JP2005315178A - Axial flow turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial flow turbine improving a turbine cascade performance, by optimally combining fundamental parameters having a direct influence on the turbine blade cascade performance. <P>SOLUTION: In at least two or more continuous turbine stages Na, Nb, Nc out of a plurality of turbine stages of the axial flow turbine under a condition wherein a throat/pitch ratio (s/t) of turbine nozzles 3a<SB>1</SB>, 3b<SB>1</SB>, 3c<SB>1</SB>, becomes larger toward the downstream turbine stage Nc from the upstream turbine stage Na, an optimum value of a pitch/axial cord ratio (t/Ca) wherein blade cascade losses of the turbine nozzles 3a<SB>1</SB>, 3b<SB>1</SB>, 3c<SB>1</SB>are minimized is acquired to set a pitch t and an axial cord Ca of each of turbine nozzles 3a<SB>1</SB>, 3b<SB>1</SB>, 3c<SB>1</SB>, from the acquired optimum value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an axial-flow turbine, and more particularly to an axial-flow turbine with an improved turbine cascade.

  The axial flow turbine is named from the classification of the flow direction of the working fluid with respect to the turbine rotor (rotary shaft). The turbine nozzle cascade and the turbine rotor cascade are arranged along the circumferential direction of the turbine rotor. Are combined as a pair to form a turbine stage, and the turbine stage is arranged in a plurality of stages along the axial direction of the turbine rotor.

  An axial turbine having such a configuration has been developed and verified based on various fluid analysis and various hydrodynamic tests in order to further improve performance.

  Recent research results on axial turbines include, for example, turbine blades that are curved in the radial direction or axial direction with respect to the turbine rotor, and shapes that change the throat pitch ratio distribution in the radial direction. No. 8-74502 (Patent Document 1) and Japanese Patent No. 3132944 (Patent Document 2).

  As for the cord length, which is one of the basic parameters of the turbine blade, a shape in which the cord at the blade tip portion is lengthened in order to further reduce the leakage loss of the fluid is disclosed in, for example, Japanese Patent Laid-Open No. 11-62506. It is disclosed in the gazette (patent document 3).

The relationship between turbine cascade performance and pitch / code ratio is also described, for example, in the literature `` Ainley, DG, and Mathieson, GCR, `` A Method of Performance Estimation for Axial Flow Turbines '', Aeronautical Research Council, RandM2974 (1957). (Non-Patent Document 1) for a long time.
JP-A-8-74502 Japanese Patent No. 3132944 Japanese Patent Laid-Open No. 11-62506 Ainley, DG, and Mathieson, GCR, “A Method of Performance Estimation for Axial Flow Turbines”, Aeronautical Research Council, RandM2974 (1957).

  For turbine nozzles and turbine blades applied to axial flow turbines, the code indicating the typical blade length, the throat indicating the narrowest part of the turbine blade row passage, and the interblade distance disposed along the circumferential direction of the turbine rotor The three elements of the pitch shown are basic parameters for investigating blade performance.

  The turbine cascade performance of an axial flow turbine is directly affected by these basic parameters and dimensionless parameters combining the basic parameters, specifically, the throat pitch ratio and pitch code ratio.

  For this reason, in order to further improve the turbine cascade performance, it is necessary to fully understand the influence of the above-mentioned basic parameters on the turbine performance and configure the turbine cascade in an optimal combination.

  Conventionally, although research has been conducted on the influence of the basic parameters on the turbine performance, a design guideline has not been clearly defined for an optimal combination of a plurality of basic parameters.

  The present invention has been made based on such background art, and provides an axial flow turbine that further improves turbine cascade performance by optimally combining basic parameters that directly affect turbine cascade performance. For the purpose.

  In order to achieve the above object, an axial turbine according to the present invention is adjacent to a cascade of turbine nozzles arranged along the circumferential direction of the turbine rotor, and A turbine blade cascade arranged along a circumferential direction, and a turbine stage is formed by combining the turbine nozzle cascade and the turbine bucket cascade, and the turbine stage is connected to the turbine rotor shaft. In an axial turbine having a plurality of stages in a direction, at least two or more continuous turbine stages among the turbine stages having a plurality of stages are targeted. On the condition that the throat pitch ratio of the turbine nozzle increases from the turbine stage toward the downstream turbine stage, the turbine nozzle Determine the optimum value of the pitch axial code ratio string loss is minimized, it is from the determined optimum values obtained by setting the pitch and axial code of the turbine nozzle.

  Moreover, in order to achieve the above-mentioned object, the axial turbine according to the present invention is adjacent to a cascade of turbine nozzles arranged along the circumferential direction of the turbine rotor, and A turbine blade cascade arranged along the circumferential direction of the rotor, and a turbine stage is configured by combining the turbine nozzle cascade and the turbine bucket cascade; In the axial flow turbine having a plurality of stages in the axial direction, at least two or more continuous turbine stages among the turbine stages having a plurality of stages are targeted, and the upstream of the target turbine stages The turbine nozzle is provided on the condition that the throat pitch ratio of the turbine nozzle is reduced from the turbine stage on the side toward the turbine stage on the downstream side. Determine the optimum value of the pitch axial code ratio cascade loss Le is minimized, it is from the determined optimum values obtained by setting the pitch and axial code of the turbine nozzle.

