A high temperature fan with a local micro-textured pre-controlled flow structure

Abstract

This invention provides a high-temperature fan with a localized micro-textured pre-flow control structure, comprising an impeller system and a volute. The volute side has first and second static gas seals, and the impeller system side has a dynamic gas seal. A first throttling cavity is formed between the first static gas seal and the dynamic gas seal, and a second throttling cavity is formed between the second static gas seal and the rotating shaft. An annular expansion cavity is provided between the two throttling cavities. A locally micro-dimpled textured area is provided on the annular end face of the impeller back plate facing the inlet of the first throttling cavity; this textured area is located at the leading edge of the inlet outside the dynamic gas seal. Leaking gas flows sequentially through the micro-dimpled textured area, the first throttling cavity, the annular expansion cavity, and the second throttling cavity, achieving pre-disturbance, pre-dissipation, and staged throttling, thereby reducing leakage flow, weakening back cavity pressure fluctuations, and suppressing hot gas backflow. This invention is applicable to back cavity leakage control of high-temperature centrifugal fans.

Description

Technical Field

[0001] This invention relates to the field of fans, and in particular to a high-temperature fan with a local microtextured pre-flow control structure. Background Technology

[0002] With the continuous growth in demand for high-temperature gas transportation and recycling in industries such as metallurgy, chemical engineering, building materials, ceramics, waste heat recovery, and energy and power, high-temperature centrifugal fans, as a key power equipment, are facing increasingly demanding operating conditions. In many practical applications, fans need to operate continuously for extended periods at temperatures of several hundred degrees Celsius or even higher, while simultaneously withstanding significant pressure differentials and high rotational speeds. Under these complex conditions, gaps inevitably form between the impeller system and the volute casing due to assembly requirements, differences in thermal expansion, and safety clearance requirements at high speeds. These gaps create natural leakage channels between the high-pressure zone of the volute casing and the impeller back cavity. High-pressure gas leaks into the back cavity through these channels, directly causing a loss of effective working fluid and reducing the overall efficiency of the fan. Furthermore, the leaked gas easily induces strong vortex flows, shear flows, and local stagnation zones within the back cavity, resulting in significant back cavity vortex losses and causing irregular fluctuations in back cavity pressure.

[0003] More challenging is the fact that the gas leaking into the back cavity is typically very hot. This high-temperature gas forms a hot gas backflow path along the shaft, bearing housing, and even the motor, significantly increasing the thermal load on the shaft system and directly affecting the bearing's lubrication and lifespan. Simultaneously, the unstable pressure distribution within the back cavity is transmitted to the rotor system via the shaft, causing fluctuations or increases in axial force, which in turn exacerbates bearing vibration and noise, and in severe cases, even threatens the overall operational safety and reliability of the machine. Therefore, effectively controlling back cavity leakage, reducing back cavity pressure fluctuations, and suppressing hot gas backflow into the shaft system have always been pressing technical challenges in the design of high-temperature centrifugal fans.

[0004] To address the aforementioned issues, existing technologies commonly employ various sealing structures. The simplest approach involves maintaining a small, single gap at the back cavity inlet, relying on the gap's own flow resistance to reduce leakage. However, this method is extremely limited in effectiveness under high temperatures and pressure differentials. Subsequent developments have led to single-stage or multi-stage labyrinth seals, which, through the alternating arrangement of multiple throttling teeth and expansion chambers, cause throttling and pressure reduction in leaking gas as it flows through each tooth tip gap. Upon entering the expansion chamber, the velocity energy is converted into heat energy and partially dissipated, thus progressively reducing pressure. Compared to single-stage gaps, multi-stage labyrinth seals significantly reduce leakage and have become the mainstream choice for back cavity seals in high-temperature fans.

[0005] However, conventional labyrinth seal structures still have significant shortcomings in practical applications. First, before entering the first throttling gap, high-pressure leaking gas often impacts the tooth tip area in a near-linear jet manner, causing the first-stage throttling teeth to bear excessively high local flow velocities and pressure differences. This not only easily leads to cavitation and wear but also concentrates the burden on the first-stage throttling, relatively weakening the throttling effect of subsequent stages. Second, due to the lack of an effective flow adjustment mechanism in the inlet section, the distribution of leaking gas in the circumferential direction is often uneven, easily forming high-speed jets in local areas. This uneven inflow interferes with the vortex structure in the subsequent expansion chamber, reducing the dissipation efficiency of the entire sealing channel. Third, when the fan operating conditions change (such as fluctuations in speed, flow rate, and pressure), conventional labyrinth seals have poor adaptability to the inlet flow state, resulting in large fluctuations in back cavity pressure and insufficient stability in suppressing hot gas backflow. Finally, simply increasing the number of labyrinth stages to improve the sealing effect will significantly increase the axial dimensions and processing costs, and the marginal benefits diminish with too many stages, which is not conducive to the compact design of the fan. Summary of the Invention

