Turbine design and manufacturing method

Abstract

The present invention provides a method for designing and manufacturing a turbine, which shortens the time required for designing and manufacturing a turbine accompanied by a material change. In the method for designing a turbine (3) accompanied by a material change of a rotor disk (9a) of a turbine rotor (102), the method is characterized in that, when the time required for the temperature of the rotor disk (9a) to reach a second temperature from a first temperature when the turbine (3) is started is set as the temperature rise time, and the distance between the surfaces on the upstream side and the downstream side of the rotor disk (9a) is set as the surface distance, a desired ratio of the temperature rise time after the material change to the temperature rise time before the material change, i.e., a temperature rise time ratio is determined, the surface distance after the material change is determined based on the determined temperature rise time ratio, and the shape of the rotor disk (9a) after the material change is determined based on the determined surface distance, and the determined shape of the rotor disk (9a) is reflected on the turbine rotor (102) to design the turbine (3).

Description

Technical Field

[0001] The present invention relates to a design and manufacturing method of a turbine. Background Art

[0002] In recent years, in order to improve the efficiency of gas turbines, the temperature of combustion gas has been increased. If the temperature of combustion gas increases, parts such as turbine rotors of turbines exposed to combustion gas are more likely to deteriorate, and their life may be shortened.

[0003] As a method of suppressing the deterioration of the turbine rotor, there is a method of applying a material having excellent high-temperature strength to the turbine rotor (see Patent Document 1, etc.).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-199680 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When the material used for the turbine rotor is changed as in Patent Document 1, the thermal expansion of the turbine rotor may also change as the physical property values ​​of the material change, so it is necessary to re-understand the thermal expansion of the turbine rotor after the material change and redesign the turbine. As a method for understanding thermal expansion, unsteady FEM (Finite Element Method) analysis is generally known. However, the time required for unsteady FEM analysis is long each time, and the number of repetitions until the design data that meets the requirements of the turbine is obtained is large, and the design and manufacture of the turbine accompanied by the material change may consume a lot of time and effort.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to shorten the time required for designing and manufacturing a turbine that involves a material change.

[0010] Solutions to Solve Problems

[0011] In order to achieve the above-mentioned object, the present invention is a design method of a turbine, which is accompanied by a material change of a rotor disk of a turbine rotor, characterized in that when the time required for the temperature of the above-mentioned rotor disk to reach a second temperature from a first temperature when the turbine is started is set as a temperature rise time, and the distance between the surfaces on the upstream side and the downstream side of the above-mentioned rotor disk is set as a surface distance, a desired ratio of the temperature rise time after the material change to the temperature rise time before the material change, that is, a temperature rise time ratio is determined, based on the determined temperature rise time ratio, the surface distance after the material change is determined, based on the determined surface distance, the shape of the above-mentioned rotor disk after the material change is determined, the above-mentioned determined rotor disk shape is reflected in the above-mentioned turbine rotor, and the above-mentioned turbine is designed.

[0012] Effects of the Invention

[0013] According to the present invention, the time required for designing and manufacturing a turbine involving a material change can be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing a configuration example of a gas turbine to which the turbine according to the first embodiment of the present invention is applied.

[0015] Figure 2 It is a cross-sectional view showing the internal structure of the turbine according to the first embodiment of the present invention.

[0016] Figure 3 This is a flowchart showing the design and manufacturing process of the turbine according to the first embodiment of the present invention.

[0017] Figure 4 It is a cross-sectional view showing the shape of the rotor disk before and after the material is changed.

[0018] Figure 5 This is a table showing the ratios of elements before and after the material of the rotor disk is changed.

[0019] Figure 6 This is a flowchart showing the design and manufacturing process of the turbine according to the second embodiment of the present invention.

[0020] Figure 7 This is a table showing the ratios of elements before and after the material of the rotor disk is changed.

[0021] In the figure:

[0022] 3 - turbine, 9a, 9b - rotor disk, 21 - inner periphery, 22 - outer periphery, 23 - stacking joint. DETAILED DESCRIPTION

[0023] <First embodiment>

[0024] (structure)

[0025] 1. Gas Turbine

[0026] Figure 1 This is a diagram showing a configuration example of a gas turbine to which the turbine of the present embodiment is applied. Hereinafter, a case where the turbine of the present embodiment is applied to a gas turbine will be described, but the application of the turbine of the present embodiment is not limited to a gas turbine, and for example, the turbine of the present embodiment can also be applied to a steam turbine.

