FR2480367A1 - AIR INTAKE STRUCTURE FOR A COMPRESSOR - Google Patents

Abstract

THE INVENTION RELATES TO AN AIR INTAKE STRUCTURE FOR A COMPRESSOR. ACCORDING TO THE INVENTION, IT INCLUDES AN INTAKE SHEATH 20 SHAPED WITH AN AIR INDUCTION PASSAGE 28 HAVING A SENSITIVELY SHORT LENGTH ALONG THE COMPRESSOR AXLE 26, THIS PASSAGE 28 HAVING A FIRST SECTION 30 EXTENDING SENSITIVELY STRAIGHT FROM THE DOWNSTREAM END OF PASSAGE 28 AND A THIRD SECTION 34 CONNECTING THE FIRST TWO, THIS THIRD SECTION HAVING A SHAPE TO CONNECT THE FIRST AND SECOND SECTIONS AT AN ANGLE; AND A GUIDING MEANS 54 PROVIDED IN PASSAGE 28 TO RETURN THE SPEED DISTRIBUTION AT THE DOWNSTREAM END OF PASSAGE 28 SENSITIVELY REGULAR. THE INVENTION APPLIES IN PARTICULAR TO A GAS TURBINE ENGINE.

Description

The present invention relates generally to an admission structure

  air for a compressor, to use

  with a gas turbine engine or the like. More particularly

  In particular, the present invention relates to an air intake structure for rendering the engine

  compact without compromising compressor performance.

  FIG. 1 shows a traditional air intake structure, an inlet or intake sheath 2 with its two concentric inner surfaces 4 and 6 respectively having the form of a truncated truncated or hyperboloid. The inner surfaces 4 and 6 are respectively symmetrical about the axis 8 of the compressor and define an air induction passage 10 between them. The induction passage 10 comprises a portion 12 which extends radially and terminates upstream by an opening 14 to draw in the air, followed by a bend 15 and a portion 16 of sufficiently short length extending axially and facing, at its downstream end, at

  a compressor rotor 17 to bring it air.

  Since there is a great demand for reducing the size of the motor structures, particularly in automobiles or industrial machines, the induction air passages of the compressor intake ducts are generally formed in the curved form. of Figure 1 to make the axial length of the intake ducts as short as possible taking into account the arrangement of the engine components. In this structure, however, there is, at the inlet of the rotor 17 of the compressor, as indicated by the arrow A, a fairly irregular distribution of speed. This is because, since the direction of flow strongly changes at the elbow 15 of the induction passage 10 from the radial direction to the axial direction, depending on the hydrodynamics of the system, the speed on the internal curve becomes considerably greater. important than that on the

  external curve of the elbow 15 and it takes a considerable length

  significantly greater in Part 16 to reduce this uneven distribution of vitese to a distribution

substantially regular.

  This uneven distribution at the compressor rotor inlet adversely affects compressor performance, and a traditional air intake structure can not provide a compact engine structure

  without compromising the compressive efficiency of the compressor.

  Therefore, the present invention is directed to an air intake structure for a compressor to be used in a gas turbine engine or the like, rendering the engine compact without impairing performance.

compression of the compressor.

  The air intake structure according to the invention comprises an intake duct which contains a curved air induction passage. The induction passage has a substantially short length along the axis of the compressor to make the axial length

  total intake duct as short as possible.

  At least one guide member is provided in the induction passage to define at least two flow channels therein to provide a substantially even velocity distribution at the end of the induction passage located

downstream.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will appear more clearly in the description

  explanatory document which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which: - Figure 1 is a partial axial sectional view of a gas turbine engine o is illustrated a traditional structure of air intake; - Figure 2 is a partial axial sectional view of a gas turbine engine o an air intake structure of a first embodiment of the invention is applied to a centrifugal compressor; FIG. 3 is a perspective view showing the shape of a guide fin for use in the structure according to the invention; FIG. 4 is a partial axial sectional view of a gas turbine engine, where an air intake structure of a second embodiment of the invention is applied to a centrifugal compressor, FIG. a partial axial sectional view of a gas turbine engine showing only the intake side of the rotor of the axial flow compressor., o the air intake structure of the first embodiment is applied to a flow compressor axial; and FIG. 6 is a partial axial sectional view of a gas turbine engine, where the air intake structure of the first embodiment is applied to an axial flow compressor. Referring now to FIG. 2, there can be seen a first embodiment of the present invention. An inlet sheath 20 has two concentric inner surfaces 22 and 24 respectively trumpet-shaped or truncated hyperboloid. The inner surfaces 22 and 24 are respectively symmetrical around the axis 26 of the gas turbine engine and define an air induction passage 28 between them. The induction passage 28 comprises a portion 30 which extends radially and ends upstream by an opening 32 to attract air, this part being followed by a bend 34 and a portion 36 of a length sufficiently short extending axially and facing, by its end enave 1, to the blades 38 of a compressor rotor

  centrifuge 40 to provide air.

