Axial flow compressor casing and design method

Abstract

This invention provides an axial-flow compressor casing and its design method, relating to the field of compressor casing technology. The casing includes: a split-type casing with multiple mounting slots evenly arranged circumferentially along its inner wall; a rotor outer ring disposed on the inner side of the split-type casing; multiple clearance adjustment blocks, each installed in a mounting slot and located between the split-type casing and the rotor outer ring, the bottom of each clearance adjustment block having an arc-shaped structure adapted to the mounting slot; the multiple clearance adjustment blocks being shape memory alloy blocks; an inner ring casing, an anti-rotation pin, and an inner ring steel sleeve; the inner ring steel sleeve being interference-fitted onto the inner side of the inner ring casing; the anti-rotation pin, arranged circumferentially and passing through both the inner ring casing and the inner ring steel sleeve; and a stator blade ring installed on the inner side of the inner ring casing. By utilizing the structure of the clearance adjustment blocks and the high-temperature deformation recovery function of the shape memory alloy, the clearance at the rotor blade tips in the first half of the split-type casing remains unchanged while achieving weight reduction and simplifying the assembly process.

Description

Technical Field

[0001] This invention relates to the field of compressor casing technology, specifically to an axial flow compressor casing and its design method. Background Technology

[0002] The stage pressure ratio of a single-row blade of an axial compressor is about 1.4. In order to improve the overall pressure ratio of aero-engine compressors and enhance compressor performance, most advanced aero-engines at home and abroad adopt multi-stage axial compressor structures, such as the LEAP engine and the CFM56 engine.

[0003] Existing designs often employ multi-stage axial-flow compressor structures, such as... Figure 1 , Figure 2 , Figure 3 As shown. The rotor blades are made of titanium alloy; the split casing is made of titanium alloy; the outer rotor ring is made of stainless steel; the inner casing is made of a low-expansion high-temperature alloy; the stator blade ring is made of a high-temperature alloy; and the anti-rotation pin is made of a high-temperature alloy.

[0004] As the number of compressor stages increases, the compressor weight also increases, leading to a rise in internal temperature. Increased temperature causes greater casing deformation, which in turn increases rotor tip clearance and consequently reduces the compressor's aerodynamic performance. Summary of the Invention

[0005] In view of this, embodiments of this specification provide an axial-flow compressor casing and its design method. This achieves the goal of weight reduction and simplified assembly process by utilizing the high-temperature deformation recovery function of shape memory alloys through the structure of the gap adjustment block, while ensuring that the gap between the rotor blade tips in the first half of the split casing remains unchanged.

[0006] The embodiments in this specification provide the following technical solutions:

[0007] An axial-flow compressor casing, comprising: The split-type casing has multiple assembly slots evenly arranged circumferentially along the inner wall of the split-type casing. The rotor outer ring is located inside the split casing; Multiple clearance adjustment blocks are installed in an assembly slot and located between the split casing and the outer ring of the rotor. The bottom of the clearance adjustment block has an arc-shaped structure that is adapted to the assembly slot. Multiple gap adjustment blocks are shape memory alloy blocks; Inner ring casing, anti-rotation pin, and inner ring steel sleeve; The inner ring steel sleeve is interference-fitted onto the inner side of the inner ring casing; Anti-rotation pins are set circumferentially and pass through both the inner ring casing and the inner ring steel sleeve. The stator blade ring is installed on the inside of the inner ring casing.

[0008] Furthermore, the axial installation position of the clearance adjustment block corresponds to the middle of the blade tip of the rotor blade; The gap adjustment block comprises at least two sets of shape memory alloy blocks with different activation temperatures.

[0009] A design method for an axial compressor casing, the method being used to design a clearance adjustment block for the axial compressor casing, includes the following steps: The radial deformation ΔR1 of the compressor casing and the radial elongation ΔR2 of the rotor blades are obtained under the working conditions, wherein the working conditions include one or more of the following: idle, takeoff, climb, cruise and landing. Based on the radial deformation ΔR1 and radial elongation ΔR2, the total compensation displacement ΔS required by the gap adjustment block is calculated. total ; Based on the casing temperature distribution pattern of the compressor under different operating conditions, the total compensation displacement ΔS total Decomposed into m step-like compensation displacements ΔS1, ΔS2, …, ΔS m Where m is the total number of gap adjustment blocks, m≥2; Based on the compensation displacement ΔS of each step i Based on the actual operating temperature field distribution of the casing, determine the parameter set {T} of the i-th group of clearance adjustment blocks. i , L i , N i H i} and the installation axial position range, wherein the parameters of the parameter set include the activation threshold temperature T i Length L i Quantity N i and thickness H i , i=1,…,m; The parameter sets {T} of the selected gap adjustment blocks were verified through finite element analysis. i , L i , N i H i} and whether the axial position of the installation meets the strength requirements, fatigue life requirements, and graded compensation accuracy requirements.

