A stator structure for suppressing turbo-aerodynamic excitation

Abstract

The application discloses a stator structure for inhibiting turbine aerodynamic excitation, which comprises a turbine casing with an elliptical cross section, a turbine hub coaxially arranged with the turbine casing, and a plurality of stator blades uniformly distributed in the circumferential direction between the turbine hub and the turbine casing. The height h of the stator blade varies with the circumferential position θ, and the plurality of stator blades form a non-equal-height stator component array. The application precisely controls the wake height in the radial dimension by adopting an elliptical cross section configuration combined with adaptive design of the stator component, effectively disperses the too concentrated disturbance energy in the traditional design, and greatly reduces the amplitude of the aerodynamic excitation at the wake passing frequency. The wake loss degree and width are stable without changing the stator component profile of the turbine, and the disturbance intensity is adjusted only by changing the wake height, so that the surface pressure distribution of the rotor blade is more reasonable, and the aerodynamic excitation on the rotor blade is significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of aero-engine turbine aerodynamics, and more particularly to a stator structure for suppressing turbine aerodynamic excitation. Background Technology

[0002] In pursuit of high thrust-to-weight ratio and high efficiency, modern advanced aero-engines continuously increase turbine stage loads, significantly exacerbating flow field unsteadiness. This makes aerodynamic excitation problems under extreme conditions of high temperature, high pressure, and high speed increasingly prominent. Rotor blades are subjected to periodic unsteady aerodynamic forces from complex disturbance sources such as wakes from upstream stator components, shock waves, and secondary flows. This unsteady aerodynamic excitation essentially originates from the non-uniform flow field at the stator component outlet, which contains various disturbance sources. Under the coupled effects of extreme conditions, forced response vibrations in rotor blades are easily induced, leading to high-cycle fatigue fracture and seriously threatening the reliability, safety, and long-life operation of aero-propulsion systems. Therefore, developing unsteady aerodynamic excitation suppression technology for high-pressure turbine rotor blades has become a core cutting-edge research topic.

[0003] However, traditional aerodynamic excitation suppression techniques have fundamental dimensional limitations: most of them only rely on reducing the non-uniformity of the flow field in the circumferential direction or changing the circumferential oscillation period to achieve suppression, directly ignoring the design dimension of changing the non-uniformity of the flow field or the oscillation period in the radial direction, and cannot achieve efficient suppression of aerodynamic excitation through multi-dimensional optimization design. The shortcomings and deficiencies of existing turbine aerodynamic suppression schemes are manifested in the following three aspects: First, the control of flow field non-uniformity is limited, only controlling the circumferential non-uniformity of the flow field while neglecting the control of the radial dimension, thus failing to fully disperse disturbance energy. Second, the excitation energy spectrum is concentrated. In excitation suppression methods designed for traditional concentric circular casings, the stator components are highly uniform, resulting in a uniform wake height. The rotor blades are continuously subjected to the same intensity of disturbance during the rotation cycle, causing the spectral amplitude of aerodynamic excitation at the wake passing frequency to be too high, exacerbating the risk of blade vibration and fracture. Third, there are reliability challenges under extreme operating conditions. Existing aerodynamic excitation suppression technologies are only effective for some turbines or some operating conditions. The effectiveness of aerodynamic excitation suppression cannot be guaranteed when the turbine is operating under extreme conditions. Unsteady aerodynamic forces can easily induce forced response vibrations in the blades, directly threatening engine safety and lifespan. These shortcomings together make it difficult for existing technologies to meet the increasingly stringent requirements of advanced aero-engines for aerodynamic excitation suppression. Summary of the Invention

[0004] This invention provides a stator structure for suppressing turbine aerodynamic excitation, addressing the technical challenges of overcoming the limitations of traditional symmetrical casing designs, significantly reducing the amplitude of aerodynamic excitation at the wake passing frequency, and substantially reducing the aerodynamic excitation experienced by rotor blades. This invention regulates the radial flow field non-uniformity through an elliptical casing and matching stator components, dispersing disturbance energy and reducing the aerodynamic excitation amplitude at the wake passing frequency, thereby suppressing rotor blade vibration and high-cycle fatigue risk.