[0006] To address the problems of large back cavity leakage, strong inlet jet at the first throttling stage, significant back cavity pressure fluctuations, severe hot gas backflow, and the resulting decrease in efficiency and reliability in existing high-temperature centrifugal fans, this invention provides a high-temperature fan with a local micro-textured pre-flow control structure. Without adding an external power unit and while meeting the safety clearance requirements for high-temperature thermal expansion and high-speed operation, a local micro-dimpled textured area is set on the annular end face of the impeller back disk before the inlet of the first throttling gap. This area works in conjunction with the subsequent multi-stage gas-sealed throttling structure, causing the high-pressure leaking gas to undergo local pre-disturbance, pre-dissipation, and flow field homogenization before entering the first throttling gap. Then, after passing through the first throttling gap, the annular expansion cavity, and the second throttling gap, it forms a graded pressure drop and eddy energy dissipation, thereby achieving comprehensive control over the leakage flow rate, leakage flow state, and back cavity pressure distribution.

[0007] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0008] A high-temperature fan with a local micro-textured pre-controlled flow structure includes an impeller system and a volute. A back cavity and a gap leakage flow channel from the high-pressure area of ​​the volute to the back cavity are formed between the impeller system and the volute. A first static gas seal and a second static gas seal are provided on the volute side, and a dynamic gas seal is provided on the impeller system side. A first throttling cavity is formed between the first static gas seal and the dynamic gas seal, and a second throttling cavity is formed between the second static gas seal and the rotating shaft. An annular expansion cavity is formed between the first throttling cavity and the second throttling cavity, located between the volute and the impeller system. A local micro-dimpled textured area is provided on the annular end face of the impeller system facing the inlet of the first throttling cavity. The local micro-dimpled textured area is located in the inlet leading edge region outside the dynamic gas seal, so that the leaked gas passes sequentially through the local micro-dimpled textured area, the first throttling cavity, the annular expansion cavity, and the second throttling cavity along the flow path.

[0009] Furthermore, the first static gas seal is a plurality of first teeth evenly distributed radially on the volute side, the second static gas seal is a plurality of second teeth evenly distributed axially on the volute side, and the dynamic gas seal is a third tooth evenly distributed radially on the impeller system side; the second teeth and the third teeth are staggered.

[0010] Furthermore, the axial distance between the tooth tips of the first tooth and the third tooth is the first throttling gap, denoted as g. t1 The radial distance between the tip of the second tooth and the surface of the rotating shaft is the second throttling clearance, denoted as g. t2 It must meet the following requirement: 0.7g t1 ≤g t2 ≤1.5g t1 .

[0011] Furthermore, the tooth height of the first tooth is l t1 Satisfying: 3g t1 ≤l t1 ≤5g t1 .

[0012] Furthermore, the tooth height of the second tooth is l t2 Satisfying: 0.6l t1 ≤l t2 ≤1.2l t1 , l t1 The height of the first tooth.

[0013] Furthermore, the localized micro-dimpled textured region is an annular textured band with an outer diameter of Φ2, satisfying: 0.0005Φ2≤g t1 ≤0.0020Φ2; The width H of the annular textured band satisfies: 0.8l t1 ≤H≤1.2l t1 , l t1 The height of the first tooth.

[0014] Furthermore, the localized micro-pit texture region comprises several micro-pits concentrically staggered along the circumferential direction; the circumferential pitch of the same row of micro-pits is L. R The circumferential misalignment between two adjacent rows of micro-pits is 0.3L. R ~0.7L R .

[0015] Furthermore, the radius of the micro-pit is R, and satisfies: 0.1H≤R≤0.3H.