  In order to achieve the above object, the axial flow turbine according to the present invention is characterized in that the throat and pitch of the throat / pitch ratio are the positions of the blade average diameter in the blade row of the turbine nozzle. Is the value of.

  In order to achieve the above object, the axial flow turbine according to the present invention has a throat pitch ratio in the range of 0.19 or more as described in claim 4.

  In order to achieve the above-mentioned object, the axial turbine according to the present invention has a pitch-axial code ratio and a throat pitch ratio, wherein the pitch is t, the axial code is Ca, A region surrounded by (t / Ca) = 0.25 × (s / t) +1.05 and (t / Ca) = 0.25 × (s / t) +0.80, where throat is s It is what.

  Moreover, in order to achieve the above-mentioned object, the axial turbine according to the present invention is adjacent to a cascade of turbine nozzles arranged along the circumferential direction of the turbine rotor, and A turbine blade cascade arranged along the circumferential direction of the rotor, and a turbine stage is configured by combining the turbine nozzle cascade and the turbine bucket cascade; In the axial flow turbine having a plurality of stages in the axial direction, at least two or more continuous turbine stages among the turbine stages having a plurality of stages are targeted, and the upstream of the target turbine stages Turbine nozzle axial code is constant or larger from the turbine stage toward the downstream turbine stage. It is obtained by the structure that reduces the number of nozzles.

  Further, in order to achieve the above object, the axial flow code according to the present invention is the axial code is a value of the position of the blade average diameter in the blade row of the turbine nozzle. is there.

  Moreover, in order to achieve the above-mentioned object, the axial turbine according to the present invention is adjacent to a cascade of turbine nozzles arranged along the circumferential direction of the turbine rotor, and the turbine A turbine blade cascade arranged along the circumferential direction of the rotor, and a turbine stage is configured by combining the turbine nozzle cascade and the turbine bucket cascade; In the axial flow turbine having a plurality of stages in the axial direction, at least two or more continuous turbine stages among the turbine stages having a plurality of stages are targeted, and the upstream of the target turbine stages The turbine rotor blade is provided on the condition that the throat pitch ratio of the turbine rotor blade increases from the turbine stage toward the downstream turbine stage. Determine the optimum value of the pitch axial code ratio wing column loss is minimized, it is from the determined optimum values obtained by setting the pitch and axial code of the turbine blade.

  Moreover, in order to achieve the above-mentioned object, the axial turbine according to the present invention is adjacent to a cascade of turbine nozzles arranged along a circumferential direction of a turbine rotor, and A turbine blade cascade arranged along the circumferential direction of the rotor, and a turbine stage is configured by combining the turbine nozzle cascade and the turbine bucket cascade; In the axial flow turbine having a plurality of stages in the axial direction, at least two or more continuous turbine stages among the turbine stages having a plurality of stages are targeted, and the upstream of the target turbine stages The turbine rotor blades on the condition that the throat pitch ratio of the turbine rotor blades decreases from the turbine stage toward the downstream turbine stage. Blade row loss is from the optimum value determined optimum value of the smallest pitch axial code ratio obtained by setting the pitch and axial code of the turbine blade.

  In order to achieve the above object, the axial flow turbine according to the present invention is characterized in that the throat and pitch of the throat / pitch ratio are equal to the blade average diameter in the cascade of turbine rotor blades. It is a position value.

  In order to achieve the above object, the axial turbine according to the present invention has a throat pitch ratio in the range of 0.28 or more as described in claim 11.

  In order to achieve the above-mentioned object, the axial turbine according to the present invention has a pitch-axial code ratio and a throat pitch ratio, wherein the pitch is t, the axial code is Ca, A region surrounded by (t / Ca) = 1.4 × (s / t) +0.51 and (t / Ca) = 1.4 × (s / t) +0.11, where throat is s It is what.

  Moreover, in order to achieve the above-mentioned object, the axial turbine according to the present invention includes at least one of the turbine nozzles according to claims 1, 2, and 6, as described in claim 13, The turbine rotor blade according to claim 7 or 9 is combined with at least one or more.

  The axial turbine according to the present invention targets at least two or more continuous turbine stages among a plurality of stages of turbine stages, and among the target turbine stages, the turbine stage downstream from the upstream turbine stage. On the condition that the throat / pitch ratio is increased toward the target, the optimum value of the pitch / axial code ratio that minimizes the turbine nozzle cascade loss is obtained from the experimental data, and the pitch and axial code are calculated from the obtained optimum values. Therefore, turbine performance can be improved by further reducing the turbine nozzle cascade loss.

  Hereinafter, embodiments of an axial flow turbine according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.

  FIG. 1 is a conceptual diagram showing a turbine stage used in explaining a first embodiment of an axial turbine according to the present invention.

