JP7216335B2 - turbine rotor blade - Google Patents

Description

The present disclosure relates to turbine blades.

A gas turbine engine, such as a turbofan engine, includes as major components a compressor, a combustor and a turbine.

Among these, the turbine, which is an element that converts the thermal energy of the combustion gas generated in the combustor into rotational energy, has one or more stages arranged in the axial direction. It consists of a plurality of stator vanes and rotor blades arranged at regular intervals.

Turbine blades typically have, in radially outward order, an airfoil portion, a platform, a shank and a dovetail.

The blade portion is a portion that extends in the radial direction across the mainstream flow path (flow path of the combustion gas) and has an airfoil-shaped cross-sectional shape (profile). and downstream located leading and trailing edges, and a concave pressure side and a convex suction side extending respectively between the leading and trailing edges. The blade section receives a reaction force in the circumferential direction from the combustion gas by deflecting the combustion gas flowing out from the stator blades arranged upstream, and the torque generated by this reaction force rotates the turbine rotor. The tip portion (radially outer tip portion) of the blade portion is a member (cylindrical turbine casing or an inner periphery of the turbine casing) that is arranged radially outwardly of the blade portion and defines the radially outer end of the main flow passage. Circularly arranged shroud segments) are opposed to each other through a small clearance.

The platform is a plate-like portion coupled to the hub portion (the radially inner proximal end) of the wing and defines the radially inner end of the mainstream flow path.

The dovetail is the radially inner end portion of the blade and is connected to the platform by a shank. The moving blade is attached to the disk by fitting the dovetail into a groove provided on the outer peripheral surface of the disk that constitutes the turbine rotor.

In addition, the rotor blades, which are arranged in the portion of the main flow passage where particularly high-temperature combustion gas flows (that is, the portion on the upstream side closer to the combustor), usually have a hollow structure and pass through the dovetail and the shank. A cooling medium introduced through a supply passage (usually air extracted from a compressor) is cooled by flowing through cooling passages provided inside the blades.

A technique of providing a squealer at the tip portion of the blade portion of the rotor blade configured as described above is known (see, for example, Patent Document 1).

A squealer is a thin plate-like portion disposed along the periphery of the profile so as to surround a radially inwardly directed recess formed in the tip of the wing, and typically has a thickness of constant along the The squealer has an outer surface (i.e., the side opposite to the inner surface facing the recess) that forms part of the pressure or suction surface, and although it is part of the airfoil, it is It is assumed that if the tip of the airfoil comes into contact with the turbine casing or shroud segment, it will wear easily due to its thin plate-like shape. As a result, if the above-described contact occurs, the turbine casing or shroud segment wears and the clearance between the blade tip and the blade becomes excessively wide, resulting in turbine rotor blades, and thus the turbine and gas turbine engine. This avoids a situation in which the performance of the

On the other hand, for the purpose of improving aerodynamic performance, there is known a technique of curving a wing in a span direction (longitudinal direction) in a bow shape.

For example, in the turbine rotor blade disclosed in Patent Literature 2, the blade portion is curved in a bow shape in the direction from the pressure surface to the suction surface as it goes from the hub portion to the tip portion. The amount of combustion gas leaking from the pressure side to the suction side through the clearance between the turbine casing and the shroud segment is suppressed, and the total pressure loss caused by the leakage of the combustion gas is reduced.

JP 2016-211556 A U.S. Pat. No. 5,525,038

The squealer is formed by machining a tip portion of a wing manufactured by a method such as casting to provide a recess. That is, the thin plate-like portion left around the recess as a result of the machining becomes the squealer.

Here, as described above, when the wing portion is curved in the direction from the pressure surface to the suction surface as it goes from the hub portion to the tip portion, a squealer having a constant thickness along the radial direction is formed. To do so, it is necessary to form an acute angle between the inner surface of the squealer and the bottom surface of the recess on the pressure surface side of the wing. That is, the corner forming the acute angle is a blind spot when viewed from the radially outer side, and cannot be machined simply by feeding the machining tool radially inwardly.

