DE1428098A1 - Compressor blading for axial compressors - Google Patents

Description

Dipl-Ing.F.Weickmann, Dr. Ing.A / Weickmann,

Dipl.-Phys. Dr. K. Fincke Patent Attorneys *

MUNICH, BRUNNSTRASSE 5 and 7, CALL NUMBER 221604 and 299078 "J 428098

General Dynamics Corporation, One Rockefeller Plaza, New York N.Y. - UNITED STATES

Compressor blading for axial compressors

The invention relates to compressor blading for axial compressors.

The blading according to the invention can, for example, be a Form stage of an axial flow compressor, which has a driven shaft and a shaft surrounding this driven, Compressor housing through which the flow flows

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The invention consists in that the rotor part of the blading consists of at least one ring of impulse blades consists, which sit on the rotor shaft and rotate with it and that the stator part has a ring of reaction guide vanes and comprises a ring of impulse vanes, which are attached to the inner wall of the stator housing in the direction of flow then, ^ to the Impulse blades ο

The conventional axial flow compressors work with the best efficiency at an inner grass speed that is just below the respective local speed of sound. This is due to the fact that the static pressure ratios that can be achieved in a compressor are dependent on the Mach numbers occurring and that these ratios increase significantly when the Mach number increases. However, an upper limit is set by the fact that the regulation of high-speed gas flows becomes extremely difficult when one comes into the supersonic range with these and that the flow losses then become correspondingly high. In normal practice, compressors are therefore built in such a way that the gas velocities are just below the respective local speed of sound. Since the speed of sound in air (33Om / sec. At room temperature) is approximately equal to the size of the blade speed permitted on the basis of static considerations.

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speed, one was forced to use blading in gas turbines operating in open circuit, in which the Ratio of the maximum gas velocity to the maximum blade velocity is kept to a minimum and not at a maximum

However, if you have to work with gases such as helium or hydrogen as working media in an axial flow compressor, the speed of sound is much higher, namely over 1350 m / second, and the requirement then exists to the blades that the highest possible gas velocities at a given blade speed be applied to perform a maximum of compression work · It follows that taking into account the loading caused by the mechanical loads restrictions, which are essentially the same, Regardless of whether you work with air or gases such as helium and hydrogen as working media, the use multi-stage axial flow compressor is necessary or that you just have to go over to centrifugal compressors to achieve a maximum of compaction work.

Lots of difficulties in using common multi-stage Axial flow compressors are based on the fact that the compression work that takes place with a certain rotor blade

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speed (blade speed limited by the mechanical stress) can be achieved, is directly dependent on the gas deflection that occurs in each case selected blade shape can be achieved. On the other hand, this diversion is of course limited by the fact that one is too rapid expansion of the effective flow cross-section leads to catastrophic expansion and similar losses » As long as the pressure increase is sought by the diffuser principle, the degree of deflection is there in a compressor is achievable, limited to a small fraction of the angle at which the gas originally entered the Compressor stage occurs.

It is known that the work done per compressor stage is proportional to the product of the blade speed and the absolute amount of the change in Vortex component of the gas velocity caused by the rotor. So the absolute value of work is directly dependent on the difference between the tangents of the flow angle at the rotor inlet and the flow angle at the rotor outlet. However, since the strict restrictions just mentioned apply to the deflection at the blades, the difference is the! tangent is only a fraction of the size of the! tangent of the entry angle and the absolute work of compression accordingly low.

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If you do without a pressure increase as a direct result of the passage of a gas through a row of blades and if only a substantial gas diversion is sought, this can be achieved without the otherwise occurring considerable flow losses have to be accepted. This leads to blade shapes, which is a change of the sign of the gas flow angle (measured with reference to the axial direction) without affecting the absolute size this gas flow angle changes. Goes on such shovels the gas flow angle from a positive value (+) to a negative value (-) of the same absolute magnitude over and also runs through the value zero. There are no significant problems, as far as the blades after progressively thicker towards their center, so that no cross-sectional enlargements of the flow passage occur while the flow angle becomes smaller and smaller. Man recognizes here that it is only the change in the effective gas flow cross-section which has so far caused the high flow losses and not the change in the gas flow angle per se· ,

If you have an Axialstromverdiohter with rotor and guide vane profiles which are substantially symmetrical and properly proportioned and which are for diffuser effect

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and have separate sections for the gas deflection »see above one circumvents various restrictions that were previously the effective ones Have reduced work of digestion in a "compressor stage. In particular if each of the symmetrical rotor and stator blade rings has a diffuser part with a corresponding static Pressure increase and a further part for the deflection of the gas flow without a simultaneous pressure increase, can per Compressor stage much more work can be conducted than with conventional compressors, if they work with the same or even with a higher blade speed

So Ss is the main object of the present invention to create a compressor blading which is relatively low blade speeds provides a large increase in pressure.

