US3719426A - Supersonic compressors with conical flow - Google Patents

Abstract

In an axial supersonic compressor with conical flow, compressing of two flows occurs together, only in that portion of their course in the mobile wheel where they are compatible in terms of pressure. The compressor thus makes it possible to subject two flows, which are compatible in terms of pressure, to two different compression ratios in one and the same compression stage, either upstream or downstream from this stage.

Description

United States Patent 1 1 3,719,426

Friberg et al. 51 March 6, 1973 [5 1 SUPERSONIC COMPRESSORS WITH 1561' References Cited CONICAL FLOW UNITED STATES PATENTS [75] inventors: Jean-Marie Eugene Friberg, Bourge- 3 010 642 11,1961 D k ta] 415/181 la-Reine; Jean-Marie Merigoux, 1c nann e Palaiseau both of France 3,447,740 6/1969 Fabn et a1. ..4i5/181 [731 Assignee: Societe Alsacienne De Constructions FOREIGN PATENTS OR APPLICATIONS Ammiques De Telecommunications 175,043 5/1953 Austria ..415 207 Et DElectroniqueAlcatel, Paris, 126,579. 1/1948 Australia ..415/77 France 10,114 1914 Great Britain. ..415/77 610,726 3 1935 G ..415 21 221 Filed: on. 19, 1970 "many [21] App]. No,; 82,026 Primary Examiner-Henry F. Raduazo Foreign Application Priority Data Oct. 17, 1969 France ..6935743 U.S.Cl. ..415/1l6,4l5/l8l,415/199 Int. Cl. ..F04d 31/00, F0ld l/02 Field of Search ..4l5/74, 75, 77, 79, 210, 181, 415/215, 116, 199

Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT In an axial supersonic compressor with conical flow,

, compressing of two flows occurs together, only in that portion of their course in the mobile wheel where they are compatible in terms of pressure. The compressor thus makes it possible to subject two flows, which are compatible in terms of pressure, to two different compression ratios in one and the same compression stage, either upstream or downstream from this stage.

4 Claims, 5 Drawing Figures PATENTEUHAR 61915 3,719,426

SHEET 20F 3 FIG. 7a

PATENTEDHAR 6W 3,719,426

SHEET 3UF 3 FIG. 3

FIG.4

SUPERSONIC COMPRESSORS WITH CONICAL FLOW BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method making it possible to subject, in the same stage of an axial supersonic compressor, two flows to different compression rates, provided however that the two flows are compatible in terms of pressure either upstream or downstream from said stage.

This invention further concerns a device employing the method, especially when the two flows come from one and the same upstream stage, and involves another device employing the above method when the flow of one stage is directed toward two different destinations where different pressures prevail.

2. Description of the Prior Art It was shown recently that it was possible to obtain a high compression rate in an axial compressor while maintaining perfectly stable operation. A compressor thus put together is particularly remarkable, since it makes it possible simultaneously to obtain a very high flow rate and a very notable pressure increase, whereas compressors made according to earlier techniques, did not offer the possibility of attaining these two fundamental characteristics at the same time. Such a method is described particularly by the common assignee in U. S. Pat. No. 3,447,740, filed July 13, 1967. It concerns more particularly an axial compressor with conical flow in which the fluid is impelled by a relative supersonic speed over a portion of its path.

U. S. Pat. No. 3,447,740 also describes a single-stage compressor which employs this method, made up essentially of an ingress which spreads out into a truncated cone and a cap whose summit portion is situated on the axis of the motor shaft and whose walls are parallel to those of the tronconic widening, of a dis tributor with fixed blades mounted in the duct between the opening and the cap, of a mobile wheel with thin deflecting blades mounted in said duct downstream from the distributor and rotated by the motor shaft and an output diffuser located downstream from the wheel.

U. S. Pat. No. 3,447,740 also describes a compressor with several stages, with simple, double, or multiple flow compatible in terms of pressure both upstream and downstream from one and the same mobile wheel. It is known, furthermore, that when two flows of different origins have very different static pressures upstream and downstream, it is nevertheless possible to compress them in the same stage of a compressor, provided however that one keeps these two flows entirely separate. According to the information supplied by this known technique, which is called the separate-flow technique, the input collectors of each one of these two flows are distinct, each mobile blade is equipped, on the level of the separation of the flows, with a partition in the shape of a fin, isolating the principal flow from the secondary flow, with the evolution of the setting and of the cambers of the blade being capable of being different on either side of this partition. The output diffusers are also separate. There is, however, still reason to fear escape flow rates between the two flows.