The axial turbine according to this embodiment includes turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ arranged along the circumferential direction of the turbine rotor 2 housed in the center of the turbine casing 1, and the turbine nozzle 3a _1. 3b ₁ , 3c ₁ of a plurality of turbine stages that are paired with a pair of turbine blades 4a ₁ , 4b ₁ , 4c ₁ that are installed on the turbine rotor 2 in pairs on the downstream side of the blade rows For example, three continuous turbine stages are applied, and among the three continuous turbine stages, turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ are applied. Further, for the convenience of explanation, the three successive turbine stages will be referred to as a turbine upstream stage Na, a turbine intermediate stage Nb, and a turbine downstream stage Nc in order along the flow direction of the working fluid.

In general, when considering the turbine cascade performance of the turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ , the most basic factor is that, as shown in FIG. A pitch (t) with the nozzle blade element 5b, a throat (s), a blade cord (c), and a blade axial cord (Ca) can be mentioned.

  The throat pitch ratio (s / t), pitch code ratio (t / c) and pitch / axial code ratio (t / Ca) combining these basic factors are the turbine nozzle cascade load and turbine nozzle cascade. It is an important parameter that directly affects performance.

  FIG. 3 is a turbine nozzle cascade loss diagram obtained from experimental data using the throat pitch ratio (s / t) and the pitch / axial code ratio (t / Ca). In the drawing, the throat pitch ratio (s / t) Na of the turbine upstream stage Na, the throat pitch ratio (s / t) Nb of the turbine intermediate stage Nb, and the throat pitch ratio (s / t) of the turbine downstream stage Nc. ) In relation to Nc, (s / t) Na <(s / t) Nb <(s / t) Nc.

  From the turbine nozzle cascade row loss diagram shown in FIG. 3, the pitch-axial code ratio (t / Ca) Na in the turbine upstream stage Na, the pitch-axial code ratio (t / Ca) Nb in the turbine intermediate stage Nb, and the turbine downstream There is a minimum value of the turbine nozzle cascade loss in each of the pitch / axial code ratio (t / Ca) Nc in the paragraph Nc, and these minimum values are the throat pitches in the turbine paragraphs Na, Nb, and Nc. It was found that the ratio changed depending on the size of the ratio (s / t) Na, (s / t) Nb, and (s / t) Nc.

It should be noted that the throat pitch ratio (s / t) Na, (s / t) Nb, (s / t) Nc in each turbine stage Na, Nb, Nc is the load distribution for each turbine stage Na, Nb, Nc. Depending on the setting of the reaction degree, it varies for each stage of the turbine, and various distributions may be given in the height direction (radial direction) of the turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ from the intention of improving the turbine performance.

  However, in the present embodiment, the turbine nozzle blade height direction as a representative value of the throat pitch ratio (s / t) Na, (s / t) Nb, (s / t) Nc of each paragraph Na, Nb, Nc of the turbine The blade average diameters PCD-a, PCD-b, and PCD-c are set to values corresponding to the center position.

Thus, in the present embodiment, the throat pitch ratio (s / t) Na in the turbine upstream stage Na, the throat pitch ratio (s / t) Nb in the turbine intermediate stage Nb, and the throat pitch ratio in the turbine downstream stage Nc. The relationship of (s / t) Nc is set to (s / t) Na <(s / t) Nb <(s / t) Nc, and each paragraph Na of the turbine is obtained using the experimental data shown in FIG. The optimum values of the pitch / axial code ratio (t / Ca) Na, (t / Ca) Nb, and (t / Ca) Nc that minimize the cascade loss in each of Nb and Nc are obtained. turbine each paragraph Na, Nb, turbine nozzle _3a 1 of _Nc, 3b _1, 3c 1 pitch in Cascade (t), since the set each axial code (Ca), Tabin'no Le blade row loss by more is further reduced thereby improving the turbine performance.

  4 to 5 are conceptual diagrams showing turbine stages used when describing the second embodiment of the axial turbine according to the present invention.

  FIG. 6 is a turbine nozzle cascade loss diagram obtained by experiments using the throat pitch ratio (s / t) and pitch / axial code ratio (t / Ca) of the axial flow turbine according to the present invention. is there.

  In addition, the same code | symbol is attached | subjected to the part which is the same as or corresponds to the component shown in 1st Embodiment, and duplication description is abbreviate | omitted.

  The axial turbine according to the present embodiment includes a throat pitch ratio (s / t) Na of the turbine upstream stage Na, a throat pitch ratio (s / t) Nb of the turbine intermediate stage Nb, and a throat pitch ratio of the turbine downstream stage Nc. The relationship with the ratio (s / t) Nc is (s / t) Na> (s / t) Nb> (s / t) Nc, and this relational expression is the turbine nozzle blade which is the experimental data shown in FIG. The minimum value of pitch / axial code ratio (t / Ca) Na, (t / Ca) Nb, (t / Ca) Nc of each paragraph Na, Nb, Nc of the turbine is obtained from the column loss diagram. is there.

  Conventionally, in an axial turbine, the fluid outflow angle of the turbine rotor blade changes during operation. Accordingly, the throat pitch ratio (s / t) of the turbine nozzle is increased at the turbine upstream stage Na in response to this change. There is a case where a turbine design method is adopted in which the size is gradually reduced from the intermediate paragraph Nb toward the turbine downstream paragraph Nc.

