JP2009243395A - Turbine blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbine blade capable of preventing a crack or breakage even when resonance occurs. <P>SOLUTION: This turbine blade 1 is the turbine blade of a radial turbine having an inlet of fluid in a radial direction and an outlet of the fluid in an axial direction, and blade thickness distribution is set so that a blade surface extended to the front and rear sides of the maximum blade thickness part forms a protrusion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure of a turbine blade, and more particularly to a structure of a turbine blade of a radial turbine used for a supercharger or the like.

  A radial turbine used for a fluid machine such as a turbocharger (turbocharger) recovers fluid energy by supplying fluid such as exhaust gas from the radial direction and rotating a turbine impeller to rotate a rotating shaft. This is a device that outputs power to the cylinder and discharges the finished fluid in the axial direction. Here, FIG. 6 is a figure which shows the component of a general radial turbine, (A) is a front view of a turbine impeller, (B) is a side view of a turbine blade. As shown in FIG. 6 (A), the turbine wheel of the radial turbine has a plurality of turbine blades 61 and a turbine disk 62 having an enlarged diameter at the end, and the turbine blade 61 stands on the turbine disk 62. It is installed. As shown in FIG. 6 (B), the turbine blade 61 includes a leading edge 61a that constitutes a front edge end portion on the inlet side, and a trailing edge 61b that constitutes a rear edge end portion on the outlet side. Generally, the side close to the turbine disk 62 is referred to as a hub surface 61c, and the side close to a turbine housing (not shown) is referred to as a tip surface 61d.

  Since the turbine blade 61 collides in sequence with the fluid supplied from the leading edge 61a side by the rotation of the turbine impeller, the turbine blade 61 is likely to vibrate. When this vibration coincides with the natural frequency of the turbine blade 61, the turbine blade 61 resonates and causes cracking or breakage. In particular, a portion near the trailing edge 61b and the tip surface 61d of the turbine blade 61, for example, a region α surrounded by a broken line in FIG. It is known that the vibration of the turbine blade 61 includes a primary mode and a secondary mode as described in Patent Document 1. Generally, in the design of a vibration member having a natural frequency, either a technique for avoiding a resonance point or a technique for withstanding resonance is employed. The technique described in Patent Document 1 is designed to make the frequency of the low primary mode close to the frequency of the high secondary mode, and belongs to the technique of avoiding the resonance point.

JP-A-8-246801

  However, in the method of avoiding the resonance point, there are cases where the resonance point cannot be avoided depending on the use conditions of the vibrating member or the design itself that completely avoids the resonance point may be difficult. Therefore, turbine blades designed by a technique that avoids the resonance point are vulnerable to resonance, and once resonated, there is a problem that cracks and breakage occur without being able to withstand the vibration.

  The present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a turbine blade that is less likely to crack or break even when resonating.

  According to the present invention, a turbine blade of a radial turbine having a fluid inlet in a radial direction and a fluid outlet in an axial direction, the blade surface extending before and after the maximum blade thickness portion forms a convex portion. A turbine blade characterized by setting a blade thickness distribution is provided.

  The convex portion may be formed in a range of 15% to 80% of the blade height, or may be formed in a range of 50% to 80% of the blade height.

  In the turbine blade, an inflection point is preferably arranged on the inlet side of the maximum blade thickness portion. For example, in the case where the outlet side of the turbine blade is 0 and the inlet side is 1, and the position in the blade length direction is expressed as a blade length ratio, the inflection point is arranged in the range of 0.6 to 0.9.

  The blade thickness distribution is such that when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1 and the blade thickness distribution is expressed as a blade thickness ratio, the blade thickness ratio is 0.5 or more. You may set so that it may become a ratio of 80% or less of length. Further, the blade thickness distribution may be set so that a portion where the blade thickness ratio is 0.6 or more is a ratio of 70% or less, or a portion where the blade thickness ratio is 0.7 or more. It may be set so that the ratio is 60% or less, the part where the blade thickness ratio is 0.8 or more may be set so that the ratio is 50% or less, and the blade thickness ratio is You may set so that the part which becomes 0.9 or more may be a ratio of 40% or less.

