EP2473743A1

EP2473743A1 - Compressor blade for an axial compressor

Info

Publication number: EP2473743A1
Application number: EP10743094A
Authority: EP
Inventors: Georg Kröger; Christian Cornelius; Eberhard Nicke
Original assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Current assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV; Siemens AG
Priority date: 2009-09-04
Filing date: 2010-08-10
Publication date: 2012-07-11
Anticipated expiration: 2030-08-10
Also published as: JP2013503999A; CN102483072A; HUE025789T2; RU2012112930A; EP2299124A1; US8911215B2; EP2473743B1; RU2534190C2; ES2548254T3; JP5678066B2; CN102483072B; US20120230834A1; WO2011026714A1

Abstract

The invention relates to a compressor blade (10) for an axially permeated compressor, preferably of a stationary gas turbine. According to the invention, the skeleton line (32) of the blade tip side profile (30) of the blade (12) of the compressor blade (10) comprises at least two inflection points (36, 38) for reducing radial gap losses. By means of two inflection points (36, 38) there is a concavely designed suction side contour segment (D) in a segment from 35% to 50% for the suction side contour (42), and a convexly implemented pressure side contour segment (E) for the pressure side contour (40). It is possible by means of said geometry to generate low-loss gap vortices, in order to increase the overall efficiency of an axial compressor comprising said compressor blades (10).

Description

description

Compressor rotor for an axial compressor

The invention relates to a Verdichterlaufschaufei for an axial compressor according to the features of the preamble of claim 1. Compressor blades for axial compressors are known from the prior art in a large scale. For example, EP 0 991 866 B1 discloses a compressor blade having a profile whose suction side contour has a radius of curvature smaller than half the length of the chord on a suction side intersection with a reference line perpendicular to the chord at 5% of the chord length. This is to be achieved that after a comparatively short distance of the flow around the blade ^¬ blade on the suction side, the maximum speed is reached and the location of the envelope of flow from laminar to turbulent coincides with the location of the ^maximum speed ^¬ , making this profile a particularly large work ^¬ area, in which it efficiently compresses the gas flow.

Furthermore, it is known that so-called radial gap losses occur at the blade tips of compressor rotor blades. Here, a part of the pressure gain is during loading ^¬ drive of the axial compressor lost by the fact that over the airfoil tip away to a suction side of the airfoil, a Lecka ^¬ geströmung adjusts from a pressure side of the blade ^¬ sheet. In order to reduce this leakage flow, it is known that a radial gap formed between the blade blade tips and an annular wall of the compressor channel opposite thereto must always be kept as small as possible. Nevertheless, minimum sizes of gaps must be adhered to in order to avoid tarnishing of blade tips on the annular wall. This applies especially for transient operating conditions in which thermally induced strains of both the channel wall and blades are not yet completed. In addition, it was often the case that the previous profiling of blade tips was adapted only to the particular inflow conditions in the area of the annular wall. However, the Eigent ^¬ Liche profiling did not take place, taking into account the actual ^¬ three-dimensional flow effects at the blade tip. Conventionally designed airfoil profilings were therefore not optimally adapted to the complex flow conditions in the area of the blade tip. This provides in particular for compaction ^¬ terlaufschaufeln with small span and large relative gap heights (in terms of span) a considerable verb ^¬ serungspotential.

As modern as known 0,991,866 Bl, EP Turbomaschi ^¬ nenbeschaufelungen have now reached a very high aerodynamic efficiency, created with the tendency towards ever higher profile loads an increasing share of total losses due to this radial gap losses that occur in the outer region near the wall of the annular space , A reduction of these significant losses thus causes a significant improvement in the efficiency of turbomachinery and axial compressors.

In order to reduce this radial gap losses, is known example ^¬ example from SU 1751430-A1, the blade airfoil tip of rotor blades of an axial compressor according to the form of an S form. The skeleton line of the profile is formed by two mutually opposite circular arcs, which merge into one another at a turning point. The inflection point is in the range between 5% and 15% of the relative chord length. As a result, secondary flow losses and

Unevenness of the flow at the exit of subsonic compressor blades is reduced due to the reduction of the pressure gradient. In particular, while the pressure gradient in front and middle area in the passages between the blades are reduced. According to SU 1 751 430-A1, the leading edge region is rotated in the direction of the suction side of the airfoil, whereby the front, ie upstream, region of the airfoil has a reverse curvature compared to the rearward, ie downstream, region of the airfoil.

Regardless of existing solutions, there is still a great deal of interest in reducing radial gap losses of turbomachinery in order to further increase the efficiency of these machines.

