EP3390833B1 - Compressor rotor blade and method for profiling said blade - Google Patents

Description

The invention relates to a compressor blade and a method of profiling the compressor blade.

An axial-flow compressor has at least one blade ring with a plurality of compressor blades for compressing a working fluid. The compressor blade has a radially inner subsonic section, in which the compression takes place by means of a deflection of the flow of the working medium. Furthermore, the compressor blade on a transonic section, in which the compression takes place for the most part by means of a compression shock, in which the working fluid is delayed from supersonic to subsonic speed.

Losses in the flow of the working fluid in the transonic section arise, for example, in the compression shock and by separation of the boundary layer on the compressor blade in the region of the compression shock. The losses cause a reduction in the efficiency of the compressor.

FR 2 551 145 A1 discloses a compressor blade according to the preamble of claim 1.

The object of the invention is therefore to provide a compressor blade, a compressor with the compressor blade and a method for profiling the compressor blade, with which an increase in the efficiency of the compressor blade having the compressor can be achieved.

The compressor blade according to the invention for a compressor in axial construction, has a blade profile having a transonic section, and extending in the transonic section profile section of Blade profile having on its suction side a concave suction side region and a convex suction side region which is disposed downstream of the concave suction side region, and which has on its pressure side a convex pressure side region and a concave pressure side region which is arranged downstream of the convex pressure side region, wherein a curvature of the pressure side of the profile section and a curvature profile on the suction side of the profile section are applied continuously over a chord of the profile section, the positions of the minimum values of the curvature curves do not differ from each other by more than 10% of the length of the chord and the positions of the maximum values of the curvature curves are no longer than 10% of the chord length, the minimum values multiplied by the chord length from -1.2 to -0.5 and the maximum values multiplied by the chord length from 1.5 to 4.

The inventive method for profiling a compressor blade for a compressor for compressing an axial working fluid having a blade row with the compressor blades, the compressor blades having a blade profile with a transonic section, comprises the steps of providing a geometric model of the blade profile Blade profile has a profile section, which extends in the transonic section, and the blade row is set, that set at a nominal operating condition of the compressor, a compression shock in which the working fluid is delayed from supersonic to subsonic speed; Determining boundary conditions for a flow around the blade that occurs at the rated operating condition; Changing the profile section such that the suction side has a concave suction side portion and a convex suction side portion disposed downstream of the concave suction side portion and having on its pressure side a convex pressure side portion and a concave pressure side portion downstream The curve of the convex pressure side region is arranged, wherein a curvature course on the pressure side of the profile section and a curvature on the suction side of the profile section each applied over a chord of the profile section are continuous, the positions of the minimum values of the curvature curves do not differ from each other by more than 10% of the length of the chord and the positions of the maximum values of the curvatures do not deviate from one another by more than 10% of the length of the chord, the minimum values multiplied by the length of the chord from -1.2 to -0.5 and the maximum values multiplied by the length of the chord of Figure 1, 5 to 4, wherein the convex suction side portion is at least partially upstream of a compression stroke, which has a set in the compressor at the boundary conditions flow, whereby the compression shock is arranged with respect to the length of the chord downstream of a compression shock, the flow would occur, which would occur in the geometric model before changing the profile section and at the nominal operating condition.

It has been found that the compressor with the compressor blade according to the invention and / or with the compressor blade profiled with the method according to the invention has a higher efficiency with at least the same operating range than a compressor with the conventional compressor blade. In addition, the Mach numbers on the suction side of the compressor blade according to the invention prior to the compression shock are lower than on the suction side of the conventional compressor blade. Thus, detachments of the flow on the suction side of the compressor blade according to the invention are less likely than in the conventional compressor blade. In addition, the compressor blade according to the invention can be performed with a shorter length of chord profile than is the case with the conventional compressor blade, without thereby sacrificing efficiency or a reduction of the working area.

It is preferable that in the convex suction side region, the curvature multiplied by the length of the chord has a maximum value which is from 2 to 4 and in the concave pressure side region the curvature multiplied by the length of the chord has a maximum value ranging from 1.5 to 2.5.

It is preferred that the point of the concave suction side region with the minimum curvature when projecting perpendicularly onto the chord of the profile section on this prescribes a projection point which is from the leading edge of the profile section of 40% to 80%, in particular 60% to 75% Length of the chord is removed. It is preferred that the point of the convex suction side region with the maximum curvature when projecting perpendicularly onto the chord of the profile section on this prescribes a projection point which is from the leading edge of the profile section of 70% to 95%, in particular 80% to 90% Length of the chord is removed. Each of these measures can further increase the efficiency of the compressor.