[0010] Furthermore, obtaining the radial deformation ΔR1 of the compressor casing and the radial elongation ΔR2 of the rotor blades under operating conditions includes: A finite element model of the compressor casing and rotor blades was established using thermo-structural coupled finite element simulation. Thermal and aerodynamic loads were applied under operating conditions, and the radial expansion of the compressor casing at the operating temperature was calculated and used as the first radial deformation ΔR. 11 ; Apply thermal and aerodynamic loads under operating conditions, calculate the radial elongation of the rotor blades under operating temperature and centrifugal force, and use this as the first radial elongation ΔR. 12 ; Through bench testing, under actual compressor operating conditions, the radial displacement of the compressor casing inner wall was measured using an eddy current displacement sensor or a capacitive gap sensor as the second radial deformation ΔR. 21 ; Under actual compressor operating conditions, the radial displacement of the rotor blade tips is measured using strain gauges or laser displacement sensors as the second radial elongation ΔR. 22 ; The first radial deformation ΔR is calculated using a weighted average method. 11 With the second radial deformation ΔR 21 Data fusion is performed to generate the fused radial deformation ΔR1, and the first radial elongation ΔR is... 12 With the second radial elongation ΔR 22 Data fusion is performed to generate the fused radial elongation ΔR2, where the weight coefficients of the weighted average method are calibrated by an optimization algorithm that minimizes the prediction error of historical operating conditions.

[0011] Furthermore, based on the radial deformation ΔR1 and the radial elongation ΔR2, the total compensation displacement ΔS required by the gap adjustment block is calculated. total : Obtain the target tip clearance G required by the design target ; The radial distance between the rotor blade tip and the inner wall of the casing was obtained from historical assembly data of engines of the same model and used as the initial clearance G. initial ; Calculate the total compensation displacement ΔS total , where ΔS total =(ΔR1-ΔR2)-(G target -G initial The total compensation displacement is used to determine whether it is necessary to control the shrinkage or elongation of the gap adjusting block through temperature changes.

[0012] Furthermore, based on the casing temperature distribution pattern of the compressor under different operating conditions, the total compensation displacement ΔS is... total It is decomposed into m stepped compensation displacements ΔS1, ΔS2, …, ΔS m ,include: The characteristic temperature range of the compressor casing under various operating conditions was determined using thermo-structural coupled finite element simulation [T]. min ,k, T max [,k], where k=1,…,K, K is the total number of working states, T min,k is the lowest temperature in the k-th operating state, T max ,k is the highest temperature in the kth operating state; Based on fitting the characteristic temperature range of the casing, a continuous functional relationship h(T) between the casing temperature T and the theoretically required compensation displacement is obtained; The objective is to minimize the variance of tip clearance across all operating states, with the number of groups and the activation threshold temperature T corresponding to each group i as the basis. i To optimize the variables, a genetic algorithm or particle swarm optimization algorithm is used for global optimization to determine the optimal number of groups m and the corresponding temperature threshold range; Based on the optimal number of groups m and the temperature threshold range, the total temperature range is divided into m consecutive temperature ranges, and each temperature range corresponds to a set of gap adjustment blocks. Within each temperature range, the theoretical average compensation demand ΔS for the current temperature range is calculated by integrating and averaging the continuous functional relationship h(T). demand,i ; Based on the total compensated displacement ΔS total Theoretical average compensation requirement ΔS for each temperature range demand,i The proportions are allocated to obtain the various stepped compensation displacements ΔS. i ; The right endpoint of each temperature range is used as the activation threshold temperature T of the i-th group of gap adjustment blocks. i ; Output m stepped compensation displacements ΔS1, ΔS2, …, ΔS m It outputs the activation threshold temperatures T1, T2, ..., T m .

[0013] Furthermore, based on the compensation displacement ΔS of each step... i Based on the actual operating temperature field distribution of the casing, determine the parameter set {T} of the i-th group of clearance adjustment blocks. i , L i , N i H i} and the installation axial position range, including: Obtain the compensation displacement ΔS i The corresponding activation threshold temperature T i ; Based on the actual operating temperature field distribution of the casing, the steady-state operating temperature T(z) at each axial position z on the casing is determined, and |T(z) - T i |Using a temperature difference less than or equal to a set threshold as the criterion, the continuous axial interval Z formed by the axial positions z that satisfy the criterion is selected. i This serves as the axial position range for the installation of the i-th group of gap adjustment blocks; Determine the number N of the gap adjustment blocks in the i-th group.i and thickness H i ; Based on the compensation displacement ΔS i The number of gap adjustment blocks in the i-th group, N i The maximum recoverable strain ε of shape memory alloy materials max The length L of the i-th group of gap adjustment blocks is calculated. i And adjust the length L based on the proportional constraint. i ,in, ; Output the parameter set {T} of the i-th group of gap adjustment blocks i , L i , N i H i} and the corresponding installation axial position range Z i .