[0027] like Figure 1 As shown, the gas turbine 100 includes a compressor 1, a combustor 2, and a turbine 3. The compressor 1 and the turbine 3 are connected to each other by a shaft (not shown). The compressor 1 is driven to rotate by the turbine 3, compresses the air 6 sucked in through the intake portion 5 to generate high-pressure air (combustion air), and supplies it to the combustor 2. The combustor 2 mixes the high-pressure air supplied from the compressor 1 with the fuel supplied from the fuel system (not shown) and burns them to generate high-temperature combustion gas 7 and supplies it to the turbine 3. The turbine 3 is driven to rotate by the expansion of the combustion gas 7 supplied from the combustor 2. A load device (not shown) is connected to the turbine 3 or the compressor 1. In this embodiment, a generator is connected to the turbine 3 as a load device, and the power obtained by subtracting the power for driving the compressor 1 from the rotational power of the turbine 3 is converted into electricity by the generator. The combustion gas 7 driving the turbine 3 is discharged into the atmosphere as turbine exhaust gas.

[0028] 2. Turbine

[0029] Figure 2 2 is a cross-sectional view showing a partial internal structure of the turbine according to this embodiment. Figure 2 As shown, the turbine 3 includes a stationary body 101 and a turbine rotor 102 constituting a rotating body that rotates relative to the stationary body 101 .

[0030] The stationary body 101 mainly includes a housing 8, an outer ring 18, stationary blades 11 (11a, 11b), an inner ring 15, a diaphragm 14, and sleeves 32 (32a, 32b).

[0031] The casing 8 is a cylindrical member that forms the outer peripheral wall of the turbine 3. The casing 8 accommodates the outer ring 18, the stator blades 11 (11a, 11b), the inner ring 15, the diaphragm 14, and the turbine rotor 102.

[0032] The outer peripheral end wall 18 is supported by the inner peripheral wall 8a of the casing 8 via a sleeve 32 described later. The outer peripheral end wall 18 is a cylindrical member extending in the circumferential direction of the turbine rotor 102.

[0033] A plurality of fixed blades 11b are provided at equal intervals along the circumference of the turbine rotor 102 on the inner circumferential surface of the outer circumferential end wall 18. The fixed blades 11b extend from the inner circumferential surface of the outer circumferential end wall 18 toward the radial inner side of the turbine rotor 102. Hereinafter, the radial inner side and radial outer side of the turbine rotor 102 are referred to as "radially inner side" and "radially outer side". In addition, the fixed blades 11b are arranged in a plurality of rows along the axial direction of the turbine rotor 102, and together with the rotating blades 12, form a turbine stage. Figure 1 In the example of FIG. 1 , the first-stage stationary blades 11 a and the second-stage stationary blades 11 b are shown as the stationary blades 11 , but the number of stages may be arbitrary.

[0034] The inner circumferential side end wall 15b is provided on the radially inner side of the fixed blade 11b. The inner circumferential side end wall 15b is a cylindrical member extending in the circumferential direction of the turbine rotor 102. The fixed blade 11b is connected to the outer circumferential surface of the inner circumferential side end wall 15b. That is, the fixed blade 11b is fixed between the outer circumferential side end wall 18 and the inner circumferential side end wall 15b. The space divided by these outer circumferential side end wall 18 and the inner circumferential side end wall 15b forms a gas passage that becomes a flow path of the combustion gas inside the turbine 3.

[0035] The diaphragm 14 is attached to the inner circumferential surface side of the inner circumferential side end wall 15 and extends in the circumferential direction of the turbine rotor 102. The diaphragm 14 has fins (not shown) extending radially inward from the inner circumferential surface (the surface facing the outer circumferential surface 30 of the isolation disk 10a described later). In addition, the sleeve 32 (32a, 32b) as a member supporting the inner ring 18 of the stationary blade 11 is fixed to the inner circumferential wall 8a of the casing 8. The sleeve 32 is an annular member and is provided at a position facing the front end of the rotating blade 12 described later. In the example shown in the figure, the sleeve 32a facing the first-stage rotating blade 12a supports the downstream side of the outer circumferential side end wall 18 of the first-stage stationary blade 11a and the upstream side of the outer circumferential side end wall 18 of the second-stage stationary blade 11b. The sleeve 32b facing the second-stage rotating blade 12b supports the downstream side of the outer circumferential side end wall 18b of the second-stage stationary blade 12a.

[0036] The turbine rotor 102 includes rotor disks 9a and 9b, a spacer disk 10a, and rotor blades 12a and 12b.