[0016] Furthermore, the solid interval width between adjacent micro-pits in the same row is denoted as d. The cross-section of the micro-pit is a semi-circular pit with a semi-circular radius of R. The solid interval width d and the semi-circular radius R satisfy: 0.5R≤d≤1.5R.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. The high-temperature fan with a local micro-textured pre-flow control structure described in this invention, by setting a local micro-dimpled textured area on the annular end face of the impeller back plate facing the inlet of the first throttling cavity, allows the leaking gas in the high-pressure area of ​​the volute to flow through this textured area before entering the first throttling gap, thus achieving the effects of pre-disturbance, pre-dissipation, and flow field homogenization of the leaking gas. Compared with the structure of conventional labyrinth seals where high-pressure gas directly impacts the first throttling tooth, this invention effectively weakens the peak velocity of the inlet jet, improves the uniformity of the inflow distribution in the circumferential direction, thereby reducing the aerodynamic load of the first throttling stage, reducing the effective gas loss caused by inlet impact, and improving the overall efficiency of the high-temperature centrifugal fan.

[0019] 2. The high-temperature fan with a local micro-textured pre-control flow structure described in this invention forms a composite leakage control path of inlet pre-control flow—first-stage throttling—expansion dissipation—secondary throttling by sequentially connecting the local micro-dimpled textured area with a first throttling cavity composed of a first static gas seal and a dynamic gas seal, an annular expansion cavity, and a second throttling cavity composed of a second static gas seal and a rotating shaft. This achieves the purpose of staged pressure drop and energy dissipation of leaked gas. Compared with structures that simply rely on labyrinth tooth throttling, this invention adds a micro-scale energy dissipation link at the front end, making the pressure drop distribution of each throttling cavity more balanced, further reducing the overall leakage flow, and effectively suppressing the back cavity pressure fluctuation amplitude.

[0020] 3. The high-temperature fan with a localized micro-textured pre-flow control structure described in this invention, by confining the localized micro-dimpled textured area to the annular ring region before the inlet of the first throttling cavity, without extending into the throttling gap, expansion cavity, or subsequent sealing channel, achieves pre-control of inlet leakage flow while retaining the original labyrinth seal's main structure and reliability. This structure requires minimal modification, has a clear processing path, does not increase additional axial space requirements, and does not introduce complex auxiliary systems, thus possessing good engineering practicality and economy.

[0021] 4. The high-temperature fan with a local micro-textured pre-flow control structure described in this invention effectively weakens the tendency of high-temperature leaked gas to flow back along the shaft direction through the pre-flow control effect of the local micro-dimpled textured area on the leaked gas and the subsequent multi-stage throttling expansion structure for the gradual dissipation of residual pressure. This not only reduces the thermal load on the shaft system area and mitigates the risk of bearing failure due to high temperature, but also reduces axial force fluctuations and vibration noise caused by back cavity pressure fluctuations, thereby significantly improving the reliability, stability, and service life of the high-temperature centrifugal fan under long-term continuous operation conditions.

[0022] 5. The high-temperature fan with a local micro-textured pre-flow control structure described in this invention achieves maximum pre-disturbance and pre-dissipation effects within a limited inlet ring area by employing a double-row staggered array of micro-pits with a semi-circular cross-section in the local micro-pit textured region, and optimizing parameters such as radial width, pit radius, arrangement pitch, and solid spacing. This ensures the structural integrity and flow continuity of the ring surface while maintaining the micro-textured design. This micro-textured design achieves a good balance between processing complexity and flow control effect, making it suitable for widespread application in industrial production. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the high-temperature fan with a local microtextured pre-controlled flow structure as described in this invention.

[0025] Figure 2 This is a schematic diagram of the impeller and back cavity sealed gap flow control structure described in this invention.

[0026] Figure 3 This is a schematic diagram of the distribution of the local micro-pit texture area described in this invention.

[0027] Figure 4This is an enlarged schematic diagram of the back cavity sealed gap flow control structure described in this invention.

[0028] Figure 5 This is a schematic diagram of the staggered arrangement of local micro-pits described in this invention.

[0029] Figure 6 This is a schematic diagram of the cross-sectional structure of the micro-pit described in this invention.

[0030] In the picture:

[0031] 1-Impeller system; 2-Flange; 3-Outlet pipe; 4-Vortex; 5-Motor body; 6-Terminal plate; 102-Shaft; 103-Second static gas seal; 105-First static gas seal; 106-Dynamic gas seal; 108-Local micro-dimpled textured area. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] The high-temperature fan with a local micro-textured pre-flow control structure described in this embodiment. For example... Figure 1 As shown, the fan includes an impeller system 1, a flange 2, an outlet pipe 3, a volute 4, a motor body 5, and a terminal block 6. The impeller system 1 is installed inside the volute 4 and is driven by the motor body 5 to rotate around the fan axis. The flange 2 and the outlet pipe 3 are used to connect to external gas pipelines, while the terminal block 6 provides electrical connection to the motor body 5.