[0014] Further, determine the number N of the gap adjustment blocks in the i-th group. i and thickness H i ,include: The total number N of clearance adjustment blocks is determined based on the circumferential dimensions of the casing and the number of mounting slots. total N total The number is even and 4≤N total ≤12; Obtain the minimum driving force F min Shape memory alloy phase transformation shrinkage stress σ SMA and the width w of the clearance adjustment block determined by the size of the housing mounting slot; Based on the total quantity N total Compensation displacement ΔS for each step i The proportion is used to allocate the number N of the gap adjustment blocks in the i-th group. i , so that the quantity N i The sum equals the total quantity N total ; Based on the minimum driving force F min Shape memory alloy phase transformation shrinkage stress σ SMA Given the width w, calculate the lower limit of the thickness H. min,i =F min / (σ SMA ·w); Within the allowable thickness range of the structural space of the axial compressor casing, a value not less than the lower limit of thickness and not exceeding the maximum allowable thickness of the structural space is selected and used as the thickness H of the i-th group of clearance adjustment blocks. i .

[0015] Furthermore, the adjustment length L is constrained based on the ratio of the length of the clearance adjustment block to the tip length of the rotor blade. i ,include: Set the length L of the gap adjustment block i The ratio of the rotor blade tip length to the rotor blade tip length is constrained to ½·L²≤L. i ≤L2, where L2 is the axial length of the rotor blade tip; Adjust length L i Until the proportional constraint is met.

[0016] Furthermore, the parameter set {T} of each selected group of gap adjustment blocks was verified through finite element analysis. i , L i , N i H i Whether the axial position of the installation meets the strength requirements, fatigue life requirements, and graded compensation accuracy requirements, including: A complete finite element model of the machine, including the split casing, rotor outer ring, various sets of clearance adjustment blocks and inner ring casing, is constructed, and thermal load, aerodynamic load and centrifugal load under working conditions are applied. The maximum equivalent stress of each group of gap adjustment blocks is set to not exceed the yield strength of the shape memory alloy material as the strength requirement. The fatigue life requirement is that the cumulative damage of each group of gap adjustment blocks is less than the set damage threshold under cyclic operating conditions. Under simulated operating temperatures, the actual compensation displacement and the compensation displacement amount ΔS generated by each group of gap adjustment blocks are compared. i The relative deviation is less than or equal to the set displacement percentage as the graded compensation accuracy requirement; The finite element model of the whole machine is used to verify whether it meets the strength requirements, fatigue life requirements and graded compensation accuracy requirements, and the verification results are output.

[0017] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: By utilizing the structure of the gap adjustment block and the high-temperature deformation recovery function of the shape memory alloy, the gap between the rotor blade tips of the first half of the split casing remains unchanged, while achieving the goal of weight reduction and simplifying the assembly process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of an existing multi-stage axial flow compressor; Figure 2This is a partially enlarged schematic diagram of the front half of the casing of an existing multi-stage axial flow compressor; Figure 3 This is a partially enlarged schematic diagram of the rear casing of an existing multi-stage axial flow compressor; Figure 4 This is a schematic diagram of the overall structure of the axial compressor casing according to an embodiment of the present invention; Figure 5 This is a partially enlarged schematic diagram of the front half of the axial compressor casing according to an embodiment of the present invention; Figure 6 This is a first schematic diagram of the gap adjustment block according to an embodiment of the present invention; Figure 7 This is a partial enlargement of the rear half of the axial compressor casing according to an embodiment of the present invention. Figure 4 Schematic diagram of part A; Figure 8 This is a first assembly schematic diagram of the front half of the casing according to an embodiment of the present invention; Figure 9 This is a second assembly schematic diagram of the front half of the casing according to an embodiment of the present invention; Figure 10 This is a first assembly schematic diagram of the rear half of the casing according to an embodiment of the present invention; Figure 11 This is a second assembly schematic diagram of the rear half of the casing according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the third assembly of the rear half of the casing according to an embodiment of the present invention; Figure 13 This is a schematic diagram of the fourth assembly of the rear half of the casing according to an embodiment of the present invention; Figure 14 This is a fifth assembly schematic diagram of the rear half of the casing according to an embodiment of the present invention; Figure 15 This is a second schematic diagram of the gap adjustment block according to an embodiment of the present invention.

[0020] The attached figures are labeled as follows: 200, rotor blade; 201, split casing; 202, rotor outer ring; 203, clearance adjusting block; 204, inner ring casing; 205, inner ring steel sleeve; 206, anti-rotation pin; 207, stator blade ring. Detailed Implementation

[0021] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Example 1: This embodiment provides an axial flow compressor casing, such as Figures 4 to 7 As shown, it includes a split casing 201, an outer rotor ring 202, multiple clearance adjustment blocks 203, an inner ring casing 204, an inner ring steel sleeve 205, and an anti-rotation pin 206.

