A centrifugal compressor with stall suppression, an injection system and a control method

Abstract

The present invention discloses a centrifugal compressor, jet system, and control method for stall suppression. The centrifugal compressor includes an impeller, a rotating shaft, an adjustable nozzle array, and multiple air pipelines. The impeller is fixed to the rotating shaft. The adjustable nozzle array includes multiple adjustable nozzles, each of which is disposed on the impeller hub. The adjustable nozzles are used to adjust the jet angle by rotating along the impeller circumference and the blade span. The air pipelines are disposed corresponding to the adjustable nozzles, each of which passes through the rotating shaft and impeller and is connected to the adjustable nozzles. The adjustable nozzle array is disposed on the impeller hub. By autonomously adjusting the jet flow rate and finely adjusting the jet angle over a wide range in two directions, fine control of the flow field within the centrifugal compressor is achieved, thereby achieving the purpose of stall suppression.

Description

Technical Field

[0001] The present invention belongs to the technical field of centrifugal compressors, and in particular relates to a stall-suppressed centrifugal compressor, an injection system and a control method. Background Art

[0002] Compressors are high-tech equipment with complex designs and strict operating requirements. Current research focuses on their operating margins. For example, regarding compressor stability margins, researchers are primarily looking to increase the compressor's stable operating range through fluid control methods without sacrificing high pressure ratio and overall compressor efficiency.

[0003] Flow control methods involve using external means to suppress or even eliminate low-energy secondary flows that can cause compressor stall. This method, based on an analysis of the compressor's internal flow field, aims to broaden the compressor's stable operating range.

[0004] Flow control can be categorized as active or passive, depending on whether additional energy is required. Common active control methods include tip micro-injection and adjustable inlet guide vanes. Tip micro-injection primarily involves placing high-frequency air jets circumferentially on the compressor shroud, acting as an exciter. These jets are controlled by the air jet system to suppress impeller stall precursors.

[0005] For example, patent CN117028300A provides an axial compressor blade tip jet anti-surge control method based on time-frequency signal analysis, which includes: when it is determined that the jet at the blade top of the axial compressor is to be regulated, determining the blade tip jet increment based on an index value associated with a pressure signal, wherein the pressure signal is collected from the compressor wall surface at the blade top of the axial compressor within a preset time period, and the preset time period is used to represent the time period before the current moment; determining a preset blade tip jet amount based on the blade tip jet increment and the first blade tip jet amount at the current moment; when it is determined that the preset blade tip jet amount meets the limit control range, determining the preset blade tip jet amount as the second blade tip jet amount; and converting the second blade tip jet amount into an electrical signal to facilitate control of the jet valve at the blade top.

[0006] In the compressor sector, the application of tip micro-injection for stall control is primarily targeted at centrifugal compressors with large relative tip clearances. These centrifugal compressors have relatively large tip clearances. High-pressure gas is generated by an external twin-screw compressor and injected into the impeller cover, mixing with the low-speed fluid. This increases the velocity of the low-speed fluid inside the impeller, thereby suppressing backflow and preventing stall precursors.

[0007] Centrifugal compressors also include semi-open centrifugal compressors and closed centrifugal compressors with small relative tip clearances. In these two types of centrifugal compressors, the tip clearances are almost non-existent or very small, resulting in very limited leakage flow in the tip area. Tip injection cannot effectively affect the leakage flow, making it difficult to change the flow field characteristics.

[0008] Therefore, for semi-open centrifugal compressors and closed centrifugal compressors with small relative tip clearance, how to perform fluid control through structural settings to achieve the purpose of stall suppression is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0009] In response to the deficiencies in the aforementioned prior art, the present invention provides a centrifugal compressor, jet system, and control method for stall suppression. The centrifugal compressor includes an impeller, a rotating shaft, an adjustable nozzle array, and multiple air pipelines. The impeller is fixed to the rotating shaft. The adjustable nozzle array includes multiple adjustable nozzles, each of which is disposed on the impeller hub and is used to adjust the jet angle by rotating along the impeller circumference and along the blade span. The air pipelines are disposed corresponding to the adjustable nozzles, each of which passes through the rotating shaft and impeller and is connected to an adjustable nozzle. The adjustable nozzle array disposed on the impeller hub allows for autonomous adjustment of the jet flow rate and fine-tuning of the jet angle over a wide range in both directions, thereby achieving fine control of the flow field within the centrifugal compressor and suppressing stall.

[0010] In a first aspect, the present invention provides a centrifugal compressor with stall suppression, specifically comprising: an impeller, a rotating shaft, an adjustable nozzle array, and a plurality of gas pipelines, wherein the impeller is fixed to the rotating shaft;

[0011] The adjustable nozzle array includes a plurality of adjustable nozzles, each of which is arranged on the impeller hub, and the adjustable nozzle is used to adjust the jet angle by rotating along the impeller circumference and blade span direction;

[0012] The gas delivery pipelines are correspondingly arranged with the adjustable nozzles. Each gas delivery pipeline passes through the rotating shaft and the impeller and is connected with the adjustable nozzle.