It is preferred that the thickness of the profile section at all points of the profile section perpendicular to the chord is shorter than 2.5% of the length of the chord.

The compressor according to the invention for compressing a working medium, comprising a blade row having the compressor blades, wherein the blade row is set that at a nominal operating condition of the compressor precompression of the working medium upstream of a compression shock, wherein the working fluid is delayed from supersonic to subsonic speed, and upstream of a flow channel defined by two adjacent compressor blades.

It is preferred that the profile section on a cylindrical surface, whose axis coincides with the axis of the compressor, on a conical surface whose axis coincides with the axis of the Compressor coincides, is located on an S ₁ flow area of the compressor or in a tangential plane of the compressor. The S ₁ flow area extends in the circumferential direction and in the axial direction of the axial flow machine and describes a surface that follows an idealized flow.

When changing the profile section whose skeleton line is preferably moved, in particular only the skeleton line is moved. As a result, it is advantageously achieved that the width of the channel between two compressor blades arranged adjacent in a rotor blade ring remains unchanged. It is preferred that the geometric model before the modification of the profile section on its pressure side exclusively concave and / or formed exclusively convex on the suction side.

It is preferable that the profile section is changed such that in the convex suction side area, the curve of the curve has a maximum value larger than the maximum value of the curve of the curve in the corresponding area of the conventional compressor blade. The profile section is preferably changed in such a way that in the convex suction side region the course of the curvature multiplied by the length of the chord has a maximum value which is from 2 to 4 and in the concave pressure side region the course of the curve multiplied by the length of the chord has a maximum value which is from 1.5 to 2.5. It is preferred that the blade row is designed such that at the nominal operating conditions there is a maximum isentropic advance Mach number of 1.4, in particular of at most 1.3. It is preferred that the profile cut is changed so that the point of the concave suction side region with the minimum curvature when projecting perpendicularly to the chord of the profile section on this one projection point, which is from the leading edge of the profile section of 40% to 80% of the length of the Chord is removed. Each of these measures can further increase the efficiency of the compressor.

• Figur 1 die erfindungsgemäße Verdichterlaufschaufel mit einem rechnerisch bestimmten Strömungsfeld,
• Figur 2 Machzahlverläufe an der herkömmlichen Verdichterlaufschaufel und an der erfindungsgemäßen Verdichterlaufschaufel,
• Figur 3 einen Profilschnitt der erfindungsgemäßen Verdichterlaufschaufel,
• Figur 4 Krümmungsverläufe an der erfindungsgemäßen Verdichterlaufschaufel und
• Figur 5 die Machzahlverläufe aus Figur 2 mit normierten Längen der Profilsehnen.

The invention will be explained in more detail below with reference to the accompanying schematic drawings and mathematically determined data. Show it

• FIG. 1 the compressor blade according to the invention with a computationally determined flow field,
• FIG. 2 Mach number curves on the conventional compressor blade and on the compressor blade according to the invention,
• FIG. 3 a profile section of the compressor blade according to the invention,
• FIG. 4 Curves of the compressor blade according to the invention and
• FIG. 5 the Machzahlverläufe FIG. 2 with standardized lengths of the chords.

Like it out FIGS. 1 and 3 As can be seen, a compressor blade 1 for a compressor in axial construction on a blade profile. The blade profile has a radially inner subsonic section and a radially outer transonic section, wherein FIGS. 1 and 3 only the transonic section is shown. The blade profile has a profile section 21 which extends in the transonic section. For example, the profile section 21 is located on a cylindrical surface whose axis coincides with the axis of the compressor, on a conical surface whose axis coincides with the axis of the compressor, on an S ₁ flow area of the compressor or in a tangential plane of the compressor.

The profile section 21 has a front edge 2, a trailing edge 3, a pressure side 4 and a suction side 5. In FIG. 3 In addition, a chord 22 is shown, which is as straight line from the leading edge 2 to the trailing edge 3 extends. Further shows FIG. 3 a skeleton line 23 which extends from the front edge 2 to the trailing edge 3 and is always located in a direction perpendicular to the chord 22 midway between the pressure side 4 and the suction side 5.

FIG. 1 shows a two-dimensional flow distribution of a working medium flowing in the compressor in a region of the compressor. In FIG. 1 1, a blade row 15 with the compressor blades 1, a blade row 15 downstream blade row 16 and a blade row 15 upstream blade row 17 are shown. The profile section 21 has on its suction side 5 a concave suction side region 10, which is arranged at least partially upstream of a compression joint 18, which has an adjusting in the compressor at a nominal operating condition of the compressor flow. The compression shock 18 is in FIG. 1 arranged in the areas of flow in which the Mach number decreases from higher than 1 to lower than 1. In addition shows FIG. 1 in that, in the nominal operating condition of the compressor, precompression of the working medium occurs upstream of the compression surge 18 and upstream of a flow channel bounded by two adjacent compressor blades 1.