[0024] The split-type casing 201 is made of titanium alloy and has multiple mounting slots evenly arranged along its inner wall circumferentially. The shape of the mounting slots is adapted to the arc-shaped structure at the bottom of the clearance adjustment block 203.

[0025] The rotor outer ring 202 is located inside the split casing 201 and is made of stainless steel.

[0026] Multiple gap adjustment blocks 203 are made of shape memory alloy material. Each gap adjustment block 203 is installed in an assembly slot and located between the split casing 201 and the rotor outer ring 202. Figure 5 As shown, the bottom of the clearance adjustment block 203 is designed with an arc-shaped structure for easy assembly. The clearance adjustment block 203 uses a block structure instead of a continuous ring structure to reduce weight. Calculations show that the weight of the front half of the casing increases by only 0.000791%.

[0027] In this embodiment, the gap adjustment block 203 includes at least two sets of shape memory alloy blocks with different activation temperatures. For example... Figure 4 As shown, the axial mounting positions of each set of clearance adjustment blocks 203 correspond to the center of the blade tip of the rotor blade 200 to optimize the clearance control effect. Figure 6 The length of the gap adjustment block 203 is L. The total number of gap adjustment blocks 203 is an even number, preferably 4 to 12.

[0028] The inner ring casing 204 is made of Ti2AlNb material, which has the characteristics of low density and high specific strength, thus contributing to weight reduction. The inner ring steel sleeve 205 is made of low-expansion high-temperature alloy material and is interference-fitted to the inside of the inner ring casing 204. This prevents titanium fire caused by friction with the rotor blades and also reduces the change in rotor blade tip clearance caused by temperature by utilizing the principle of low expansion.

[0029] Four anti-rotation pins 206 are arranged circumferentially, passing through both the inner ring housing 204 and the inner ring steel sleeve 205. This simultaneously achieves the anti-rotation function of both the inner ring steel sleeve 205 relative to the inner ring housing 204 and the stator blade ring 207 relative to the inner ring housing 204. Without adding unnecessary parts, weight reduction is achieved. Actual measurements show that the weight of the rear half of the housing is reduced by 16.65%.

[0030] The stator ring 207 is made of high-temperature alloy material and is installed inside the inner ring casing 204.

[0031] Example 2: The present invention also includes an assembly method for an axial flow compressor casing.

[0032] like Figure 8 and Figure 9 As shown, the assembly of the front half of the casing includes the following steps: The first step is to machine a groove for mounting the clearance adjustment block on the split housing 201. To ensure ease of assembly, multiple grooves are evenly distributed within the entire ring, and the design aims to ensure that there are no clearance adjustment block mounting grooves on the longitudinal mounting edge of the split housing.

[0033] The second step is to process the gap adjustment block 203. To facilitate assembly, the bottom of the gap adjustment block 203 is designed with an arc-shaped structure.

[0034] The third step is to use special adhesive to fix the gap adjustment block 203 into the assembly slot.

[0035] The fourth step is to slide the rotor outer ring 202 into the split casing 201 along the T-slot. For ease of assembly, the clearance adjusting block 203 and the rotor outer ring 202 are fitted with a clearance.

[0036] The fifth step is to merge the two halves of the split casing together and secure them with bolts along the longitudinal mounting edge.

[0037] like Figures 10 to 14 As shown, the assembly of the rear half of the casing includes the following steps: The first step is to interference fit the inner ring steel sleeve 205 into the inner ring housing 204 (e.g., Figure 10 (As shown).

[0038] The second step is to assemble and machine the anti-rotation pin holes, setting four in the circumferential direction (e.g., ...). Figure 11 (As shown).

[0039] The third step is to install the inner ring housing assembly into the previous stage inner ring housing assembly and secure it with bolts (e.g., Figure 12 (As shown).

[0040] Step 4: Install anti-rotation pin 206 (e.g.) Figure 13 (As shown).

[0041] Step 5: Install the stator ring 207 (e.g.) Figure 14 (As shown).

[0042] Repeat the above steps in sequence to complete the multi-level assembly.

[0043] Example 3: This embodiment provides a design method for a clearance adjustment block in an axial compressor casing, used to design the clearance adjustment block 203 in the aforementioned casing. The method includes the following steps.

[0044] 1. Obtain the radial deformation and radial elongation.

[0045] The radial deformation ΔR1 of the compressor casing and the radial elongation ΔR2 of the rotor blades under operating conditions are obtained through two methods: Finite element simulation approach: Establish finite element models of the compressor casing and rotor blades, apply thermal and aerodynamic loads under operating conditions, and calculate the radial expansion of the compressor casing at operating temperature as the first radial deformation ΔR. 11 Simultaneously, the radial elongation of the rotor blades under operating temperature and centrifugal force is calculated as the first radial elongation ΔR. 12 .

[0046] Bench test method: Under the actual operating conditions of the compressor, the radial displacement of the inner wall of the compressor casing is measured using an eddy current displacement sensor or a capacitive gap sensor as the second radial deformation ΔR. 21 Simultaneously, strain gauges or laser displacement sensors are used to measure the radial displacement of the rotor blade tips as the second radial elongation ΔR. 22 .