On the other hand, when two flows to be compressed have essentially the same static pressure, only at one of the ends of the compression stage, either at the input or at the output, it appeared advantageous to resort to a technique that is simpler than the separate-flow technique.

SUMMARY OF THE INVENTION This invention is thus intended to assure the compression of two flows which, either upstream or downstream from a mobile wheel, present definitely different arresting pressures, that is to say, when the two flows are not compatible in the sense mentioned above, either upstream of downstream from said wheel.

Under these conditions, the method making it possible to subject two flows compatible in terms of pressure either upstream or downstream from said stage, to different compression rates, in one and the same compression stage, is characterized by the fact that it consists, in its more general form of the invention, in compressing, together, the two flows only in that portion of their course in the mobile wheel where they are compatible in terms of pressure. The above compression method can be applied both to supersonic and to transsonic compressors.

In the case where the flows are incompatible upstream, the method is characterized by the fact that the flow whose upstream pressure is weaker is first of all compressed separately from the other flow until the static pressures of the two flows have been made compatible and until the portion of the blade communicating its energy to the flow whose upstream pressure is the stronger presents a leading edge situated at the point where the static pressures of the two flows have become compatible, downstream from the leading edge concerning the flow whose upstream pressure was weaker. y

In the case where the flows are incompatible downstream, the method is characterized by the fact that the trailing edge of the portion of the blade communicating its energy to the flow whose downstream pressure is weaker, is arranged in a place where the two flows are compatible, upstream from the trailing edge of the portion of the blade concerning the flow whose downstream pressure is the higher, the latter then being compressed separately.

The improvements according to the invention here are characterized by the fact that the paddles of the mobile wheel of the stage are so constructed that the position of the leading edge and of the trailing edge of the portion of the paddle concerning the flows subjected to the weaker compression rate will be determined so as to assure, upstream and downstream from said portion of the paddle, compatibility of pressures, with the flow undergoing the higher compression rate.

The blades of the mobile wheel involve a portion extending over the entire depth of the wheel and another portion extending over only a fraction of this depth; the upstream or downstream edges, respectively, of these two portions are common, that is to say, in one case, the upstream edges are located essentially in the plane of entry of the mobile wheel and in the other case, the downstream edges are essentially in the output plane of said mobile wheel.

In the portion common to the two flows, where a certain portion of the direction or the value of the relative speed may be different, it is a good idea to separate the flows by means of the fins, the setting and the cambers of the blades here being capable of being different on either side of the mobile partition.

On the other hand, in order to take into account the fact that the value or the direction of the absolute speed may be different for the two flows, in the fixed portions of the apparatus, it may be preferable here to separate the flows in this zone in the known manner, at least over a certain distance.

BRIEF DESCRIPTION OF THE DRAWINGS Below is a description of two nonrestrictive examples of the invention, referring to the attached drawings. In these drawings:

FIG. I is a vertical axial cross-section of a compressor according to the invention.

FIG. 10 represents a partial view, in a vertical crosssection, of a compressor operating with fluids whose upstream pressures are incompatible.

FlG. 2 represents, in perspective, on a large scale, a type of blade that can be used in a compressor according to FIG. 1.

FIG. 3 is a partial view, in an axial cross-section, of a supersonic compressor of fluids whose downstream pressures are incompatible.