Thus, it has been difficult or impossible in the past to provide a squealer for the purpose of reducing the wear of the turbine casing or shroud segment on the blade curved in a bow shape in the span direction for the purpose of improving aerodynamic performance. rice field.

The present disclosure has been made in view of the problems described above, and provides a turbine rotor blade capable of achieving both improved aerodynamic performance and maintenance of workability of a squealer for reducing wear of a turbine casing or shroud segment. intended to provide

In order to solve the above problems, a turbine rotor blade of the present disclosure includes a blade portion extending in a span direction from a hub portion to a tip portion, and the blade portion extends from a squealer base end position to the tip portion in the span direction. A squealer is formed in the range, and the wing has the same shape as the base wing in the range from the hub to the squealer base end position. A stacking line connecting the center of gravity of the profile at the spanwise position is the direction from the pressure surface to the suction surface with reference to a straight line in the radial direction passing through the center of gravity of the profile in the hub portion as it goes from the hub portion to the tip portion. and the profile at each spanwise location of the base wing comprises a leading edge curve including the leading edge, a trailing edge curve including the trailing edge, and the pressure surface a pressure side curve connecting said leading edge curve and said trailing edge curve on said side; and a suction side curve connecting said leading edge curve and said trailing edge curve on said suction side, and , the pressure side curve comprises a forward pressure side curve on the leading edge side and a rear pressure side curve on the trailing edge side; The blade surfaces of the base blade formed by stacking the pressure side curve, the aft pressure side curve, and the suction surface curve, respectively, from the hub portion to the tip portion are referred to as a leading edge base blade surface and a trailing edge, respectively. When referred to as the front pressure side base blade surface, the rear pressure side base blade surface, and the suction side base blade surface, the blade surfaces of the blade portions in the range from the squealer base end position to the tip portion are the same. The suction side blade surface and the trailing edge blade surface, which are the same curved surfaces as the suction side base blade surface and the trailing edge base blade surface, respectively, and the forward pressure side curve at the squealer proximal position are defined by the tip portion. The front pressure side blade surface, the front pressure side blade surface and the suction side blade surface are formed by radially stacking up to the curvature of the leading edge base blade surface. and the forward pressure side blade surface and the trailing edge blade surface in such a manner that the sign of curvature thereof is the same as the sign of the aft pressure side over the entire surface. and an aft pressure side surface that smoothly connects in a manner that is identical to the sign of curvature of the base surface.

Advantageous Effects of Invention According to the present disclosure, it is possible to obtain an excellent effect that both improvement in aerodynamic performance and maintenance of squealer workability for reducing wear of a turbine casing or shroud segment can be achieved.

1 is a schematic explanatory diagram showing the appearance of a turbine rotor blade according to an embodiment of the present disclosure, where (A) is an overall perspective view (viewed from the front side in the axial direction and the side of the pressure side in the circumferential direction), and (B) is the blade portion. FIG. 4 is an enlarged perspective view of a portion near the tip portion where a squealer is formed; FIG. 4A is a schematic explanatory diagram showing a process for obtaining the airfoil portion of the turbine rotor blade of the embodiment of the present disclosure based on the base airfoil portion, and (A) shows a curve forming the profile of the base airfoil portion at the squealer proximal end position; , (B) respectively show the relationship between the wing surface of the base wing portion and the wing surface of the wing portion in the range from the base end position of the squealer to the tip portion.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

1A and 1B are schematic explanatory diagrams showing the appearance of a turbine rotor blade according to an embodiment of the present disclosure, in which (A) is an overall perspective view (viewed from the front side in the axial direction and the side of the pressure side in the circumferential direction), and (B) is a FIG. 4 is an enlarged perspective view of a portion of the wing near the tip portion where the squealer is formed. In FIG. 1A, arrows R, Z, and C indicate the radial direction, axial direction, and circumferential direction of the turbine, respectively.

The turbine rotor blade RB, as shown in FIG. 1(A), has a blade portion AF, a platform PM, a shank SK and a dovetail DT. Note that the functions of these parts are the same as those in the conventional turbine rotor blade described in the background art section, so descriptions thereof will be omitted here.