[0047] The two sets of data above are then combined: using a weighted average method, the first radial deformation ΔR is... 11 With the second radial deformation ΔR 21 Data fusion is performed to generate the fused radial deformation ΔR1; the first radial elongation ΔR 12 With the second radial elongation ΔR 22 Data fusion is performed to generate the fused radial elongation ΔR2. The weighting coefficients of the weighted average method are calibrated using an optimization algorithm that minimizes the prediction error of historical operating conditions.

[0048] In this embodiment, the working state includes at least several working conditions such as idle, takeoff, climb, cruise and landing, and the deformation amount under each working condition is obtained.

[0049] 2. Calculate the total compensation displacement.

[0050] Obtain the target tip clearance G required by the design target Furthermore, the radial distance between the rotor blade tip and the inner wall of the casing was obtained from historical assembly data of the same engine model, and used as the initial clearance G. initial .

[0051] Calculate the total compensation displacement ΔS using the following formula. total ΔS total =(ΔR1-ΔR2)-(G target -G initial ), where ΔS total The sign is used to determine whether the gap adjustment block needs to be controlled to shrink or stretch through temperature changes: a positive value indicates that shrinkage compensation is required, and a negative value indicates that no compensation is required.

[0052] III. Decompose the step-type compensation displacement.

[0053] The characteristic temperature range of the compressor casing under various operating conditions was determined using thermo-structural coupled finite element simulation [T]. min ,k,T max Based on these interval fittings, a continuous functional relationship h(T) between the casing temperature T and the theoretically required compensation displacement is obtained.

[0054] The objective is to minimize the variance of tip clearance across all operating states, with the number of groups m and the activation threshold temperature T corresponding to each group i as the basis. i To optimize the variables, a genetic algorithm or particle swarm optimization algorithm is used for global optimization to determine the optimal number of groups m and the corresponding temperature threshold range. m ≥ 2, and the temperature difference between adjacent activation thresholds is at least 20℃.

[0055] Based on the optimal number of groups m and the temperature threshold range, the total temperature range is divided into m consecutive temperature intervals, each corresponding to a set of gap adjustment blocks. Within each temperature interval, the theoretical average compensation requirement ΔS for that interval is calculated by integrating and averaging the function h(T). demand,i .

[0056] Displacement amounts for each step compensation are allocated according to the following formula: ΔS i =(ΔS demand,i / ΣΔS demand,j )×ΔS total .

[0057] The right endpoint of each temperature range is used as the activation threshold temperature T of the i-th group of gap adjustment blocks. i Output m stepped compensation displacements ΔS1, ΔS2, ..., ΔS m and the corresponding activation threshold temperatures T1, T2, ..., T m , where j is any group index from 1 to m.

[0058] IV. Determine the parameters and axial installation position of each group of gap adjustment blocks.

[0059] For each group of gap adjustment blocks (i=1,…,m), perform the following sub-steps: (1) Determine the quantity N i and thickness H i .

[0060] The total number N of clearance adjustment blocks is determined based on the circumferential dimensions of the casing and the number of mounting slots. total N total The number is even and 4≤N total ≤12.

[0061] Obtain the minimum driving force F min (Obtained through finite element analysis or bench testing), shape memory alloy phase transformation shrinkage stress σ SMA , and the width w of the clearance adjustment block determined by the size of the casing mounting slot.

[0062] The quantity is allocated according to the compensation ratio: so that N in each group i The sum equals N total And N i / N j =ΔS i / ΔS j .

[0063] Calculation of lower limit for thickness: H min,i =F min / (σ SMA ·w).

[0064] Within the allowable thickness range of the structural space, select a thickness not less than H. min,i And the value not exceeding the maximum allowable thickness is taken as the thickness H. i .

[0065] (2) Determine the axial position range for installation.

[0066] Based on the actual operating temperature field distribution of the casing, determine the steady-state operating temperature T(z) at each axial position z on the casing. This will satisfy |T(z) - T i The continuous axial interval Z formed by axial positions z ≤ 5℃ i , which serves as the axial position range for the installation of the i-th group of gap adjustment blocks.

[0067] (3) Calculate the length L i And check the proportional constraints.

[0068] Calculate length L using the following formula. i :L i =ΔS i / (N i ·ε max ), where ε max This represents the maximum recoverable strain of the shape memory alloy material, with a value ranging from 3% to 5%.

[0069] like Figure 15 As shown ( Figure 15 In the middle, the length of the gap adjustment block 203 is marked as L1), and the length ratio constraint is set as: ½·L2≤L i ≤L2, where L2 is the axial length of the rotor blade tip. If the length L of the i-th gap adjustment block 203 is... i If this constraint is not met, then adjust N. i Or reallocate ΔS i Recalculate until the condition is met.