[0005] In view of the above technical problems, embodiments of the present invention provide a stator structure for suppressing turbine aerodynamic excitation, comprising: a turbine casing with an elliptical cross section, wherein the major axis radius of the turbine casing is R;

[0006] A circular turbine hub is arranged coaxially with the turbine casing, and the radius of the turbine hub is r;

[0007] Multiple stator blades are evenly distributed circumferentially between the turbine hub and the turbine casing;

[0008] The height h of the stator blades varies with the circumferential position θ. Multiple stator blades form a non-uniform stator component array, used to modulate the exit wake height to suppress rotor blade aerodynamic excitation. The height h of the stator blades satisfies the following functional relationship:

[0009]

[0010] Where h represents the height of the stator blade, c represents the ratio of the minor axis length to the major axis length of the turbine casing, r represents the radius of the turbine hub, R represents the major axis radius of the turbine casing, and θ represents the circumferential position of the stator blade.

[0011] Preferably, c is the ratio coefficient of the minor axis radius to the major axis of the turbine casing, satisfying 0.9≤c<1.

[0012] Preferably, the stator blade adopts the same blade shape as the original circular casing design, and the wake modulation is achieved only by changing the height of the stator blade. The blade shape includes, but is not limited to, a uniform cross-section blade shape or a twisted blade shape.

[0013] The present invention also provides a design method for a stator structure to suppress turbine aerodynamic excitation, comprising the following steps:

[0014] S1. Determine the basic structural parameters of the original turbine, retain the radius r of the circular turbine hub, and use the radius of the original circular casing as the major axis radius R of the elliptical casing;

[0015] S2. Construct a turbine casing with an elliptical cross-section, and design the length of the short axis of the turbine casing to be c times its length of the long axis, where 0.9≤c<1;

[0016] S3. Based on the circumferential height difference between the turbine casing and the turbine hub with elliptical cross sections, the height h of the stator blades at different circumferential positions θ is matched and designed, and a functional mapping relationship between h and θ is established:

[0017]

[0018] Where h represents the height of the stator blade, c represents the ratio of the minor axis length to the major axis length of the turbine casing, r represents the radius of the turbine hub, R represents the major axis radius of the turbine casing, and θ represents the circumferential position of the stator blade.

[0019] S4. By modulating the airflow through an array of non-uniformly high stator components, a wake with varying height in the circumferential direction is formed, causing the rotor blades to withstand periodically varying disturbance intensity during rotation, thereby reducing the aerodynamic excitation amplitude at the wake passing frequency.

[0020] This invention pioneers a novel mechanism for aerodynamic excitation suppression from a radial perspective: By employing a non-fully axisymmetric elliptical casing design, the stator blade height periodically varies with its circumferential position, creating a gradient-distributed wake field. This applies a periodically modulated disturbance input to the rotor blades, dispersing the spectral energy concentrated at the wake passage frequency under traditional concentric casings to a wider modulation band. This fundamentally overcomes the technical limitation that merely regulating the circumferential flow field uniformity cannot adequately suppress excitation. This design, by altering the temporal distribution characteristics of the disturbance intensity, simultaneously achieves efficient suppression of the disturbance intensity, enabling deeper control over the forced response of the blades. This invention also achieves parameter decoupling and engineering inheritance. While fully retaining mature stator airfoils (including constant cross-section or torsion airfoils), it achieves independent control of stator height by only changing the casing geometry, avoiding the aerodynamic performance uncertainty caused by redesigning the airfoils. By constraining the ratio coefficient of the short axis to the long axis, it ensures that the secondary flow loss in the end region is controllable, effectively suppressing excitation while maintaining the aerodynamic efficiency of the turbine. This provides a modification path for engineering applications without sacrificing performance, significantly reducing the technical implementation threshold and R&D costs. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the stator structure for suppressing turbine aerodynamic excitation in one embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram showing the relative height comparison of the stator components in one embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram comparing the relative amplitudes of the aerodynamic excitation of the rotor blades when designing a circular casing and an elliptical casing, according to one embodiment of the present invention.

[0025] The reference numerals in the accompanying drawings are as follows:

[0026] 1-Turbine casing, 2-Turbine hub, 3-Stator blade, 4-Original circular casing. Detailed Implementation

[0027] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and 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. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 based on the specific circumstances.

[0030] like Figure 1 As shown, one embodiment of the present invention provides a stator structure for suppressing turbine aerodynamic excitation, comprising:

[0031] A turbine casing 1 has an elliptical cross-section, and the major axis radius of the turbine casing 1 is R.

[0032] A circular turbine hub 2 is arranged coaxially with the turbine casing 1, and the radius of the turbine hub 2 is r.

[0033] Multiple stator blades 3 are evenly distributed circumferentially between the turbine hub 2 and the turbine casing 1.