  The present embodiment has been made in consideration of such a turbine design technique, and the throat pitch ratio (s / t) Na of the turbine upstream stage Na and the throat pitch ratio (s / t) of the turbine intermediate stage Nb. The relationship between Nb and the throat pitch ratio (s / t) Nc of the turbine downstream stage Nc is (s / t) Na> (s / t) Nb> (s / t) Nc. The minimum values of the pitch / axial code ratios (t / Ca) Na, (t / Ca) Nb, and (t / Ca) Nc in each paragraph Na, Nb, and Nc of the turbine were obtained using the experimental data shown in FIG. Is.

As described above, in the present embodiment, the pitch axial code that minimizes the blade row loss in each of the turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ of each turbine stage Na, Nb, Nc is obtained from the experimental data shown in FIG. The optimum values of the ratios (t / Ca) Na, (t / Ca) Nb, and (t / Ca) Nc are obtained, and the turbine nozzles 3a ₁ , 3b of the turbine stages Na, Nb, Nc are obtained from the obtained optimum values. _{Since the} pitch (t) and the axial code (Ca) in ₁ and 3c ₁ are set, the turbine nozzle cascade loss can be further reduced and the turbine performance can be improved.

  FIG. 9 shows the application range of the pitch / axial code ratio (t / Ca) and the application of the throat pitch ratio (s / t) for further reducing blade row loss in the turbine nozzle of the axial flow turbine according to the present invention. It is a diagram which shows a range.

  Conventionally, the application range of the throat pitch ratio (s / t) for reducing the turbine blade row loss of the turbine nozzle is set to throat pitch ratio (s / t) ≧ 0.19 as shown in FIG.

  This is because the throat pitch ratio (s / t) of each turbine stage Na, Nb, Nc varies depending on the load distribution for each turbine stage Na, Nb, Nc and the setting after the reaction, which is a very small value. Is set as a loss limit value based on experience based on the fact that the outflow angle of the turbine nozzle is reduced and the turbine blade row loss is remarkably increased.

  On the other hand, the relationship between the pitch / axial code ratio (t / Ca) of the turbine nozzle and the turbine nozzle cascade loss is, as can be seen from FIG. 6, the pitch / axial code ratio that is below the limit value of the turbine nozzle cascade loss. There is an optimal range of (t / Ca).

  Now, assuming that the throat pitch ratio (s / t) is s / t = 0.19, the optimum range (loss limit value range) of the pitch / axial code ratio (t / Ca) is shown in FIG. It can be determined as 85 ≦ (t / Ca) ≦ 1.10.

  Since the optimum range of the pitch / axial code ratio (t / Ca) obtained from FIG. 8 varies depending on the size of the throat pitch ratio (s / t), the throat pitch ratio (s / t) is used as a parameter over a wide range. From the test data and analysis results, the optimum range was determined as shown in FIG.

  That is, the pitch-axial chord ratio (t / Ca) and the throat pitch ratio (s / t) are expressed by two relational expressions (t / Ca) = 0.25 × (s / t) +1.05 (t /Ca)=0.25×(s/t)+0.80, the turbine nozzle cascade loss can be suppressed below the limit value.

  Thus, in this embodiment, the pitch / axial code ratio (t / Ca) of the turbine nozzle is 0.25 × (s / t) + 0.80 ≦ (t / Ca) ≦ 0.25 × (s / t) +1.05, and the pitch (t), the axial code (Ca), and the throat (s) are set within the determined range, so that the turbine nozzle cascade loss is further reduced and the turbine is reduced. Performance can be improved.

  FIGS. 10-11 is a conceptual diagram which shows the turbine stage used when describing 3rd Embodiment of the axial flow turbine which concerns on this invention.

  FIG. 12 is a graph showing the number of turbine nozzles in each of the turbine upstream stage, turbine intermediate stage, and turbine downstream stage of the axial flow turbine according to the present invention.

  In addition, the same code | symbol is attached | subjected to the part which is the same as or corresponds to the component shown in 1st Embodiment, and duplication description is abbreviate | omitted.

Axial turbine according to the present embodiment, as shown in FIG. 13, the turbine nozzle 3a 1 of the turbine upstream paragraph _Na, turbine nozzle 3b 1 of the turbine intermediate paragraph _Nb, each of the root of the turbine nozzle 3c ₁ turbine downstream paragraph Nc The blade average diameters PCD-a, PCD-b, and PCD of the turbine upstream stage Na, the turbine intermediate stage Nb, and the turbine downstream stage Nc where the blade height becomes high by a design method in which the reaction degree of the section (root part) is constant. The recoil at -c increases.

  As the degree of reaction increases, the ratio of the pressure drop at the turbine nozzle to the turbine stage pressure drop decreases. In other words, the throat pitch ratio (s / t) of the turbine nozzle increases as shown in FIG. 14 in order to cope with the reduction of the restriction in the turbine nozzle passage portion. Therefore, the optimum value of the pitch / axial code ratio (t / Ca) increases as shown in FIG.