[0070] (4) Output parameter set.

[0071] Output the parameter set {T} of the i-th group of gap adjustment blocks i ,L i N i H i} and the installation axial position range Z i .

[0072] V. Finite element verification.

[0073] A complete finite element model of the machine, including the split casing 201, the outer ring of the rotor 202, the various sets of clearance adjustment blocks 203 and the inner ring casing 204, is constructed, and thermal load, aerodynamic load and centrifugal load under working conditions are applied.

[0074] Verify the following requirements respectively: Strength requirement: The maximum equivalent stress of each group of gap adjustment blocks shall not exceed the yield strength of the shape memory alloy material.

[0075] Fatigue life requirement: Under cyclic operating conditions (idle-takeoff-climb-cruise-landing), the cumulative damage of each set of clearance adjustment blocks is less than the set damage threshold.

[0076] Graded compensation accuracy requirements: Under simulated operating temperatures, the actual compensation displacement generated by each group of gap adjustment blocks and the ΔS decomposed in step three are required. i The relative deviation is ≤10%.

[0077] If any check fails, adjust the parameter set or install the axial position, and re-verify until the requirements are met.

[0078] Beneficial effects of the embodiments of the present invention: In this embodiment of the invention, a clearance adjustment block made of shape memory alloy material is installed in the first half of the compressor casing. When the engine operating temperature rises and the casing expands radially, the shape memory alloy block automatically contracts using its high-temperature deformation recovery function to compensate for the radial deformation of the casing, thus keeping the rotor blade tip clearance constant. Compared to the traditional passive method of relying solely on coating scraping, this invention achieves active compensation for blade tip clearance, effectively reducing interstage gas leakage rate and improving the compressor's aerodynamic performance, efficiency, and surge margin.

[0079] This invention designs the clearance adjustment blocks as at least two sets of shape memory alloy blocks with different activation temperatures. As the engine progresses from idle, takeoff, climb to cruise, the casing temperature gradually increases. Each set of clearance adjustment blocks is activated sequentially according to a preset activation threshold temperature, providing a stepped compensation displacement so that the blade tip clearance remains near its optimal value throughout the entire operating range. Compared to a single temperature-triggered solution, this invention avoids the "all or nothing" compensation defect and achieves refined, adaptive clearance management without external control.

[0080] This invention designs the clearance adjustment block as a block structure, rather than the traditional ring structure, effectively reducing the total weight of the clearance adjustment block. Actual measurement data shows that the weight increase of the first half of the casing is only 0.000791%, which is almost negligible. Meanwhile, the second half of the casing uses lightweight Ti2AlNb material to replace traditional materials, and combined with structural optimization, the overall weight reduction reaches 16.65%. These weight reduction measures have engineering value for improving the thrust-to-weight ratio of aero-engines.

[0081] The embodiments of the present invention utilize anti-rotation pins to simultaneously achieve the anti-rotation function of the inner ring steel sleeve relative to the inner ring casing and the anti-rotation function of the stator blade ring relative to the inner ring casing. There is no need to set up an anti-rotation structure for each component, no additional parts are added, further achieving the weight reduction goal, while simplifying the assembly process.

[0082] The inner ring steel sleeve is made of low-expansion high-temperature alloy material. On the one hand, it can prevent titanium fire from being generated when the rotor blades and the casing rub violently, thus improving safety. On the other hand, its low coefficient of thermal expansion reduces the radial deformation of the casing caused by temperature rise, and assists the shape memory alloy block in controlling the blade tip clearance, thus achieving a balance between safety and performance.

[0083] This invention provides a complete design method, including: obtaining deformation through the fusion of dual-source data from finite element simulation and bench testing; determining the optimal grouping and stepped compensation based on the temperature distribution under operating conditions and optimization algorithms; establishing a quantitative relationship between quantity, thickness, and length; and verifying strength, fatigue life, and graded compensation accuracy using a whole-machine finite element model. This method is scientific and rigorous, enabling the precise design of clearance adjustment blocks that meet the requirements of all operating conditions, significantly reducing trial-and-error costs and improving design reliability.

[0084] The detailed assembly method of the front and rear casings in this embodiment of the invention adopts mature processes such as slot assembly, special glue fixing, T-slot sliding, and interference fit. The assembly process is simple and highly operable. Furthermore, through online clearance measurement and compensation steps, assembly errors can be corrected in real time to ensure the accuracy of the blade tip clearance after assembly.

[0085] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A type of axial-flow compressor casing, characterized in that, include: The split-type casing (201) has a plurality of mounting slots evenly arranged along the circumferential direction of the inner wall of the split-type casing (201); The rotor outer ring (202) is disposed on the inner side of the split casing (201); Multiple gap adjustment blocks (203) are installed in one of the assembly slots and located between the split casing (201) and the rotor outer ring (202). The bottom of the gap adjustment block (203) is an arc-shaped structure that is adapted to the assembly slot. The plurality of gap adjustment blocks (203) are shape memory alloy blocks; Inner ring casing (204), anti-rotation pin (206) and inner ring steel sleeve (205); The inner ring steel sleeve (205) is interference-fitted to the inner side of the inner ring casing (204); The anti-rotation pin (206) is arranged circumferentially and passes through both the inner ring housing (204) and the inner ring steel sleeve (205). The stator blade ring (207) is installed on the inside of the inner ring casing (204).

