JP2001248595A - Centrifugal compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor improved in suction performance and balance especially and applicable to a comparatively small gas turbine as a compressor used in a dispersion type power generator, an automobile engine, or a propeller for a ship. SOLUTION: This centrifugal compressor is constructed of a easing 5 arranged in the circumference part of an impeller 3, a suction casing 6 connected to the front end of the casing 5 for sucking gas in the axis center direction, and a diffuser 7 leading the gas compressed by rotation of the impeller 3 to the outside in the centrifugal direction. In this centrifugal compressor, initial end parts of a plurality of vanes 10 wound on a conical hub 1 are arranged along the rotation axial center, while the outer circumferential tip parts 10a on the initial end side of the vanes 10 are protruded toward the suction casing 6, so that the inner circumferential part of a suction port for the vanes 10 is spread widely for guiding inflow of the gas in the front edge part of the suction port. In this way, suction performance and volume efficiency is improved, while balance efficiency is improved by a plurality of vanes 10 wound on the hub 1, and consequently, local separation of the compressed gas is prevented and vibration and noise due to surging can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor used for a distributed generator, a vehicle engine or a propulsion unit of a ship, and more particularly to an improvement of a centrifugal compressor applicable to a relatively small gas turbine. .

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional centrifugal compressor has an impeller 3 in which a large number of blades 2 are fixed to a conical hub 1.
Is fitted to the front end of the rotary shaft 4, the starting end of the blade 2 is fixed along the axial direction of the rotary shaft 4, and its rear portion is gently curved rearward in the rotational direction to form a rear end. It is fixed in the centrifugal direction. A casing 5 is provided on the periphery of the blade 2 so as to approach the outer peripheral end of the blade 2, and a suction casing 6 having a front end expanded at the front end of the casing 5.
Are connected. The rear part of the casing 5 is formed so as to diverge along the outer peripheral end of the blade 2, and the rear end of the casing 5 is connected to the diffuser 7. A guide vane 8 is provided inside the diffuser 7 to guide the compressed swirling flow into a linear flow, and has a structure in which the rectified compressed gas is sent to the spiral chamber 9. In the conventional centrifugal compressor shown in FIG. 7, in order to improve the suction performance of the pump, the leading end of the blade 2 is bent in the turning direction to be an inducer 2a.

[0003] In these compressors, the shape of the tip of the casing surrounding the impeller and the area of the inlet of the impeller have an important influence on the performance. Then, when the amount of air flowing between the blades is compressed and decreases to a flow rate below the limit value, the flow of the compressed gas is separated from the blades, and the pressure rise is discontinuously reduced, causing severe pressure fluctuation. Noise occurred, causing surging which was an unstable phenomenon of the entire compressor accompanied by flow pulsation. As a countermeasure against this surging, a device for providing an inlet guide blade in front of the suction casing and controlling the angle of the inlet guide blade and the number of revolutions of the impeller to prevent flow separation is disclosed in, for example, JP-A-9-133093. It is known as described in US Pat. In addition, a device that bends the inducer at the tip of the blade in the rotation direction to cause a gas flow to flow between the blades along the inducer is known, for example, as described in Japanese Patent Application Laid-Open No. 8-193598 for a blower. is there.

[0004]

