0.74 and 0.76, and / or in one 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 vane grille according to the first, second and / or third aspect, the medium is advantageously essentially only deflected without being significantly accelerated, so that the pressure before and after the vane grille is reduced only to a lesser extent. A low-separation boundary layer flow along the pressure and suction side and / or a larger flow deflection can also advantageously be achieved, i.e. the pulse transmitted from the fluid to the vane grille can be increased. The efficiency of the flow grid can thus be increased. In particular in the case of control stages of steam turbines which are often only partially acted upon, the deflection can have an advantageous effect without significant pressure reduction. A further advantage can be that a vane grille according to the invention can be manufactured more easily, in particular without any obstructing relocation processes.

Preferably, the chord or a tangent to the front and rear edge of the blade includes 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 is also in contrast to conventional stagger angles has an advantageous effect on the efficiency.

In a vane grille according to the present invention, a division ratio of a distance to the axial direction of parallel tangents on suction sides in the circumferential direction of adjacent vanes to the chord length can be in a range between 0.70 and 0.79, in particular between 0.71 and 0.78. If the circumferential extent of the profile is smaller than the pitch, no rhomboidal foot shapes or platforms are required, which has an advantageous effect during manufacture, particularly with regard to the inventory of tools and materials.

Small pitch ratios allow higher blade numbers with the same chord length, which is preferably at most 70 mm, in particular at most 63 mm, which not only advantageously improves the strength, but also allows higher mass flows due to the improved strength. In one embodiment of the present invention, the number of blades can be increased by approximately 20% with the same chord length.

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

• 1: eine Laufschaufel eines Schaufelgitters nach einer Ausführung der vorliegenden Erfindung in perspektivischer Ansicht;
• 2: die Laufschaufel nach 1 in einem Querschnitt II-II normal zur radialen Richtung mit charakteristischen Schaufelhöhen und - kreisen im Bitangentensystem;
• 3: die Laufschaufel nach 1 in 2 entsprechender Darstellung mit charakteristischen Schaufelkrümmungen; und
• 4: zwei in Umfangsrichtung benachbarte Laufschaufeln des Schaufelgitters nach 1 in entsprechender Querschnittansicht.

Further advantages and features result from the subclaims and the exemplary embodiments. Here shows, partly schematically:

• 1 : a rotor blade of a blade screen according to an embodiment of the present invention in a perspective view;
• 2nd : the blade after 1 in a cross section II-II normal to the radial direction with characteristic blade heights and circles in the bitangent system;
• 3rd : the blade after 1 in 2nd corresponding representation with characteristic blade curvatures; and
• 4th : two adjacent blades of the vane grid in the circumferential direction 1 in a corresponding cross-sectional view.

1 shows a profiled blade 1 a vane grille according to an embodiment of the present invention with a three-lobed plug-in foot. The radial direction r, the circumferential direction U and the axial direction a are shown for orientation.

2nd shows this blade in a cross section II-II normal to the radial direction r (cf. 1 ) with characteristic blade heights and circles in the bitangent system, the axes of which, with the axial or circumferential direction, each include the staggering angle β _s explained in more detail below. There is a first axis (from left to right in 2nd ) of the bitangent system, to which the following dimensions refer, parallel to a tendon 5 the blade 1 , ie tangential to a leading and trailing edge circle 3rd , 4th , a second axis / from bottom to top in 2nd ) tangential to the front edge. The other blades, not shown, are identical in their dimensions.

The blade 1 has a front suction side in the direction of rotation SS (above in 1 ), a pressure side at the back in the direction of rotation DS and a skeleton line Sk which is at the same distance from the suction and pressure side in every point, ie lies exactly in cross section between the pressure and suction side.

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

$${\text{f}}_{\text{Sk}}/\text{s}=\mathrm{0,37,}$$

$${\text{f}}_{\text{DS}}/\text{s}=\mathrm{0,20.}$$

The suction side SS has a maximum height fss of the tendon in cross section 5 off on, measured in the bitangent system, whose quotient fss / s with the chord length s is 0.54. The print page DS has a maximum height in cross section f _DS on whose quotient f _DS / s with the chord length s is 0.20. The skeleton line Sk has a maximum height in cross section f _Sk on whose quotient f _Sk / s with the chord length s 0.37 is: $${\text{f}}_{\text{SS}}/\text{s}=\mathrm{0.54.}$$