2. The axial compressor casing according to claim 1, characterized in that, The axial installation position of the gap adjustment block (203) corresponds to the middle of the blade tip of the rotor blade; The gap adjustment block (203) includes at least two sets of shape memory alloy blocks with different activation temperatures.

3. A design method for an axial-flow compressor casing, the design method being used to design the clearance adjustment block (203) of the axial-flow compressor casing according to any one of claims 1 to 2, characterized in that, Includes the following steps: The radial deformation ΔR1 of the compressor casing and the radial elongation ΔR2 of the rotor blades are obtained under operating conditions, wherein the operating conditions include one or more of the following: idle, takeoff, climb, cruise and landing. Based on the radial deformation ΔR1 and the radial elongation ΔR2, the total compensation displacement ΔS required by the gap adjustment block (203) is calculated. total ; Based on the casing temperature distribution pattern of the compressor under different operating conditions, the total compensation displacement ΔS total Decomposed into m step-like compensation displacements ΔS1, ΔS2, …, ΔS m Where m is the total number of groups of the gap adjustment block (203), m≥2; Based on the compensation displacement ΔS of each step i Based on the actual operating temperature field distribution of the casing, determine the parameter set {T} of the i-th group of clearance adjustment blocks (203). i , L i , N i H i } and the installation axial position range, wherein the parameters of the parameter set include the activation threshold temperature T i Length L i Quantity N i and thickness H i , i=1,…,m; The parameter set {T} of each selected group of gap adjustment blocks (203) was verified by finite element analysis. i , L i , N i H i } and whether the axial position of the installation meets the strength requirements, fatigue life requirements, and graded compensation accuracy requirements.

4. The design method according to claim 3, characterized in that, Obtain the radial deformation ΔR1 of the compressor casing and the radial elongation ΔR2 of the rotor blades under operating conditions, including: A finite element model of the compressor casing and rotor blades was established using thermo-structural coupled finite element simulation. Thermal and aerodynamic loads were applied under operating conditions, and the radial expansion of the compressor casing at the operating temperature was calculated and used as the first radial deformation ΔR. 11 ; Apply thermal and aerodynamic loads under operating conditions, calculate the radial elongation of the rotor blades under operating temperature and centrifugal force, and use this as the first radial elongation ΔR. 12 ; Through bench testing, under actual compressor operating conditions, the radial displacement of the compressor casing inner wall was measured using an eddy current displacement sensor or a capacitive gap sensor as the second radial deformation ΔR. 21 ; Under actual compressor operating conditions, the radial displacement of the rotor blade tips is measured using strain gauges or laser displacement sensors as the second radial elongation ΔR. 22 ; The first radial deformation ΔR is calculated using a weighted average method. 11 With the second radial deformation ΔR 21 Data fusion is performed to generate the fused radial deformation ΔR1, and the first radial elongation ΔR is then calculated. 12 With the second radial elongation ΔR 22 Data fusion is performed to generate the fused radial elongation ΔR2, where the weight coefficients of the weighted average method are calibrated by an optimization algorithm that minimizes the prediction error of historical operating conditions.

5. The design method according to claim 3, characterized in that, Based on the radial deformation ΔR1 and the radial elongation ΔR2, the total compensation displacement ΔS required by the gap adjustment block (203) is calculated. total : Obtain the target tip clearance G required by the design target ; The radial distance between the rotor blade tip and the inner wall of the casing was obtained from historical assembly data of engines of the same model and used as the initial clearance G. initial ; Calculate the total compensation displacement ΔS total , where ΔS total =(ΔR1-ΔR2)-(G target -G initial The total compensation displacement is used to determine whether it is necessary to control the shrinkage or elongation of the gap adjustment block (203) through temperature changes.