The object of the invention is to provide a compaction has terlaufschaufei with a blade tip, which drove particularly low leakage currents and radial clearance losses during loading ^¬ in a turbomachine.

This object is achieved with a compressor rotor for an axial compressor, with a curved blade, which comprises a pressure side wall and a suction side wall, which in each case from a common leading edge to a common trailing edge and on the other hand to form a span of a mounting side blade end to an airfoil tip, wherein for each airfoil height present along the span, the airfoil has a profile with a suction side contour and a pressure side contour, an at least partially curved skeleton line and a straight chord, which contours, skeleton line and chord each extend from one on the leading edge arranged leading edge point to a rear edge point arranged on the trailing edge, wherein that at least one of the skeleton lines of the profile in a region of the blade tip (ie some skeleton lines of the blade spit zseit profiles) have at least two turning points. The invention is based on the finding that losses in the radial gap can be reduced if a gap vortex which is also responsible for the losses is correspondingly influenced. According to the invention, the gap vortex, which is generated and driven by the gap mass flow, compared to a conventional airfoil tip profile, now later, ie at a downstream point, arise. The splitting vortex, which thus arises later relative to the conventional profile, can be explained by a lower load on the improved profile at the leading edge.

Contrary to the previous general tendency to weaken the gap swirl as a whole, according to the invention will now a strength ^¬ rer local pulse to generate the slit vortex to be generated, in which case the flow-technical support, however, is expected to decrease much more than in the conventional profile. Overall, this leads to low Strömungsver ^¬ losses in the radial gap. In order to produce the desired gap vortex, at least some of the skeleton lines, preferably all the skeleton lines of the blade tip-side profiles, have at least two inflection points. Due to the presence of two turning points in the skeleton line and through the USAGE ^¬ dung a conventional thickness distribution exhibit the schau- felspitzseitigen profiles, and the suction-side and the pressure side contour of a rather unusual for the expert eye kink, which below with reference to the relevant profile as a Profile bend is called. The profile bend itself caused in its place a local increase of the cleavage mass stream, driving the gap vertebral how ge ^¬ wishes more than ever and expels him from the suction side of the airfoil. In the downstream

Zone behind the kink in the suction side contour, the mass flow density in the radial gap drops significantly more than when using previous profilings on the blade tip. Overall, this results in a reduced Spaltmas- senstrom, compared with the conventional profilings.

Due to the suction-side contour of the profile bend, the gap vortex develops along a line which also has a bend downstream of the bend of the suction side contour. The Early bending of the gap vortex coincides with the strong to ^¬ the mass flow density increased in the radial gap to its maximum and the subsequent decrease of the same together. The gap vortex line depends on its kink at a larger angle from the suction side wall than in the ^{herkömmli ¬} chen profile of the case. As a result, the gap ^¬ vortex continues to run away from the suction side at a greater distance than in conventional profiling. The larger angle is due to the larger gradient of the mass flow density of the Spaltströmung both in the increase and in the waste.

Overall, the profiling invention Weni ^¬ ger radial gap losses and reduced blockage of the flow field at the outlet of the blade row causes. Through the achieved reduction of the radial gap losses las ^¬ the efficiency of the blades and thus the efficiency of the Verdichterlaufschaufei out ^¬ endowed turbomachinery sen significantly improve. Advantageous embodiments are specified in the subclaims.

Preferred dimensions of the first of the two turning points in the case of perpendicular projection on the chord on this one first projection point, which is removed from the leading edge point between 10% and 30% of the length of the chord. At the same time, the second of the two points of inflection, in the case of a vertical projection on the chord, ^{predetermines} the chord on this one second projection point, which is 30% to 50% of the length of the chord from the leading edge point. In particular, with such arranged inflection points, the advantages associated with the invention occur to a particularly great extent. The two turning points lie apart Minim ^¬ least 3% of the length of the chord.

According to a further preferred embodiment of the invention, the skeleton lines of the profiles comprise a front portion which extends from the leading edge point up to extends an end point of the front portion, the Pro ^¬ jection point is at a vertical projection on the chord from the leading edge point between 2% and 10% of the length of Pro ^¬ filsehne removed, wherein at least some of the front sections, preferably all of the front sections of the blade tip side profiles a Radius of curvature aufwei ^¬ sen, which is greater than 100 times the chord. In other words, the front portions of the skeleton line of blade tip side profiles respectively correspond to a straight line, or at least almost. Accordingly, the ^{profile is} symmetrical in the relevant front section-virtually without buckling-which means that even the local velocity distribution around the blade tip side leading edge region of the blade leaves virtually no pressure potential from the pressure side to the suction side. Since the pressure ^¬ potential between the pressure side and suction side in the leading edge ^¬ area as the cause of the occurrence of the crevasse vortex and thus as a cause for the gap losses is considered here causes this relief of the leading edge region attenuation and a delayed, ie downstream ^¬ kick the crevice vortex , Preferably, the Saugseitenenkon ^¬ tur and the pressure side contour of blade tip side profiles in the front portion of the skeleton line are symmet ^¬ risch trained or in a wedge shape with almost straight contour sections on the suction side and pressure side.