[0036] In the actual operation of high-temperature centrifugal fans, due to assembly requirements, differences in thermal expansion, and safety clearance requirements under high-speed rotation, a back cavity and a leakage flow channel from the high-pressure area of ​​the volute 4 to this back cavity will inevitably form between the impeller system 1 and the volute 4. If this leakage channel is not effectively controlled, high-pressure gas will leak into the back cavity along this channel, which will not only cause the loss of effective working fluid and reduce the overall efficiency of the machine, but also induce complex vortex flow and pressure fluctuations in the back cavity, which will cause hot gas to flow back along the shaft direction, affecting the bearing life and operational stability.

[0037] To address the aforementioned issues, this embodiment incorporates a composite leakage control structure in the back cavity region. For example... Figure 2 and Figure 4 As shown, a first static gas seal 105 and a second static gas seal 103 are fixedly installed on one side of the volute 4. A dynamic gas seal 106, which rotates synchronously with the impeller, is installed on one side of the impeller system 1. Through the cooperation of the above components, a multi-stage throttling and expansion path is formed. Specifically, a first throttling cavity is formed between the first static gas seal 105 and the dynamic gas seal 106. A second throttling cavity is formed between the second static gas seal 103 and the rotating shaft 102. It should be noted that in this embodiment, the second static gas seal 103 does not directly cooperate with the dynamic gas seal 106 to form the second throttling cavity, but maintains a small radial gap with the cylindrical surface of the rotating shaft 102 to form the second throttling cavity. This design makes the flow path of the leaked gas in the radial direction more compact, while avoiding the processing difficulty caused by too many fits of the dynamic gas seal 106. In addition, between the first throttling cavity and the second throttling cavity, the volute 4 and the impeller system 1 together form an approximately annular expansion cavity. The expansion chamber is located between the first static gas seal 105 and the second static gas seal 103, providing space for the leaking gas to expand, decelerate, and dissipate energy. The working mechanism of the multi-stage throttling sealing channel is to use the first throttling chamber to form an initial pressure drop, which then causes the gas to expand, flow back, and experience eddy current loss in the annular expansion chamber, and then be throttled again through the second throttling chamber, thereby reducing the driving force and leakage flow rate of leakage from the high-pressure area of ​​the volute to the back cavity.

[0038] like Figure 3 and Figure 4As shown, a localized micro-dimpled textured area 108 is provided on the annular end face of the volute 4 side facing the inlet of the first throttling cavity. This textured area does not cover the entire back plate end face, but is an annular textured band defined by the inner diameter Φ1 and the outer diameter Φ2, located outside the dynamic gas seal 106, that is, in the inlet leading edge region before the leaked gas flows into the first throttling cavity.

[0039] like Figure 2 As shown, the impeller system 1 includes an impeller and a rotating shaft 102. Figure 2 In this diagram, B1 represents the axial distance between the front and rear impeller disks, and B2 represents the structural height of the impeller system along the axial direction of the fan. To balance the aerodynamic dimensions of the impeller's main flow channel with the arrangement space for the back cavity sealing structure, in this embodiment, B1 and B2 satisfy the following condition: 0.8B1≤B2≤1.5B1. This relationship ensures a relatively reasonable structural proportion between the impeller outlet main flow channel, the back disk end face, and the air seal arrangement area, allowing the back cavity inlet, the dynamic air seal 106, and the local micro-dimpled textured area 108 to be arranged on the outer end face area of ​​the impeller back disk without significantly altering the original overall impeller structure.

[0040] The first static gas seal 105 consists of several first teeth radially evenly distributed on both sides of the volute 4; the second static gas seal 103 consists of several second teeth axially evenly distributed on both sides of the volute 4; and the dynamic gas seal 106 consists of third teeth radially evenly distributed on both sides of the impeller system 1. The second and third teeth are staggered. The axial distance between the tooth tips of the first and third teeth is the first throttling clearance, denoted as g. t1 The first throttling gap should not be too large, otherwise the initial throttling effect will be insufficient; nor should it be too small, otherwise rubbing may easily occur under high temperature thermal expansion and high speed rotation conditions. In a preferred embodiment, the first throttling gap g t1 The outer diameter Φ2 of the local micro-pit texture region 108 satisfies: 0.0005Φ2≤g t1 ≤0.0020Φ2.

