JP3794543B2 - Centrifugal compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compressor used in a distributed generator, an automobile engine, a marine vessel propulsion device, or the like, and more particularly to an improvement of a centrifugal compressor that can be applied to a relatively small gas turbine.
[0002]
[Prior art]
In the conventional centrifugal compressor, as shown in FIG. 6, an impeller 3 in which a large number of blades 2 are fixed to a conical hub 1 is fitted to the tip end portion of the rotary shaft 4, and the start end portion of the blade 2 Is fixed along the axial direction of the rotating shaft 4, the rear portion thereof is gently curved backward in the rotational direction, and the rear end portion is fixed toward the centrifugal direction. And the casing 5 is provided in the peripheral part of the blade | wing 2 so that it may approach the outer peripheral end of the blade | wing 2, and the suction casing 6 which expanded the front-end | tip part is connected to the front | former stage part of the casing 5. FIG. The rear part of the casing 5 is formed in a divergent shape along the outer peripheral end of the blade 2, and the rear end part of the casing 5 is connected to the diffuser 7. Inside the diffuser 7 is provided a guide vane 8 that guides the compressed swirl flow into a linear flow, and has a structure for sending the rectified compressed gas 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 start end portion of the blade 2 is bent in the turning direction to form an inducer 2 a.
[0003]
In these compressors, the shape of the front end portion of the casing surrounding the impeller and the area of the inlet portion of the impeller have an important influence on the performance. When the airflow 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 increase is discontinuously reduced, resulting in severe pressure fluctuations. Noise occurred and caused surging, an unstable phenomenon of the entire compressor accompanied by flow pulsations. As a countermeasure against this surging, an apparatus for preventing the separation of the flow by providing an inlet guide vane in front of the suction casing and controlling the angle of the inlet guide vane and the rotation speed of the impeller is disclosed in, for example, Japanese Patent Laid-Open No. 9-133093. As known in the art. Also, a device that bends the inducer at the tip of the blade in the rotation direction and causes a gas flow to flow between the blades along the inducer is known, for example, as described in Japanese Unexamined Patent Publication No. Hei 8-193598. is there.
[0004]
[Problems to be solved by the invention]
However, in the apparatus provided with the inlet guide vanes at the front stage, the transient fluctuation of the fluid flowing into the suction port of the impeller can be reduced, but there are many fluctuation elements of pressure, temperature and air volume, and the structure is also It had become complicated. Also, in the device provided with an inducer at the tip of the rear impeller, the suction performance is improved, but the gas flowing in from the axial direction is suddenly changed in the centrifugal direction, so the turbulent flow of gas And the efficiency is reduced, making it difficult to apply in a compressor. An object of this invention is to provide the compressor which improved the suction performance and balance efficiency by devising the shape of an impeller.
[0005]
[Means for Solving the Problems]
The gist of the present invention is that a casing disposed around the periphery of the impeller, a suction casing connected to the front end of the casing and sucking gas from the axial direction, and a gas compressed by the rotation of the impeller are centrifuged. In a compressor consisting of a diffuser that guides outward in the direction, the starting end of a plurality of blades wound around a conical hub is arranged along the axis of rotation, and the outer peripheral tip on the starting end side of the blade is sucked Projecting in the direction of the casing, widening the inner periphery of the blade suction port to guide the inflow of gas at the tip of the blade, improving the suction performance and volume efficiency, and wrapped around the hub The balance efficiency is improved by a plurality of blades, local peeling of the compressed gas is prevented, and vibration and noise due to surging are eliminated. If the leading end of the blade is further bent in the swivel direction to form an inducer, and the outer peripheral tip of the inducer protrudes in the direction of the suction casing, the gas is guided and the suction performance is enhanced. The retan channel connected to the diffuser is connected to the rear casing to guide the compressed gas along the axis of the rear casing, and the hub is fitted to the rotating shaft extending inside the rear casing. If the start end of the blade wound around this hub is arranged along the rotation axis and the outer peripheral tip protrudes, high compression of gas becomes possible, and fluid energy is converted into pressure energy. A turbine or the like can be rotated at a high speed.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the compressor according to the present invention, since the outer peripheral tip portion on the start end side of the blade disposed along the rotation axis projects in the direction of the suction casing , a wide suction port is formed, the diameter is increased, and the suction air volume is increased. Increases and the suction efficiency in the vicinity of the suction port can be increased. And since the blades are arranged in a well-balanced manner on all surfaces perpendicular to the drive shaft to give energy to the gas, the volume efficiency and the balance efficiency are good, and the gas sucked from the suction port with a large diameter is The suction performance and discharge amount are increased without peeling from the blade surface, and vibration and noise based on surging can be prevented.
[0007]
【Example】
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, and an opening on the suction side between the blades 10 and 10 is formed. Arranged along the axis of rotation, the opening on the discharge side is arranged outward in the centrifugal direction. The blades 10 wound around the hub 1 are arranged in a balanced manner in a balanced manner on all surfaces perpendicular to the rotation shaft 4 so as to give energy to the gas, and volume efficiency and balance efficiency can be obtained. It is like that. The outer peripheral tip portion 10a on the start end side of the blade 10 protrudes in the direction of the suction casing 6, and a wide suction port is formed inside the outer peripheral tip portion 10a of the blade 10 so that the suction air volume is increased. , The compressed gas flowing between the blades 10 and 10 does not drop discontinuously, and the compressed gas is prevented from peeling off locally from the blades 10, and severe pressure fluctuations and noise are prevented. Is. Then, by providing the outer peripheral tip portion 10a of the projecting 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 end portion flows by centrifugal force. The surging which is an unstable phenomenon of the whole compressor accompanied by flow pulsation is eliminated.