[0037] The rotor disks 9a, 9b and the spacer disk 10a are disk-shaped components arranged along the flow direction of the combustion gas 7. Hereinafter, the upstream and downstream of the flow direction of the combustion gas 7 are simply referred to as "upstream" and "downstream". The rotor disks 9a, 9b and the spacer disk 10a are integrally fastened by stacking bolts 13. A plurality of stacking bolts 13 are provided on the same circumference with the central axis I of the turbine 3 as the center.

[0038] The rotor disk 9a has an inner peripheral portion 21, an outer peripheral portion 22, and a stack joint portion 23. The structure of the rotor disk 9a will be described below, but the other rotor disks including the rotor disk 9b have the same structure except for the presence or absence of a center hole.

[0039] The inner circumference 21 constitutes the radially inner side (central axis I side) of the rotor disk 9a. The inner circumference 21 is formed so that the inter-surface distance D1 becomes shorter toward the radially outer side in the cross section of the rotor disk 9a cut by a plane containing the central axis I (hereinafter referred to as the cross section of the rotor disk 9a). In the present embodiment, the "inter-surface distance" refers to the distance between the surfaces on the upstream side and the downstream side of the rotor disk 9a, specifically, the distance between two surfaces at any radial position of the rotor disk 9a in the cross section of the rotor disk 9a. The inner circumference 21 is opposed to the isolation disk 10a provided adjacent to the downstream side of the rotor disk 9a via the gap 28.

[0040] The stacking joint 23 is a portion located between the inner circumference 21 and the outer circumference 22. A plurality of holes (not shown) through which the stacking bolts 13 can be inserted are formed in the stacking joint 23 along the circumferential direction of the turbine rotor 102. The stacking joint 23 is formed so that the surface on the upstream side and the surface on the downstream side are parallel to the surface orthogonal to the central axis I, and in the cross section of the rotor disk 9a, the distance D3 between the surfaces is constant in the radial direction of the turbine rotor 102. The surface on the downstream side of the stacking joint 23 is set to contact the surface on the upstream side of the adjacent isolation disk 10a (the surface on the downstream side of the stacking joint 23 is in contact with the surface on the upstream side of the bonding surface of the isolation disk 10a). A plurality of rotor disks are overlapped with the isolation disks interposed therebetween and are fastened by the stacking bolts 13 that penetrate the stacking joint 23.

[0041] The outer peripheral portion 22 constitutes the radially outer portion of the rotor disk 9a. The outer peripheral portion 22 is formed so that the inter-surface distance D2 thereof in the cross section of the rotor disk 9a is shorter than the inter-surface distance D3 of the stack joint 23. The outer peripheral portion 22 faces the spacer disk 10a with a gap 29 therebetween.

[0042] The annular space formed between the rotor disks 9a, 9b and the inner ring 15 and the inner peripheral wall 8a and outer ring 18 of the housing 8 constitutes a flow path (combustion gas flow path) 31 for the flow of the combustion gas 7. The inner peripheral wall of the combustion gas flow path 31 is formed by the outer peripheral surface of the rotor disks 9a, 9b and the outer peripheral surface of the inner ring 15, and the outer peripheral wall is formed by the inner peripheral wall 8a of the housing 8 and the inner peripheral surface of the outer ring 18.

[0043] The separator disk 10a is provided between the rotor disks 9a and 9b. The separator disk 10a includes a protrusion 27 protruding radially outward from a radially outer surface (outer peripheral surface) 30. The protrusion 27 of the separator disk 10a cooperates with the fins of the diaphragm 14 to form a seal.

[0044] A plurality of rotor blades 12a and 12b are provided at equal intervals on the outer peripheral surfaces of the rotor disks 9a and 9b along the circumferential direction of the turbine rotor 102. The rotor blades 12a and 12b extend from the outer peripheral surfaces of the rotor disks 9a and 9b toward the radially outer side (the inner peripheral wall 8a side of the casing 8). Gaps 19 and 20 are formed between the outer peripheral portions (radially outer ends) of the rotor blades 12a and 12b and the sleeves 32a and 32b attached to the casing 8. The rotor blades 11a and 12a rotate about the central axis I together with the rotor disks 9a and 9b and the isolation disk 10a by the combustion gas 7 flowing in the combustion gas flow path 31.

[0045] The rotating blades 12a, 12b and the fixed blades 11a, 11b are alternately arranged along the flow direction of the combustion gas 7. That is, from the inlet of the combustion gas flow path 31 toward the downstream side, the rotating blades and the fixed blades are alternately arranged in a manner of first-stage fixed blades 11a, first-stage rotating blades 12a, second-stage fixed blades 11b, second-stage rotating blades 12b, ...