[0013] Furthermore, the impeller includes a plurality of blades, the number of the adjustable nozzles is the same as the number of the blades, and the adjustable nozzles are arranged between adjacent blades;

[0014] The 40%-60% chord length position of all blades forms an air jet surface, and the adjustable nozzles between adjacent blades are located on the air jet surface. The air supply pipeline is connected to the gap opened on the impeller hub surface and connected to the adjustable nozzle.

[0015] Furthermore, the gas transmission pipeline includes an outlet section, a first pipeline section and a second pipeline section connected in sequence, the outlet section and the first pipeline section are both arranged in the impeller, the outlet section is connected to the adjustable nozzle, and the second pipeline section is arranged in the rotating shaft;

[0016] The inner diameter of the gas outlet section is larger than the inner diameters of the first pipe section and the second pipe section.

[0017] Furthermore, the adjustable nozzle includes a spherical joint, a telescopic rod and an adjustment assembly, the spherical joint is rotatably fixed to the gas outlet section of the gas pipeline, and the spherical joint is provided with a through gas outlet nozzle;

[0018] The front end of the telescopic rod is connected to the spherical joint, and the rear end of the telescopic rod is connected to the adjustment component. The adjustment component realizes the rotation of the spherical joint along the circumference of the impeller and the span direction of the blade through the telescopic rod.

[0019] Furthermore, the spherical joint is a sphere, the air outlet nozzle is a cylindrical structure and passes through the center of the spherical joint, and the inner diameter of the air outlet nozzle is not greater than the inner diameter of the first pipe section;

[0020] A ball socket is provided on one side of the inner portion of the spherical joint, and a first spherical interface is provided at the front end of the telescopic rod. The first spherical interface cooperates with the ball socket to realize the connection between the telescopic rod and the spherical joint.

[0021] Furthermore, the adjustment component includes a lever bracket and an actuator, the actuator is fixed to the wheel back of the impeller, the upper end of the lever bracket is connected to the actuator, and the lower end of the lever bracket is connected to the telescopic rod.

[0022] Furthermore, the lever bracket includes a first lever bracket and a second lever bracket, the connection point between the first lever bracket and the telescopic rod is located between the front end and the rear end of the telescopic rod, and the second lever bracket is connected to the rear end of the telescopic rod;

[0023] The lower end of the second lever bracket is provided with a groove base, and the rear end of the telescopic rod is provided with a second spherical interface, and the second spherical interface cooperates with the groove base to realize the connection between the second lever bracket and the telescopic rod;

[0024] The actuator is used to control the rotation of the first lever bracket, lengthen or shorten the telescopic rod, and realize the rotation of the spherical joint along the circumference of the impeller; the actuator is also used to control the second lever bracket to drive the spherical joint along its own axis through the telescopic rod to realize the rotation of the spherical joint along the span direction of the blade.

[0025] In a second aspect, the present invention further provides a centrifugal compressor jet system for stall suppression, specifically comprising: a centrifugal compressor for stall suppression as described above, a first pressure-stabilizing tube, a second pressure-stabilizing tube, and an air storage tank, wherein the centrifugal compressor is sequentially connected to the first pressure-stabilizing tube and the air storage tank to form an air storage circuit, for inputting an intermediate-stage pressure gas flow through the first pressure-stabilizing tube and storing the intermediate-stage pressure gas in the air storage tank when the centrifugal compressor is operating at a safe flow rate, thereby forming high-pressure gas;

[0026] The gas storage tank is connected to the second pressure-stabilizing tube, the gas pipeline of the centrifugal compressor, and the adjustable nozzle array in sequence to form a bleed circuit, which is used to eject the high-pressure gas in the gas storage tank through the second pressure-stabilizing tube, the gas pipeline and the adjustable nozzle array when the centrifugal compressor is running below the flow threshold.

[0027] Furthermore, the centrifugal compressor jet system also includes a control module, and a first control valve, a second control valve and a sensor connected to the control module by signal, the first control valve is arranged between the centrifugal compressor and the first voltage regulator tube, the second control valve is arranged between the centrifugal compressor and the second voltage regulator tube, and the sensors include a temperature sensor, a pressure sensor and a vibration sensor;

[0028] A gas transmission control valve is provided on the gas transmission pipeline, and the gas transmission control valve is connected to the control module signal;

[0029] The control module is used to control the opening of the first control valve, the second control valve and the gas transmission control valve based on the analysis of the temperature, pressure and vibration signals of the sensors.

[0030] In a third aspect, the present invention further provides a centrifugal compressor jet control method for stall suppression, which uses the centrifugal compressor jet control system for stall suppression as described above, and specifically includes the following steps:

[0031] Obtain the safe flow range of the centrifugal compressor;

[0032] Open the gas storage circuit or the gas release circuit according to the real-time flow of the centrifugal compressor;

[0033] Among them, if the real-time flow of the centrifugal compressor is within the safe flow range, the centrifugal compressor will input the intermediate-stage pressure air flow through the first pressure-stabilizing tube and store it in the gas storage tank until it stabilizes to form high-pressure gas; if the real-time flow of the centrifugal compressor is less than the flow threshold, the gas storage tank will input the high-pressure gas into the second pressure-stabilizing tube and the gas pipeline in sequence and spray it out through the adjustable nozzle array.