The blade portion AF extends in the span direction (longitudinal direction) from the hub portion HB to the tip portion TP. A concave pressure surface PS and a convex suction surface SS extend respectively between LE and trailing edge TE.

Further, as shown in FIG. 1B, the tip portion TP of the wing portion AF is formed with a concave portion (tip cavity) TC extending radially inward. A thin plate-like squealer SQ is formed along the periphery of the . Here, the outer surface of the squealer SQ (that is, the side surface opposite to the inner surface facing the chip cavity TC) forms part of the pressure surface PS and the suction surface SS. In the illustrated embodiment, the squealer SQ is formed as a plate-like portion having uniform thickness and height (dimensions in the radial direction) along the entire periphery of the wing portion AF. However, the squealer SQ may be interrupted at a part of the peripheral edge of the wing AF, and its thickness and height may not be uniform.

The turbine rotor blade RB of the present disclosure is characterized by the shape of the portion of the blade portion AF in the vicinity of the tip portion TP where the _squealer SQ is formed. is obtained by changing the shape of the part in the vicinity of . This will be explained in detail below.

As described above, the base airfoil portion AF _B is a base airfoil portion for obtaining the airfoil portion AF of the turbine rotor blade RB of the present disclosure, and has the following characteristics.
(1) The total height is the same as the total height of the blade portion AF (the height from the hub portion HB to the tip portion TP; Span).
(2) The stacking line, which connects the centers of gravity of the profiles at each spanwise position, moves from the pressure surface to the suction surface with respect to the straight line in the radial direction passing through the center of gravity of the profile in the hub portion as it goes from the hub portion to the tip portion. It is in the form of gradually moving away in the direction toward.

In other words, it can be said that the base airfoil AF _B is a airfoil curved toward the suction side and having the same overall height as the airfoil AF. The base wing AF _B may be of any type as long as it has the features described above, and may be newly designed or existing.

A portion of the base wing portion AF _B whose shape is to be changed is a portion of the wing portion AF where the squealer SQ is to be formed. In one embodiment, this region ranges from 95-100% Span in the span direction. Here, %Span is the dimensionless percentage of the height measured from the hub portion HB divided by the total height (Span).

In the above-described embodiment, the 95% Span is the base end portion (radial inner end) of the squealer SQ protruding radially outward from the bottom surface of the chip cavity TC so as to surround the chip cavity TC formed in the tip portion TP. ), which will be referred to as a squealer proximal position SR.

The wing portion AF has the same shape as the base wing portion AF _B in the range from the hub portion HB to the squealer base end position SR (the range of 0 to 95% Span in the above embodiment). On the other hand, in the range from the squealer base end position SR to the tip portion TP (the range of 95 to 100% Span in the above embodiment), the wings _AF have a shape different from that of the base wings AFB. A method of changing the shape of the wing in the range from the squealer proximal position SR to the tip TP will be described in detail below with reference to FIG.

FIG. 2 is a schematic explanatory diagram showing a process for obtaining the airfoil portion AF of the turbine rotor blade RB of the embodiment of the present disclosure based on the base airfoil portion AF _{B ;} (B) shows the relationship between the wing surface of the base wing portion AF _B and the wing surface of the wing portion AF in the range from the squealer base end position SR to the tip portion TP. ing. However, illustration of the squealer SQ is omitted in FIG. 2(B).

As shown in FIG. 2(A), the profile PF _B of the base airfoil portion AF _B at each spanwise position has four curves: a leading edge curve CL, a trailing edge curve CT, a pressure side curve CP, and a suction side curve CS. It is a closed curve consisting of curved lines.

The leading edge curve CL is a curve with a large curvature from the pressure side curve front end _FCP to the suction side curve front end _FCS via the leading edge LE.

The trailing edge curve CT is a curve with a large _curvature that extends from the pressure side curve trailing end _RCP to the suction side curve trailing end RCS via the trailing edge TE.