  For this reason, as shown in FIG. 12, the axial codes of the blade average diameters PCD-a, PCD-b, and PCD-c in each turbine stage Na, Nb, Nc are constant from the turbine upstream stage Na to the turbine downstream stage Nc. Or when it becomes larger, the optimum value of the pitch (t) becomes larger, and the number of turbine nozzles na, nb, nc of the turbine stages Na, Nb, Nc gradually decreases.

  The blade average diameters PCD-b and PCD-c increase as the turbine intermediate stage Nb and the turbine downstream stage Nc become larger than the turbine upstream stage Na. As the pitch (t) increases, the optimum value of the pitch-axial code ratio (t / Ca) changes more than the influence.

  Further, in the case of a design method in which the reaction degrees of the blade average diameters PCD-a, PCD-b, and PCD-c of each turbine stage Na, Nb, and Nc are kept constant, the throat pitch of each turbine stage Na, Nb, and Nc Since the ratio (s / t) is substantially constant, the optimum value of the pitch / axial code ratio (t / Ca) is also constant. In this case, when the axial code (Ca) increases, the number of turbine nozzles na, nb, and nc decreases, and the turbine blade row loss decreases.

  Thus, in this embodiment, the number of turbine nozzles suitable for the axial code (Ca), which is one of the parameters that directly affects the performance of the turbine cascade, is selected, so that the turbine cascade loss can be further reduced. Turbine performance can be improved.

  FIG. 16 is a conceptual diagram showing a turbine stage used when explaining the fourth embodiment of the axial turbine according to the present invention.

The axial turbine according to this embodiment includes turbine nozzles 3a ₂ , 3b ₂ , 3c ₂ arranged along the circumferential direction of the turbine rotor 2 housed in the center of the turbine casing 1, and the turbine nozzle 3a _2. Among a plurality of turbine stages in which turbine blades 4a ₂ , 4b ₂ , and 4c ₂ cascaded in pairs on the downstream side of the blade rows 3b ₂ and 3c ₂ are combined as a pair. For example, the application target is three continuous turbine stages, and the turbine rotor blades 4a ₂ , 4b ₂ , and 4c ₂ are the application targets among the three continuous turbine stages. In addition, for convenience of explanation, the three successive turbine stages are described in the order of the flow direction of the working fluid, in order, the turbine upstream stage Ba, the turbine intermediate stage Bb, and the turbine downstream stage Bc.

In general, when considering the turbine cascade performance of the turbine blades 4a ₂ , 4b ₂ , 4c ₂ , the most basic factor is adjacent to one turbine blade element 6a as shown in FIG. A pitch (t), a throat (s), a blade cord (c), and a blade axial cord (Ca) with the other turbine blade element 6b can be mentioned, and are the same as in the case of the turbine nozzle.

  The throat pitch ratio (s / t), pitch code ratio (t / c) and pitch / axial code ratio (t / Ca) combined with these basic factors are the turbine blade cascade load and turbine blade cascade. It is an important parameter that directly affects performance.

FIG. 18 is a turbine rotor blade cascade loss diagram obtained from experimental data using the throat pitch ratio (s / t) and the pitch / axial code ratio (t / Ca). In the figure, the throat pitch ratio (s / t) Ba on the same blade row of the turbine rotor blade 4a ₂ in the turbine upstream stage Ba, and the throat pitch ratio on the same blade row of the turbine rotor blade 4b ₂ in the turbine intermediate stage Bb. (S / t) Bb and the throat pitch ratio (s / t) Bc on the same blade row of 4c ₂ in the turbine downstream stage Bc are both constant, and the throat pitch ratio (s / T) Ba, the throat pitch ratio (s / t) Bb of the turbine intermediate stage Bb and the throat pitch ratio (s / t) Bc of the turbine downstream stage Bc, (s / t) Ba <(s / T) Bb <(s / t) Bc.

  From the turbine rotor blade cascade loss diagram shown in FIG. 18, the pitch / axial code ratio (t / Ca) in the turbine upstream stage Ba, the pitch / axial code ratio (t / Ca) Bb in the turbine intermediate stage Bb, and the turbine downstream stage There is a minimum value of the turbine blade cascade loss of each pitch-axial code ratio (t / Ca) Bc in Bc, and these minimum values are the respective throat pitch ratios in each turbine stage Ba, Bb, Bc. It turned out that it changes with the magnitude of (s / t) Ba, (s / t) Bb, and (s / t) Bc.

Note that the throat pitch ratio (s / t) Ba, (s / t) Bb, (s / t) Bc in each turbine stage Ba, Bb, Bc is the load distribution for each turbine stage Ba, Bb, Bc. Depending on the setting of the reaction degree, it varies for each stage of the turbine, and various distributions may be given in the height direction (radial direction) of the turbine rotor blades 4a ₂ , 4b ₂ , 4c ₂ from the intention of improving the turbine performance.

  However, in this embodiment, the turbine blade height direction as a representative value of the throat pitch ratio (s / t) Ba, (s / t) Bb, and (s / t) Bc of each stage Ba, Bb, and Bc of the turbine. The blade average diameters PCD-a, PCD-b, and PCD-c are set to values corresponding to the center position.