[0034] The present invention provides a centrifugal compressor with stall suppression, an injection system, and a control method, which have at least the following beneficial effects:

[0035] (1) The centrifugal compressor provided by the present invention mainly refers to a semi-open centrifugal compressor and a closed centrifugal compressor with a small relative blade tip clearance. An adjustable nozzle array is provided on the impeller hub. By autonomously adjusting the jet flow rate and finely adjusting the jet angle in a wide range in two directions, the flow field in the centrifugal compressor is finely regulated to achieve the purpose of suppressing stall.

[0036] (2) The adjustable nozzles provided by the present invention have the same number as the blades and achieve jetting at a position between 40% and 60% of the blade chord length on the impeller hub. The adjustable nozzle array distributed on the impeller hub and the gas transmission channel running through the center of the shaft and the impeller ensure that high-pressure gas from the gas transmission pipeline is evenly sprayed into the centrifugal compressor, thereby improving the flow field within the centrifugal compressor.

[0037] (3) The adjustable nozzle designed in the present invention realizes the adjustment of the jet angle under high-pressure gas circulation through a spherical joint, a telescopic rod and an adjustment component; at the same time, the actuator and the first lever bracket and the second lever bracket in the adjustment component produce two adjustment forms with different functions, thereby realizing a large range of autonomous and fine adjustment of the jet angle of the adjustable nozzle.

[0038] (4) The jet system for stall suppression provided by the present invention monitors the airflow state (temperature, pressure, vibration, flow, etc.) in the impeller in real time through sensors, adjusts the opening of the first control valve, the second control valve and the air supply control valve through the control module, and coordinates the adjustment components of the adjustable nozzle to adjust the jet flow rate and jet angle, thereby improving the fluid flow rate and flow field distribution on the disk side of the centrifugal compressor, delaying and suppressing the stall phenomenon of the diffuser and the entire centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic structural diagram of a centrifugal compressor with stall suppression provided by the present invention;

[0040] Figure 2 A schematic diagram of an adjustable nozzle array arrangement according to an embodiment of the present invention;

[0041] Figure 3 A front cross-sectional view of an adjustable nozzle structure according to an embodiment of the present invention;

[0042] Figure 4 A side sectional view of an adjustable nozzle structure according to an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of a centrifugal compressor jet system for stall suppression provided by the present invention;

[0044] Figure 6 A schematic flow chart of a centrifugal compressor jet control method for stall suppression provided by the present invention.

[0045] Explanation of the reference numerals: 1-impeller, 11-blade, 2-rotating shaft, 3-adjustable nozzle, 31-spherical joint, 311-air outlet nozzle, 312-ball socket, 32-telescopic rod, 321-first spherical interface, 322-second spherical interface, 331-lever bracket, 3311-first lever bracket, 3312-second lever bracket, 3313-groove base, 332-actuator, 4-gas pipeline, 41-gas outlet section, 42-first pipeline section, 43-second pipeline section, 100-centrifugal compressor, 200-first pressure-stabilizing tube, 300-gas storage tank, 400-second pressure-stabilizing tube, 500-first control valve, 600-second control valve, 700-gas supply control valve. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0048] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0049] Impeller stall in closed centrifugal compressors and semi-open centrifugal compressors with small relative tip clearances occurs primarily in the opposite direction of impeller rotation. For example, in the case of a closed centrifugal compressor, the flow at the diffuser inlet is uneven, resulting in uneven local airflow velocity and pressure distribution, forming stall zones. These stall zones move in the opposite direction of impeller rotation, disrupting the axial symmetry of the pressure within the impeller and causing stall. For semi-open centrifugal compressors with small relative tip clearances, when operating under off-design conditions, the airflow entering the impeller is less than the rated flow rate. The relative velocity direction of the gas entering the impeller is inconsistent with the blade inlet installation angle, impacting the working surface of the blade and forming airflow vortices near the concave surface of the blade. The gradual increase in vortices reduces the effective flow area of the flow channel, leading to stall.

[0050] Based on this, the present invention provides an active jet injection system for a centrifugal compressor for injecting air in the impeller, injecting high-pressure gas on the disk side of a semi-open centrifugal compressor or a closed centrifugal compressor with a small relative blade tip clearance, and mixing it with the low-speed fluid on the disk side to achieve the purpose of suppressing stall.

[0051] like Figure 1 As shown, the present invention provides a centrifugal compressor with stall suppression, which specifically includes: an impeller 1, a rotating shaft 2, an adjustable nozzle array and a plurality of gas pipelines 4, wherein the impeller 1 is fixed on the rotating shaft 2;

[0052] The adjustable nozzle array includes a plurality of adjustable nozzles 3, each of which is arranged on the impeller hub. The adjustable nozzle 3 is used to adjust the jet angle by rotating along the impeller circumference and the blade span direction; wherein the impeller circumference refers to the tangential direction of the impeller rotation (such as Figure 2 The A direction in the impeller is the direction of movement of a certain point on the edge of the impeller during rotation; the span direction is the direction of the blade from the hub (the center of the impeller) to the rim (the outer edge of the impeller) (such as Figure 2 The B direction in the figure), that is, the length direction of the blade, is roughly consistent with the radial direction of the impeller.