According to a further advantageous embodiment, each front portion of an angle of incidence with respect to a ankom ^¬ Menden gas flow, whereby in addition to or instead of the almost straight front camber line portion of at least some of the angle of attack, but preferably all Anstell ^¬ angle of the blade sharp side profiles are smaller than the angle of attack of the remaining Profiles of the airfoil. Before ^¬ preferably the angle of the front portion Skelettlinien- Schaufelspitz sided profiles this case are smaller than 10 °, preferably even 0 °. In other words, the metal entry angle of the blade tip-side profiles is significantly smaller than the metal entry angle of the others Profiles of the airfoil. It can thus be said that the leading edge region of the blade tip, in

Opposition to the solution according to SU 1751430 AI, is screwed into the flow, which also ensures that a

Pressure potential between the pressure and suction side in the front ^¬ edge area shovel tip side is avoided. This also prevents the generation of the gap in the leading edge vortex ^¬ area. As an alternative or in addition to the proposed further developments, preferably at least some of the leading edge points, preferably all leading edge points of the blade tip-side profiles, can be arranged further upstream than the leading edge points of the remaining profiles of the blade leaf. In other words, the leading edge of the profiles for blade ^{tips is} preceded by an extension of the profile to the front - in the upstream direction - compared to the rest of the leading edge. This has the consequence that no radia ^¬ ler pressure gradient in the leading edge region of the blade airfoil can work top, so that it can not come to a potential between pressure side and suction side and in the radial pressure distribution.

Preferably, only the skeleton lines existing in the area of the airfoil tip profiles two Wen ^¬ depunkte, with the airfoil tip includes a side loading ^¬ reaching a maximum of 20% of the span of the airfoil ^¬ tip. The remaining area of the airfoil, from a mounting-side airfoil end to a blade height of at least 80% of the span, may be profiled in a conventional manner.

Accordingly, the invention in principle relates to a modi fied ^¬ blade tip arranged in a ring compressor rotor blades for axial compressors.

According to a further advantageous embodiment, the skeleton lines comprise a rear portion, which in each case extends from a starting point of the rear portion to the Hin ^¬ terkantenpunkt, wherein the rear portion of ^{¬ at} least some, preferably all shovel tip skeleton lines has a greater curvature than the rear portions of skeleton lines of the other profiles of the show ^¬ felblatts. Consequently, the outlet metal angles of blade tip-side profiles are smaller than the outlet metal angles of profiles at the level of half the span or in the region of the attachment-side, ie hub-side

Blade end. Preferably, the section starting point of the rear skeleton line section at ^{senkrech ¬} ter projection on the chord before a projecting on the chord projection point, which is removed from the leading edge point a maximum of 60% of the length of the chord. The trailing edge is therefore more curved in the blade tip area than in the remaining area of the blade. The increased curvature leads to a larger work conversion in the preferably rear 40% of the airfoil, so that overall the load of the airfoil is shifted to the rear. This embodiment can serve as a balance of relief on the leading edge to achieve despite the relief of the blade tip side profile in the front region of the chord still a high work transformation. Overall, the flow of the following guide blade in the outer annular wall region can thus also be improved by reducing the blockage in the blade tip region of the compressor blade. This reduces the local misfire of the downstream vanes. Preferred dimensions are at least some, preferably all of the blade tip-side profiles in the "Aft-Loaded Design" and the other, ie not schaufelspitzseitigen profiles in the "Front Loaded Design" configured. The person responsible for the gap losses spina bifida can be extremely efficient affected if the Saugsei ^¬ tenkontur and the pressure side contour at least three consecutive curved sections with alternating sign have, which adjoin adjacent curved portions in each case a turning point. This can be achieved with a suitable thickness distribution, which is applied in a conventional manner perpendicular and symmetrical, ie on both sides in equal parts on the skeleton line. Such measures lead on the suction side to concave contour sections and on the pressure side to convex contour sections, with which the slit vertebrae can be influenced ideegemäß to a particularly simple extent.

Conveniently, the blade tip is freestanding.