$${\text{f}}_{\text{Sk}}/\text{s}=\mathrm{0.37.}$$

$${\text{f}}_{\text{DS}}/\text{s}=\mathrm{0.20.}$$

$${\text{f}}_{\text{fSk}}/\text{s}=\mathrm{0,43,}$$

$${\text{f}}_{\text{fDS}}/\text{s}=\mathrm{0,52.}$$

The suction side SS has its maximum height fss in one position x _fSS which, based on the chord length s, is 0.41, measured along the chord 5 in the bitangent system (from left to right in 2nd ) from the front edge of the bucket. In other words, the ratio is x _fSS / s 0.41. The print page DS reaches its maximum height f _DS in an axial position x _fDS which, based on the chord length s, is 0.52. The skeleton line Sk shows their maximum height f _Sk in an axial position x _fSk which, based on the chord length s, is 0.43. $${\text{f}}_{\text{fSS}}/\text{s}\mathrm{0.41.}$$

$${\text{f}}_{\text{fSk}}/\text{s}=\mathrm{0.43.}$$

$${\text{f}}_{\text{fDS}}/\text{s}=\mathrm{0.52.}$$

$${\text{D}}_{\text{e}}/\text{s}=\mathrm{0,035,}$$

$${\text{D}}_{\text{a}}/\text{s}=\mathrm{0,015.}$$

A maximum circle inscribed between the suction and pressure side 2nd has, again based on the chord length s, a diameter D _max / s from 0.35, its center from the front edge of the blade along the chord 5 a distance in the bitangent system x _Dmax / s of 0.38, from the tendon 5 a height f _xDmax / s of 0.36. The leading edge circle 3rd has, based on the chord length s, the diameter D _e / s 0.035, a trailing edge circle 4th a diameter D _a / s of 0.015: $${\text{D}}_{\text{Max}}/\text{s}=\mathrm{0.35.};{\text{x}}_{\text{Dmax}}/\text{s}=0.38;{\text{f}}_{\text{xDmax}}/\text{s}=\mathrm{0.36.}$$

$${\text{D}}_{\text{e}}/\text{s}=\mathrm{0.035.}$$

$${\text{D}}_{\text{a}}/\text{s}=\mathrm{0.015.}$$

$${\text{x}}_{\text{RkSS}\mathrm{0,75}}/\text{s}=\mathrm{0,75};{\text{ R}}_{\text{kSS}\mathrm{0,75}}/\text{s}=\mathrm{0,84.}$$

As in 3rd shown, has the suction side SS at an axial distance x _RkSS0.1 of 0.1 times the chord length s, measured from the _{front edge} of the blade along the chord 5 , a radius of curvature R _kSS0.1 , the quotient R _kSS0.1 / s with the chord length s is 0.40. At a distance x _RkSS0.75 of 0.75 times the chord length s is a quotient R _kSS0.75 / s with the chord length s of a radius of curvature R _kSS0.75 0.84. $${\text{x}}_{\text{RkSS}0.1}/\text{s}=0.1;{\text{R}}_{\text{KSS}0.1}/\text{s}=\mathrm{0.40.}$$

$${\text{x}}_{\text{RkSS}0.75}/\text{s}=0.75;{\text{R}}_{\text{KSS}0.75}/\text{s}=\mathrm{0.84.}$$

$${\text{x}}_{\text{RkDS}\mathrm{0,80}}/\text{s}=\mathrm{0,80};{\text{ R}}_{\text{kDS}\mathrm{0,80}}/\text{s}=\mathrm{0,56.}$$

On the pressure side, the quotient is R _kDS0.15 / s, the radius of curvature R _kDS0.15 at a distance x _RkDS0.15 of 0.15 times the chord length s, measured from the _{front edge} of the blade along the chord 5 , with the chord length s forms 0.75, a quotient R _kDS0.80 / s of a radius of curvature R _kDS0.80 at an axial distance x _RkDS0.80 of 0.80 times the chord length s 0.56. $${\text{x}}_{\text{RDS}0.15}/\text{s}=0.15;{\text{R}}_{\text{kDS}0.15}/\text{s}=\mathrm{0.75.}$$

$${\text{x}}_{\text{RkDS}0.80}/\text{s}=0.80;{\text{R}}_{\text{kDS}0.80}/\text{s}=\mathrm{0.56.}$$

The tendon 5 or a tangent to the leading and trailing edge of the blade includes a staggering angle β _S with the circumferential direction U, which in 4th is entered and is 78 °. A division ratio t / s of a distance t (cf. 4th ) axially parallel tangents on suction sides SS in the circumferential direction of adjacent blades to the chord length s is 0.74.