[0046] On the upstream side of the first-stage rotating blades 12a, a plurality of first-stage stationary blades 11a are provided at equal intervals in the circumferential direction of the turbine rotor 102. The first-stage stationary blades 11a are connected to an inner peripheral support portion 26 provided on the upstream side of the rotor disk 9a and an outer peripheral support portion 25 provided opposite to the inner peripheral support portion 26 across the combustion gas flow path 31.

[0047] 3. Design and manufacture of turbines

[0048] Figure 3 1 is a flow chart showing the design and manufacturing process of the turbine of the present embodiment. In the present embodiment, the design and manufacturing method of the turbine accompanied by the material change of the rotor disk of the turbine rotor is described by taking the case of changing to a material with high heat resistance as an example. The rotor disk 9a is exemplified below, but the same is true for other rotor disks including the rotor disk 9b.

[0049] Step S1

[0050] A temperature rise time ratio is determined as a desired ratio of the temperature rise time after the material change to the temperature rise time before the material change. In the present embodiment, the "temperature rise time" refers to the time required for the temperature of the rotor disk to reach the second temperature from the first temperature when the turbine is started. The first temperature and the second temperature are both set values, and the first temperature is, for example, room temperature (e.g., 20°C ± 15°C), and the second temperature is the average temperature of any selected part or parts of the rotor disk during rated operation (e.g., 500°C). In the present embodiment, the case where the temperature rise time ratio is set to 1.0 is described, but the temperature rise time ratio can also be set in a range of, for example, greater than 0.9 and less than 1.1. The temperature rise time is described below.

[0051] In this embodiment, the specific heat equation and the heat conduction equation are defined as equations (1) and (2), respectively.

[0052] Q = c × m × ΔT ··· Formula (1)

[0053] Here, Q is the heat capacity of the rotor disk 9a, c is the specific heat of the rotor disk 9a, m is the weight of the rotor disk 9a, and ΔT is the temperature change of an arbitrarily selected portion of the rotor disk 9a.

[0054] Q = k × S × t × (T1-T2) / L ··· Formula (2)

[0055] Among them, k is the thermal conductivity of the rotor disk 9a, S is the cross-sectional area of ​​the cross section when the rotor disk 9a is cut by a plane orthogonal to the central axis I at an arbitrary position in the direction of the central axis I of the rotor disk 9a (the cross-sectional area of ​​the annular cross section centered on the central axis I of the rotor disk 9a), t is the temperature rise time of an arbitrarily selected portion of the cross section of the rotor disk 9a, T1 and T2 are the temperatures of the upstream and downstream surfaces at arbitrary radial positions of the cross section of the rotor disk 9a (T1>T2), and L is the distance between the surfaces at the above-mentioned arbitrary radial position.

[0056] In the present embodiment, ΔT= T1 - T2 is assumed. Then, based on equations (1) and (2), the temperature rise time t can be expressed as equation (3).

[0057] t=c×m×L / (k×S) ···Formula (3)

[0058] When the temperature rise time before and after the material change is equal, it can be said that the ease of heating the rotor disk before and after the material change is equal. When the temperature rise time after the material change is shorter than before the material change (temperature rise time ratio <1), the rotor disk after the material change is easier to heat up than before the material change. When the temperature rise time after the material change is longer than before the material change (temperature rise time ratio >1), the rotor disk after the material change is more difficult to heat up than before the material change. In addition, in this embodiment, the method of calculating the temperature rise time t based on the specific heat formula and the heat conduction formula is described, but the method of calculating the temperature rise time t is not limited to this.

[0059] Step S2

[0060] Based on the temperature rise time ratio determined in step S1 , the distance between surfaces after the material change is determined.

[0061] According to equation (3), the temperature rise time t before and after the material change can be expressed as equation (4) and (5): 1 ,t 2 .

[0062] t1 =c 1 ×m 1 ×L 1 / (k 1 ×S 1 )···Formula (4)

[0063] t 2 =c 2 ×m 2 ×L 2 / (k 2 ×S 2 )···Formula (5)

[0064] In this embodiment, the temperature rise time ratio is set to 1.0, so according to (t 2 / t 1 =1.0), equations (4) and (5) give equation (6).

[0065] c 2 ×m 2 ×L 2 / (k 2 ×S 2 )=c 1 ×m 1 ×L 1 / (k 1 ×S 1 )···Formula (6)

[0066] In this embodiment, for the sake of convenience, the cross-sectional area of ​​the rotor disk 9a before and after the material change is assumed to be unchanged (S 1 =S 2 ), set the weight ratio (m 2 / m 1 ) and the ratio of the distance between the surfaces after the material change to the distance between the surfaces before the material change, i.e., the distance ratio between the surfaces (L 2 / L 1 ) are equal. Therefore, according to formula (6), formula (7) is obtained.