If along the suction surface profile from the leading edge point to the trailing edge point at a flow around sets with a gas a velocity distribution of the gas, at least some, preferably all Schaufelspitz side profile selected so that a velocity ^¬ maximum occurs at a Maximumort whose projection point in vertical projection on the chord on this from the leading edge point is between 10% and 30% of the length of the chord. This measure ensures a particularly great in ^¬ pulse to the emergence of the gap vortex. Then, to keep the radial gap ^¬ losses as low as possible, provided that the energy supply for the spina bifida particularly fast, that decreases to a particularly short length, particularly great extent. For this purpose, it is provided that the respective profiles are selected so that adjusts itself in a maximum at ^¬ closing suction side of the Saugseitenenkontur with a maximum length of 15% of the length of the chord, a gradient of speed, the slope is maximum. As a result, the gap vortex is severely underserved for its size, which causes it to move away from the surface of the suction side at a larger angle. This leads to particularly low Spaltverlus ^¬ th in an axial compressor whose rotor is equipped with the Verdichterlaufschaufein invention. The further explanation of the invention is based on the embodiment shown in the drawing.

In detail show:

1 shows an inventive profile and a from the

Prior art profile for a compressor rotor;

FIGs 2, 3, 6 the velocity distributions along the

Suction side contour and the pressure side contour of the profile according to the invention and the conventional profile of Figure 1;

4 shows the contour of the suction side and pressure side of the profile according to the invention for a compressor blade; 5 shows the curvature of the invention

Profiles along the suction side and pressure side;

7 shows the mass flow density of the mass flow in one

Radial gap when using a erfindungsge- MAESSEN profile for a detached blade ^¬ blade tip;

FIG 8 shows the topology of Spaltwirbeltraj ectors for the profile according to the invention and the conventional profile and

Figures 9, 10 are perspective views of the freest ^¬ rising blade tip of a erfindungsge ^¬ MAESSEN Verdichterlaufschaufei.

FIG 9 and FIG 10 each show a freestanding compressor ^¬ moving blade 10 from different perspectives. their Airfoil 12 includes a pressure sidewall 14 and a suction sidewall 16, which on the one hand in each case open from a ^¬ common itself, is traversed by the gas flow leading edge 18 to a common trailing edge 20 and on the other dung a span of a in Figures 9 and 10 with formation not shown fastening side airfoil end to a blade tip 22 extend.

In FIG. 9, the perspective is selected such that the view of the trailing edge 20 of the airfoil 12 falls; in FIG. 10, the view of the leading edge 18 of the airfoil 12 drops. The attachment-side airfoil end can be a platform and a platform arranged thereon in a known manner Shovel be provided. Actuating depending on the type and manner of the blade root of the Befes- Verdichterlaufschaufei 10 ent ^¬ neither dovetail, firtree or hammer-shaped. The compressor rotor may also be welded to a rotor. Mounted in the rotor of an axial compressor the Orien ^¬ orientation of the blade 12 is such that the

Airfoil 12 extends from the front edge 18 to the trailing edge 20 in approximately the axial direction of the axial compressor, which is designated in the coordinate system associated with FIG 9 and FIG with the axis X. The radial direction of the axial displace ^¬ dichters coincides with the Z-axis of the coordinate system shown, and the tangential direction, that is, the circumferential direction with the Y-axis. A span of the airfoil 12 is thus detected in the Z-axis direction.

As is known, compressor blades 10 are designed for axial compressors in such a way that along a rectilinear or slightly curved, not shown

Stacking axis different or identical profiles are ^¬ strung to ^¬ whose enclosed space the Define the blade 12. In principle, each profile has a centroid on the stack axis.

A profile is understood in detail to mean an endless polyline, which comprises a suction-side contour and a pressure-side contour of an airfoil. The contours meet on the one hand in a leading edge point and on the other hand in a trailing edge point, which are also part of the profile and lie on the corresponding edge of the airfoil. Such a profile exists for each existing along the span shovel ^¬ leaf height. In this respect, the profile represents the contour of a cross section through the airfoil for a specific blade height, wherein the cross section ^¬ either perpendicular to the radial direction of the Axialver or slightly inclined - according to a Ringkanalkontraktion - may be oriented. In FIG. 9, printed page contours 40 of three profiles 28, 30 are shown in solid line. In FIG. 10, a plurality of suction side contours 42 of profiles 28, 30 of different blade blade heights are also shown in solid lines.

The illustrated in FIG 9 and FIG 10 curved blade 12 has a comparison with the prior art according to the invention modified blade tip region 43, the specific configuration and operation will be described in more detail below.