In other words, the task is that when a relatively small number of stages is used, a large total compression work is to be carried out in a compressor. Preferably using a symmetrical heap arrangement, the solution to this problem is approached in such a way that the functions of the diffuser and the gas jet deflection are taken over by separate parts in both the rotor part and the stator part, the deflection taking place without Druokanetitg.

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The attached figures explain the invention. Bs put dar »

FIG. 1 shows a part through a preferred embodiment of an angled compressor blading an axial flow compressor * e,

FIG. 2 shows an axial section through the rotor and stator of a compressor stage,

Figure 3 is a section along lines 3-3 of Figure 1,

FIG. 4 is a view similar to FIG. 2 in another Embodiment of the invention,

Figure 5 is a view similar to Figures 1 and 4 at a third embodiment of the invention

Preferred embodiments of the Verdiohter blading according to the invention are shown in Figures 2 and 4. One recognizes in these figures the reaction blades | usual in axial flow compressors close to these Impulse or reverse flow blade rings, where the number of their blades is equal to or greater than the number of blades in the reaction rotor blades. To the reaction and impulse blade rings that are on the driven shaft of the compressor rotor sit and revolve with this, it includes a pair of stator

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blades or guide vane rings, which are identical in shape to the blades of the rotor blade rings, but rotated by 180 °, that is, in a mirror image of these. The reaction blades of the rotor and the stator, ie the reaction blades and the heating guide blades act as diffusers for the gas passing through them.
without a static pressure increase taking place in them.
The combination of reaction and impulse blades results in a maximum of compression work per evaporator stage
given blade speed.

In Figure 5, another embodiment of a compressor blading is shown. In this embodiment
a rotor is used that is only equipped with impulse or reverse flow blades. In the stator part
Two groups of vanes are employed, reaction vanes and impulse vanes. In this embodiment
occurs due to the diffuser effect, a pressure increase in the
Reaction part of the stator blades, while the
Impulse guide vanes of the stator and the impulse guide vanes
of the rotor cause a deflection of the gas flow during the passage.

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As shown in Figures 1 and 3, one of the present invention comprises Compressor a stator housing 10 with an inner wall which enclose one or more compressor stages; every this compressor stage comprises a double blading, namely a double blade ring 11 and a double vane ring 12 · Each blade ring 11 includes one Row of reaction blades 11a and a row of Impulse or reverse flow blades 11 b. The reaction blades 11a and the impulse blades 11b protrude in the radial direction from a hub 13 which is on the driven Verdiohterwelle 14 is seated.

The blade roots of each rotor blade 11 a and 11 b are united with foot plates 16. The base plates 16 are equipped with dovetail profiles 16a} these dovetail profiles are fastened to the circumference of the hub 13 in corresponding hollow profiles. The cylindrical hub 13 thus has a plurality of spaced grooves or hollow profiles in Omfangerichtung 17, in which the blades 11a and 11b are mounted so ¹ that they rotate as a unit with the hub. The guide vanes 12a and 12b project inward, starting from the wall of the stator housing 10, in each case between two double rows of rotor blades. Grooves or hollow profiles 19 are also provided in the inner wall of the housing 10

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Each of these grooves 19 receives a dovetail 21 which is attached to foot plates 22 of the guide vanes 12a and 12b. The tips of the rotor blades and the guide vanes are spaced from the housing 10 or _{0 of} the hub 13 in such a way that king gaps that do not impede the operation of the compressor are formed.