[0041] The radial distance between the tip of the second tooth and the surface of the rotating shaft 102 is the second throttling clearance, denoted as g. t2 To achieve a good match between the two stages of throttling, g t2 With g t1 The optimal value is 0.7g. t1 ≤g t2 ≤1.5g t1 If g t2 Relative to g t1 If the value is too small, the second throttling stage will be overburdened, easily generating localized high-speed airflow; if g t2 If the flow rate is too high, the second throttling effect will be weakened, and the overall sealing effect will decrease.

[0042] The tooth height of the first tooth is l t1 To ensure the first throttling tooth can achieve an effective throttling effect, and to avoid insufficient strength due to an excessively thin tooth tip, the tooth height of the first tooth must meet the following requirement: 3g. t1 ≤l t1 ≤5g t1 .

[0043] The tooth height of the second tooth is l t2 The tooth height of the second tooth has a certain proportional relationship with that of the first tooth to ensure that the two static gas seals can be coordinated on the volute side. The tooth height of the second tooth satisfies: 0.6l t1 ≤l t2 ≤1.2l t1 .

[0044] like Figure 3 As shown, the localized micro-dimpled textured area 108 is an annular textured band defined by an inner diameter Φ1 and an outer diameter Φ2. Its radial width H = (Φ2 - Φ1) / 2. This width is related to the tooth height l of the first static gas seal. t1 The preferred value is 0.8l. t1 ≤H≤1.2l t1 , l t1 The tooth height is the first tooth. The radial width of the annular textured band is controlled to be on the order of the tooth height to match the effective range of the micro-dimples with the main incoming flow area before the inlet of the first throttling cavity. If the textured band is too narrow, the contact path between the leaking gas and the micro-dimples is too short, resulting in insufficient pre-disturbance and pre-dissipation effects; if the textured band is too wide, it will extend excessively upstream, not only increasing the processing area but also potentially causing unnecessary interference to the upstream incoming flow.

[0045] like Figure 5 and Figure 6 As shown, the arrangement and cross-sectional shape of the micro-dimples are core factors in achieving the pre-control flow function. In this embodiment, the micro-dimples in the local micro-dimple texture region 108 are arranged in a double-row concentric staggered array. That is, on the annular texture zone, one row of micro-dimples is distributed along the inner annular trajectory, and another row of micro-dimples is distributed along the outer annular trajectory. The circumferential pitch of adjacent dimples in the same row is denoted as L. R The adjacent rows of micro-dimples are not aligned in the circumferential direction, but are staggered, with the preferred misalignment being 0.3L. R Up to 0.7L R Between. This staggered arrangement can effectively interrupt the straight channel that the leaked gas may form along the circumference, forcing the airflow to undergo local deflection and mixing continuously before entering the first throttling cavity, thereby enhancing the pre-disturbance and energy dissipation effects.

[0046] like Figure 6As shown, the cross-section of each micro-dimple is semi-circular. Let the radius of the semi-circle be R, and the solid spacing between adjacent micro-dimples in the same row be d. Then the circumferential pitch L R The relationship between L and R, d is: R =2R+d. To ensure sufficient pit coverage to produce a pre-controlled flow effect, while retaining sufficient solid area to ensure the structural integrity and flow continuity of the ring surface, the solid interval width d and the semicircle radius R preferably satisfy: 0.5R≤d≤1.5R.

[0047] Because a standard semi-circular cross-section is used, the maximum depth h of the micro-pit is naturally equal to the radius R, i.e., h = R. This semi-circular cross-section has three advantages: First, it is relatively easy to manufacture, and can be stably shaped using laser processing, precision machining, or micro-electrolytic machining; second, the semi-circular transition is smooth, without forming sharp corners or edges, which helps to reduce local stress concentration under high-temperature conditions, and also reduces the possibility of solid particles or carbon deposits being trapped; third, when gas sweeps across the surface of the annular zone over the micro-pit, the semi-circular pit is more likely to induce the formation of local backflow and micro-scale vortices, causing a certain degree of energy dissipation in the gas before it enters the first throttling cavity.