[0034] The height h of the stator blade 3 varies with the circumferential position θ. Multiple stator blades 3 form a non-uniform stator component array, used to modulate the exit wake height to suppress rotor blade aerodynamic excitation. The height h of the stator blade 3 satisfies the following functional relationship:

[0035]

[0036] Where h represents the height of the stator blade 3, c represents the ratio of the minor axis length to the major axis length of the turbine casing 1, r represents the radius of the turbine hub 2, R represents the major axis radius of the turbine casing 1, and θ represents the circumferential position of the stator blade 3.

[0037] Understandably, in traditional turbine designs, the casing and hub are often designed as concentric circles. Within the annular area enclosed by the hub and the circular casing, stator components (composed of stator blades 3) are evenly distributed at a consistent height. The main characteristic parameters of the hub and casing include the radius of the original circular casing 1. and hub radius At this time, the height of the stator component is This invention maintains the original turbine hub length unchanged, using the original circular casing 4's radius... The major axis radius of the turbine casing 1 with an elliptical cross section is used as the feature of this invention.

[0038] In one embodiment, such as Figure 1 As shown, c is the ratio coefficient of the minor axis radius to the major axis of the turbine casing 1, which satisfies 0.9≤c<1.

[0039] Understandably, the proportionality coefficient c is defined as the ratio of the minor axis radius to the major axis of the turbine casing 1. The ratio of the minor axis length to the major axis length should not be too small, otherwise it will lead to the blades being too short and the end area loss increasing sharply.

[0040] In one embodiment, such as Figure 1 As shown, the stator blade 3 adopts the same blade shape as the original circular casing 4 design. The wake modulation is achieved only by changing the height of the stator blade 3. The blade shape includes, but is not limited to, a uniform cross-section blade shape or a twisted blade shape.

[0041] Understandably, by using the exact same blade profile as the original circular casing 4 and only changing the height of the stator blades 3 to achieve wake modulation, this design cleverly overcomes the limitation of traditional aerodynamic excitation suppression technology, which only focuses on circumferential non-uniformity control, and effectively controls flow field non-uniformity from the radial dimension. Since the blade profile remains unchanged and only the height changes, the basic shape of the wake (such as the degree of deficit and width) is kept stable, while the height difference forms a wake with circumferential height variation, allowing the rotor blades to withstand periodically changing disturbance intensity during rotation.

[0042] Furthermore, besides the method of adjusting the stator component height using an elliptical casing as described above in this invention, there are many other feasible methods to achieve the control of the stator component height. For example, the original shape of the turbine casing can be kept unchanged, and only the turbine hub can be designed as an ellipse to create a stator component height difference at different circumferential positions; or, both the turbine casing and the hub can be designed as ellipses, and the stator component height can be modulated by the difference in elliptical parameters; in addition, an eccentric design of the hub and casing can be used to create stator components of different heights using the eccentricity; even various curve design methods can be used to design the turbine hub and casing as other types of curved shapes, thereby creating the required stator component height difference at different circumferential positions.

[0043] The present invention also provides a design method for a stator structure to suppress turbine aerodynamic excitation, characterized by comprising the following steps:

[0044] S1. Determine the basic structural parameters of the original turbine, retain the radius r of the circular turbine hub 2, and use the radius of the original circular casing 4 as the major axis radius R of the elliptical casing.

[0045] In one specific embodiment, step S1 further includes the following sub-steps:

[0046] S101. Obtain the radius r of the circular turbine hub 2, obtain the radius of the original circular casing 4 as the major axis radius R of the elliptical casing, and use r and R as the reference geometric parameters.

[0047] S102. Keep the turbine hub 2 circular and the radius r unchanged to ensure that the elliptical casing design only changes the casing profile without altering the hub structure.

[0048] S2. Construct a turbine casing 1 with an elliptical cross section. Design the length of the short axis of the turbine casing 1 to be c times the length of its long axis, where 0.9 ≤ c < 1.

[0049] In one specific embodiment, step S2 further includes the following sub-steps:

[0050] S201. Set the ratio c of the short shaft length to the long shaft length of the turbine casing (1) to 0.9≤c<1;

[0051] S202. When c=0.95, the short axis length of the turbine casing (1) is 95% of the long axis length, forming a preferred elliptical cross section configuration to balance the excitation suppression effect and end area loss control.

[0052] S3. Based on the circumferential height difference between the turbine casing 1 and the turbine hub 2 with elliptical cross sections, the height h of the stator blade 3 at different circumferential positions θ is matched and designed, and a functional mapping relationship between h and θ is established:

[0053]

[0054] Where h represents the height of the stator blade (3), c represents the ratio of the short axis length to the long axis length of the turbine casing (1), r represents the radius of the turbine hub (2), R represents the long axis radius of the turbine casing (1), and θ represents the circumferential position of the stator blade (3).