Due to the concave suction side region, the compression shock 18 is located downstream of a compression shock relative to the length of the chord 22, which would have a flow which in a conventional compressor blade, which may differ from the compressor blade 1, is exclusive to its suction side 5 convex, and set at the nominal operating condition.

FIG. 2 FIG. 4 shows a comparison of the Mach number curves on the compressor blade 1 and the Machzahlverläufe on the conventional compressor blade. Above the horizontal axis 19 is a point on the chord 22 of the profile section 21 and over the vertical axis 20, the Mach number is plotted. Reference numeral 6 designates Machzahlverlauf on the pressure side of the conventional compressor blade, with the reference numeral 7 is the Machzahlverlauf on the suction side of the conventional compressor blade, with the reference numeral 8 is the Machzahlverlauf on the pressure side 4 of the compressor blade 1 and the reference numeral 9 the Machzahlverlauf on the suction side 5 of the compressor blade 1 denotes.

FIG. 5 shows the Machzahlverläufe FIG. 2 For this purpose, the Machzahlverlauf the compressor blade 1 has been scaled such that the leading edge 2 and the trailing edge 3 of the compressor blade 1 coincide with the leading edge and the trailing edge of the conventional compressor blade.

Out FIG. 2 It can be seen that the Machzahlverlauf 9 on the suction side 5 of the compressor blade 1 immediately upstream of the compression shock 18 lower supersonic Mach numbers than the Machzahlverlauf 7 on the suction side of the conventional compressor blade immediately upstream of the compression shock. These lower supersonic Mach numbers are maintained over a longer extent along the chord 22 than in the conventional compressor blade. Due to the lower supersonic Mach numbers before the compression shock 18 losses are reduced. By keeping the supersonic Mach numbers over the longer extent, the total profile load correlated with the Mach number difference on the pressure side 4 and the suction side 5 is comparably high in the subsonic region downstream of the compression stroke 18 as in the conventional compressor blade. Moreover, it is off FIG. 1 It can be seen that the compression stroke 18 is arranged obliquely, which means that with increasing distance from the suction side 5, the compression shock 18 moves upstream. This also leads to a reduction of losses. Of Further, the FIG. 2 It can be seen that the profile load on the compressor blade 1 after the compression stroke 18 is significantly higher than in the conventional compressor blade. Due to the reduced losses and higher profile load in the subsonic region, a higher efficiency can be achieved with the compressor rotor blade 1 than with the conventional compressor rotor blade. Due to the higher efficiency, the compressor blade 1, as it is in FIG. 2 is shown to be shorter than the conventional compressor blade, whereby losses due to friction of the working fluid on the compressor blade 1 can be reduced.

wobei Δs die Länge eines Kreisbogens und Δα der Differenzwinkel zwischen den Tangenten an den Endpunkten des Kreisbogens ist. FIG. 4 shows a curvature 27 along the pressure side 4 and a curvature 28 along the suction side 5. Both curvature curves 27, 28 are continuous. About the horizontal axis 25, the length of the chord 22 and the vertical axis 26, the curvature k multiplied by the length of the chord 22 is applied. The curvature k is defined as $$k=\underset{\mathrm{\Delta }s\to 0}{\lim }\frac{\mathrm{\Delta }\alpha }{\mathrm{\Delta }s}=\frac{\mathit{d.alpha}}{\mathit{ds}}.$$

where Δs is the length of a circular arc and Δα is the difference angle between the tangents at the end points of the circular arc.

Concave suction side areas and convex pressure side areas are characterized by a negative sign of the curvature. Convex suction side regions and concave pressure side regions are characterized by a positive sign of the curvature.

In the concave suction side region 10, the curve of the curvature multiplied by the length of the chord 22 has a minimum value that is from -1.2 to -0.5. The profile section 21 has on its suction side 5 a first convex suction side region 11, which is located downstream of the concave suction side region 10. The profile section 21 has on its suction side 5 a second convex suction side region 12, which is arranged upstream of the concave suction side region 10. In the convex suction side region 11, the curve of curvature has a maximum value greater than the maximum value of the curve of the curvature in the corresponding region of the conventional compressor blade. Specifically, in the convex suction side region 11, the curve of the curvature multiplied by the length of the chord 22 has a maximum value which is from 2 to 4.