[0067] (L 2 / L 1 ) 2 =c 1 ×k 2 / (c 2 ×k 1 )···Formula (7)

[0068] Generally, the specific heat c of the rotor disk 9a before and after the material change is 1 、c 2 and thermal conductivity k 1 , k 2Determined by the physical properties of the material. Therefore, the distance L between the surfaces after the material change can be determined according to formula (7): 2 .

[0069] Step S3

[0070] Based on the inter-surface distance determined in step S2 , the shape of the rotor disk 9 a after the material change is determined.

[0071] In this embodiment, the distance between the surfaces at any radial position of the rotor disk 9a is changed based on the distance between the surfaces determined in step S2, and the shape of the rotor disk 9a after the material change is determined by the isostatic disk method. In this embodiment, the "isostatic disk method" refers to a method of determining the shape of the rotor disk so that the stresses applied by the centrifugal force to each part of the rotor disk are equal regardless of the radial position of the turbine rotor.

[0072] Figure 4 2 is a cross-sectional view showing the shape of the rotor disk 9a before and after the material change. Figure 4 In FIG. 1 , the dotted line indicates the shape of the rotor disk 9 a after the material is changed, and the solid line indicates the shape of the rotor disk 9 a before the material is changed.

[0073] like Figure 4 As shown, in this embodiment, the distance between the inner circumference 21 and the outer circumference 22 of the rotor disk 9a before the material change is changed, so that the distance D1 between the inner circumference 21 before the material change becomes D1' (<D1), and the distance D2 between the outer circumference 22 becomes D2' (<D2). Figure 4In the embodiment, the distances between the surfaces of the inner circumference 21 and the outer circumference 22 are changed in the same manner so that the change rate (D1' / D1) of the distance between the surfaces of the inner circumference 21 and the change rate (D2' / D2) of the distance between the surfaces of the outer circumference 22 are equal before and after the material change, so that the distance between the surfaces of the outer circumference 22 of the planes C1 and C2 (dash-dotted lines) respectively including the surfaces A1' and A2' on the upstream and downstream sides of the inner circumference 21 after the material change is equal to the distance D2' between the surfaces of the outer circumference 22 after the material change. That is, the surfaces on the upstream side (downstream side) of the inner circumference 21 and the outer circumference 22 before and after the material change are included in the same plane. In addition, the shape of the rotor disk 9a after the material change is not limited to the above case. For example, the inter-surface distance of the outer peripheral portion 22 after the material change may be larger than the inter-surface distance D2' of the outer peripheral portion 22 when the inter-surface distances of the inner peripheral portion 21 and the outer peripheral portion 22 are changed in the same manner, the inter-surface distance of the inner peripheral portion 21 after the material change may be smaller than the inter-surface distance D1' of the inner peripheral portion 21 when the inter-surface distances of the inner peripheral portion 21 and the outer peripheral portion 22 are changed in the same manner, and the inter-surface distance of the outer peripheral portion 22 when the inter-surface distance of the inner peripheral portion 21 after the material change is extended to the outer peripheral portion 22 may be longer than the inter-surface distance of the outer peripheral portion 22 after the material change. The outer peripheral portion 22 of the rotor disk 9a is located radially outward (on the combustion gas flow path 31 side) of the inner peripheral portion 21, and therefore tends to become higher in temperature than the inner peripheral portion 21 due to heat transfer from the combustion gas 7. However, by ensuring that the inter-surface distance of the outer peripheral portion 22 after the material change is large (thick), the heat resistance of the outer peripheral portion 22 can be improved, and the reliability of the turbine 3 can be ensured.

[0074] Step S4

[0075] The shape of the rotor disk 9a determined in step S3 is reflected in the turbine rotor 102, and the turbine 3 is designed. In the present embodiment, the rotor disk 9a is set to the shape determined in step S3, and the isolation disk 10a and the rotor blade 12a are in the shape before the material change, and the turbine rotor 102 is designed. Using the designed turbine rotor 102, the components of the stationary body 101 (casing 8, outer peripheral end wall 18, fixed blades 11b, inner peripheral end wall 15a, diaphragm 14, etc.) are in the shape before the material change, and the turbine 3 is designed.