[0055] In one specific embodiment, step S3 further includes the following sub-steps:

[0056] Step S3 further includes the following sub-steps:

[0057] S301, Using the calculation formula Determine the height h of the stator blade (3) at different circumferential positions θ;

[0058] S302. Obtain the maximum stator height at positions θ=0° and θ=180°. Minimum stator heights were obtained at positions θ=90° and θ=270°. This creates a height difference Δh= .

[0059] S4. By modulating the airflow through an array of non-uniformly high stator components, a wake with varying height in the circumferential direction is formed, causing the rotor blades to withstand periodically varying disturbance intensity during rotation, thereby reducing the aerodynamic excitation amplitude at the wake passing frequency.

[0060] In one specific embodiment, step S4 further includes the following sub-steps:

[0061] S401. After the airflow passes through the stator blades (3) at different heights, a wake is formed with a height positively correlated with the height of the stator blades (3). The degree of wake loss and width remain unchanged.

[0062] S402. As the rotor blades rotate, they alternately pass through high-intensity wake regions and low-intensity wake regions, causing the pressure load on the rotor blade surface to exhibit periodic modulation characteristics, dispersing the concentrated spectral energy to the low-frequency modulation band.

[0063] Understandably, the stator structure for suppressing turbine aerodynamic excitation of the present invention breaks through the traditional design paradigm of a completely symmetrical casing. By adopting an elliptical cross-section configuration and combining it with the adaptive design of the stator components, it achieves precise control of the stator component exit wake in radial space. By adjusting the wake height distribution at the stator component exit, the radial non-uniformity of the flow field at the stator component exit is controlled, effectively changing the characteristics of the flow field at the stator component exit, regulating the intensity of the aerodynamic excitation source on the rotor blade surface at different times, and reducing pressure pulsation and blade vibration caused by unsteady turbine flow. This design can significantly reduce the amplitude of aerodynamic excitation at the wake passing frequency, thereby significantly reducing the aerodynamic excitation experienced by the rotor blades. Specifically, the height of the stator component is changed by altering the height difference between the casing and the hub, thereby modulating the stator component exit wake height, changing the wake disturbance intensity when the rotor is subjected to wake impact, and achieving effective control of aerodynamic excitation.

[0064] When airflow passes through these stator components at different heights, it creates wakes of varying heights. Airflow passing through lower-height stator components creates a lower-height wake, and vice versa. Since the turbine stator airfoil profile remains unchanged, the wake loss and wake width do not change significantly; that is, the elliptical casing and stator components only alter the wake height. In this case, the wake height adjusts the disturbance intensity exerted by the stator components on the rotor blades. Figure 2 The study compared the wake disturbance intensity before and after the elliptical design of the casing. The wake disturbance intensity after the elliptical design of the casing showed a periodic variation pattern, which effectively dispersed the overly concentrated disturbance energy.

[0065] For rotor blades, when they are in different circumferential positions, they will be subjected to wake disturbances of varying intensities. These alternating wake impacts result in an unsteady pressure load on the rotor blade surface with periodically modulated amplitude. Specifically, when the rotor blade is subjected to a weaker wake impact, the pressure fluctuation on the blade surface is smaller; however, when the rotor blade is subjected to a stronger wake impact, the pressure fluctuation increases significantly. This wake input, whose disturbance intensity varies with time, causes the pressure distribution on the rotor blade surface to exhibit asymmetrical fluctuation characteristics within a single wake passage period, and induces a low-frequency load history with varying amplitude envelope over longer multiple wake passage periods. Comparing the aerodynamic excitation amplitude distribution characteristics before and after the elliptical casing design verifies the effectiveness of the elliptical casing and matched stator components in suppressing aerodynamic excitation. Figure 3Specifically, the elliptical casing design was demonstrated to suppress the aerodynamic excitation amplitude of the rotor blades. The analysis revealed that the excitation amplitude concentrated at the blade passage frequency (within the blue box) was significantly reduced, while the excitation amplitude dispersed at other frequencies did not increase significantly. This indicates that the elliptical casing and the matching stator components are an effective means of suppressing aerodynamic excitation.

[0066] This invention, based on an elliptical casing and its matching stator components, modulates the wake height radially, altering the intensity of the wake disturbance and effectively suppressing turbine aerodynamic excitation. A quantitative comparison of the aerodynamic excitation amplitude at the wake passage frequency after the design of the circular and elliptical casings further verifies the aerodynamic excitation suppression effect; the relative magnitude of the aerodynamic excitation amplitude decreases from 0.31 to 0.24, a reduction of approximately 23%.