[0048] There is also a reasonable proportional relationship between the radius R of the micro-pit and the width H of the annular textured band. If R is too small, the disturbance and dissipation effect of a single micro-pit on the leaked gas is weak; if R is too large, it will compress the solid area between adjacent micro-pits, which is not conducive to the structural integrity of the annular band surface. Therefore, R preferably satisfies: 0.1H ≤ R ≤ 0.3H.

[0049] Furthermore, the number of micro-dimples on the inner and outer rings also needs to be reasonably set. Let the number of micro-dimples on the inner ring be N1, and the number of micro-dimples on the outer ring be N2. N1 and N2 can be equal or unequal, depending on the values ​​of Φ1, Φ2, and R. Generally speaking, N1 and N2 should ensure that they form a continuous and not too dense arrangement on their respective circular trajectories. In practical design, the following requirements can be met respectively:

[0050] π(φ1+2R) / (3.5R)≤N1≤π(φ2-2R) / (2.5R),

[0051] π(φ1+2R) / (3.5R)≤N2≤π(φ2-2R) / (2.5R).

[0052] From the perspective of the overall flow path, in this embodiment, the first static gas seal 105 is located radially outward near the impeller outlet side, and the second static gas seal 103 is located radially inward near the back cavity side. Therefore, the leakage path of the leaking gas from the high-pressure zone of the volute 4 to the back cavity is generally radially flowing from the outside to the inside. Specifically, the high-pressure leaking gas first flows through the local micro-dimple textured area 108 located at the outer inlet leading edge region of the dynamic gas seal 106. On this annular textured zone, the gas repeatedly contacts the double-row staggered semi-circular micro-dimples, the local flow stream is dispersed, the peak velocity of the inlet jet is weakened, and the distribution of the incoming flow in the circumferential direction tends to be uniform. Subsequently, the pretreated gas enters the first throttling cavity, forming a first-stage throttling and pressure reduction at the radial gap between the tooth tip of the first static gas seal 105 and the dynamic gas seal 106. Then, the gas enters the annular expansion cavity, where it expands, decelerates, forms vortices, and dissipates some of its kinetic energy. Finally, the gas passes through the axial gap between the tooth tip of the second static gas seal 103 and the surface of the rotating shaft 102, and enters the depth of the back cavity after completing the secondary throttling.

[0053] It is important to note that the localized micro-dimple textured region 108 in this embodiment is strictly limited to the annular ring region before the inlet of the first throttling cavity, and does not extend into the interior of the first throttling gap, the second throttling gap, or the annular expansion cavity. This is done so that the micro-dimple texture is only pre-treated before the leaking gas enters the main channel of the labyrinth seal; the subsequent main throttling, pressure reduction, and sealing tasks are primarily accomplished through the first throttling cavity, the annular expansion cavity, and the second throttling cavity. If the micro-dimples were further arranged inside the inter-tooth throttling cavity or the expansion cavity, it might alter the original tooth tip throttling boundary and the dominant flow pattern of the inter-tooth cavity, thereby weakening the originally clear and stable throttling mechanism of the subsequent multi-stage sealing structure. In other words, this invention does not simply replace the original labyrinth seal structure with a large-area surface texture.

[0054] The first static gas seal 105 consists of several first teeth radially evenly distributed on both sides of the volute 4; the second static gas seal 103 consists of several second teeth axially evenly distributed on both sides of the volute 4; and the dynamic gas seal 106 consists of third teeth radially evenly distributed on both sides of the impeller system 1. The first and third teeth can be considered as staggered throttling teeth, forming a reversible labyrinthine leakage channel. The reversible labyrinthine leakage channel and the front-end local micro-pit textured area 108 are not simply superimposed, but have a clear division of labor: the local micro-pit textured area 108 is responsible for weakening the inlet jet peak, increasing front-end micro-scale dissipation, and improving the uniformity of the incoming flow; the reversible labyrinthine leakage channel is responsible for establishing a stable graded pressure drop and expansion dissipation process on a macroscopic scale. After the two work together, the overall suppression capability of back cavity leakage, hot gas backflow, and back cavity pressure fluctuation can be improved without significantly increasing structural complexity.