[0053] The gas pipelines 4 are arranged corresponding to the adjustable nozzles 3 . Each gas pipeline 4 passes through the rotating shaft 2 and the impeller 1 and is connected to the adjustable nozzle 3 .

[0054] Optionally, the impeller inlet radius is set to 10-20mm, the impeller outlet radius is set to 40-50mm, the blade tip clearance is 0.15-0.45mm, and the shaft radius is 5-10mm. The impeller inlet refers to the area where the airflow enters the impeller, which is usually the central part of the impeller and has a smaller radius, that is, the impeller inlet is located at the end of the impeller away from the inductive balance disk; the impeller outlet refers to the area where the airflow flows out of the impeller, which is located at the outer edge of the impeller and has a larger radius; the blade tip clearance refers to the gap between the top of the impeller blade and the compressor casing, wherein the blade top refers to the end of the blade away from the hub along its span, that is, the blade top is the part of the blade at the rim position.

[0055] The centrifugal compressor of the present invention further includes a diffuser connected to the impeller outlet. The airflow at the impeller outlet flows directly into the diffuser. The diffuser inlet shape and size match the impeller outlet. Optionally, the diffuser outlet radius is set to 50-70 mm.

[0056] The centrifugal compressor provided by the present invention is provided with an adjustable nozzle array on the impeller hub. By autonomously adjusting the jet flow rate and finely adjusting the jet angle in a large range in two directions, fine control of the flow field inside the centrifugal compressor is achieved, thereby achieving the purpose of suppressing stall.

[0057] Specifically, when the impeller rotates, the gas flows in a complex manner inside the impeller (the area between the blades). Through the autonomous adjustment of the jet flow rate and angle of the adjustable nozzle array, a series of controllable jet flows are formed inside the impeller. These jet flows mix and interfere with the mainstream gas in the impeller, and can change parameters such as the flow direction, velocity, and pressure distribution of the flow field in the impeller. In the area where stall occurs, the jet flow can suppress or eliminate the phenomenon of airflow separation. Stall refers to the separation of airflow on the surface of the impeller blades, forming vortices or backflows, resulting in reduced compressor efficiency, flow fluctuations, and even surge. The stall area is located in the area between the blades, mainly concentrated on the back of the blades, where the back of the blades refers to the curved side of the blades.

[0058] like Figure 2 As shown, the impeller 1 includes a plurality of blades 11, and the number of adjustable nozzles 3 is the same as that of the blades 11. The positions of 40%-60% of the chord length of all blades form an air jet surface, and the adjustable nozzles 3 between adjacent blades are located on the air jet surface; wherein, the chord length refers to the length of the blade along its span from the root to the tip of the blade, and the air jet surface is located in the middle of the blade.

[0059] A hole is provided on the impeller hub surface of each blade 11 at a position corresponding to 40%-60% of the blade chord length. The air delivery pipe 4 is connected to the hole and is connected to the adjustable nozzle 3 .

[0060] The number of adjustable nozzles is consistent with the number of blades, and they are respectively set at the position of 40%-60% of the blade chord length on the impeller hub, that is, the adjustable nozzle array is evenly arranged. The evenly arranged adjustable nozzle array is connected to the gas pipeline that runs through the center of the shaft and the impeller, which can ensure that the high-pressure gas from the gas pipeline is evenly sprayed into the impeller, thereby improving the flow field inside the impeller. When the centrifugal compressor is running, the complex three-dimensional vortex and low-speed fluid in the middle and rear sections of the impeller (the middle and rear sections of the impeller along the gas flow direction) are close to the disk side, and the location where the countercurrent fluid occurs is mainly on the disk side (the side of the impeller close to the impeller outlet). When the blades are running, the adjustable nozzle rotates with the impeller, remains relatively still with the blades, and sprays towards the disk side and the blade suction surface in the middle of the impeller outlet flow channel, which can eliminate the low-energy fluid in this low flow velocity area. At the same time, if Figure 1 and Figure 3 As shown, the gas pipeline 4 includes an outlet section 41, a first pipeline section 42 and a second pipeline section 43 connected in sequence. The outlet section 41 and the first pipeline section 42 are both arranged in the impeller 1, the outlet section 41 is connected to the adjustable nozzle 3, and the second pipeline section 43 is arranged in the rotating shaft 2.

[0061] like Figure 3 and Figure 4 As shown, the adjustable nozzle 3 includes a spherical joint 31, a telescopic rod 32 and an adjustment assembly. The spherical joint 31 is rotatably fixed to the gas outlet section 41 of the gas pipeline 4. The spherical joint 31 is provided with a through gas outlet nozzle 311.

[0062] The front end of the telescopic rod 32 is connected to the spherical joint 31 , and the rear end of the telescopic rod 32 is connected to the adjustment assembly. The adjustment assembly drives the spherical joint 31 to rotate along the circumference of the impeller and the span direction of the blades through the telescopic rod 32 .