FIG. 4 represents, in perspective, a type of blade that can be used in the compressor of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I shows only the portion of an axial compressor with conical flow for two fluids with incompatible upstream pressures, where a mixture of the two flows occurs at the end of compression. In FIGS. 1 and 1a, the first stage 4 has a tronconic inlet opening 6 defining ingress of a fluid cap 9, blade 12, mobile wheel 11, ingress 17 of the second fluid, with its tronconic opening 18, essentially parallel to the prolongation 19 of the cap 9, and the rectifier 24 in the manner of FIG. 2 of the above-mentioned patent. The inside wall 30 for the separation of the two fluids is prolonged beyond the blade 12. This blade according to the invention involves a portion 12' which is prolonged over the entire depth of the wheel and a portion 12" linked to the portion 12' and occupying only a portion of the depthof the wheel. The leading edge of portion 12" is situated at an intermediate point where the pressures of the two flows are compatible and its trailing edge is essentially blended with the trailing edge of the element 12'. The two portions 12' and 12" of the blade 12 are separated by a thin partition 31 linked to the blade which is called a fin and which, beyond the mobile wheel, is prolonged by a fixed partition 32 (see FIG. la).

in FIG. 2. it is seen that the blade 12 has a paddle foot 13. The portion 12' of the blade occupies all of the depth of the mobile wheel and portion 12" occupies only a portion of this depth. Finally, it is seen that the arrangement of tin 31 maintains a separation between the two flows so as to take into account the incompatibilityof their speeds.

This device works in the following manner: assuming that. in the outside upstream duct, limited by partition 30, the pressure of the secondary fluid is 300 millibars, that it is 200 millibars in the principal flow, one wants to. obtain a pressure of 400 millibars downstream from the Compressor stage.

Under these conditions, the maximum compression rate of the wheel is 2 and the ratio between the higher pressure (300 millibars) and the pressure of the principal flow (200 millibars) is 1.5, in other words, it is smaller than the maximum possible compression rate.

In the duct of the principal flow, separated from the secondary flow by the prolongation of inside wall 30, the flow is compressed from 200 to 400 millibars gradually, as it moves downstream. Starting with a pressure of 200 millibars, it attains 300 millibars, which is the entry pressure of the secondary flow. One can then compress the two flows together because of the prolongation of the blade portion 12' by portion 12". From this we can see that the leading edge of the portion 12 lies exactly at the point where the increasing pressure in the principal duct passes through the value of 300 millibars, corresponding to the pressure of the second flow at the input. It is thus possible, in principle, to make the two flows communicate freely since they henceforth become compatible in terms of pressure. However, the directions of these flows materialized in FIG. la by the arrows are not yet perfectly parallel or, at any rate, they are not sufficiently parallel. To reduce this difference, it is arranged, according to the invention, a fin 31 at the separation of the two portions 12 and 12 of the blade 12. The directions of the flows are still different at the output of the wheel and therefore the partition 32 is prolonged over a certain distance to make it possible simultaneously to have compatibility of pressures and of flow speeds.

In the example shown in FIGS. 3 and 4, the upstream pressures of the compression stage 33 are identical but the downstream pressures are different. This is particularly true when one portion of the flow, coming out of a compression stage, is taken away for an annexed function. The example considered concerns more particularly the first stage 33 of an axial supersonic compressor with conical flow but is also suitable for any other type of compressor.

The ingress of the flow is accomplished through an input inlet 34 in accordance with the one in the previously mentioned patent.

After having traversed the first stage 33, a portion of the flow is directed to the succeeding stage, 35, another portion of the flow is taken away at the level of the first stage 33 and is directed, under a weaker pressure, toward a helix 36.

Contrary to the blades in applicants US. Pat. No. 3,447,740, the blades 37 according to this invention involve (FIG. 4.) a portion 37 occupying all of the depth of the duct corresponding to the flow that has to undergo the stronger pressure, while the portion 37" corresponding to the derived flow presents a common leading edge with portion 37', although its trailing edge is situated upstream from the trailing edge of the portion 37, perpendicularly from the point where the static pressure in the two ducts attains the value which it should have downstream from the derivation duct.

A partition such as 38 separates the two flows and helps form the derivation duct.

Such a compression stage operates in the following manner: a portion of the flow coming out of the input inlet 34 moves across the stages 33 and 35 of the compressor and comes out of the first stage 33 after having undergone, for example, a compression ratio of 2,

whereas the derived flow has to undergo a compression ratio of only 1.2. The evolution of the inter-blade ducts of the blade portion 37 and the position of the trailing edge of portion 37" are such that the recompression zone with the strong gradient in the portion of the duct limited by the portions 37" is situated downstream from the plane containing the trailing edges of blade elements such as 37", that is to say, in the hatched zone of the paddle in FIG. 4.