In Figure 1, two fundamentally different profiles 28, 30 are shown. The first, shown in dotted line type profile 28 shows a cross section through the Verdichterlauf- blade or vane 10 according to FIG 10 in a blade height of half the span of the blade 12. The profile 28 may be a conventional, known from the prior art Pro ^¬ fil. The profile shown in solid line 30 shows a cross section through the inventive compressor rotor 10 according to FIG 10 in the area 43 of the blade tip 22. Each profile 28, 30 of FIG 1 has a skeleton line associated therewith, for reasons of clarity in 1 shows only one skeleton line 32 of the blade tip-side profile 30 is shown in dashed line style. The skeleton line 32 begins at a leading edge point 24, terminates at an associated trailing edge point 26, and is always centered between the pressure side contour 40 and suction side contour 42. It is also known as the profile center line.

In addition to the skeleton line 32, profiles are also defined in the prior art with the aid of a straight chord. The chord is a straight line which extends from the leading edge ^¬ point to the trailing edge point. In FIG. 1, only one profile chord 34 for the blade tip-side profile 30 is shown. Since the profile chord 34 is subsequently used for the geometrical definition of significant points of the profile 30, its length is normalized to one, wherein in the leading edge point 24, the length of the chord 0% and in the trailing edge point 26, the length of the chord 100%. This also means a relative chord length.

Of course, there is also a profile chord for the profile 28 known from the prior art. However, the clarity is profile ^¬ This tendon sake not Darge ^¬ represents in Fig. 1

The normalized chord 34 is indicated by x / c. The profile 30 shown in FIG 1 is representative of the radially outermost of the blade tip side profiles 30. The conventional profile 28 shown in FIG 1 is on the one hand representative of the known from the prior art profiles and on the other hand for the other profiles of the compressor blade 10th Sub the remaining sections 28 are the ones to understand which are not arranged schaufelspitzsei- tig and thus for example in the soapy mounting area of the blade 12 or the center between airfoil tip 22, and may be arranged to the fastening-side show ^¬ felblattende. The transition from the conventional profile 28 to the blade tip-side profile 30 takes place, as shown in FIG 10, steplessly.

A characteristic feature of a compressor runner 10 according to the invention is that the skeleton lines 32 of the blade ^tip-side profiles 30 have at least two turning points 36, 38. This means that the skeleton line 32 upstream of the front ^¬ th inflection point 36 has a first curvature section A with a first curvature and downstream of the first turning point 36 to the second inflection point 38 has a second curvature B with a second curvature. The signs of the first curvature and the second curvature are different. Downstream of the second curvature section B, in the second inflection point 38, a third curvature section C follows, whose curvature in turn has a different sign than that of the second curvature. Due to the different signs of the curvatures of the curved sections A, B, C, suction side contour 42 and pressure side contour 40 also have corresponding curved sections: the predominantly convex curved suction side contour 42 has a concave shape in a section D between 35% and 50% of the relative chord length. The mainly concavely curved ge ^¬ pressure side contour 40 has a section E, which is convex. Contrary to the previous known from the prior art profile shapes for compressor blades of axial compressors this concave Saugseitenenkon- turabschnitt D and convex pressure side contour section E leads to a locally kinking profiling, which is referred to here as a profile kink.

It is provided that the first of the two turning ^¬ points 36 when perpendicular to the profile chord on this predetermines a first projection point AP, which is removed from the leading edge point 24 between 10% and 30% of the length of the profile tendon 34 and in the the second of the two

Turning points 38 in perpendicular projection on the chord 34 on this one second projection point BP, wel ^¬ cher from the leading edge point 24 between 30% and 50% of the length the chord 34 is removed. Furthermore, from Figure 1 clearly shows that the profile 30 has side Schaufelspitz ^¬ against the conventional profile 28 is a Pre-emptive way to the inflowing gas flow leading edge 18th The forwardly displaced front edge 18 of the blade tip-side profile 30 can be seen especially in the perspective views according to FIG. 9 and FIG.

Furthermore, it is provided that the skeleton line 32 of blade tip side profiles 30 in a rear portion G has a greater curvature than the rear portions of skeleton lines of the remaining profiles 28 of the airfoil 12. The rear portion G of the skeleton line 32 extends from the section start point GA to the trailing edge point 26 of the skeleton line 32, which section start point GA when projecting onto the chord 34 on this one projection point GP, which is removed from the leading edge point 24 a maximum of 60% of the length of the chord 34. Furthermore, it is apparent from Figure 1 that the shovel-pointed side profile 30 comprises a skeleton line 32 with a prede ^¬ ren H section. The front portion H of ^¬ skeleton line 32 extends from the leading edge point 24 to a projection point HP of the skeleton line 32, which is located at 10% of the length of the chord 34th The projection point HP results from the projection of an end point HE of the front portion H perpendicular to the chord 34. In this front portion H of the skeleton line 32, the skew ^¬ lettlinie 32 is almost not arched, ie approximately straight.