[0063] The adjustable nozzle realizes jet angle adjustment under high-pressure gas circulation through a spherical joint, a telescopic rod and an adjustment component.

[0064] The gas transmission pipeline of the present invention is arranged inside the rotating shaft and the impeller, and can directly input high-pressure gas into the impeller to adjust the flow field inside the impeller (the gas enters through the impeller inlet and passes through the space area between the blades); wherein, the inner diameter of the gas outlet section 41 is larger than the inner diameters of the first pipe section 42 and the second pipe section 43. The gas outlet section with a larger inner diameter can ensure that the adjustment component has sufficient movement space, so that the adjustable nozzle angle can be adjusted over a wider range.

[0065] In one embodiment, the spherical joint 31 may be a sphere, and the air outlet nozzle 311 may be a cylindrical structure and pass through the center of the sphere. The inner diameter of the air outlet nozzle 311 may be no larger than the inner diameter of the first pipe section 42 .

[0066] A ball socket 312 is located on one side of the ball joint 31 (the portion of the ball joint located within the outlet section 41). A first spherical interface 321 is located at the front end of the telescopic rod 32. The first spherical interface 321 cooperates with the ball socket 312 to connect the telescopic rod 32 to the ball joint 31. Specifically, the ball socket 312 is positioned away from the outlet nozzle 311. The adjustment assembly includes a lever bracket 331 and an actuator 332. The actuator 332 is fixed to the impeller back (i.e., the hub surface). The upper end of the lever bracket 331 is connected to the actuator 332, while the lower end of the lever bracket 331 is connected to the telescopic rod 32.

[0067] During specific implementation, the diameter of the ball socket opening is slightly smaller than the diameter of the spherical interface. The spherical interface is aligned with the ball socket opening and a certain external force is applied to make the spherical interface enter the ball socket to achieve engagement. The engagement connection method of the ball socket and the first spherical interface can ensure a strong fixing effect of the joint, and its structure is simpler than the multi-directional articulation method. The engagement method of the present invention can achieve angle adjustment of the adjustable nozzle by controlling the movement of a single lever by a single actuator, and can achieve angle fixation in a certain direction after a single actuator locks the position of a single lever, thereby ensuring a continuous jet effect at a certain angle. If a multi-directional articulation method is adopted, multiple actuators or other structures will be required to ensure that the nozzle direction is fixed at a certain angle, and the structure will be more complicated.

[0068] In one embodiment, the lever bracket 331 includes a first lever bracket 3311 and a second lever bracket 3312 . The connection point between the first lever bracket 3311 and the telescopic rod 32 is located between the front end and the rear end of the telescopic rod 32 . The second lever bracket 3312 is connected to the rear end of the telescopic rod 32 .

[0069] A groove base 3313 is provided at the lower end of the second lever bracket 3312, and a second spherical interface 322 is provided at the rear end of the telescopic rod 32. The second spherical interface 322 cooperates with the groove base 3313 to achieve the connection between the second lever bracket 3312 and the telescopic rod 32;

[0070] The actuator 332 is used to control the first lever bracket 3311 to rotate, extend or shorten the telescopic rod 32, and realize the rotation of the ball joint 31 along the circumference of the impeller;

[0071] Actuator 332 is also used to control the reciprocating motion of second lever bracket 3312 along its own axis, driving spherical joint 31 via telescopic rod 32 to achieve rotation of spherical joint 31 along the span of the blade. Specifically, the actuator controls the movement of the second lever bracket along its own axis, pulling the second spherical joint to achieve positional transition in the same direction. This, in turn, drives the first spherical joint via the telescopic rod to achieve positional transition in the opposite direction. Ultimately, the first spherical joint drives the spherical joint to rotate along the span of the blade, achieving angle adjustment.

[0072] Among them, the telescopic rod 32 can be arranged in a manner of two telescopic rods, that is, the telescopic rod includes a first telescopic rod and a second telescopic rod, one end of the first telescopic rod is arranged in the second telescopic rod, and when the first lever bracket 3311 rotates and the second lever bracket 3312 reciprocates, the first telescopic rod and the second telescopic rod slide relative to each other, thereby achieving the effect of extension or shortening. Furthermore, the telescopic rod 32 may also include a support ring, which is sleeved on the first telescopic rod and / or the second telescopic rod (the support ring is sleeved on the first telescopic rod and the second telescopic rod, which means that the support ring is located at a position where the first telescopic rod and the second telescopic rod overlap), and the support ring is rotationally fixed to the first lever bracket 3311 and the rotation plane of the support ring is parallel to the second lever bracket 3312, that is, when the second lever bracket 3312 reciprocates, it can drive the support ring and the first telescopic rod and the second telescopic rod thereon to rotate within the rotation plane; and the setting of the support ring can prevent the first lever bracket 3311 from being subjected to additional stress when the first telescopic rod and the second telescopic rod are relatively telescopic, resulting in its position displacement, affecting the overall adjustment effect of the adjustment component on the spherical joint.

[0073] The actuator, first lever bracket, and second lever bracket within the adjustment assembly provide two distinct adjustment modes, enabling precise and autonomous adjustment of the adjustable nozzle's jet angle over a wide range. Specifically, the centrifugal compressor's adjustment assembly controls the adjustable nozzle's free rotation within a range of 40° to 140° along the impeller's circumference and 40° to 140° along the blade's span.