What is claimed is:

1. In an axial flow compressor having axial flow means for impelling fluid at a relative supersonic speed over a portion of an axial flow path in the same compression stage, said same compression stage having an inlet at one end of the axial flow path and an outlet at the other end of the axial flow path, wherein two flows are compatible in terms of pressure at one end of said axial flow path in the same stage but not at the other end of said axial flow path in said same stage, said stage comprising:

blades on a mobile wheel of said same stage, said blades having a leading edge and a trailing edge, each of said blades having two different axial depths between said leading edge and trailing edge, the axial depth between the leading edge and trailing edge of the portion of the blades compressing the flow subjected to the lower compression ratio being greater than the axial depth between the leading edge and trailing edge of the portion of the blade compressing the flow subjected to the higher compression ratio, the axial depths of the two portions of each of said blades in said same compression stage being such to assure compatibility of pressures at a common point in said same compression stage.

2. The compressor according to claim 1, where the blades of the mobile wheel include a portion extending over the entire depth of the blade and another portion extending over only a fraction of this depth with one pair of edges, respectively, of these two portions being common.

3. The compressor according to claim 2, where the upstream pair of edges of each blade portion are located essentially in the entry plane of the mobile zone when the pressures are compatible upstream.

4. The compressor according to claim 2, where the downstream pair of edges of each blade portion are located essentially in the outlet plane of the mobile wheel when the pressures are compatible downstream.

; UNITED STATES PATENT OFFICE EEETEFECATE OF CORREQTION Patent No. 3, 426 Dated March 6, 1973 Jean-Marie Eugene Friberg and Jean-Marie Merigoux lnventor(s) 1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In claim 1; column 6, line 2, after "the" (second instance) and before "compres-" change [lower] to higher x In claim 1, column 6, line 6, after the" (first instance) and before i "compression change [higher] to lower i Signed and sealed this 18th day of December 1973.

(SEAL) Attest: i

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents ORM PO-iOSO (IO-69) UscOMM-DC 80376-P69 w us. covznumznr PRINTING OFFICE: lass o-aes-au,

Claims (4)

1. In an axial flow compressor having axial flow means for impelling fluid at a relative supersonic speed over a portion of an axial flow path in the same compression stage, said same compression stage having an inlet at one end of the axial flow path and an outlet at the other end of the axial flow path, wherein two flows are compatible in terms of pressure at one end of said axial flow path in the same stage but not at the other end of said axial flow path in said same stage, said stage comprising: blades on a mobile wheel of said same stage, said blades having a leading edge and a trailing edge, each of said blades having two different axial depths between said leading edge and trailing edge, the axial depth between the leading edge and trailing edge of the portion of the blades compressing the flow subjected to the lower compression ratio being greater than the axial depth between the leading edge and trailing edge of the portion of the blade compressing the flow subjected to the higher compression ratio, the axial depths of the two portions of each of said blades in said same compression stage being such to assure compatibility of pressures at a common point in said same compression stage.

1. In an axial flow compressor having axial flow means for impelling fluid at a relative supersonic speed over a portion of an axial flow path in the same compression stage, said same compression stage having an inlet at one end of the axial flow path and an outlet at the other end of the axial flow path, wherein two flows are compatible in terms of pressure at one end of said axial flow path in the same stage but not at the other end of said axial flow path in said same stage, said stage comprising: blades on a mobile wheel of said same stage, said blades having a leading edge and a trailing edge, each of said blades having two different axial depths between said leading edge and trailing edge, the axial depth between the leading edge and trailing edge of the portion of the blades compressing the flow subjected to the lower compression ratio being greater than the axial depth between the leading edge and trailing edge of the portion of the blade compressing the flow subjected to the higher compression ratio, the axial depths of the two portions of each of said blades in said same compression stage being such to assure compatibility of pressures at a common point in said same compression stage.

2. The compressor according to claim 1, where the blades of the mobile wheel include a portion extending over the entire depth of the blade and another portion extending over only a fraction of this depth with one pair of edges, respectively, of these two portions being common.

3. The compressor according to claim 2, where the upstream pair of edges of each blade portion are located essentially in the entry plane of the mobile zone when the pressures are compatible upstream.

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