Likewise, the thickness distribution, which is known to be applied perpendicular to the skeleton line 32 on both sides to the same Tei ^¬ len, here chosen so that there is a wedge-shaped leading edge region for the blade tip side profiles 30 in principle. Generally, in the front section H of blade tip-side profiles 30, a symmetrical course of the suction side contour 42 and pressure side contour 40 is symmetrically desirable. In FIG. 2, the velocity distributions along the blade tip-side profile 30 and along the conventional profile 28 are compared both for the suction-side flow and for the pressure-side flow. Each velocity distribution is plotted along the normalized chord x / c. The speeds are given in Mach numbers, Mach = 1 means the Schallgeschwindig ^¬ speed for a given temperature. The VELOCITY ^¬ speed distribution is thereby recorded on that blade height of compressor rotor blades, which is removed 0.5% of the gap ^¬ size of a radial gap between the blade tip 22 and the surrounding annular wall of the axial compressor of the airfoil tip 22nd In dashed line type, the speed distributions 48, 50 of a conventional profile 28 for the suction side wall 16 and pressure side wall 14 are shown in FIG. 2, FIG. 3 and FIG. The velocity distributions 44, 46 for the suction side wall 16 and pressure side wall 14 of the blade tip-side profile 30 are shown in full line. The respective lower line represents the velocity distribution for the corresponding pressure-side, each top line represents the VELOCITY ^¬ speed distribution for the corresponding suction side. The Saugseitengeschwindigkeitsverteilung for Schaufelspitz side profile 30 is indicated at 44, the Druckseitenge- velocity distribution for the Schaufelspitz side profile with 46, the Saugseitengeschwindigkeitsverteilung for the conventional profile 28 with 48 and the Druckseitengeschwindig ^¬ keitsverteilung for the conventional profile 28 with 50. The greater the distance between the course of the suction-side velocity distribution 44, 48 and the pressure-side velocity distribution 46, 50 for each location is the normalized chord 34, the greater is the pressure difference and thus the load at the respective considered location of the chord of the respective considered profile 28, 30. From FIG. 2, it can be seen that with the aid of the invention modified blade tip portion 43, the blade ^¬ sheet 12 in the front half, ie in particular on the first 15% of the chord 34 seen from the leading edge point 24, has been relieved.

Due to the self-adjusting speed distributions 44, 46, a higher load in the rear portion G of the blade tip profile 30 occurs because the area between the suction side velocity distribution 44 and pressure side velocity distribution 46 for a rear profile section from 60% of the chord 34 to 100% of the chord 34 greater than the corresponding surface area between the ent ^¬ speaking velocity distributions 48, 50 of the known from the prior art conventional profile 28. Since the conventional profile 28 is provided for non Schaufelspitz sided preparation ^¬ surface of the compressor blade 10, thus occurs along the blade height, a change of Load from the front section ("front-loaded design") to the rear section of the airfoil ("aft-loaded design"). Characteristic ^¬ is that the profile shape of the airfoil 12 blade tip side is selected so that the speed increase is achieved to a maximum speed in a maximum location at about 20% of the length of the chord 34 in the shortest possible chord section. Furthermore, a comparatively large decrease in the speed of the suction-side gas flow in a profile chord section that is as short as possible is desired in the subsequent 15% of the chord 34 following the maximum location. Insbeson ^¬ particular this speed course along the suction sides ^¬ wall 16 causes a responsibility for the gap losses ^¬ wortlicher gap vortex is evidence ER- with relatively more energy, but continues to be fed only comparatively little energy by the large speed decrease after reaching the maximum velocity that which weakens him all the more. Overall, this leads to redu ^¬ ed radial gap losses.

Figures 3 to 8 give a further overview of the effects caused by the profile bend. In FIG. 3 and FIG. 6, the Mach number distributions of the conventional one are again Profile 28 and the blade tip side profile 30 shown on the relative chord length. FIG 4 describes the schau- felspitzseitige profile 30 in ungestaffelten m'-theta Koordi ^¬ natensystem. The lower illustration, FIG. 5, shows a curvature 52 of the suction side contour 42 and a curvature 54 of FIG

It can be clearly seen that in the region of a Druckseitenknicks 56 a sharp increase in Machzahldifferenz and thus the pressure potential between Saugseitenenkontur 42 and Druckseitenkontur 40 is formed.