An inflow angle β ₁ one in 4th The flow toward the circumferential direction of the blade leading edge indicated by an arrow is 32 °, and a corresponding outflow angle β _{2 is} 25 °.

Reference symbol list

1

Blade

2nd

maximum inscribed circle

3rd

Leading edge circle

4th

Trailing edge circle

5

tendon

SS

Suction side

DS

Printed page

Sk

Skeletal line

Claims (12)

Blade grille 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 skeleton line (Sk) and a chord length (s) between a blade front edge and a blade rear edge, characterized in that the suction side (SS) has a maximum height (fss) in cross section, the quotient (fss / s) with the chord length (s) 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 _DS), the quotient (f _DS / s) with the chord length (s) in a range between 0.18 and 0.22, in particular between 0.19 and 0.21, and / or that the cross-section of the skeleton line (Sk) has a maximum height (f _Sk ), the quotient (fsk / s) of the chord length (s) in a range between 0.35 and 0.39, in particular between 0.36 and 0.38 left egt. Shovel grid after Claim 1 , characterized in that the suction side (SS) its maximum height (fss) in a range (x _fSS / s) between 0.39 and 0.43, in particular between 0.40 and 0.42, measured from the blade _{front edge} and related to the tendon length (s). Blade grid according to one of the preceding claims, characterized in that the pressure side (DS) its maximum height (f _DS ) in a range (x _fDS / s) between 0.50 and 0.54, in particular between 0.51 and 0.53 , measured from the front edge of the blade and related to the chord length (s). Blade grid according to one of the preceding claims, characterized in that the skeleton line (Sk) its maximum height (f _Sk ) in a range (x _fSk / s) between 0.41 and 0.45, in particular between 0.42 and 0.44 , measured from the front edge of the blade and related to the chord length (s). Blade grille 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 skeleton line (Sk) and a chord length (s) between a blade front edge and a blade trailing edge, in particular according to one of the preceding claims, characterized in that a maximum circle inscribed between the suction and pressure sides, based on the chord length (s), has 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-to-center _distance (x _Dmax / s), measured from the _{front edge} of the blade, in a range between 0.36 and 0.40, in particular between 0.37 and 0, 39, and / or a center point _height in cross section (f _xDmax / 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), based on the tendons length (s), a diameter (D _e / 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), based on 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. Blade grille 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 skeleton line (Sk) and a chord length (s) between a blade front 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 (x _RkSS0.1 ) 0.1 times the chord length (s), measured from the blade _{leading edge} , has a radius of curvature (R _kSS0.1 ), whose quotient (R _kSS0.1 / s) with the chord length (s) is in a range between 0.38 and 0.42, in particular between 0.39 and 0.41, and / or in one Distance (x _RkSS0.75 ) of 0.75 times the chord length (s), measured from the _{leading edge} of the blade, has a radius of curvature (R _kSS0.75 ), the Quotient (R _kSS0.75 / s) with the chord length (s) in a range between 0.82 and 0.86, in particular between 0.83 and 0.85, and / or that the pressure side (DS) at a distance (x _RKD0.15 ) 0.15 times the chord length (s), measured from the _{front edge} of the blade, has a radius of curvature (R _kDS0.15 ), the quotient (R _kDS0.15 / s) with the chord length (s) in a range between 0.73 and 0.77, in particular between 0.74 and 0.76, and / or at a distance (x _RkDS0.80 ) of 0.80 times the chord length (s), measured from the _{front edge} of the blade , has a radius of curvature (R _kDS0.80 ), the quotient (R _kDS0.80 / s) with the chord length (s) is in a range between 0.54 and 0.58, in particular between 0.55 and 0.57. Blade grid according to one of the preceding claims, characterized in that a chord (5) of the rotor blades (1) includes a staggering angle (β _S ) with the circumferential direction (U) which is in a range between 73 ° and 83 °, in particular between 74 ° and is 82 °. Blade grid 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. Blade grid 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. Turbomachine, in particular steam turbine, with at least one vane grille according to at least one of the preceding claims. Fluid machine after Claim 10 , characterized in that a flow angle (β ₁ ) of a flow against the leading edge of the blade to the circumferential direction lies in a range between 26 ° and 38 °, in particular between 27 ° and 37 °. Fluid machine according to one of the Claims 10 to 11 , characterized in that an outflow angle (β ₂ ) of an outflow from the trailing edge of the blade to the circumferential direction lies in a range between 20 ° and 30 °, in particular between 21 ° and 29 °.

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