[0008]
In the centrifugal compressor shown in FIG. 2, the start end of the blade 10 wound around the conical hub 1 is further bent in the turning direction to form an inducer 11, and the outer peripheral tip 11 a projects in the direction of the suction casing 6. The wide suction port and the suction performance are further improved. The two-stage compressor shown in FIG. 3 is provided with a high-pressure centrifugal compressor in the subsequent stage of the centrifugal compressor shown in FIG. 1 , and a return channel 12 connected to the diffuser 7 shown in FIG. 13, the compressed gas is guided along the axis of the rotating shaft 4. The rear casing 13 is internally provided with a blade 15 wound around a hub 14 fitted to a rotating shaft 4 extending rearward, and an outer peripheral tip 15a on the start end side of the blade 15 is in the inflow direction of compressed gas. The gas compressed in the previous stage from the axial direction of the rotating shaft 4 is guided to the high-pressure side compressor. The outer peripheral tip 10a of the front blade 10 extending in the suction direction and the outer peripheral tip 15a of the rear blade 15 form a wide suction port on the inner side to increase the suction air volume. Suction-based vibration and noise can be prevented by improving the suction performance so that the gas flowing between the blades 10 and 10 and the subsequent blades 15 and 15 is compressed and does not drop discontinuously. It is.
[0009]
Further, the two-stage compressor shown in FIG. 4 is a centrifugal compressor according to another embodiment, and the two-stage compressor shown in FIG. 3 and the centrifugal compressor shown in FIG. A centrifugal compressor on the high pressure side of the compressor is connected. And the outer periphery front-end | tip part 11a of the former-stage inducer 11 extended in the suction direction and the outer-periphery front-end | tip part 15a of the back | latter stage blade | wing 15 have formed the wide suction inlet in the inside, and the front | former blade | wings 10 and 10 and a back | latter stage | paragraph The amount of suction air is increased so that the gas flowing between the blades 15 and 15 is not compressed and discontinuously decreases. Reference numeral 16 denotes a rectifying guide vane provided inside the retan channel 12, reference numeral 17 denotes a high-pressure side diffuser, reference numeral 18 denotes a guide vane provided inside the diffuser 17, and reference numeral 19 denotes a spiral for sending compressed gas. It is a room.
[0010]
FIG. 5 is a chart showing the relationship between the specific speed (ns) and the efficiency (η) of the centrifugal compressor according to the present invention and the conventional centrifugal, mixed flow, and axial flow compressor, and the present invention improves the suction performance. It is effective in improving the efficiency on the low specific speed (ns) side, that is, on the high speed rotation side or on the high compression ratio side. By expanding the application range of the centrifuge, it can be seen that the large gap between the axial flow and the centrifuge has been reduced. That is, the present invention helps to increase the flow rate of a centrifugal compressor, and is a relatively small gas turbine using a centrifugal or mixed flow compressor that is being developed as a distributed generator or an automobile engine. Can contribute to the reduction of size and weight.
[0011]
【The invention's effect】
The centrifugal compressor according to the present invention is configured as described above, and the flow separation from the blade surface causing the stall occurs from the suction end and the tip end side of the blade. Then, the outer peripheral tip on the start end side of the blade is projected in the direction of the suction casing, and the inner peripheral portion of the suction port of the blade is greatly expanded to guide the inflow of gas at the tip of the blade. Even if the intake air volume increases and the air volume flowing between the blades is compressed, the flow rate does not decrease to a limit value or less, the gas is prevented from peeling off from the blade surface, and vibration and noise caused by surging are prevented. It will disappear. Further, if an inducer in which the starting end portion of the blade is further bent in the turning direction is provided, the suction performance is improved, the flow becomes smooth and the flow becomes smooth, and the turning stall hardly occurs.
[Brief description of the drawings]
FIG. 1 is a partially longitudinal side view of a centrifugal compressor in which a leading end portion of a blade according to the present invention is protruded.
FIG. 2 is also a partially longitudinal side view of another embodiment in which an inducer is provided on the leading end side of a blade.
FIG. 3 is also a partially longitudinal side view of an embodiment in which centrifugal compressors are continuously arranged in two stages.
FIG. 4 is also a partially longitudinal side view of another embodiment in which centrifugal compressors are continuously arranged in two stages.
FIG. 5 is a chart comparing the relationship between the specific speed and efficiency of the centrifugal compressor according to the present invention and the conventional compressor.
FIG. 6 is a partially longitudinal side view of a conventional centrifugal compressor.
FIG. 7 is a partially longitudinal side view of a conventional centrifugal compressor in which a diffuser portion is provided at the tip of a blade.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 14 Hub 3 Impeller 4 Rotating 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

Claims (3)

The casing (5) disposed on the peripheral part of the impeller (3), the suction casing (6) connected to the front end of the casing (5) and sucking gas from the axial direction, and the rotation of the impeller (3) In the compressor comprising the diffuser (7) for guiding the gas compressed in the centrifugal direction outward, the starting end portions of the plurality of blades (10 ...) wound around the conical hub (1) are used as the rotation axis. Centrifugal compression characterized in that the 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 thereof. Machine.   The leading end of the blade (10) is further bent in the swivel direction to form an inducer (11), and the outer peripheral tip (11a) of the inducer (11) is projected in the direction of the suction casing (6). The centrifugal compressor according to claim 1, wherein:   The return channel (12) connected to the diffuser (7) is connected to the rear casing (13) to guide the compressed gas along the axial center of the rear casing (13), and the rear casing (13) A hub (14) is fitted to a rotating shaft (4) extending inside, and a starting end portion of a blade (15) wound around the hub (14) is disposed along the rotating shaft center, and an outer peripheral tip thereof. The centrifugal compressor according to claim 1 or 2, wherein the portion (15a) is provided in a projecting manner.

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