7 shows the mass flow density of the mass flow, which flows orthogonal to the chord 34 through the radial gap, based on the considered local area. The

Mass flow density for a conventional profile 28 is denoted by 58, that for the blade tip-side profile 30 by 60. For the blade tip-side profile 30 is a clear relationship between the increase in the pressure potential and the increase in the mass flow density in the radial gap recognize. The mass flow density in the radial gap also reached its globa ^¬ les maximum shortly after the profile described crease. The global maximum of the mass flow density for the schaufelspitzsei ^¬ term profile 30 is higher than the conventional one. The Ab ^¬ fall of the mass flow density in the radial gap to its maximum is also greater than in the conventional profiling 28th

8 shows the topology of the Spaltwirbeltraj ectors

(Slit vortex lines) for the two profiles 28, 30. The gap vortex line for the conventional profile 28 is 62 ^{¬ be} distinguished, the gap vortex line for the blade tip profile with 64. Relative to the leading edge 18 of the gap ^¬ vortex arises at the blade tip side profile 30 clearly later - based on the relative chord length of the respective profile - and then kinks from the suction side wall 16 at a greater angle than in the conventional profiling 28. The early kinking of the slit vortex coincides with the sharp increase in mass flow density to its maximum and that following decrease of the same together. The larger angle is due to the larger gradient in both the increase and decrease in mass flow density. The relative to the conventional profile 28 relatively late emergence of the crevice vertebra can be explained by the low load on the improved profile 30 at the front edge 18.

By relieving the blade tip 22 in the leading edge region, the formation of the gap vortex is delayed. Subsequently, in the region of the suction-side profile bend, a strong increase in the gap mass flow follows, which drives the gap vortex and drives it away from the suction side wall 16 of the blade tip-side profile 30. In the zone downstream of the suction-side profile bend, the mass flow density in the radial gap drops considerably more than in conventional profiling 28. Overall, this results in a lower gap mass flow. The gap vortex line bends after the suction-side profile bend at a higher angle from the suction side wall 16 than in the conventional profiling 28 is the case. From now on, it runs away from the suction side wall 16 at a greater distance than in the conventional profiling 28. Overall, the gap flow in the modified profiling 30 thus causes less losses and a lower one

Blocking of the flow field at the outlet of the blade row. In order to achieve a high work conversion despite the relief of the profile 30 in the front half of the chord 34, the load is increased by a higher curvature of the profile 30 in the rear 40% of the chord 34. Particularly preferred is the embodiment in which the Zusammenam ^¬ menspiel the shift of the load from front to back with the particular curvature distribution of the new profile 30 at about 20% of the chord 34 constitutes. In particular, those specified in the table below

Compressor blades whose remaining profiles largely correspond to the profile shape shown in FIG 1 28 have been found to be particularly effective. Table 1:

Parameter: scoop scoop

No. 1 No. 2

Position of the first turning point (AP) 28 18 of the skeleton line

[Percent of profile chord length]

Position of the second inflection point (BP) 49 47 of the skeleton line

[Percent of profile chord length]

Length of non-curved leading edge 10 5 [percent of chord length]

Angle of attack of the 5 7 blade tip side profiles

[Degree]

Incident angle of other profiles 25 25 [degrees]

Location of section start point GA 51 53 [percent of chord length]

Curvature of the blade tip side 1 / (2 * 2 / profile

Profiles in the rear section profile ^¬ tendon

[length of neck]

Curvature of the other profiles in 1 / (10 * 1 / (10 * rear section profile ^¬ profile ^¬ [] tendon length) length)

Length of the shovel-side 20 10 area

[Percent of span]

Position of the suction, shovel-spit 20 10 z side speed maximum

[Percent of chord length]

Length of the maximum gradients of 10 10 suction speed ^¬ distribution downstream of the location of the

maximum speed

[Percent of chord length] Overall, the invention thus relates to a compressor run 10 for axially flowed compressor preferably stationary gas turbine. The invention provides that in order to reduce radial gap losses, the skeleton line 32 of the blade tip-side profiles 30 of the blade 12 of the compressor blade 10 have at least two inflection points 36, 38. Due to the presence of two turning points 36, 38 are obtained for the suction surface 42 in the portion from 35% to 50% of a Saugseitenkonturabschnitt D which is concave ausgebil ^¬ det and a Druckseitenkon- for the pressure side contour 40 turabschnitt E, which is convex. With this geometry, it is possible to generate low-loss gap swirl to increase the overall efficiency of a vehicle equipped with these Ver ^¬ tight running blades 10 axial compressor.

Claims

claims

A compressor rotor (10) for an axial compressor comprising a curved airfoil (12) comprising a pressure sidewall (14) and a suction sidewall (16) extending from a common leading edge (18) to a common trailing edge, respectively (20) and on the other hand to form a span from a mounting side airfoil end to an airfoil tip (22),

wherein for each along the span existing Schau ^¬ Felblatthöhe the airfoil (12)

A profile (28, 30) having a suction side contour (42) and a pressure side contour (40),

· An at least partially curved skeleton line (32) and

• a straight chord (34)

comprising which contours (40, 42), skeleton line (32) and chord (34) each extend from a tenpunkt Vorderkan- (24) to a trailing edge point (26) erstre ^¬ CKEN,

characterized in that

at least some of the skeleton lines (32) of the blade tip-side profiles (30) have at least two inflection points (36, 38).