  According to the turbine blade of the present invention described above, the blade thickness distribution is set so that the blade surface extending before and after the maximum blade thickness portion forms a convex portion, whereby a turbine blade resistant to resonance can be obtained. Even when the wings resonate, cracks and breakage can be made difficult to occur. Further, by forming the convex portion within a predetermined range of the blade height, a turbine blade that is effectively resistant to resonance can be obtained. Moreover, the said convex part can be effectively formed by arrange | positioning an inflection point in a predetermined position. Moreover, the said convex part can be effectively formed by setting blade | wing thickness distribution so that the part which satisfy | fills a predetermined | prescribed blade | wing thickness ratio becomes a predetermined | prescribed ratio.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Here, FIG. 1 is a figure which shows the turbine blade which concerns on this invention, (A) is 1st embodiment, (B) has shown 2nd embodiment.

  A turbine blade 1 according to the present invention shown in FIGS. 1A and 1B is a turbine blade of a radial turbine having a fluid inlet in a radial direction and a fluid outlet in an axial direction, and has a maximum blade thickness. The blade thickness distribution is set so that the blade surface extending before and after the portion forms a convex portion. The turbine blade 1 is erected on a turbine disk 2, and includes a leading edge 1a constituting a front edge end portion on the inlet side, a trailing edge 1b constituting a rear edge end portion on the outlet side, and a turbine disk. 2 has a hub surface 1c which is a surface erected on 2 and a tip surface 1d facing a turbine housing (not shown).

  In the first embodiment shown in FIG. 1A, the convex portion is formed in a wide range in the blade height direction. In the present invention, the “blade height” means a span S from the hub surface 1c to the tip surface 1d when a perpendicular is made to the hub surface 1c. In general, the maximum blade thickness portion of the turbine blade 1 is a range of a region T1 surrounded by a broken line in the figure (for example, the outlet side of the turbine blade 1 is 0 and the inlet side is 1, and the blade length direction position is expressed by the blade length ratio. In many cases, it is set within the range of 0.3 to 0.5. The region T1 in the first embodiment is set so as to include a range of 15% to 80% of the blade height (span S) in the maximum blade thickness portion, and the portion of the region T1 becomes a convex portion. Has a blade thickness distribution. Here, the region T1 is shown in a circular shape, but may be set in an elliptical shape or a polygonal shape, or may be set in a shape along the hub surface 1c and the chip surface 1d. In this way, by forming the convex portion in the range of the region T1, a turbine blade resistant to resonance can be obtained.

  In the second embodiment shown in FIG. 1B, the convex portion is formed in a narrow range in the blade height direction. The region T2 in the second embodiment is set so as to include a range of 50% to 80% of the blade height (span S) in the maximum blade thickness portion, and the region T2 has a convex portion. The thickness distribution is set. Here, although the region T1 is shown as an elliptical shape, it may be set in a circular shape or a polygonal shape, or may be set in a shape along the hub surface 1c and the chip surface 1d. In general, since the turbine blade is thick on the hub surface 1c side and thin on the tip surface 1d side, by forming a convex portion in the region T2 formed relatively thin, the turbine blade resistant to resonance can be effectively formed. Can be formed.

  Next, the blade thickness distribution of the turbine blade according to the present invention will be described. Here, FIG. 2 is a view showing the blade thickness distribution of the turbine blade according to the present invention, (A) shows the position of the inflection point, and (B) shows the portion where the blade thickness ratio is 0.6 or more. The ratio to the wing length is shown. In each figure, the vertical axis indicates the blade thickness ratio, the horizontal axis indicates the blade length ratio, and the illustrated blade thickness distribution indicates the blade thickness distribution at a position where the blade height is 50%. The “blade thickness ratio” is the ratio of the blade thickness expressed as a ratio, where the minimum blade thickness of the turbine blade 1 is 0 and the maximum blade thickness is 1, and the “blade length ratio” is the outlet of the turbine blade 1. The blade length direction position is expressed as a ratio, with 0 on the side (trailing edge 1b) and 1 on the inlet side (leading edge 1a).

  As shown in FIG. 2A, the blade thickness distribution of the conventional example is indicated by ● and a broken line, Example 1 according to the present invention is indicated by □ and a solid line, and Example 2 is indicated by Δ and a solid line (FIG. 2). The same applies to 2 (B) and thereafter. The inflection point is expressed by a mark combining ◯ and x, and the inflection point of Example 1 is P1, and the inflection point of Example 2 is P2. In addition, the blade thickness distribution of Example 1 and Example 2 can be applied to each of the first embodiment and the second embodiment shown in FIG.