[0076] Step S5

[0077] The turbine 3 designed in step S4 is subjected to an unsteady FEM analysis. In the present embodiment, the "unsteady FEM analysis" is an analysis method that virtually divides the turbine into finite elements, and in an environment where the temperature can change with time and position, during the process of temperature rise at the start of the turbine, confirms whether there is a part in the rotor disk 9a where a high stress exceeding a set value is generated.

[0078] If the result of the unsteady FEM analysis is "Yes", the process proceeds from step S5 to step S6. In the present embodiment, the result of the unsteady FEM analysis is "Yes", which means that in the unsteady FEM analysis, there is no portion of the rotor disk 9a where a high stress exceeding a set value is generated in the process of the temperature rising from the first temperature to the second temperature at the start of the turbine. On the contrary, if the result of the unsteady FEM analysis is "No", the process returns to step S2. In the present embodiment, the result of the unsteady FEM analysis is "No", which means that in the unsteady FEM analysis, there is a portion of the rotor disk 9a where a high stress exceeding a set value is generated in the process of the temperature rising from the first temperature to the second temperature at the start of the turbine. If the result of the unsteady FEM analysis is "No", in step S2, the inter-surface distance determined last time is adjusted (for example, the inter-surface distance of the inner peripheral portion 21 and the outer peripheral portion 22 is changed based on the result of the unsteady FEM analysis), and the inter-surface distance is re-determined. Then, the shape of the rotor disk 9a is determined in step S3, the turbine 3 is redesigned in step S4, and an unsteady FEM analysis is performed in step S5. Thereafter, steps S2 to S5 are repeated until the result of the unsteady FEM analysis becomes "Yes".

[0079] Step S6

[0080] The turbine is manufactured based on the design of step S4. In the present embodiment, the rotor disk 9a is manufactured into the shape determined in step S3 using the changed material, and the components of the isolation disk 10a, the rotor blades 12a, and the stationary body 101 are manufactured into the shape before the material change using the material before the change, thereby manufacturing the turbine 3. In the case of manufacturing (modifying) the turbine based on the existing turbine, for example, the rotor disk 9a is manufactured into the shape determined in step S3 using the changed material, and the components of the isolation disk 10a, the rotor blades 12a, and the stationary body 101 continue to use the corresponding parts of the existing turbine, thereby manufacturing the turbine 3.

[0081] (Effect)

[0082] (1) In the present embodiment, the temperature rise time ratio is determined, and the distance between the surfaces after the material change is determined based on the determined temperature rise time ratio, and the turbine 3 is designed. By determining the distance between the surfaces after the material change based on the temperature rise time ratio, it is possible to easily determine the shape of the rotor disk 9a so that the temperature rise time, that is, the ease of heating of the rotor disk 9a before and after the material change becomes a desired value determined by the temperature rise time ratio. Therefore, the appropriateness of the design of the rotor disk 9a after the material change can be made high from the beginning, so that the result of the unsteady FEM analysis is likely to be "Yes". As a result, the number of repetitions of the unsteady FEM analysis in the design of the turbine 3 accompanied by the material change can be reduced, and the time required for the design and manufacture of the turbine 3 can be shortened accordingly. In particular, in the present embodiment, the temperature rise time ratio is set to 1.0, so that the ease of heating of the rotor disk 9a before and after the material change can be equal, and the time required for the design and manufacture of the turbine 3 can be further shortened.

[0083] (2) In the present embodiment, the distance between the surfaces of the inner circumference 21 and the outer circumference 22 of the rotor disk 9a is changed to determine the shape of the rotor disk 9a after the material change. Since the gaps 28 and 29 are formed between the inner circumference 21 and the outer circumference 22 of the rotor disk 9a and the isolation disk 10a, it is not necessary to change the shape of the isolation disk 10a in accordance with the change in the distance between the surfaces of the inner circumference 21 and the outer circumference 22. Therefore, it is possible to reduce the amount of work required for designing and manufacturing the turbine 3 in accordance with the material change. In addition, it is possible to utilize the shape of the isolation disk 10a before the material change, thereby suppressing the increase in the time required for designing and manufacturing the turbine 3 in accordance with the material change.

[0084] Example 1

[0085] Figure 5 This is a table showing the ratios of elements before and after the material of the rotor disk is changed. This embodiment shows the case where the material of the rotor disk 9a is changed from high Cr steel (high chromium steel) to Ni-based (nickel-based alloy).