[0055] In summary, this embodiment achieves composite control of the leakage flow in the back cavity of a high-temperature centrifugal fan by setting a local micro-dimpled textured area 108 on the annular end face of the impeller back disk facing the inlet of the first throttling cavity, and combining it with a multi-stage throttling expansion structure composed of a first static gas seal 105, a second static gas seal 103, a dynamic gas seal 106, and a rotating shaft 102. This control encompasses inlet pre-control flow, first-stage throttling, expansion dissipation, and secondary throttling. Compared with existing structures that rely solely on labyrinth tooth throttling, this embodiment not only effectively reduces leakage flow but also weakens back cavity pressure fluctuations, suppresses high-temperature gas backflow along the shaft, and reduces back cavity eddy current losses and shaft thermal load. Therefore, this embodiment is particularly suitable for centrifugal fan devices operating under high-temperature, high-speed, and long-cycle continuous operation conditions.

[0056] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0057] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-temperature fan with a local micro-textured pre-controlled flow structure, comprising an impeller system (1) and a volute (4), wherein a back cavity is formed between the impeller system (1) and the volute (4) and a gap leakage flow channel from the high-pressure area of ​​the volute to the back cavity; characterized in that, The volute (4) side is provided with a first static gas seal (105) and a second static gas seal (103), and the impeller system (1) side is provided with a dynamic gas seal (106); a first throttling cavity is formed between the first static gas seal (105) and the dynamic gas seal (106), a second throttling cavity is formed between the second static gas seal (103) and the rotating shaft (102), and an annular expansion cavity is formed between the first throttling cavity and the second throttling cavity between the volute (4) and the impeller system (1); a local micro-dimpled textured area (108) is provided on the annular end face of the volute (4) side facing the inlet of the first throttling cavity, and the local micro-dimpled textured area (108) is located in the inlet leading edge area outside the dynamic gas seal (106), so that the leaked gas passes through the local micro-dimpled textured area (108), the first throttling cavity, the annular expansion cavity and the second throttling cavity in sequence along the flow path.

2. The high-temperature fan with a local micro-textured pre-controlled flow structure according to claim 1, characterized in that, The first static gas seal (105) consists of a plurality of first teeth that are radially evenly distributed on the side of the volute (4), the second static gas seal (103) consists of a plurality of second teeth that are axially evenly distributed on the side of the volute (4), and the dynamic gas seal (106) consists of a third tooth that is radially evenly distributed on the side of the impeller system (1); the second teeth and the third teeth are staggered.

3. The high-temperature fan with a local micro-textured pre-controlled flow structure according to claim 2, characterized in that, The axial distance between the tooth tips of the first tooth and the third tooth is the first throttling gap, denoted as g. t1 The radial distance between the tip of the second tooth and the surface of the rotating shaft (102) is the second throttling clearance, denoted as g. t2 It must meet the following requirement: 0.7g t1 ≤g t2 ≤1.5g t1 .

4. The high-temperature fan with a local micro-textured pre-flow control structure according to claim 3, characterized in that, The tooth height of the first tooth is l t1 Satisfying: 3g t1 ≤l t1 ≤5g t1 .

5. The high-temperature fan with a local micro-textured pre-flow control structure according to claim 3, characterized in that, The tooth height of the second tooth is l t2 Satisfying: 0.6l t1 ≤l t2 ≤1.2l t1 , l t1 The height of the first tooth.

6. The high-temperature fan with a local micro-textured pre-controlled flow structure according to claim 1, characterized in that, The localized micro-pit textured region (108) is an annular textured band with an outer diameter of Φ2, satisfying: 0.0005Φ2≤g t1 ≤0.0020Φ2; The width H of the annular textured band satisfies: 0.8l t1 ≤H≤1.2l t1 , l t1 The height of the first tooth.

7. The high-temperature fan with a local micro-textured pre-controlled flow structure according to claim 6, characterized in that, The local micro-pit texture region (108) includes several micro-pits arranged concentrically and staggered along the circumferential direction; the circumferential pitch of the same row of micro-pits is L. R The circumferential misalignment between two adjacent rows of micro-pits is 0.3L. R ~0.7L R .

8. The high-temperature fan with a local micro-textured pre-controlled flow structure according to claim 7, characterized in that, The radius of the micro-pit is R, and satisfies: 0.1H≤R≤0.3H.

9. The high-temperature fan with a local micro-textured pre-flow control structure according to claim 7, characterized in that, The solid interval width between adjacent micro-pits in the same row is denoted as d. The cross-section of the micro-pit is a semi-circular pit with a semi-circular radius of R. The solid interval width d and the semi-circular radius R satisfy: 0.5R≤d≤1.5R.

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