  As shown in FIG. 2A, the blade thickness distributions of the conventional example, the first embodiment, and the second embodiment have the maximum blade thickness portion at a position where the blade length ratio is 0.4. The blade thickness distribution of the conventional example is expressed by an upwardly convex curve having no inflection point in the range of the blade length ratio 0-1. On the other hand, in the blade thickness distribution of Example 1 and Example 2, the inflection points P1 and P2 are arranged on the inlet side of the maximum blade thickness part (blade length ratio 0.4). Specifically, the inflection point P1 of Example 1 is arranged at a position where the blade length ratio is about 0.7, and the inflection point P2 of Example 2 is located at a position where the blade length ratio is about 0.85. Is arranged. As in these embodiments, by arranging the inflection points P1 and P2 between the maximum blade thickness portion and the inlet side (here, the blade length ratio is in the range of 0.4 to 1.0), the inlet side And inflection points P1 and P2, a downward convex curve can be drawn, and a convex portion can be formed on the blade surface across the front and rear of the maximum blade thickness portion. In order to effectively form such a convex portion, it is preferable to arrange the inflection points P1 and P2 in a region U surrounded by a one-dot chain line in the figure. Specifically, the inflection points P1 and P2 are preferably arranged in the range of the blade length ratio 0.6 to 0.9. Further, in order to effectively form the convex portion, the blade thickness distribution in the portion on the outlet side from the maximum blade thickness portion may be set to be gradually decreased linearly.

  The blade thickness distribution of the first and second embodiments described above can also be defined using the blade thickness ratio. FIG. 2 (B) shows the ratio of the blade thickness ratio to the blade length in the portion where the blade thickness ratio is 0.6 or more. Here, in the conventional example, the length of the portion where the blade thickness ratio is 0.6 or more is LP, in Example 1, the length of the portion where the blade thickness ratio is 0.6 or more is L1, and in Example 2, the blade thickness ratio is The length of the portion of 0.6 or more is L2. In the turbine blade of the conventional example, since the blade thickness distribution is set to be convex upward as a whole, the length LP of the portion where the blade thickness ratio is 0.6 or more tends to be long, and the blade length ratio is about 0. It accounts for 77% of the blade length over the range of .06 to about 0.83. On the other hand, in the turbine blades of Example 1 and Example 2, since the blade thickness distribution is set so that convex portions are formed on the blade surface over the front and rear of the maximum blade thickness portion, the blade thickness ratio is 0.6 or more. The lengths L1 and L2 of the portion are set to be short. Specifically, the length L1 of the portion having the blade thickness ratio of 0.6 or more in the first embodiment is about 55 to the blade length over the range of the blade length ratio of about 0.11 to about 0.66. % Accounted for. Further, the length L2 of the portion where the blade thickness ratio is 0.6 or more in the embodiment 2 is a ratio of about 60% with respect to the blade length over the range of the blade length ratio of about 0.13 to about 0.73. Accounted for. Comparing the blade thickness distributions of Examples 1 and 2 and the conventional example, the portion where the blade thickness ratio is 0.6 or more is 70% or less, preferably about 60% or less of the blade length. By setting the blade thickness distribution so as to be, a turbine blade strong against resonance can be obtained.

  The blade thickness distribution of the first and second embodiments described above can also be defined using other blade thickness ratios. Here, FIG. 3 is a view showing the blade thickness distribution of the turbine blade according to the present invention, wherein (A) shows the ratio of the blade thickness ratio to a blade length of 0.5 or more, and (B) shows the blade thickness. The ratio with respect to the blade length of the part whose thickness ratio is 0.7 or more is shown. FIG. 4 is a view showing the blade thickness distribution of the turbine blade according to the present invention, where (A) shows the ratio of the blade thickness ratio to the blade length of the portion of 0.8 or more, and (B) shows the blade thickness. The ratio with respect to the blade length of the part whose ratio is 0.9 or more is shown.