The pressure side curve _CP is a curve that connects the leading edge curve CL and the trailing edge curve CT on the pressure surface PS side, and extends from the pressure side curve front end FCP to the pressure side curve rear end _RCP .

The suction side curve _CS is a curve that connects the leading edge curve CL and the trailing edge curve CT on the side of the suction surface SS, and extends from the suction side curve front end FCS to the suction side curve rear end _RCS .

The pressure-side curve _CP is defined on the front pressure side of the leading edge LE side with the pressure-side curve midpoint MCP located approximately midway in the chord direction (the direction of a straight line passing through the leading edge LE and the trailing edge TE) as a boundary. It consists of a curve _CPF and a rear pressure side curve _CPR on the trailing edge TE side.

The wing surface of the base wing portion AF _B is formed by stacking each curve described above from the hub portion HB to the tip portion TP. Here, the blade surfaces formed by the leading edge curve CL, the trailing edge curve CT, the forward pressure side curve _CPF , the rear pressure side curve _CPR , and the suction side curve CS are respectively defined as the leading edge base blade surface FL _B , trailing edge base surface FT _B , forward pressure side base surface FP _FB , aft pressure side base surface FP _RB , suction side base surface FS _B .

As described above, the blade portion AF of the turbine rotor blade RB of the present disclosure has a shape different from that of the base blade portion AF _B in the range from the squealer base end position SR to the tip portion TP. The blade surface of the blade portion AF in this range consists of the following (1) to (5) blade surfaces (see FIG. 2(B)).
(1) Suction side blade surface FS which is the same curved surface as suction side base blade surface FS _B in the above range
(2) Trailing edge blade surface FT that is the same curved surface as trailing edge base blade surface FT _B in the above range
(3) A forward pressure side blade surface _{FP F formed} by radially stacking the forward pressure side curve CPF at the squealer base end position SR up to the tip portion TP.
(4) Smooth the front pressure side FP _F and the suction side FS in such a manner that the sign of the curvature is the same as the sign of the curvature of the leading edge base wing surface FL _B over the entire surface. Connecting leading edge blade surface FL
(5) Smooth the forward pressure side surface FP _F and the trailing edge surface FT in such a manner that the sign of curvature thereof is the same as the sign of curvature of the aft pressure side base surface FP _RB over the entire surface. Aft pressure side blade surface FP _R connected to

It should be noted that the rear pressure side blade surface FPR of (5) is radially extended from the rear pressure side curve _CPR at the _squealer base end position SR to the tip portion TP in the same manner as the front pressure side blade surface _FPR of (3). The reason why the blades are not formed by stacking is that if such a blade is formed, the blade thickness in the vicinity of the trailing edge TE becomes too large, which may lead to deterioration of the aerodynamic performance.

As described above, the blade surface of the portion of the blade portion AF of the turbine rotor blade RB of the present disclosure from the squealer base end position SR to the tip portion TP has the following characteristics.
(1A) The suction side blade surface FS and the trailing edge blade surface FT are curved toward the suction surface SS in the same manner as the suction side base blade surface FS _B and the trailing edge base blade surface FT _B of the base blade portion AF _B. ing.
(1B) The leading edge airfoil _FL , except for the connecting portion with the radially extending front pressure side airfoil FPF, is less than the leading edge base airfoil FL _B of the base airfoil AF _B. Although small, it curves toward the suction surface SS.
(2A) The forward pressure side base blade surface _FPFB of the base blade portion _AFB is curved toward the suction surface SS side, whereas the forward pressure side blade surface _FPF extends radially.
(2B) The rear pressure side blade surface _{FP R} does not extend in the radial direction except for the connecting portion with the front pressure side blade surface FPF, but the rear pressure side base blade surface FP _RB of the base blade portion AF _B does not extend in the radial direction. By comparison, the degree of curvature toward the suction surface SS is small.

By having the features (1A) and (1B) described above, the airfoil portion AF of the turbine rotor blade RB of the present disclosure has improved aerodynamic performance compared to airfoil portions that are not curved toward the suction surface SS side. can be improved. In addition, due to having the features (2A) and (2B) described above, the airfoil portion AF of the turbine rotor blade RB of the present disclosure has the pressure surface PS curved toward the suction surface SS over the entire span direction. The workability of the squealer SQ can be improved as compared with the wing portion having the squealer.