[0074] The operating principle of the stall-suppressed centrifugal compressor main shaft is:

[0075] When the air flow velocity and pressure distribution in the impeller are uneven and the air flow vortex increases, the stall suppression mechanism of the centrifugal compressor is triggered.

[0076] When a stall condition or a pre-stall condition occurs, the adjustable nozzle array activates the jet flow, forming a series of jet flows within the impeller.

[0077] After the jet starts, firstly, the actuator can drive the first lever bracket, thereby lengthening or shortening the telescopic rod, so that the spherical joint in the adjustable nozzle rotates along the circumference of the impeller, and adjusts the jet angle and position of the adjustable nozzle along the circumference of the impeller; secondly, the actuator can also control the second lever bracket to move along its own axis, drive the spherical joint through the telescopic rod, and rotate the spherical joint along the span direction of the blade to ensure that the jet airflow is ejected from the appropriate angle and position.

[0078] When the adjustable nozzle is adjusted to the appropriate angle and position, the actuator remains fixed, so that the adjustable nozzle is aimed at the disk side and the blade suction surface (the back of the blade) in the middle of the impeller outlet flow channel and continuously sprays the air, mixing with the low-speed fluid on the disk side and starting to improve the flow field inside the impeller.

[0079] As the flow field inside the impeller changes, the actuator controls the lever bracket to drive the adjustable nozzle, gradually changing the jet position and angle, and adjusting the jet flow until the stall condition is completely eliminated and the airflow inside the impeller returns to normal flow state.

[0080] like Figure 5 As shown, the present invention also provides a centrifugal compressor jet system for stall suppression, specifically comprising: a centrifugal compressor 100 for stall suppression as described above, a first pressure-stabilizing tube 200, a second pressure-stabilizing tube 400, and an air storage tank 300, wherein the centrifugal compressor 100 is sequentially connected to the first pressure-stabilizing tube 200 and the air storage tank 300 to form an air storage circuit, for inputting the intermediate-stage pressure airflow through the first pressure-stabilizing tube 200 and storing it in the air storage tank 300 when the centrifugal compressor 100 is operating at a safe flow rate, thereby forming high-pressure gas;

[0081] The gas storage tank 300 is connected in sequence with the second pressure-stabilizing tube 400 and the gas pipeline 4 and the adjustable nozzle array of the centrifugal compressor 100 to form a bleed circuit, which is used to eject the high-pressure gas in the gas storage tank 300 through the second pressure-stabilizing tube 400, the gas pipeline 4 and the adjustable nozzle array when the centrifugal compressor 100 is running at a flow rate less than the flow threshold.

[0082] When the centrifugal compressor is operating at a safe flow rate and storing gas, a first pressure-stabilizing tube is installed between the centrifugal compressor and the gas storage tank. The first pressure-stabilizing tube regulates and stabilizes the airflow pressure to avoid damage to equipment in the gas storage circuit or abnormal operation due to excessively high or low pressure.

[0083] For supercritical CO2 centrifugal compressors, the high density of supercritical CO2 in high-temperature, high-pressure environments places higher demands on the sealing and corrosion resistance of external air supply devices. Therefore, air storage tanks are more suitable for use in twin-screw compressors, such as those used for traditional tip micro-injection. The intermediate-stage pressure flow at the centrifugal compressor volute outlet is stored in the air storage tank through a first pressure-stabilizing tube. This serves as the injection air source for stall suppression when the centrifugal compressor is operating below the flow threshold, reducing the air supply to external air supply devices and saving energy.

[0084] After the fluid enters the centrifugal compressor normally, the impeller performs work on the fluid, increasing its speed and pressure. After exiting the impeller, it flows into the diffuser, where it decelerates and increases its pressure, generating high-pressure gas. If the centrifugal compressor is operating at a safe flow rate, the intermediate-stage compressed air from the centrifugal compressor is fed through the first pressure-stabilizing tube and stored in the air tank, serving as the source of jet air for stall suppression below the flow rate threshold. If the centrifugal compressor is operating at a low flow rate, the high-pressure gas stored in the air tank is released, stabilized by the second pressure-stabilizing tube, and then ejected through an adjustable nozzle. This ejected high-pressure gas improves the flow field within the impeller, delaying and suppressing stall in the diffuser and the entire compressor.

[0085] In different models of centrifugal compressors or in different application scenarios, the values of the safety flow and flow threshold are different and can be set according to the stability margin. Here, no further restrictions are imposed on the values of the safety flow and flow threshold.

[0086] In one embodiment, the centrifugal compressor jet system further includes a control module (not shown), and a first control valve 500, a second control valve 600, and sensors (not shown) connected to the control module by signal. The first control valve is disposed between the centrifugal compressor and the first voltage regulator tube, and the second control valve is disposed between the centrifugal compressor and the second voltage regulator tube. The sensors include a temperature sensor, a pressure sensor, and a vibration sensor.