2. Verdichterlaufschaufei (10) according to claim 1,

in which the first of the two inflection points (36), when the projection is ^{perpendicular} to the profile chord (34), predetermines ^thereon a first projection point (AP), which is from the

Lead edge point (24) between 10% and 30% of the length of the chord (34) is removed and

in which the second of the two inflection points (38) when projecting perpendicularly onto the chord (34) on this a second projection point (BP), which is from the leading edge point (24) between 30% and 50% of the length of the chord (34) removed , A compressor rotor (10) according to claim 1 or 2, wherein the skeleton lines (32) include a front portion (H) extending from the leading edge point (24) to a section end point (HE) whose projection point (HP) is projected perpendicularly the chord (34) from the leading edge point (24) Zvi ^¬ rule 2% and 10% of the length of the chord (34) ent ^¬ removed,

wherein at least some of the front portions (H) of the blade tip side profiles (30) have a radius of curvature greater than 100 times the chord (34).

A compressor blade (10) according to claim 3,

wherein each front section (H) has an angle of incidence with respect to an incoming gas flow, wherein at least some of the angles of attack of the blade tip side profiles (30) are smaller than the angles of incidence of the remaining profiles (28) of the airfoil (12).

A compressor blade (10) according to claim 4,

wherein the angle of attack of the front portion (H) blade tip side profile (30) is less than 10 °.

A compressor blade (10) according to any one of claims 3 to 5,

the suction side contour (42) and pressure side contour (40) of blade tip side profiles (30) in the front portion (H) of the skeleton line (32) are symmetrically ^{ausgebil ¬} det.

A compressor blade (10) according to any one of claims 1 to 6,

wherein at least some of the leading edge points (24) of the blade tip side profiles (30) are located further upstream than the leading edge points (24) of the remaining profiles (28) of the airfoil (12). A compressor rotor (10) according to any one of claims 1 to 7,

in which exclusively the skeleton lines (32) of the profiles (30) present in the area of the blade tip (22) have two turning points (36, 38).

A compressor rotor (10) according to any one of claims 1 to 8,

wherein the mean lines (32) comprise a rear section (G) extending from a portion of the initial point (GA) and to the trailing edge point (26) he stretches ^¬,

wherein the rear portion (G) of at least some of the blade tip side skeleton lines (32) has a greater curvature than the rear portions of skeleton lines (32) of the remaining profiles of the airfoil (12).

A compressor blade (10) according to claim 9,

wherein the portion starting point (GA) to the profile chord in a perpendicular projection (34) arranged one on the Pro ^¬ filsehne (34) projection point (GP) specifies ^¬ which the leading edge point (24) a maximum of 60% of the length of the chord (34) is removed.

A compressor blade (10) according to any one of claims 1 to 10,

in which the suction side contour (42) and the pressure side contour (40) of blade tip-side profiles (30) each have at least two inflection points.

A compressor blade (10) according to any one of claims 1 to 11,

in which the blade tip (22) is free-standing. A compressor blade (10) according to any one of claims 1 to 12,

in which at least some of the blade ^tip-side projectiles (30) are configured in the "Aft-Loaded Design" and the remaining profiles (28) in the "front-loaded design".

A compressor blade (10) according to any one of claims 1 to 13,

wherein the blade tip side includes a region (43) of at most 20% of the span ^¬ blade tip from the blade (22).

A compressor blade (10) according to any one of claims 1 to 14,

wherein along the suction surface (42) from the leading edge point (24) for trailing edge point (26) at a flow around with a gas a velocity distribution ^¬ (44) of the gas is established,

wherein at least some of the blade tip-side Pro ^¬ file (30) are selected so that at a maximum location a maximum velocity occurs whose projection point at a perpendicular projection on the chord (34) from the leading edge point (24) between 10% and 30% of the length of chord ( 34) is removed.

A compressor blade (10) according to claim 15,

in which the relevant profiles (30) are selected such that in a subsequent to the maximum location suction side portion of the Saugseitenenkontur (42) with a maximum length of 15% of the length of the chord (34) adjusts a gradient of speed, the maximum gradient is.

Axial compressor with a rotor,

At the outer periphery of which at least one blade ring with Verdichterlaufschaufein (10) according to one of Ansprü che 1 to 16 is formed.