However, in the apparatus provided with the inlet guide vanes at the preceding stage, the transient fluctuation of the fluid flowing into the suction port of the impeller can be reduced. However, there were many fluctuation factors of the air volume, and the structure became complicated. In addition, in a device in which an inducer is provided at the tip of the latter impeller, the suction performance is improved, but the gas flowing from the axial direction is suddenly changed in the centrifugal direction, so that the gas turbulence And the efficiency was reduced, so that application to a compressor was difficult. An object of the present invention is to provide a compressor in which suction performance and balance efficiency are improved by devising the shape of an impeller.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a casing disposed around a periphery of an impeller, a suction casing connected to a front end of the casing to suction gas from an axial direction, and a blade. In a compressor comprising a diffuser for guiding gas compressed by rotation of a car outward in a centrifugal direction, the start ends of a plurality of blades wound around a conical hub are arranged along a rotation axis, and the blades The leading end of the outer periphery on the starting end side is projected in the direction of the suction casing, and the inner periphery of the suction port of the blade is greatly expanded to guide the inflow of gas at the tip of the blade. The efficiency is improved, and the balance efficiency is improved by the plurality of blades wound around the hub. The compressed gas is prevented from being locally peeled, and the vibration and noise due to surging are eliminated. If the leading end of the blade is further bent in the turning direction to form an inducer, and the outer peripheral end of the inducer is protruded toward the suction casing, the gas is guided and the suction performance is enhanced. In addition, the return channel connected to the diffuser is connected to the rear casing, and the compressed gas is guided along the axis of the rear casing, and a hub is fitted to a rotating shaft extending inside the rear casing. If the starting end of the blade wound around this hub is arranged along the rotation axis and the outer end is protruded, high compression of the gas becomes possible and the fluid energy is converted into pressure energy, This enables high-speed rotation of a turbine or the like.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the compressor according to the present invention, a wide suction port is formed because the outer peripheral tip of the blade disposed along the rotation axis at the start end side protrudes in the direction of the suction case sink. The diameter becomes large, the suction air volume increases, and the suction efficiency in the vicinity of the suction port can be increased. And
The blades are arranged in a well-balanced axisymmetric manner on all surfaces perpendicular to the drive shaft and give energy to the gas, so that the volume efficiency and balance efficiency are good, and the gas sucked from the suction port with a large diameter is the blade surface. Without peeling from
The suction performance and discharge amount are increased, and vibration and noise due to surging can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. First, in FIG. 1, a plurality of blades 10 are wound around a conical hub 1 at equal intervals. The opening on the side is disposed along the rotation axis, and the opening on the discharge side is disposed outward in the centrifugal direction. The blades 10 wound around the hub 1 are arranged in a well-balanced manner with the blades 10 being axially symmetrical on all surfaces perpendicular to the rotation axis 4 so as to apply energy to the gas, thereby obtaining volume efficiency and balance efficiency. It is like that. An outer peripheral tip 10a on the start end side of the blade 10 is projected in the direction of the suction casing 6, and a wide suction port is formed inside the outer peripheral tip 10a of the blade 10 so that the amount of suction air is increased. ,
The compressed gas which flows between the blades 10 and 10 is not discontinuously reduced, and the compressed gas is prevented from being locally peeled off from the blades 10, thereby preventing severe pressure fluctuation and noise. It is. By providing the outer peripheral tip 10a of the protruding blade 10, the gas flow in the direction of the rotation axis is efficiently introduced between the blades 10, 10, and the radial blade 10 at the terminal end flows by centrifugal force. Is sent to the outer periphery, and surging, which is an unstable phenomenon of the entire compressor accompanied by flow pulsation, is eliminated.

The centrifugal compressor shown in FIG.
The leading end of the blade 10 wound around the wing is further bent in the turning direction to form an inducer 11, and the outer peripheral tip 11a thereof
Are projected in the direction of the suction casing 6 so as to further improve the wide suction port and the suction performance. The two-stage compressor shown in FIG. 3 has a centrifugal compressor for high pressure provided downstream of the centrifugal compressor shown in FIG. 1, and a return channel 12 connected to the diffuser 7 shown in FIG. 13 to guide the compressed gas along the axis of the rotating shaft 4. Rear casing 13
A blade 15 is wound around a hub 14 fitted on the rotating shaft 4 extending rearward, and an outer peripheral end 15a on the starting end side of the blade 15 is protruded in the inflow direction of the compressed gas. The gas compressed in the preceding stage from the axial direction of the rotary shaft 4 is guided to the high-pressure side compressor. And
The outer peripheral tip portion 10a of the front blade 10 extending in the suction direction
And the outer peripheral tip 15a of the rear-stage blade 15 forms a wide suction port inside thereof to increase the suction air volume, and the gas flowing between the front-stage blades 10, 10 and the rear-stage blade 15, 15 Is compressed so that the suction performance is improved so as not to be discontinuously reduced, so that vibration and noise due to surging can be prevented.