[0087] A gas transmission control valve 700 is provided on the gas transmission pipeline, and the gas transmission control valve is connected to the control module signal;

[0088] The control module is used to control the opening of the first control valve, the second control valve and the gas transmission control valve based on the analysis of the temperature, pressure and vibration signals of the sensors.

[0089] When the centrifugal compressor operates at a safe flow rate, the high-pressure gas stored in the pressure regulator reaches a stable state, and gas storage ends. At this point, the control module can close the first control valve, the second control valve, and the gas supply control valve to prevent high-pressure gas from continuously flowing through the first pressure regulator tube into the gas storage tank and back into the centrifugal compressor impeller disc.

[0090] The stable state varies for centrifugal compressors of different models or in different application scenarios and can be set according to the stability margin. Here, no further limitation is imposed on the specific parameter values of the stable state.

[0091] The jet system used for stall suppression uses sensors to monitor the airflow status (temperature, pressure, vibration, flow, etc.) in the impeller in real time, adjusts the opening of the first control valve, the second control valve and the air supply control valve through the control module, and coordinates the adjustment components of the adjustable nozzle to adjust the jet flow and jet angle, improve the fluid flow rate and flow field on the disc side of the centrifugal compressor, and delay and suppress the stall of the diffuser and the entire centrifugal compressor.

[0092] The automatic flow regulation of the centrifugal compressor jet system adjusts the real-time jet flow according to the control algorithm in the closed-loop system.

[0093] The control algorithm is specifically expressed as:

[0094] in, is the real-time jet flow, is the error signal, that is, the real-time deviation between the preset stable pressure value and the pressure value monitored by the sensor. is the proportional gain, is the integral gain, is the differential gain;

[0095] If the compressor stalls and the pressure fluctuation inside the impeller exceeds the set threshold, Increase, triggering the adjustable nozzle array to spray.

[0096] Specifically, when gas pressure is regulated and controlled through a control algorithm, the pressure regulation process is achieved through the PID (proportional-integral-differential) control law. The proportional gain mainly affects the response speed of the gas control, the integral gain is used to eliminate steady-state errors, and the differential gain is used to suppress overshoot and oscillation.

[0097] In actual application scenarios, the control algorithm includes proportional term, integral term and differential term, among which the proportional term (P) is calculated based on the current error signal. The output is adjusted rapidly; larger errors result in more dramatic changes in the control variable. Specifically, when the monitored pressure is less than the preset stable pressure value, the proportional term outputs a positive control variable (e.g., increasing gas flow). The integral term (I) is used to accumulate historical errors and eliminate steady-state errors (e.g., long-term pressure deviations). Specifically, if there is a persistent pressure deviation (e.g., insufficient actual input gas flow), the integral term can gradually increase the control variable. The differential term (D) can predict error trends and suppress overshoot and oscillation. Specifically, when the rate of pressure change is high (e.g., due to rapid pressure fluctuations caused by the inertia of the impeller), the differential term preemptively adjusts in the opposite direction.

[0098] The total control quantity of the control law is obtained by superimposing the three items P, I, and D and outputting the adjustment instruction (such as the increment of gas flow, that is, the increment of valve opening). When outputting the adjustment instruction, the real-time jet flow needs to be Limiting is performed to prevent the actuator (the device that regulates the gas flow) from exceeding the limit (e.g., the maximum valve opening is 100%). When the real-time jet flow control quantity reaches the limit, the integral term accumulation is suspended to avoid over-regulation.

[0099] like Figure 6As shown, the present invention also provides a centrifugal compressor jet control method for stall suppression, which uses the centrifugal compressor jet system for stall suppression as described above, and specifically includes the following steps:

[0100] Obtain the safe flow range of the centrifugal compressor;

[0101] Open the gas storage circuit or the gas release circuit according to the real-time flow of the centrifugal compressor;

[0102] If the centrifugal compressor's real-time flow rate is within the safe flow range, the centrifugal compressor directs the intermediate-stage compressed air flow through the first pressure-stabilizing tube and stores it in the air storage tank until it stabilizes, forming high-pressure gas. If the centrifugal compressor's real-time flow rate is less than the flow threshold, the air storage tank sequentially directs the high-pressure gas into the second pressure-stabilizing tube, the gas pipeline, and discharges it through the adjustable nozzle array. The flow threshold is less than the minimum value of the safe flow range. The flow threshold can be determined based on actual scenarios and is not limited here.

[0103] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and their equivalents.

Claims

1. A centrifugal compressor with stall suppression, characterized in that: Specifically include: An impeller, a rotating shaft, an adjustable nozzle array and a plurality of gas pipelines, wherein the impeller is fixed on the rotating shaft; The adjustable nozzle array includes a plurality of adjustable nozzles, each of which is arranged on the impeller hub, and the adjustable nozzle is used to adjust the jet angle by rotating along the impeller circumference and blade span direction; The adjustable nozzle includes a spherical joint, a telescopic rod and an adjustment component. The spherical joint is rotatably fixed to the gas outlet section of the gas pipeline, and the spherical joint is provided with a through gas outlet nozzle. The front end of the telescopic rod is connected to the spherical joint, and the rear end of the telescopic rod is connected to the adjustment component. The adjustment component realizes the rotation of the spherical joint along the circumference of the impeller and the span direction of the blade through the telescopic rod; The gas delivery pipelines are correspondingly arranged with the adjustable nozzles. Each gas delivery pipeline passes through the rotating shaft and the impeller and is connected with the adjustable nozzle.