6. The design method according to claim 3, characterized in that, Based on the casing temperature distribution pattern of the compressor under different operating conditions, the total compensation displacement ΔS total Decomposed into m stepped compensation displacements ΔS1, ΔS2, …, ΔS m ,include: The characteristic temperature range of the compressor casing under various operating conditions was determined using thermo-structural coupled finite element simulation [T]. min ,k, T max [,k], where k=1,…,K, K is the total number of working states, T min ,k is the lowest temperature in the k-th operating state, T max ,k is the highest temperature in the kth operating state; Based on the fitting of the characteristic temperature range of the casing, a continuous functional relationship h(T) between the casing temperature T and the theoretically required compensation displacement is obtained; The objective is to minimize the variance of tip clearance across all operating states, with the number of groups and the activation threshold temperature T corresponding to each group i as the basis. i To optimize the variables, a genetic algorithm or particle swarm optimization algorithm is used for global optimization to determine the optimal number of groups m and the corresponding temperature threshold range; Based on the optimal number of groups m and the temperature threshold range, the total temperature range is divided into m consecutive temperature ranges, and each temperature range corresponds to a set of the gap adjustment blocks (203). Within each temperature range, the continuous functional relationship h(T) is integrated and averaged to calculate the theoretical average compensation requirement ΔS for the current temperature range. demand,i ; According to the total compensated displacement ΔS total Theoretical average compensation requirement ΔS for each temperature range demand,i The proportions are allocated to obtain the various stepped compensation displacements ΔS. i ; The right endpoint of each temperature range is used as the activation threshold temperature T of the i-th group of gap adjustment blocks (203). i ; Output m stepped compensation displacements ΔS1, ΔS2, …, ΔS m It outputs the activation threshold temperatures T1, T2, …, T m .

7. The design method according to claim 3, characterized in that, Based on the compensation displacement ΔS of each step i Based on the actual operating temperature field distribution of the casing, determine the parameter set {T} of the i-th group of clearance adjustment blocks (203). i , L i , N i H i } and the installation axial position range, including: Obtain the compensation displacement ΔS i The corresponding activation threshold temperature T i ; Based on the actual operating temperature field distribution of the casing, the steady-state operating temperature T(z) at each axial position z on the casing is determined, and |T(z) - T i |Using a temperature difference less than or equal to a set threshold as a criterion, the continuous axial interval Z formed by the axial positions z that satisfy the criterion is selected. i As the axial position range for the installation of the i-th group of gap adjustment blocks (203); Determine the number N of the i-th group of gap adjustment blocks (203). i and thickness H i ; According to the compensation displacement ΔS i The number N of the gap adjustment blocks (203) in the i-th group i The maximum recoverable strain ε of shape memory alloy materials max The length L of the i-th group of gap adjustment blocks (203) is calculated. i And adjust the length L based on the proportional constraint. i ,in, ; Output the parameter set {T} of the i-th group of gap adjustment blocks (203) i , L i , N i H i } and the corresponding installation axial position range Z i .

8. The design method according to claim 7, characterized in that, Determine the number N of the i-th group of gap adjustment blocks (203). i and thickness H i ,include: The total number N of clearance adjustment blocks (203) is determined based on the circumferential dimensions of the casing and the number of mounting slots. total N total The number is even and 4≤N total ≤12; Obtain the minimum driving force F min Shape memory alloy phase transformation shrinkage stress σ SMA and the width w of the clearance adjustment block (203) determined by the size of the housing mounting slot; Based on the total quantity N total The compensation displacement ΔS of each step i The proportion is used to allocate the number N of the i-th group of gap adjustment blocks (203). i , so that the quantity N i The sum equals the total quantity N. total ; According to the minimum driving force F min The phase transformation shrinkage stress σ of the memory alloy SMA And the width w, calculate the lower limit of thickness H min,i = F min / (σ SMA ·w); Within the allowable thickness range of the structural space of the axial compressor casing, a value not less than the lower limit of the thickness and not exceeding the maximum allowable thickness of the structural space is selected, and this value is used as the thickness H of the i-th group of gap adjustment blocks (203). i .

9. The design method according to claim 7, characterized in that, The length L is adjusted based on the ratio of the length of the gap adjustment block (203) to the tip length of the rotor blade. i ,include: The length L of the set gap adjustment block (203) i The ratio of the rotor blade tip length to the rotor blade tip length is constrained to ½·L²≤L. i ≤L2, where L2 is the axial length of the rotor blade tip; Adjust length L i Until the aforementioned proportional constraint is met.

10. The design method according to claim 3, characterized in that, The parameter set {T} of each selected group of gap adjustment blocks (203) was verified by finite element analysis. i , L i , N i H i Whether the axial position of the installation meets the strength requirements, fatigue life requirements, and graded compensation accuracy requirements, including: Construct a whole machine finite element model including the split casing (201), the rotor outer ring (202), each set of gap adjustment blocks (203) and the inner ring casing (204), and apply thermal load, aerodynamic load and centrifugal load under working conditions; The maximum equivalent stress of each group of gap adjustment blocks (203) is set to not exceed the yield strength of the shape memory alloy material as the strength requirement; The fatigue life requirement is that the cumulative damage of each group of gap adjustment blocks (203) is less than the set damage threshold under cyclic operating conditions. Under simulated operating temperatures, the actual compensation displacement generated by each set of gap adjustment blocks (203) is compared with the compensation displacement amount ΔS. i The relative deviation is less than or equal to the set displacement percentage as the graded compensation accuracy requirement; The finite element model of the whole machine is used to verify whether the strength requirements, fatigue life requirements, and graded compensation accuracy requirements are met, and the verification results are output.

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