  As shown in FIG. 3A, in the conventional turbine blade, the length LP of the portion where the blade thickness ratio is 0.5 or more is in the range of the blade length ratio of about 0.05 to about 0.86. It accounts for 81% of the wing length. Further, the length L1 of the portion where the blade thickness ratio in the first embodiment is 0.5 or more is a ratio of about 65% with respect to the blade length over the range of the blade length ratio of about 0.06 to about 0.71. Accounted for. Further, the length L2 of the portion having the blade thickness ratio of 0.5 or more in Example 2 is a ratio of about 66% with respect to the blade length over the range of the blade length ratio of about 0.11 to about 0.77. Accounted for. Comparing the blade thickness distributions of Examples 1 and 2 and the conventional example, the portion where the blade thickness ratio is 0.5 or more is 80% or less, preferably about 70% or less of the blade length. By setting the blade thickness distribution so as to be, a turbine blade strong against resonance can be obtained.

  As shown in FIG. 3B, in the conventional turbine blade, the length LP of the portion where the blade thickness ratio is 0.7 or more is in the range of the blade length ratio of about 0.1 to about 0.77. It accounts for 67% of the wing length. Further, the length L1 of the portion where the blade thickness ratio is 0.7 or more in Example 1 is a ratio of about 47% with respect to the blade length over the range of the blade length ratio of about 0.15 to about 0.62. Accounted for. Further, the length L2 of the portion where the blade thickness ratio is 0.7 or more in the embodiment 2 is a ratio of about 50% with respect to the blade length over the range of the blade length ratio of about 0.17 to about 0.67. Accounted for. Comparing the blade thickness distributions of Examples 1 and 2 and the conventional example, the portion where the blade thickness ratio is 0.7 or more is 60% or less, preferably about 50% or less of the blade length. By setting the blade thickness distribution so as to be, a turbine blade strong against resonance can be obtained.

  As shown in FIG. 4A, in the conventional turbine blade, the length LP of the portion where the blade thickness ratio is 0.8 or more is in the range of the blade length ratio of about 0.13 to about 0.73. It accounts for 60% of the wing length. Further, the length L1 of the portion where the blade thickness ratio is 0.8 or more in Example 1 is a ratio of about 37% with respect to the blade length over the range of the blade length ratio of about 0.2 to about 0.57. Accounted for. Further, the length L2 of the portion where the blade thickness ratio is 0.8 or more in Example 2 is a ratio of about 41% with respect to the blade length over the range of the blade length ratio of about 0.22 to about 0.63. Accounted for. Comparing the blade thickness distributions of Examples 1 and 2 and the conventional example, the portion where the blade thickness ratio is 0.8 or more is a ratio of 50% or less with respect to the blade length, preferably a ratio of about 45% or less. By setting the blade thickness distribution so as to be, a turbine blade strong against resonance can be obtained.

  As shown in FIG. 4B, in the conventional turbine blade, the length LP of the portion where the blade thickness ratio is 0.9 or more is in the range of the blade length ratio of about 0.2 to about 0.65. It accounts for 45% of the wing length. In addition, the length L1 of the portion where the blade thickness ratio is 0.9 or more in Example 1 is a ratio of about 27% with respect to the blade length over the range of the blade length ratio of about 0.25 to about 0.52. Accounted for. Further, the length L2 of the portion where the blade thickness ratio is 0.9 or more in Example 2 is a ratio of about 29% with respect to the blade length over the range of the blade length ratio of about 0.27 to about 0.56. Accounted for. Comparing the blade thickness distributions of Examples 1 and 2 and the conventional example, the portion where the blade thickness ratio is 0.9 or more is 40% or less, preferably about 30% or less of the blade length. By setting the blade thickness distribution so as to be, a turbine blade strong against resonance can be obtained.

  When the blade thickness distribution of the turbine blade according to the present invention is defined by using the blade thickness ratio based on Example 1 and Example 2, the ratio of the portion satisfying the conditions of each blade thickness ratio to the blade length is too small. For example, in FIG. 4 (B), the blade length ratio is in the range of 0.3 to 0.5 because the protrusions are formed remarkably and the fluid flow on the blade surface may be hindered. It is preferable not to include L1. Therefore, the lower limit of the ratio with respect to the blade length of the portion satisfying the condition of each blade thickness ratio is set to 20%, for example.