As described above, in the present embodiment, the throat pitch ratio (s / t) of one turbine stage is made constant, the throat pitch ratio (s / t) Ba in the turbine upstream stage Ba, and the turbine intermediate stage Bb. The relationship between the throat pitch ratio (s / t) Bb and the throat pitch ratio (s / t) Bc in the turbine downstream stage Bc is expressed as (s / t) Ba <(s / t) Bb <(s / t) Bc. From this relational expression, using the experimental data shown in FIG. 18, the pitch-axial code that minimizes the cascade loss in each of the turbine rotor blades 4a ₂ , 4b ₂ , 4c ₂ of the turbine paragraphs Ba, Bb, Bc Optimum values of the ratios (t / Ca) Ba, (t / Ca) Bb, and (t / Ca) Bc are determined, and the turbine blades of the turbine paragraphs Ba, Bb, and Bc are determined from the determined optimal values. a _2, 4b _2, 4c 2 pitch in the blade row (t), since the set each axial code (Ca), can be a turbine moving blade cascade loss more by further reduced to improve the turbine performance.

  19-20 is a conceptual diagram which shows the turbine stage used when describing 5th Embodiment of the axial flow turbine which concerns on this invention.

  FIG. 21 is a turbine rotor blade cascade loss diagram obtained through an experiment on the axial turbine according to the present invention.

  In addition, the same code | symbol is attached | subjected to the part which is the same as or corresponds to the component shown in 4th Embodiment, and duplication description is abbreviate | omitted.

The axial turbine according to the present embodiment includes a throat pitch ratio (s / t) Ba of the turbine upstream stage Ba, a throat pitch ratio (s / t) Bb of the turbine intermediate stage Bb, and a throat pitch ratio of the turbine downstream stage Bc. The relationship with the ratio (s / t) Bc is (s / t) Ba> (s / t) Bb> (s / t) Bc, and the turbine rotor blade, which is the experimental data shown in FIG. From the row loss diagram, the pitch / axial code ratio (t / Ca) Ba, (t where the blade row loss in each of the turbine rotor blades 4a ₂ , 4b ₂ , 4c ₂ of each turbine stage Ba, Bb, Bc is minimized. / Ca) Bb, (t / Ca) Bc optimum values are obtained.

This embodiment is similar to the turbine nozzles 3a ₁ , 3b ₁ , 3c ₁ of the turbine stages Na, Nb, Nc, and has a throat pitch ratio (s / t) Ba of the turbine upstream stage Ba, and a throat of the turbine intermediate stage Bb. The relationship between the pitch ratio (s / t) Bc and the throat pitch ratio (s / t) Bc of the turbine downstream stage Bc is expressed as (s / t) Ba> (s / t) Bb> (s / t) Bc From this relational expression, the pitch-axial code ratio (t / Ca) Ba, (t / Ca) Bb that minimizes the cascade loss in each stage Ba, Bb, Bc of the turbine using the experimental data shown in FIG. , (T / Ca) Bc, and the pitch (t) in the turbine blades 4a ₂ , 4b ₂ , 4c ₂ of the turbine paragraphs Ba, Bb, Bc, and the axial code ( C Since each of a) is set, the turbine blade cascade loss can be further reduced and the turbine performance can be improved.

  FIG. 24 shows the application range of the pitch / axial code ratio (t / Ca) and the throat pitch ratio (s / t) for further reducing cascade loss in the turbine rotor blade of the axial flow turbine according to the present invention. It is a diagram which shows an application range.

  Conventionally, the application range of the throat pitch ratio (s / t) for reducing the turbine blade row loss of the turbine rotor blade is set as throat pitch ratio (s / t) ≧ 0.28 as shown in FIG.

  This is because the throat pitch ratio (s / t) of each turbine stage Ba, Bb, Bc varies depending on the load distribution and reaction degree setting for each turbine stage Ba, Bb, Bc, and it is a very small value. Is set as a loss limit value based on experience based on the fact that the outflow angle of the turbine rotor blade is reduced and the turbine rotor blade cascade loss is remarkably increased.

  On the other hand, the relationship between the pitch / axial code ratio (t / Ca) of the turbine blade and the turbine blade cascade loss is, as can be seen from FIG. 21, the throat pitch ratio (s / t) of the turbine blade cascade. ), There is an optimum range of the pitch / axial code ratio (t / Ca) that is not more than the limit value of the turbine blade cascade loss.

  Now, assuming that the throat pitch ratio (s / t) is s / t = 0.28, the optimum range (loss limit value range) of the pitch / axial code ratio (t / Ca) is shown in FIG. 50 ≦ (t / Ca) ≦ 0.90.

  The pitch / axial code ratio (t / Ca) obtained from FIG. 23 was varied over a wide range as a parameter, and the optimum range was determined as shown in FIG. 24 from the test data and analysis results.

  That is, the pitch-axial chord ratio (t / Ca) and the throat pitch ratio (s / t) are expressed by two relational expressions (t / Ca) = 1.4 × (s / t) +0.51 (t /Ca)=1.4×(s/t)+In the range between 0.11, the turbine rotor blade cascade loss can be suppressed to a limit value or less.