Thus, according to the turbine rotor blade RB of the present disclosure, it is possible to achieve both an improvement in aerodynamic performance and maintenance of workability of the squealer for reducing wear of the turbine casing or shroud segment. Obtainable.

In the above description, 95% span was exemplified as the squealer proximal position SR, but the squealer proximal position SR can be set at other appropriate positions.

In addition, among the curves forming the profile PF _B of the base blade portion AF _B at each span direction position, the pressure side curve midpoint _MCP , which is the connection point between the front pressure side curve _CPF and the rear pressure side curve _CPR , The position can be, for example, 30-70% Chord. Here, %Chord is the distance measured in the chord direction from the leading edge LE to the pressure side curve midpoint _MCP divided by the chord length (the length of the line segment connecting the leading edge LE and the trailing edge TE). It is a dimensionless percentage.

AF Airfoil AF _B Base Airfoil CL Leading Edge Curve CP Pressure Side Curve CP _F Forward Pressure Side Curve CP _R Rear Positive Pressure Side Curve CS Suction Side Curve CT Trailing Edge Curve FL Leading Edge Blade Surface FL _B Leading Edge Base Blade surface FP _F Forward pressure side blade surface FP _FB Forward pressure side base blade surface FP _R Rear pressure side blade surface FP _RB Rear positive pressure side base blade surface FS Suction side blade surface FS _B Suction side base blade surface FT Trailing edge blade surface FT _B trailing edge base blade surface HB Hub LE Leading edge PF _B profile PS Pressure surface RB Turbine rotor blade SQ Squealer SR Squealer base position SS Suction surface TE Trailing edge TP Tip

Claims (1)

A turbine rotor blade comprising a blade portion extending in a span direction from a hub portion to a tip portion,
A squealer is formed in a range from a squealer base end position to the tip portion in the span direction of the wing portion,
The wing has the same shape as the base wing in the range from the hub to the squealer base end position,
In the base wing portion, a stacking line connecting the center of gravity of the profile at each spanwise position is positive with respect to a radial straight line passing through the center of gravity of the profile at the hub portion as it goes from the hub portion to the tip portion. It has a shape that gradually recedes in the direction from the pressure surface to the suction surface,
The profile at each spanwise location of the base airfoil includes a leading edge curve including the leading edge, a trailing edge curve including the trailing edge, and on the pressure side, the leading edge curve and the trailing edge curve. and a suction side curve connecting the leading edge curve and the trailing edge curve on the suction side, and the pressure side curve is a front positive edge on the leading edge side. comprising a pressure side curve and a back pressure side curve on the trailing edge side;
Each of said leading edge curve, said trailing edge curve, said forward pressure side curve, said aft pressure side curve and said suction side curve at each spanwise position is formed by stacking each of said curves from said hub to said tip. When the wing surfaces of the base wing portions are respectively referred to as a leading edge base wing surface, a trailing edge base wing surface, a forward pressure side base wing surface, an aft pressure side base wing surface, and a suction side base wing surface,
The wing surface of the wing portion in the range from the squealer base end position to the tip portion is
a suction side blade surface and a trailing edge blade surface that are curved surfaces identical to the suction side base blade surface and the trailing edge base blade surface in the same range, respectively;
a forward pressure side airfoil formed by radially stacking the forward pressure side curve at the squealer proximal position to the tip;
a leading edge smoothly connecting the forward pressure side airfoil and the suction side airfoil in such a manner that the sign of curvature of the forward airfoil is the same as the sign of the curvature of the leading edge base airfoil over the entire surface; a wing surface;
an aft positive surface that smoothly connects the forward pressure side blade surface and the trailing edge blade surface in such a manner that the sign of curvature thereof is the same as the sign of curvature of the aft pressure side base blade surface over the entire surface; a pressure side wing surface;
Turbine rotor blades, which consist of

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