[0086] like Figure 5 As shown, in this embodiment, the specific heat ratio cr, which is the ratio of the specific heat after the material change of the rotor disk 9a to the specific heat before the material change, is set to 0.8, the thermal conductivity ratio kr, which is the ratio of the thermal conductivity after the material change of the rotor disk 9a to the thermal conductivity before the material change, is set to 0.6, and the temperature rise time ratio tr is set to 1.0. In addition, similarly to the first embodiment, for convenience, the cross-sectional area of ​​the rotor disk 9a before and after the material change is set to be unchanged (the cross-sectional area ratio Sr, which is the ratio of the cross-sectional area after the material change to the cross-sectional area before the material change, is set to 1.0), and the weight ratio mr and the surface distance ratio Lr of the rotor disk 9a are set to be equal.

[0087] Under the above conditions, according to equation (7), the surface distance ratio Lr is 0.87. Therefore, in this embodiment, the shape of the rotor disk after the material change is determined so that the surface distance ratio Lr is 0.87, and the turbine is designed and manufactured, thereby achieving the above effect.

[0088] <Second embodiment>

[0089] This embodiment is different from the first embodiment in that the temperature rise time ratio is determined based on the gap between the turbine rotor and the casing. Other points are the same as the first embodiment.

[0090] Generally, a gap is provided between the turbine rotor as a rotating body and the casing as a stationary body so that the rotation of the turbine rotor is not hindered. In order to ensure the flow rate of the combustion gas involved in the rotation of the turbine rotor, it is desirable to reduce the gap. On the other hand, when the turbine is started, the turbine rotor is heated by the high-temperature combustion gas and expands in the radial direction by thermal expansion (thermal expansion). If the thermal expansion is greater than the above-mentioned gap, the turbine rotor and the casing may contact. Therefore, in the design and manufacture of the turbine accompanied by the material change of the turbine rotor, it is desirable to also consider the gap between the turbine rotor and the casing.

[0091] Figure 6 This is a flowchart showing the design and manufacturing process of the turbine according to the present embodiment.

[0092] Step S200

[0093] The clearance ratio is determined as a desired ratio of the clearance after the material change of the rotor disk 9a to the clearance before the material change when starting the turbine 3. In this embodiment, the "clearance" refers to the radially opposed distance between the turbine rotor 102 (rotor disk 9a) and the inner peripheral wall of the casing 8.

[0094] In this embodiment, the gap D is defined as shown in equation (8).

[0095] D=α×t···(8)

[0096] Here, α is the linear expansion coefficient of the rotor disk 9a.

[0097] In the present embodiment, the gap ratio is set to 1.0, but the gap ratio may be set within a range of, for example, 0.9 to 1.1.

[0098] Step S201

[0099] The temperature rise time ratio is determined based on the gap ratio determined in step S200. Hereinafter, the process of determining the temperature rise time ratio based on the gap ratio will be described.

[0100] According to equation (8), the gap D before and after the material change can be expressed as equations (9) and (10): 1 , D 2 .

[0101] D 1 =α 1 ×t 1 ···(9)

[0102] D 2 =α 2 ×t 2 ···(10)

[0103] In this embodiment, the gap ratio is set to 1.0 (D 2 / D 1 =1.0), so according to equations (9) and (10), we can get equation (11).

[0104] α 1 ×t 1 =α 2 ×t 2 ···(11)

[0105] According to formula (11), the temperature rise time ratio (t 2 / t 1 ).

[0106] Steps S202 to S206

[0107] The same as steps S2-S6 of the first embodiment. That is, in step S202, the distance between the surfaces after the material change is determined using the temperature rise time ratio determined in step S201. In step S203, the shape of the rotor disk 9a after the material change is determined based on the distance between the surfaces determined in step S202. In step S204, the shape of the rotor disk 9a determined in step S203 is reflected in the turbine rotor, and the turbine 3 is designed. In step S205, an unsteady FEM analysis is performed on the turbine 3 designed in step S204. When the result of the unsteady FEM analysis is "Yes", the process proceeds from step S205 to step S206. On the contrary, when the result of the unsteady FEM analysis is "No", the process returns to step S202. In step S206, the turbine is manufactured based on the design of step S204.

[0108] (Effect)

[0109] In the present embodiment, the gap ratio is determined, and the temperature rise time ratio is determined based on the determined gap ratio, and the turbine 3 is designed. In the present embodiment, the surface distance after the material change is determined based on the temperature rise time ratio, so the shape of the rotor disk 9a can be easily determined so that the temperature rise time of the rotor disk 9a before and after the material change, that is, the ease of heating, becomes a desired value determined by the temperature rise time ratio, and the same effect as the first embodiment can be obtained. In addition, in the present embodiment, the temperature rise time ratio is determined based on the gap ratio, so the shape of the rotor disk 9a can be easily determined so that the gap before and after the material change becomes a desired value determined by the gap ratio. Therefore, in the turbine 3 after the material change, the contact between the turbine rotor 102 and the casing 8 can be avoided, and the reliability of the turbine 3 can be ensured. In particular, in the present embodiment, the gap ratio is set to 1.0, so the gaps before and after the material change can be equal, and the reliability of the turbine 3 can be more reliably ensured.