  Thus, in this embodiment, the pitch-axial code ratio (t / Ca) of the turbine rotor blade is 1.4 × (s / t) + 0.11 ≦ (t / Ca) = 1.4 × (s /T)+0.51, and the pitch (t), axial code (Ca), and throat (s) are set within the determined range, so that the turbine blade cascade loss can be further reduced. Turbine performance can be improved.

  The axial flow turbine according to the present invention has been studied and considered separately for improving the performance of the turbine nozzle cascade and improving the performance of the turbine bucket cascade, but in combination with the turbine nozzle and the turbine bucket. The same effect can be obtained even if they are handled and examined together.

  At that time, the pitch / axial code ratio (t / Ca), which is one of dimensionless parameters, is the same even if the pitch / blade code ratio (t / c) with the blade code (C) as a factor is replaced. Properties and effects are obtained.

  Further, the axial turbine according to the present invention has been applied to three continuous turbine stages. However, the present invention is not limited to this example, and any two or more paragraphs may be selected as long as they are arbitrarily selected. There may be.

The conceptual diagram which shows the turbine stage used when describing 1st Embodiment of the axial flow turbine which concerns on this invention. Sectional drawing cut | disconnected from the AA arrow direction of FIG. In the first embodiment of the axial flow turbine according to the present invention, a turbine nozzle cascade loss diagram obtained from experimental data using a throat pitch ratio and a pitch axial code ratio. The conceptual diagram which shows the turbine stage used when describing 2nd Embodiment of the axial flow turbine which concerns on this invention. Sectional drawing cut | disconnected from the BB arrow direction of FIG. In the second embodiment of the axial turbine according to the present invention, a turbine nozzle cascade loss diagram obtained from experimental data using a throat pitch ratio and a pitch axial code ratio. FIG. 6 is a turbine nozzle cascade loss diagram with the throat pitch ratio of the turbine nozzle as a parameter. A turbine nozzle cascade loss diagram with a throat pitch ratio of 0.19 and a turbine nozzle pitch / axial code ratio as a parameter. The axial flow turbine which concerns on this invention WHEREIN: The diagram which shows the applicable range of the throat pitch ratio of a turbine nozzle, and the applicable range of the pitch-axial code ratio of a turbine nozzle. The conceptual diagram which shows the turbine paragraph used when describing 3rd Embodiment of the axial flow turbine which concerns on this invention. Sectional drawing cut | disconnected from CC arrow direction of FIG. In 3rd Embodiment of the axial flow turbine which concerns on this invention, the graph which shows the number of turbine nozzles in each of a turbine upstream stage, a turbine middle stage, and a turbine downstream stage. The diagram which shows each reaction degree of the blade root of a turbine nozzle, blade center, and blade tip in each of the turbine upstream stage, turbine intermediate stage, and turbine downstream stage. The diagram which shows the throat pitch ratio of the turbine nozzle in each of a turbine upstream stage, a turbine middle stage, and a turbine downstream stage. The diagram which shows the pitch-axial code ratio of the turbine nozzle in each of a turbine upstream stage, a turbine middle stage, and a turbine downstream stage. The conceptual diagram which shows the turbine stage used when describing 4th Embodiment of the axial flow turbine which concerns on this invention. FIG. 17 is a cross-sectional view taken along line DD in FIG. 16. In 4th Embodiment of the axial flow turbine which concerns on this invention, the turbine rotor blade cascade row loss figure calculated | required from experimental data using throat pitch ratio and pitch axial code ratio. The conceptual diagram which shows the turbine paragraph used when describing 5th Embodiment of the axial flow turbine which concerns on this invention. Sectional drawing cut | disconnected from the EE arrow direction of FIG. In 5th Embodiment of the axial flow turbine which concerns on this invention, the turbine rotor blade cascade diagram calculated | required from experimental data using the throat pitch ratio and the pitch axial code ratio. The turbine rotor blade cascade loss diagram with the throat pitch ratio of the turbine rotor blade as a parameter. FIG. 6 is a turbine rotor blade cascade loss diagram in which a throat pitch ratio is 0.28 and a pitch / axial code ratio of a turbine rotor blade is a parameter. In the axial turbine which concerns on this invention, the diagram which shows the applicable range of the throat pitch ratio of a turbine rotor blade, and the applicable range of the pitch-axial code ratio of a turbine rotor blade.