  Finally, the effect of the turbine blade according to the present invention will be described. Here, FIG. 5 is a diagram showing a result of vibration stress analysis using the turbine blades having the blade thickness distribution of the conventional example and the first embodiment described above. In FIG. 5, the vertical axis indicates the vibration stress ratio. The “vibration stress ratio” represents the maximum vibration stress value in the first embodiment as a ratio with the maximum vibration stress value in the conventional example being 1.

  As shown in FIG. 5, when the maximum vibration stress value of the conventional example is 1, the maximum vibration stress value of Example 1 is 0.838. That is, the vibration stress reduction value ΔF in Example 1 was 0.162, and it was confirmed that there was a 16.2% reduction effect. The maximum vibration stress value means the maximum value of stress generated when the turbine blades of the conventional example and the first embodiment are vibrated at their natural frequencies.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

It is a figure which shows the turbine blade which concerns on this invention, (A) is 1st embodiment, (B) has shown 2nd embodiment. It is a figure which shows the blade thickness distribution of the turbine blade which concerns on this invention, (A) shows the position of an inflection point, (B) has shown the range whose blade thickness ratio is 0.6 or more. It is a figure which shows the blade thickness distribution of the turbine blade which concerns on this invention, (A) shows the ratio with respect to the blade length of the part whose blade thickness ratio is 0.5 or more, (B) is a blade thickness ratio of 0.7 or more. The ratio with respect to the wing length is shown. It is a figure which shows the blade thickness distribution of the turbine blade which concerns on this invention, (A) shows the ratio with respect to the blade length of the part whose blade thickness ratio is 0.8 or more, (B) is a blade thickness ratio of 0.9 or more. The ratio with respect to the wing length is shown. It is a figure which shows the result of having performed the vibration stress analysis using the turbine blade which has a blade thickness distribution of a prior art example and Example 1. FIG. It is a figure which shows the component of a general radial turbine, (A) is a front view of a turbine impeller, (B) is a side view of a turbine blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine blade 1a Leading edge 1b Trailing edge 1c Hub surface 1d Tip surface 2 Turbine disk 61 Turbine disk 62 Turbine blade 62a Leading edge 62b Trailing edge

Claims (10)

A turbine blade of a radial turbine having a fluid inlet in a radial direction and a fluid outlet in an axial direction,
A turbine blade characterized in that a blade thickness distribution is set so that a blade surface extending before and after the maximum blade thickness portion forms a convex portion.   The turbine blade according to claim 1, wherein the convex portion is formed in a range of 15% to 80% of the blade height.   The turbine blade according to claim 1, wherein the convex portion is formed in a range of 50% to 80% of the blade height.   The turbine blade according to claim 1, wherein an inflection point is disposed on an inlet side of the maximum blade thickness portion.   The inflection point is arranged in the range of 0.6 to 0.9 when the outlet side of the turbine blade is 0 and the inlet side is 1, and the blade length direction position is expressed in blade length ratio. The turbine blade according to claim 4.   The blade thickness distribution is such that when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1 and the blade thickness distribution is expressed as a blade thickness ratio, the blade thickness ratio is 0.5 or more. The turbine blade according to claim 1, wherein the turbine blade is set to have a ratio of 80% or less of the length.   The blade thickness distribution is such that when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1, and the blade thickness distribution is expressed as a blade thickness ratio, the portion where the blade thickness ratio is 0.6 or more is 70. 2. The turbine blade according to claim 1, wherein the turbine blade is set to have a ratio of not more than%.   In the blade thickness distribution, when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1 and the blade thickness distribution is expressed as a blade thickness ratio, the portion where the blade thickness ratio is 0.7 or more is 60. 2. The turbine blade according to claim 1, wherein the turbine blade is set to have a ratio of not more than%.   In the blade thickness distribution, when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1 and the blade thickness distribution is expressed as a blade thickness ratio, the blade thickness ratio is 50 or more. 2. The turbine blade according to claim 1, wherein the turbine blade is set to have a ratio of not more than%.   In the blade thickness distribution, when the minimum blade thickness of the turbine blade is 0 and the maximum blade thickness is 1 and the blade thickness distribution is expressed as a blade thickness ratio, the portion where the blade thickness ratio is 0.9 or more is 40. 2. The turbine blade according to claim 1, wherein the turbine blade is set to have a ratio of not more than%.