As can be seen from the figure, the construction and Impulse blade 11a and 11b in a divergent one (Jaskanal housed, which by a 3feil the Innenwasd des Statorgehätiaes 10 is defined · by the Current auerat beaisfsehal & gtflBKanten der Heaktionaleitsühaufeln 11a and 12a aind. against sighting the on them incoming fluida inclined and cause a deflection of the flow mean by a wiskel amount that * is comparable to Uffi steering with conventional blading. This differs from the previous technique Invention, however, in that additional rows of blades 11b and 12b are accommodated in each stage, the impulse run chauf a and the impulse / Qitschaufeln namely · The Puncture of the impulse bucket rows is the circumferential component to reverse the flow velocities at the exit of the rotor blades and the guide vanes. the Reversal of the gas direction caused by the impulse blades

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According to the definition, it is not accompanied by a significant increase in pressure. Therefore, large deflection angles can be produced in these impulse blades without significant losses , occur in the rotor part and in the stator part of each stage of the compressor approximately the same pressure increases and one speaks τοπ an ^M 50 ^ igen reaction blades ¹¹ .

In the embodiment described so far, the number of flow reversal or momentum guide heaps 11b was equal to the number of reaction blades 11a. However, this need not be the case and it is not even always desirable. In the figure, twice as many impulse blades 11b ¹ and 12b ^{1 can be seen} in the impulse blade ^{sections as reaction blades 11a 1} and 12a ¹ in their sections.

Finally, in a further embodiment of FIG. 5, the rotor comprises only a single row of pure impulse or flow reversal rotor blades 11b ¹¹ . In this embodiment of the invention, this impulse blading of the rotor causes the gas to be deflected while at the same time providing a considerable increase in the kinetic energy.

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The resulting static pressure increase during the subsequent passage of the gas flow through the reaction ^{guide vanes 12a 11 of} the stator blades results in an even greater work performance per stage than in the previously described embodiment.

The method of operation and the possibilities of the invention Compressor blading can best be seen from the operating description of an exemplary embodiment which now follows.

The operational description is applicable to any of the three embodiments, but relates in particular to the Embodiment of FIG. 2. The gas flow also passes through inlet guide vanes or inlet guide valves of the compressor a certain axial speed. The inlet or Vorwirbeileitschaufeln share a component of the gas flow in the circumferential direction with and that opposite to the direction the rotor rotation shown in the figure. 2 from left to right is intended. That coming from the vortex guide vanes Gas enters the reaction blading part of the rotor at an angle α-a, this angle is here considered to be more positive Fixed angle. Steer the reaction blades 11a the gas flow from a fairly small angle and the gas leaves the reaction blading part with a

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Exit angle a ^, which is also noon a positive angle, even if its absolute value is slightly smaller than the absolute value of the angle a ..

The gas flow, which comes from the reaction part of the rotor impregnation, then enters its impulse part.The impulse impeller 11to cause a deflection of the ßaeatroms, whereby the gas flow in the course of its angular variation runs the angle value lall and finally reaches the angle a, _f at which it exits from the impulse mounting part of the Laufera | a, is equal in magnitude, but opposite in _{terms of Bach sign, to the angular value of a 2} , measured again with reference to the direction of the rotor axis. The gas flow then enters the stator blading, that is to say first of all into the reaction guide vanes 12a and then into the impulse guide vanes 12b. The entry occurs at an angle α. and the gas undergoes essentially the same deflections in the stator part that have occurred in the rotor part. Since the design of the rotor blades and the stator blades are symmetrical, the angle a, in terms of magnitude, is equal to the angle a .., but opposite in terms of the advance ·

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You can see that in addition to the rather small deflection, entering the reaction blades 12a and 11a as a result

rise

a static pressure / takes place on the diffuser arrangement. On the other hand, there is a strong deflection in the impulse blades 11b and 12b show no pressure increase. In some circumstances it may be appropriate to apply a small pressure drop also occur in the impulse bucket parts to leave with a corresponding slight enlargement the gas velocity j diaea could be an improvement (tesaniroirkungegsades of blading lead *

At äeii previously known “yer & Lehterbesehaufeluxigea” the ümi angles were “a- and a”. The entry angle a. and the exit angle oil are both positive. According to the invention, ifaöecfa * "*** nooh the entrance angle a is done by each stage is proportional to the numerical sum of the tangents of the angles & ^ and a ,. As a result, the work performed by the double rotor blades 11 according to the invention, that is, the work performed by the reaction blades 11a and the flow reversing blades 11b is many times greater when the work could be done with conventional compressor blades that did not provide for a reversal of the gas flow angle.