[0067] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A stator structure for suppressing turbine aerodynamic excitation, characterized in that, include: A turbine casing (1) with an elliptical cross section, the major axis radius of the turbine casing (1) being R; A circular turbine hub (2) is arranged coaxially with the turbine casing (1), and the radius of the turbine hub (2) is r; Multiple stator blades (3) are evenly distributed circumferentially between the turbine hub (2) and the turbine casing (1); The height h of the stator blade (3) varies with the circumferential position θ. Multiple stator blades (3) form a non-uniform stator component array, used to modulate the exit wake height to suppress rotor blade aerodynamic excitation. The height h of the stator blade (3) satisfies the following functional relationship: ； Where h represents the height of the stator blade (3), c represents the ratio of the short axis length to the long axis length of the turbine casing (1), r represents the radius of the turbine hub (2), R represents the long axis radius of the turbine casing (1), and θ represents the circumferential position of the stator blade (3).

2. The stator structure for suppressing turbine aerodynamic excitation according to claim 1, characterized in that, c is the ratio coefficient of the minor axis radius to the major axis radius of the turbine casing (1), which satisfies 0.9≤c<1.

3. The stator structure for suppressing turbine aerodynamic excitation according to claim 2, characterized in that, The stator blade (3) adopts the same blade shape as the original circular casing (4) design, and the wake modulation is achieved only by changing the height of the stator blade (3). The blade shape includes, but is not limited to, equal cross-section blade shape or twisted blade shape.

4. A design method for a stator structure to suppress turbine aerodynamic excitation, characterized in that, Includes the following steps: S1. Determine the basic structural parameters of the original turbine, retain the radius r of the circular turbine hub (2), and use the radius of the original circular casing (4) as the major axis radius R of the elliptical casing. S2. Construct a turbine casing (1) with an elliptical cross section. Design the short axis length of the turbine casing (1) to be c times its long axis length, where 0.9≤c<1. S3. Based on the circumferential height difference between the turbine casing (1) and the turbine hub (2) with an elliptical cross section, the height h of the stator blades (3) at different circumferential positions θ is matched and designed, and a functional mapping relationship between h and θ is established: ； Where h represents the height of the stator blade (3), c represents the ratio coefficient of the short axis length to the long axis length of the turbine casing (1), r represents the radius of the turbine hub (2), R represents the long axis radius of the turbine casing (1), and θ represents the circumferential position of the stator blade (3). S4. By modulating the airflow through an array of non-uniformly high stator components, a wake with varying height in the circumferential direction is formed, causing the rotor blades to withstand periodically varying disturbance intensity during rotation, thereby reducing the aerodynamic excitation amplitude at the wake passing frequency.

5. The stator structure for suppressing turbine aerodynamic excitation according to claim 4, characterized in that, Step S1 further includes the following sub-steps: S101. Obtain the radius r of the circular turbine hub (2), obtain the radius of the original circular casing (4) as the major axis radius R of the elliptical casing, and use r and R as the reference geometric parameters. S102. Keep the turbine hub (2) circular and the radius r unchanged to ensure that the elliptical casing design only changes the casing profile without altering the hub structure.

6. The stator structure for suppressing turbine aerodynamic excitation according to claim 5, characterized in that, Step S2 further includes the following sub-steps: S201. Set the ratio c of the short shaft length to the long shaft length of the turbine casing (1) to 0.9≤c<1; S202. When c=0.95, the short axis length of the turbine casing (1) is 95% of the long axis length, forming a preferred elliptical cross section configuration to balance the excitation suppression effect and end area loss control.

7. The stator structure for suppressing turbine aerodynamic excitation according to claim 5, characterized in that, Step S3 further includes the following sub-steps: S301, Using the calculation formula Determine the height h of the stator blade (3) at different circumferential positions θ; S302. Obtain the maximum stator height at positions θ=0° and θ=180°. Minimum stator heights were obtained at positions θ=90° and θ=270°. This creates a height difference Δh= .

8. The stator structure for suppressing turbine aerodynamic excitation according to claim 5, characterized in that, Step S4 further includes the following sub-steps: S401. After the airflow passes through the stator blades (3) at different heights, a wake is formed with a height positively correlated with the height of the stator blades (3). The degree of wake loss and width remain unchanged. S402. As the rotor blades rotate, they alternately pass through high-intensity wake regions and low-intensity wake regions, causing the pressure load on the rotor blade surface to exhibit periodic modulation characteristics, dispersing the concentrated spectral energy to the low-frequency modulation band.

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