The point of the concave suction side region 10 with the minimum curvature when projecting perpendicularly onto the chord 22 of the profile section 21 on this projecting point 24, which is from the leading edge of the profile section 21 of 40% to 80% of the length of the chord 22. The point of the convex suction side region 11 with the maximum curvature when projecting perpendicularly onto the chord 22 of the profile section 21 on this projecting point 24, which is from the leading edge of 21 of 80% to 100% of the length of the chord 22. The profile section 21 has on its pressure side 4 a convex pressure side region 14, which is arranged in a region which is arranged opposite the concave suction side region 10.

The compressor blade 1 is to be profiled as follows: providing a geometric model of the blade profile, wherein the blade profile has a profile section 21 which extends in the transonic section and on a surface of revolution, whose axis coincides with the axis of the compressor, on a conical surface whose Axis coincides with the axis of the compressor, is located on an S ₁ flow area of the compressor or in a tangential plane of the compressor, and the blade row 15 is arranged that sets at a nominal operating condition of the compressor, a compression shock 18, in which the working medium is delayed from supersonic speed to subsonic speed; - Setting boundary conditions for a flow around the blade 14, 15, which occurs at the nominal operating condition; Changing the profile section 21 such that only the skeleton line is displaced and the suction side 5 has a concave suction side region 10 and a convex suction side region 11, which is arranged downstream of the concave suction side region 10, and which has a convex pressure side region 14 and a concave one on its pressure side 4 Pressure side region 13 which is disposed downstream of the convex pressure side region 14, wherein a curvature 27 on the pressure side 4 of the profile section 21 and a curvature 28 on the suction side 5 of the profile section 21 respectively applied via a chord 22 of the profile section 21 are continuous, the layers of Minimum values of the curvature courses 27, 28 differ by not more than 10% of the length of the chord 22 and the positions of the maximum values of the curvature courses 27, 28 do not deviate from one another by more than 10% of the length of the chord 22, the minimum values multiplied by the length of the chord profile Sehn e (22) is from -1.2 to -0.5 and the maximum values multiplied by the length of the chord 22 are from 1.5 to 4, the convex suction side region 11 being at least partially upstream of a compression shock 18, which is in adjusting the compressor at the boundary conditions, whereby the compression shock 18 is located downstream of a compression shock relative to the length of the chord 22, which would have a flow that would occur in the geometric model before changing the profile section and at the nominal operating condition.

Whether the compaction shock 18 shifts downstream by changing the profile section can be determined by calculation, in particular by a finite volume method, or experimentally.

Although the invention in detail by the preferred embodiment is more particularly illustrated and described, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. The scope of the invention is defined solely by the claims.

Claims (14)

1. Compressor rotor blade for a compressor of axial design, having a blade profile which has a transonic section, and a profile section (21) of the blade profile, which profile section (21) extends in the transonic section and, on its suction side (5), has a concave suction side region (10) and a convex suction side region (11) which is arranged downstream of the concave suction side region (10), and which, on its pressure side (4), has a convex pressure side region (14) and a concave pressure side region (13) which is arranged downstream of the convex pressure side region (14), characterized in that a curvature progression (27) on the pressure side (4) of the profile section (21) and a curvature progression (28) on the suction side (5) of the profile section (21) are constant in each case plotted over a profile chord (22) of the profile section (21), in that the positions of the minimum values of the curvature progressions (27, 28) differ from one another by no more than 10% of the length of the profile chord (22), and the positions of the maximum values of the curvature progressions (27, 28) differ from one another by no more than 10% of the length of the profile chord (22), and in that the minimum values multiplied by the length of the profile chord (22) are from - 1.2 to - 0.5, and the maximum values multiplied by the length of the profile chord (22) are from 1.5 to 4.
2. Compressor rotor blade according to Claim 1, the curvature progression (28) multiplied by the length of the profile chord (22) having a maximum value which is from 2 to 4 in the convex suction side region (11), and the curvature progression (27) multiplied by the length of the profile chord (22) having a maximum value which is from 1.5 to 2.5 in the concave pressure side region (13).
3. Compressor rotor blade according to Claim 1 or 2, the point of the concave suction side region (10) with the minimum curvature in the case of a perpendicular projection onto the profile chord (22) of the profile section (21) defining a projection point (24) on said profile chord (22), which projection point (24) is spaced apart from the front edge (2) of the profile section (21) by from 40% to 80% of the length of the profile chord (22).
4. Compressor rotor blade according to one of Claims 1 to 3, the thickness of the profile section perpendicularly with respect to the profile chord (22) being shorter than 2.5% of the length of the profile chord (22).
5. Compressor for compressing a working medium, having a rotor blade row (15) which has the compressor rotor blades (1) according to one of Claims 1 to 4, the rotor blade row (15) being set up such that, in the case of a nominal operating condition of the compressor, a precompression of the working medium takes place upstream of a compression shock (18), at which the working medium is retarded from supersonic speed to subsonic speed, and upstream of a flow duct which is delimited by two adjacent compressor rotor blades (1).
6. Method for profiling a compressor rotor blade (1) for a compressor for compressing a working medium of axial design, which compressor has a rotor blade row (15) with the compressor rotor blades (1), the compressor rotor blades (1) having a blade profile with a transonic section, and the method having the following steps:

   - providing of a geometric model of the blade profile, the blade profile having a profile section (21) which extends in the transonic section, and the rotor blade row (15) being set up such that, in the case of a nominal operating condition of the compressor, a compression shock (18) sets in, at which the working medium is retarded from supersonic speed to subsonic speed;

   - fixing of boundary conditions for a flow which flows around the blade (14, 15) and occurs in the case of the nominal operating condition;

   - changing of the profile section (21) in such a way that the suction side (5) has a concave suction side region (10) and a convex suction side region (11) which is arranged downstream of the concave suction side region (10), and which, on its pressure side (4), has a convex pressure side region (14) and a concave pressure side region (13) which is arranged downstream of the convex pressure side region (14), a curvature progression (27) on the pressure side (4) of the profile section (21) and a curvature progression (28) on the suction side (5) of the profile section (21) being constant in each case plotted over a profile chord (22) of the profile section (21), the positions of the minimum values of the curvature progressions (27, 28) differing from one another by no more than 10% of the length of the profile chord (22), and the positions of the maximum values of the curvature progressions (27, 28) differing from one another by no more than 10% of the length of the profile chord (22), the minimum values multiplied by the length of the profile chord (22) being from - 1.2 to - 0.5, and the maximum values multiplied by the length of the profile chord (22) being from 1.5 to 4, the convex suction side region (11) being arranged at least partially upstream of a compression shock (18) which is exhibited by a flow which sets in in the compressor in the case of the boundary conditions, as a result of which, in relation to the length of the profile chord (22), the compression shock (18) is arranged downstream of a compression shock which would be exhibited by a flow which would set in in the case of the geometric model before the profile section is changed and in the case of the nominal operating condition.
7. Method according to Claim 6, the profile section (21) lying on a cylindrical surface, the axis of which coincides with the axis of the compressor, on a conical surface, the axis of which coincides with the axis of the compressor, on a flow surface which extends in the circumferential direction and in the axial direction of the compressor and which describes a surface which follows an idealized flow (S₁ flow surface), or in a tangential plane of the compressor.
8. Method according to Claim 6 or 7, the camber line (23) of the profile section (21) being shifted when said profile section (21) is changed, in particular only the camber line (23) being shifted.
9. Method according to one of Claims 6 to 8, the geometric model, before the change of the profile section (21), being of exclusively concave configuration on the pressure side (4) of said profile section (21) and/or being of exclusively convex configuration on the suction side (5) of said profile section (21) .
10. Method according to one of Claims 6 to 9, the profile section (21) being changed in such a way that the progression of the curvature has a maximum value in the convex suction side region (11), which maximum value is greater than the maximum value of the progression of the curvature in the corresponding region of the conventional compressor rotor blade.
11. Method according to one of Claims 6 to 10, the profile section being changed in such a way that the progression of the curvature multiplied by the length of the profile chord (22) has a maximum value which is from 2 to 4 in the convex suction side region (11), and the progression of the curvature multiplied by the length of the profile chord (22) has a maximum value which is from 1.5 to 2.5 in the concave pressure side region (13).
12. Method according to one of Claims 6 to 11, the profile section (21) being changed in such a way that the point of the concave suction side region (10) with the minimum curvature in the case of a perpendicular projection onto the profile chord of the profile section defines a projection point (24) on said profile chord, which projection point (24) is spaced apart from the front edge of the profile section by from 40% to 80% of the length of the profile chord (22).
13. Method according to one of Claims 6 to 12, the rotor blade row (15) being designed in such a way that it has a maximum isentropic Mach number of 1.4, in particular of at most 1.3, in the case of the nominal operating conditions.
14. Method according to one of Claims 6 to 13, the profile section being designed in such a way that the thickness of the profile section perpendicularly with respect to the profile chord (22) is shorter than 2.5% of the length of the profile chord (22).

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