  The air is attracted by the operation of the rotor 40 in the induction passage 28 through the opening 32 and is then drawn into the blades of the rotating compressor 38 to be compressed. The compressed air is introduced into a combustion chamber 42 through an in-line diffuser 44, where it is mixed with fuel and ignited to produce a high temperature, high pressure gas. This gas is then introduced into the blades 46 of a turbine rotor 48 by a spiral casing 50 and a turbine injector 52 and expands to drive the turbine rotor 48, which rotor 48 drives the rotor

  compressor 40 by means of a shaft 53.

  A guide fin 54 in the form of a trumpet 4 or a truncated hyperboloid, as can be seen in FIG. 3, is provided in the induction passage 28 at its elbow 34. The fin 54 is arranged concentrically

  internal surfaces 22 and 24, and it extends substantially

  parallel to said cell: the upstream end facing the opening 32 at the downstream end facing the compressor blades 38. The guide fin 54 is disposed substantially in the middle between the inner surfaces 22 and 24 to define two flow channels 56 and 58 and is supported at its downstream end by a number of support means 60 attached to the inner surface 22 and spaced at substantially intervals

regular on the circumference.

  As described above, if no guide fin 54 is provided in the bend 34, the speed on the inner curve (on the inner surface 24) becomes considerably greater than that on the outer curve (on the inner surface 22) of the bend 34, so the speed distribution at the inlet of the rotor 40 of the compressor becomes considerably irregular. More particularly, according to the hydrodynamics of the system, the static air pressure in the elbow 34 is lower on the inner curve than on the outer curve, and the air velocity in the elbow 34 is greater on the curve. internal than on the external curve because this speed is inversely proportional

at the static pressure.

  By providing the guide fin 54 of FIG.

  the width of each of the channels 56 and 58 is sensitively

  Equally equal to half of the entire width W of the elbow 34, and the flow rate in each channel also becomes smaller than the total flow in the elbow 34. Thus, according to the hydrodynamics of the system, the static pressure difference between the curves internal and external of the elbow 34 is correspondingly lower, resulting in a substantially balanced distribution

  Pressure in the elbow 34. As a result, the distribution

  velocity in the elbow 34 is also substantially balanced and the velocity distribution at the inlet of the compressor rotor 40 becomes substantially regular, as shown by the arrows B, which

  superior performance of the compressor.

  Referring now to FIG. 4, there can be seen a second embodiment of the present invention, wherein parts or members corresponding or identical to those of FIG.

the same landmarks.

  In this embodiment, two guide vanes

  64 and 66 respectively trumpet-shaped or hyper-

  truncated bolody as can be seen in Figure 3,

  are provided in the induction passage 28 in its elbow 34.

  The guide vanes 64 and 66 are respectively concentrically disposed at the inner surfaces 22 and 24 and define three flow channels 68, 70 and 72 having substantially the same width, between the inner surfaces 22 and 24. Each of the fins 64 and 66 is extends substantially parallel to the inner surfaces 22 and 24 from the upstream end facing the opening 32 to the downstream end facing the blades 38

of the compressor.

  The guide fin 64 is supported at its downstream end by a number of support means 74 which are attached to the inner surface 22 and are spaced apart.

  at substantially regular intervals on the circumference

  ence. Guide fin 66 is supported at its downstream end by a number of support means 76 which are attached to the outer periphery of guide fin 64, and spaced at substantially regular intervals.

on its circumference.

  The other components are similar to those of the

figure 2.

  With this construction, the flow rate in each of the channels 68, 70 and 72 and the width of each channel are respectively decreased in comparison with those of the first embodiment, so a much more even speed distribution is obtained as is designated by

  arrows C, at the input of the rotor 40 of the compressor.