Explanation of symbols

1 turbine casing 2 turbine rotor _{3a 1, 3a 2, 3b 1} , 3b 2, 3c 1, 3c 2 turbine nozzle _{4a 1, 4a 2, 4b 1} , 4b 2, 4c 1, 4c 2 turbine blades 5a, 5b nozzle blade Element 6a, 6b Turbine blade element

Claims (13)

A turbine rotor blade cascade arranged along the circumferential direction of the turbine rotor is provided adjacent to a turbine nozzle cascade disposed along the circumferential direction of the turbine rotor, and the turbine nozzle cascade and the turbine motion A turbine stage is configured by combining blade cascades, and the turbine stage is provided with a plurality of stages in the axial direction of the turbine rotor. In the axial turbine including the plurality of stages, at least two of the turbine stages having a plurality of stages are provided. And the turbine nozzle throat pitch ratio is increased from the upstream turbine stage toward the downstream turbine stage. The optimum value of the pitch-axial code ratio that minimizes the cascade loss of the turbine nozzle is obtained, and the optimum value is obtained from the obtained optimum value. Axial flow turbine, characterized in that setting the pitch and axial code Bin'nozuru. A turbine rotor blade cascade arranged along the circumferential direction of the turbine rotor is provided adjacent to a turbine nozzle cascade disposed along the circumferential direction of the turbine rotor, and the turbine nozzle cascade and the turbine motion A turbine stage is configured by combining blade cascades, and the turbine stage is provided with a plurality of stages in the axial direction of the turbine rotor. In the axial turbine including the plurality of stages, at least two of the turbine stages having a plurality of stages are provided. The target turbine stage is a continuous turbine stage, and the throat pitch ratio of the turbine nozzle is reduced from the upstream turbine stage toward the downstream turbine stage. The optimum value of the pitch-axial code ratio that minimizes the cascade loss of the turbine nozzle is obtained, and the optimum value is obtained from the obtained optimum value. Axial flow turbine, characterized in that setting the pitch and axial code Bin'nozuru. The axial flow turbine according to claim 1 or 2, wherein the throat and pitch of the throat pitch ratio are values of a position of a blade average diameter in a cascade of turbine nozzles. The axial flow turbine according to claim 1 or 2, wherein the throat pitch ratio is in a range of 0.19 or more. The pitch / axial code ratio and throat / pitch ratio are (t / Ca) = 0.25 × (s / t) +1.05, where t is the pitch, Ca is the axial code, and s is the throat. The axial flow turbine according to claim 1 or 2, wherein the axial flow turbine is in a region surrounded by (Ca) = 0.25 x (s / t) + 0.80. A turbine rotor blade cascade arranged along the circumferential direction of the turbine rotor is provided adjacent to a turbine nozzle cascade disposed along the circumferential direction of the turbine rotor, and the turbine nozzle cascade and the turbine motion A turbine stage is configured by combining blade cascades, and the turbine stage is provided with a plurality of stages in the axial direction of the turbine rotor. In the axial turbine including the plurality of stages, at least two of the turbine stages having a plurality of stages are provided. And the turbine nozzle axial code is made constant or larger from the upstream turbine stage toward the downstream turbine stage. An axial flow turbine characterized in that the number of turbine nozzles is reduced. The axial flow turbine according to claim 6, wherein the axial code is a value of a position of a blade average diameter in a cascade of turbine nozzles. A turbine rotor blade cascade arranged along the circumferential direction of the turbine rotor is provided adjacent to a turbine nozzle cascade disposed along the circumferential direction of the turbine rotor, and the turbine nozzle cascade and the turbine motion A turbine stage is configured by combining blade cascades, and the turbine stage is provided with a plurality of stages in the axial direction of the turbine rotor. In the axial turbine including the plurality of stages, at least two of the turbine stages having a plurality of stages are provided. The turbine turbine blades have a throat pitch ratio that increases from the upstream turbine stage toward the downstream turbine stage among the continuous turbine stages. Next, an optimum value of the pitch / axial code ratio that minimizes the cascade loss of the turbine rotor blade is obtained, and the tar is determined from the obtained optimum value. Axial flow turbine, characterized in that setting the pitch and axial code Ndotsubasa. A turbine rotor blade cascade arranged along the circumferential direction of the turbine rotor is provided adjacent to a turbine nozzle cascade disposed along the circumferential direction of the turbine rotor, and the turbine nozzle cascade and the turbine motion A turbine stage is configured by combining blade cascades, and the turbine stage is provided with a plurality of stages in the axial direction of the turbine rotor. In the axial turbine including the plurality of stages, at least two of the turbine stages having a plurality of stages are provided. The turbine blades have a throat pitch ratio that decreases from the upstream turbine stage toward the downstream turbine stage among the continuous turbine stages. Next, an optimum value of the pitch / axial code ratio that minimizes the cascade loss of the turbine rotor blade is obtained, and the tar is determined from the obtained optimum value. Axial flow turbine, characterized in that setting the pitch and axial code Ndotsubasa. The axial flow turbine according to claim 8 or 9, wherein the throat and pitch of the throat pitch ratio are values of a position of a blade average diameter in a cascade of turbine blades. The axial flow turbine according to claim 8 or 9, wherein the throat pitch ratio is in a range of 0.28 or more. The pitch / axial code ratio and throat / pitch ratio are (t / Ca) = 1.4 × (s / t) +0.51, where t is the pitch, Ca is the axial code, and s is the throat. The axial flow turbine according to claim 8 or 9, wherein the axial flow turbine is in a region surrounded by (Ca) = 1.4 × (s / t) +0.11. An axial-flow turbine comprising a combination of at least one of the turbine nozzles according to claim 1, 2 and 6, and at least one of the turbine rotor blades according to claims 7 and 9. .

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