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An essential distinguishing feature of the embodiment according to FIG. 5 compared to the other embodiments is that the pulse ^{flow hoppers 11b f} 'exclusively assume the function of gas reversal. This means that the gas velocity before entering the reaction guide vanes of the compressor part is increased, where a substantial static pressure increase then takes place as a result of the diffuser effect to which the gas between the reaction guide vanes 12a ¹ ♦ is subjected.

The following example shows the advantage of the blading according to the invention insofar as a higher work performance can be achieved. A conventional axial flow compressed with ^w 50 # agitation blading ¹¹ and with a blade speed of approximately 270 m per second require 7 stages in order to achieve a certain compression of a gas such as helium. The gas coming out of the compressor emerges from it at a positive angle of direction.

In contrast to this, in one designed according to the invention Compressors of similar dimensions for helium gas the same degree of compression, can be achieved with only 4 steps and at a peripheral speed of only 1350 m / second. That from the The gas escaping from the compressor stage has a negative value Angle of exit direction; the angle value is slightly larger

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than with conventional compressors. The exit vortex, i.e., the circumferential component of the flow at the outlet can be easily eliminated by adding an additional reaction blade ring in the final compressor stage provides.

In a practical embodiment of the B * according to the invention Compressor blading, the tip diameter is approximately 75 cm. The ratio of the blade angle to the blade chord length is approximately 0.8 to 1.0, depending on the desired change in angle and also depending on the strength Considerations. The ratio of the tip diameter to the hub diameter in such an embodiment should be about 1.4, but this size is again prescribed by the respective application for which the blading is determined.

From the above it follows that a new Verdiohterblading was procured, which an effective compression of gaseous media, such as helium, with a minimum number of compression stages causes the Laufersehaufein with proportionately rotate at low speed. The Verdiohterbesaufelung according to the invention is of course also in many other circulatory systems applicable. E.g. the invention could

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be used with advantage in a free-running turbo compressor, as described in the simultaneous application Q 34 224 VIII o / 21 g of the applicant. It is precisely the reduction in the heave speed, which is achieved by the shaping according to the invention, with an approximately constant axial speed, that makes the blading according to the invention particularly suitable for this application.

The above description is based only on exemplary embodiments. Many deviating designs that nevertheless fall under the spirit of the invention, but are at any time at the discretion of the specialist.

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Claims (1)

Claims / M. \ Blading for one stage of an axial compressor, which ^ - ^ a runner and a runner surrounding this, by a gas flow comprises penetrated stator housing, characterized in that the running part of the blading consists of at least one ring consists of impulse blades, which are installed on the I & ufell e sit and revolve with this and that the stator part one Wreath of reaction guide vanes and a wreath of impulse guide vanes ugfafili, -die * on the inner wall of the stator housing are attached, namely the impulse blades in the direction of flow adjoining the reaction blades. 2 · Blading according to Claim 1, characterized in that the edges initially acted upon by the gas flow and the edges of the impulse blades last touched both in the sifting process the rotor rotation inclined bind, so that a reversal of the flow angle, in relation to the axial direction of the compressor, enters 3. Blading according to claim 1 and / or 2, characterized in that that also the rotor part of the compressor stage consists of a ring of reaction blades and a ring of impulse guide blades which is built by the shaft of the 90982970370 U28098 Compressor go out and revolve with this and that the reaction and impulse flow units are arranged in such a way that they are a mirror image of the reaction and momentum guide vanes dee stator result 4. Blading according to claim 3, characterized in that the tone of the flow hit the edges of the reaction blades first and that of the flow last touched edges of the Bapule blades in the direction of rotation are inclined in such a way that successively a static pressure rise and a reversal of the flow angle, based on the axial direction, can occur without a corresponding increase in pressure. 5 · Blading according to claim 3 and / or 4> characterized in that that the impulse blade ring of the rotor has at least twice as many blades as the Beaktiosalaufsohatifelkranz of the runner and that the impulse blade » and the reaction blade so arranged are that the former with its edges initially acted upon in the direction of flow to those last touched by the flow Connect the edges of the reaction blades and do so as they pass through the reaction blades a static pressure increase, but during the passage through the Iar pulse blades a change of direction without pressure increase, occur. 90 9 8 29/0370