  The number of guide vanes can be increased in the same way as in the second embodiment, for

  achieve even more balanced speed distribution.

  It should be noted that since the present invention relates exclusively to an improvement in the intake side of the compressor rotor, the air intake structure according to the invention applies to compressors of any type.

construction.

  For example, FIG. 5 shows the air intake structure of the first embodiment, applied to an axial flow compressor of the gas turbine engine, where identical or corresponding parts or members are designated by the same as in Figure 2, and only the inlet side of the compressor rotor is

  illustrated to simplify the explanation.

  The marks 78 and 80 respectively designate mobile and stationary fins of the first stage. Other components not shown in Figure 5 may have any known construction in axial flow compressors. As is clear in FIG. 5, since there is no factor introduced to hinder or reduce the effect of the air intake structure according to the invention, FIG. 5 gives the same effect. 2, that the air intake structure according to the invention is applied to centrifugal compressors or axial flow compressors. For a better understanding, FIG. 6 also shows an example of parts or corresponding members are designated by the same reference numerals as in FIG. 2 and the air intake structure of the first embodiment is incorporated in a type of compressor

axial flow.

  The guide vanes of the first and second embodiments may have various shapes to smoothly guide the flow of air, and to make the velocity distribution at the downstream end of the passage

  d induction substantially regular.

  Of course, the invention is not limited to the embodiments described and shown which have been given by way of example. In particular, it includes all means constituting technical equivalents

  described means as well as their combinations if these

  These are executed according to his spirit and implemented

  as part of the protection as claimed.

Claims (9)

  RE V ENDICATI 0 NS 1. Air intake structure for a compressor, characterized in that it comprises: an inlet duct (20) formed with an air induction passage (28) having a length substantially short along the axis (26) of the compressor, said passage   (28) having a first section (30) extending substantially   straight from the upstream end of said induction passage, a second section (36) extending substantially straight from the downstream end of said induction passage (28) and a third section (34) connecting said first and second sections (30, 36) and having a shape such that it connects, at an angle, said first and second sections; guide means (54; 64,66) provided in said induction passage (28) for rendering the velocity distribution at the downstream end of said induction passage (28) substantially regular.   2. Structure according to claim 1, characterized in that the aforesaid guiding means is formed of at least one guide fin (54; 64, 66) which extends in the direction of the flow and defines at least two channels   flow (56, 58; 68, 70, 72) in the induction passage tion (28).   3. Air intake structure for a compressor, characterized in that it comprises: an inlet duct (20) formed with an induction passage (28) of bent shape, having a substantially short length along the axis of said compressor; guide means (54; 64; 66) provided in said induction passage (28) for rendering the velocity distribution at the downstream end of said substantially uniform induction passage (28); 4. Structure according to claim 3, characterized in that the aforementioned guide means is at least one guide fin (54; 64, 66) which extends in the direction of the flow and defines at least two channels of flow (56, 58; 68, 70, 72) in the passage induction device (28).   5. Air intake structure for a compressor, characterized in that it comprises: an intake duct (20) having first and second   second concentric inner surfaces (22, 24)   in the form of a trumpet, which are respectively symmetrical about the axis of said compressor, said first and second inner surfaces (22, 24) being spaced from each other to define between them   an air induction passage (28) having a substantial length   short along the axis of said compressor; guide means (54; 64,66) provided in said induction passage (28) for rendering the speed distribution at the downstream end of said passage (28) substantially regular.   6. Structure according to claim 5, characterized in that the aforementioned guide means is a fin   trumpet-shaped guide (54) and   the first and second internal surfaces (22, 24) above and which extends substantially parallel to said inner surfaces (22, 24), said guide fin being disposed substantially in the middle between said internal surfaces to define between them two channels; 'flow, 7. Structure according to claim 6, characterized in that the guide fin (54) above is supported   by a number of support means (60).   8. Structure according to claim 5, characterized in that said guide means is formed of a number of guide vanes (64, 66) respectively   trumpet-shaped, each being arranged concentrically   said first and second inner surfaces (22, 24), said fins respectively extending substantially parallel to said inner surfaces and defining a number of flow channels (68, 70, 72) having substantially the same width between said internal surfaces.   9. Structure according to claim 8, characterized in that each fin (64, 66) above is supported   by a number of support means (74, 76).