[0110] Example 2

[0111] Figure 7 : is a table showing the ratios of elements before and after the material of the rotor disk is changed. This embodiment shows the case where the material of the rotor disk 9a is changed from high-Cr steel to Ni-based steel.

[0112] like Figure 7 As shown, in this embodiment, the linear expansion coefficient ratio αr, which is the ratio of the linear expansion coefficient of the rotor disk 9a after the material change to the linear expansion coefficient before the material change, is set to 1.2, and the gap ratio Dr is set to 1.0. Therefore, according to equation (8), the temperature rise time ratio tr is 0.8.

[0113] In this embodiment, the specific heat ratio cr is set to 0.8, and the thermal conductivity ratio kr is set to 0.6. In addition, in this embodiment, for convenience, the cross-sectional area of ​​the rotor disk 9a before and after the material change is set to be unchanged, and the weight ratio mr and the surface distance ratio Lr of the rotor disk 9a are set to be equal.

[0114] Under the above conditions, according to equation (7), the surface distance ratio Lr is 0.79. Therefore, in this embodiment, the shape of the rotor disk after the material change is determined so that the surface distance ratio Lr is 0.79, and the turbine is designed and manufactured, thereby achieving the above effect.

[0115] <Other>

[0116] The present invention is not limited to the above-mentioned embodiments, and includes various modified examples. For example, the above-mentioned embodiments are examples described in detail to explain the present invention in an easy-to-understand manner, and are not limited to having all the structures described. For example, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and a part of the structure of each embodiment can be deleted.

[0117] In the above-mentioned embodiments, the case where the distance D1 between the surfaces of the inner peripheral portion 21 before the material change is set to D1' (<D1) and the distance D2 between the surfaces of the outer peripheral portion 22 is set to D2' (<D2) is exemplified. However, the essential effect of the present invention is to shorten the time required for designing and manufacturing a turbine with a material change, and as long as this essential effect can be obtained, it is not necessary to be limited to the above-mentioned structure. For example, the distance D1 between the surfaces of the inner peripheral portion 21 before the material change may be set to D1' (>D1), and the distance D2 between the surfaces of the outer peripheral portion 22 may be set to D2' (>D2).

Claims

1. A method for designing a turbine, which is accompanied by a change in the material of a rotor disk of a turbine rotor, characterized in that: When the time required for the temperature of the rotor disk to reach the second temperature from the first temperature at the start of the turbine is defined as the temperature rise time, and the distance between the upstream and downstream surfaces of the rotor disk is defined as the surface distance, Determine the desired ratio of the temperature rise time after the material change to the temperature rise time before the material change, i.e., the temperature rise time ratio. Based on the temperature rise time ratio determined above, the distance between the surfaces after the material change is determined. Based on the determined inter-surface distance, the shape of the rotor disk after the material change is determined. The turbine is designed by reflecting the determined shape of the rotor disk on the turbine rotor.

2. The method for designing a turbine according to claim 1, characterized in that: The above temperature rise time is defined by the following formula: t = c × m × L / (k × S), Among them, c is the specific heat of the rotor disk, m is the weight of the rotor disk, L is the distance between the surfaces, k is the thermal conductivity of the rotor disk, and S is the cross-sectional area of ​​the annular cross section centered on the central axis of the rotor disk.

3. The method for designing a turbine according to claim 1, characterized in that: The rotor disk has an inner peripheral portion as a radially inner portion of the turbine rotor, an outer peripheral portion as a radially outer portion of the turbine rotor, and a stacking joint portion between the inner peripheral portion and the outer peripheral portion. The distance between the surfaces of the inner peripheral portion and the outer peripheral portion is changed to determine the shape of the rotor disk after the material is changed.

4. The method for designing a turbine according to claim 3, characterized in that: The distance between the surfaces of the inner and outer peripheral parts is changed so that the distance between the surfaces of the outer peripheral part after the material change is longer than the distance between the surfaces when the upstream and downstream surfaces of the inner peripheral part after the material change are extended to the outer peripheral part.

5. The method for designing a turbine according to claim 1, characterized in that: The above-mentioned temperature rise time ratio is set to 1.

0.

6. A method for manufacturing a turbine, characterized in that: The turbine is designed and manufactured by the design method according to claim 1.

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