A two-stage compressor shown in FIG. 4 is a centrifugal compressor of another embodiment, in which an inducer 11 is provided at the starting end of a blade 10 as shown in FIG. The high pressure side centrifugal compressor of the two-stage compressor shown is connected. The front end 11a of the front inducer 11 and the front end 15a of the rear blade 15 extending in the suction direction form a wide suction port inside thereof, and the front blades 10, 10 and the rear The gas flow between the blades 15, 15 is compressed, and the intake air volume is increased so as not to be discontinuously reduced. Note that reference numeral 16
Is a guide vane for rectification provided inside the return channel 12, reference numeral 17 is a high-pressure side diffuser, and reference numeral 18 is
Reference numeral 19 denotes a guide vane provided inside the diffuser 17, and reference numeral 19 denotes a spiral chamber for sending out a compressed gas.

FIG. 5 is a table showing the relationship between the specific speed (ns) and the efficiency (η) between the centrifugal compressor according to the present invention and a conventional centrifugal, oblique flow or axial flow compressor. This is effective for improving the suction performance, and has a great effect on improving the efficiency on the low specific speed (ns) side, that is, on the high-speed rotation side or the high compression ratio side, and the effect is particularly remarkable in the case of a centrifugal compressor. It can be seen that by widening the application range of centrifugation, the large gap between axial flow and centrifugation has been reduced. That is, the present invention contributes to increasing the flow rate of a centrifugal compressor, and a relatively small gas turbine using a centrifugal or mixed flow compressor which is being developed as a distributed generator or an automobile engine. It can contribute to a reduction in size and weight of the device.

[0011]

The centrifugal compressor according to the present invention is constructed as described above, and the flow separation from the blade surface which causes the stall is generated from the suction end and the tip end of the blade. However, according to the present invention, the leading end of the outer periphery on the starting end side of the blade is protruded in the direction of the suction casing, and the inner periphery of the suction port of the blade is greatly expanded so that gas flows in at the leading end of the blade. So that even if the intake air volume increases and the air volume flowing between the blades is compressed, it does not decrease to a flow rate below the limit value, preventing local peeling of gas from the blade surface and causing surging. Vibration and noise are eliminated. Also,
By providing an inducer in which the starting end of the blade is further bent in the turning direction, the suction performance is improved, the flow is smooth and the flow becomes smooth, and the turning stall hardly occurs.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional side view of a centrifugal compressor in which a leading end on the starting end side of a blade according to the present invention is projected.

FIG. 2 is a partially longitudinal side view of another embodiment in which an inducer is provided on the starting end side of the blade.

FIG. 3 is a partially longitudinal side view of an embodiment in which centrifugal compressors are connected in two stages.

FIG. 4 is a partially longitudinal side view of another embodiment in which centrifugal compressors are connected in two stages.

FIG. 5 is a table comparing the relationship between the specific speed and the efficiency of the centrifugal compressor according to the present invention and the conventional compressor.

FIG. 6 is a partial longitudinal side view of a conventional centrifugal compressor.

FIG. 7 is a partially longitudinal side view of a conventional centrifugal compressor provided with a diffuser portion at the tip of a blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 14 Hub 3 Impeller 4 Rotation shaft 5 Casing 6 Suction casing 7 Diffuser 10, 15 Blade 10a, 15a Outer peripheral tip 11 Inducer 11a Outer peripheral tip 12 Return channel 13 Rear casing

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F04D 29/66 F04D 29/66 M

Claims (3)

[Claims] 1. A casing (5) disposed around a periphery of an impeller (3), a suction casing (6) connected to a front end of the casing (5) to suction gas from an axial direction, and an impeller. (3) A compressor comprising a diffuser (7) for guiding the gas compressed by rotation in a centrifugal direction outward, wherein a plurality of blades (10...) Wound around a conical hub (1) have leading ends. A centrifugal compressor characterized in that the outer peripheral tip (10a) at the start end side of the blade (10) protrudes in the direction of the suction casing (6). 2. A starter end of the blade (10) is further bent in a turning direction to form an inducer (11), and an outer peripheral end (11a) of the inducer (11) projects toward the suction casing (6). The centrifugal compressor according to claim 1, wherein the centrifugal compressor is provided. 3. A return channel (12) connected to the diffuser (7) is connected to a rear casing (13) to guide the compressed gas along the axis of the rear casing (13), A hub (14) is fitted to a rotating shaft (4) extending inside the casing (13), and a starting end of the blade (15) wound around the hub (14) is disposed along the rotating shaft center. 3. The centrifugal compressor according to claim 1, wherein the outer peripheral end portion (15a) is protruded.