2. The stall-suppressed centrifugal compressor according to claim 1, wherein: The impeller includes a plurality of blades, the number of the adjustable nozzles is the same as the number of the blades, and the adjustable nozzles are arranged between adjacent blades; The 40%-60% chord length position of all blades forms an air jet surface, and the adjustable nozzles between adjacent blades are located on the air jet surface. The air supply pipeline is connected to the gap opened on the impeller hub surface and is connected to the adjustable nozzle.

3. The stall-suppressed centrifugal compressor according to claim 1, wherein: The gas transmission pipeline includes an outlet section, a first pipeline section and a second pipeline section connected in sequence, the outlet section and the first pipeline section are both arranged in the impeller, the outlet section is connected to the adjustable nozzle, and the second pipeline section is arranged in the rotating shaft; The inner diameter of the gas outlet section is larger than the inner diameters of the first pipe section and the second pipe section.

4. The stall-suppressed centrifugal compressor according to claim 1, wherein: The spherical joint is a sphere, the air outlet nozzle is a cylindrical structure and passes through the center of the spherical joint, and the inner diameter of the air outlet nozzle is not larger than the inner diameter of the first pipe section; A ball socket is provided on one side of the inner portion of the spherical joint, and a first spherical interface is provided at the front end of the telescopic rod. The first spherical interface cooperates with the ball socket to realize the connection between the telescopic rod and the spherical joint.

5. The stall-suppressed centrifugal compressor according to claim 1, wherein: The regulating assembly comprises a lever bracket and an actuator, the actuator is fixed to the wheel back of the impeller, the upper end of the lever bracket is connected to the actuator, and the lower end of the lever bracket is connected to the telescopic rod.

6. The stall-suppressed centrifugal compressor according to claim 5, wherein: The lever bracket includes a first lever bracket and a second lever bracket, wherein a connection point between the first lever bracket and the telescopic rod is located between the front end and the rear end of the telescopic rod, and the second lever bracket is connected to the rear end of the telescopic rod; The lower end of the second lever bracket is provided with a groove base, and the rear end of the telescopic rod is provided with a second spherical interface, and the second spherical interface cooperates with the groove base to realize the connection between the second lever bracket and the telescopic rod; The actuator is used to control the rotation of the first lever bracket, lengthen or shorten the telescopic rod, and realize the rotation of the spherical joint along the circumference of the impeller; the actuator is also used to control the second lever bracket to move along its own axis, drive the spherical joint through the telescopic rod, and realize the rotation of the spherical joint along the span direction of the blade.

7. A centrifugal compressor jet system for stall suppression, characterized in that: Specifically include: A centrifugal compressor with stall suppression, a first voltage regulator tube, a second voltage regulator tube, and an air storage tank according to any one of claims 1 to 6, wherein the centrifugal compressor is sequentially connected to the first voltage regulator tube and the air storage tank to form an air storage circuit, for inputting the intermediate pressure gas through the first voltage regulator tube and storing it in the air storage tank when the centrifugal compressor is operating at a safe flow rate to form high-pressure gas; The gas storage tank is connected to the second pressure-stabilizing tube, the gas pipeline of the centrifugal compressor, and the adjustable nozzle array in sequence to form a bleed circuit, which is used to eject the high-pressure gas in the gas storage tank through the second pressure-stabilizing tube, the gas pipeline and the adjustable nozzle array when the centrifugal compressor is running below the flow threshold.

8. The centrifugal compressor jet injection system for stall suppression according to claim 7, wherein: The centrifugal compressor jet system also includes a control module, and a first control valve, a second control valve and a sensor connected to the control module by signal. The first control valve is arranged between the centrifugal compressor and the first voltage regulator tube, and the second control valve is arranged between the centrifugal compressor and the second voltage regulator tube. The sensors include a temperature sensor, a pressure sensor and a vibration sensor. A gas transmission control valve is provided on the gas transmission pipeline, and the gas transmission control valve is connected to the control module signal; The control module is used to control the opening of the first control valve, the second control valve and the gas transmission control valve based on the analysis of the temperature, pressure and vibration signals of the sensors.

9. A centrifugal compressor jet control method for stall suppression, characterized in that: The centrifugal compressor jet system for stall suppression according to claim 7 or 8 specifically comprises the following steps: Obtain the safe flow range of the centrifugal compressor; Open the gas storage circuit or the gas release circuit according to the real-time flow of the centrifugal compressor; Among them, if the real-time flow of the centrifugal compressor is within the safe flow range, the centrifugal compressor will input the intermediate-stage pressure air flow through the first pressure-stabilizing tube and store it in the gas storage tank until it stabilizes to form high-pressure gas; if the real-time flow of the centrifugal compressor is less than the flow threshold, the gas storage tank will input the high-pressure gas into the second pressure-stabilizing tube and the gas pipeline in sequence and spray it out through the adjustable nozzle array.

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