Low-pressure turbine structure combining non-axisymmetric end wall and winged knife

Abstract

The invention discloses a low-pressure turbine structure combining non-axisymmetric end walls and a winged knife. The turbine comprises a hub and a plurality of turbine blades installed on the hub, inclined U-shaped wing cutters are arranged at the blade roots of the front edges of the turbine blades, the wing cutters extend from the front edges of the turbine blades to the tail edges along the pressure faces and the suction faces on the two sides, and the heights of the wing cutters are gradually reduced in the extending process; and meanwhile, different concave and convex areas are arranged in a blade channel on the hub, so that a non-axisymmetric end wall is formed. The low-pressure turbine structure combining the non-axisymmetric end wall and the winged knife has the following beneficial effects that under the condition that the blade outlet angle, the blade maximum thickness and the blade maximum thickness position are not changed, the axisymmetric end wall and the low-pressure turbine blade are subjected to remodeling design, a new flow control structure does not need to be introduced, and the cost is reduced; the structure is simple, design and machining are convenient, and implementation is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of aeroengines, and in particular relates to a low-pressure turbine structure in which a non-axisymmetric end wall is combined with a wing blade. Background Art

[0002] Based on the considerations of thrust-to-weight ratio and unit thrust fuel consumption, reducing the weight of aircraft engines is one of the research goals of new aircraft engines. The high-load blade design can reduce the number of low-pressure turbine blades and even the number of low-pressure turbine stages, thereby greatly reducing the weight of the aircraft engine, thereby improving the thrust-to-weight ratio and reducing the unit thrust fuel consumption. However, the increase in blade load will inevitably increase the adverse pressure gradient in the blade boundary layer, which is easy to cause boundary layer separation, aggravating blade loss and secondary flow loss. In order to improve the efficiency of the low-pressure turbine, researchers have proposed a variety of improvement methods, including non-axisymmetric end wall technology and wing knife technology. Among them, the non-axisymmetric end wall structure can effectively control vortex and reduce loss compared with the traditional axisymmetric end wall structure. The wing knife structure has the function of preventing the development of secondary flow, combing the flow field, and thus reducing flow loss. At present, the research on these two technologies has developed to varying degrees, but the coupling structure design of the two has not been fully studied. Summary of the invention

[0003] In order to solve the above problems, the object of the present invention is to provide a low-pressure turbine structure in which a non-axisymmetric end wall is combined with a wing blade.

[0004] In order to achieve the above-mentioned purpose, the low-pressure turbine structure provided by the present invention in which a non-axisymmetric end wall and a wing blade are combined includes a hub and a plurality of turbine blades mounted on the hub, wherein an inclined U-shaped wing blade is provided at the leading edge root of the turbine blade, and the wing blade starts from the leading edge of the turbine blade and extends along the pressure surface and the suction surface on both sides to the trailing edge, and the height gradually decreases during the extension process; at the same time, different recessed and raised areas are provided in the blade channel on the hub, thereby forming a non-axisymmetric end wall.

[0005] The winglet is highest at the leading edge of the turbine blade, and is 0.2 times the axial chord length (Cax) away from the end wall of the hub; from the leading edge to the trailing edge, the winglet height gradually decreases, the pressure surface extends to a position 0.2 times the axial chord length away from the leading edge, and the height is reduced by 0.1 times the axial chord length, and the suction surface extends to a position 0.27 times the axial chord length away from the leading edge, and the height is reduced by 0.1 times the axial chord length.

[0006] In a blade channel of the non-axisymmetric end wall, a recessed area is set from the leading edge of the turbine blade on the suction surface side to 0.24 times the axial chord length, and the maximum depth of the recess is 5% of the axial chord length; a recessed area is set from 0.80 times to 1.0 times the axial chord length on the suction surface side, and the maximum depth of the recess is 5% of the axial chord length; a recessed area is set from 0.52 times to 0.74 times the axial chord length on the pressure surface side, and the maximum depth of the recess is 7% of the axial chord length; at the same time, a raised area is set from 0.10 times to 0.38 times the axial chord length on the pressure surface side to 0.52 times to 0.74 times the axial chord length of the suction surface of the adjacent turbine blade, and the maximum height of the raised area is 7% of the axial chord length.

[0007] The cross-section of the blade is defined by a cubic polynomial, and the cross-sectional shape remains unchanged at different cross-sectional positions. The size of the blade is defined by the width, which gradually becomes thinner from the thickest in the middle to the two ends, and the maximum thickness is located at a position slightly biased towards the suction surface on the leading edge of the turbine blade.

[0008] The low-pressure turbine structure in which the non-axisymmetric end wall and the blade are combined has the following beneficial effects:

[0009] Under the condition that the blade outlet angle, the maximum thickness of the blade and the position of the maximum thickness of the blade remain unchanged, the axisymmetric end wall and the low-pressure turbine blade are modified and redesigned. There is no need to introduce a new flow control structure, and the structure is simple, the design and processing are convenient, and it is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The S1 flow surface diagram of the position of the maximum thickness of the blade in the low-pressure turbine structure in which the non-axisymmetric end wall and the blade are combined provided by the present invention.

[0011] Figure 2 (a) and (b) are schematic diagrams of the suction side and pressure side of the wing blade in the present invention, respectively.

[0012] Figure 3 It is a schematic diagram of the contour lines of the non-axisymmetric end wall in the present invention.

[0013] Figure 4 A schematic diagram of the low-pressure turbine structure in which a non-axisymmetric end wall and a wing blade are combined provided by the present invention. DETAILED DESCRIPTION

[0014] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] like Figures 1 to 4As shown, the low-pressure turbine structure in which the non-axisymmetric end wall and the wing blade are combined provided by the present invention comprises a hub 1 and a plurality of turbine blades 2 mounted on the hub 1, wherein an inclined U-shaped wing blade 3 is provided at the leading edge blade root of the turbine blade 2, and the wing blade 3 starts from the leading edge of the turbine blade 2 and extends toward the trailing edge along the pressure surface 4 and the suction surface 5 on both sides, and the height gradually decreases during the extension process; at the same time, different recessed and raised areas are provided in the blade channel on the hub 1, thereby forming a non-axisymmetric end wall.

[0016] The blade 3 is at the highest point from the end wall of the hub 1 at the leading edge of the turbine blade 2, and the height h max =0.2Cax; from the leading edge to the trailing edge, the height of the wing blade 2 gradually decreases, and ends at a position 0.2 times Cax from the leading edge on the pressure surface 4, with a height h2 = 0.1Cax, and ends at a position 0.27 times Cax from the leading edge on the suction surface 5, with a height h1 = 0.1Cax.

[0017] In a blade channel of the non-axisymmetric end wall, a recessed area is set from the leading edge of the turbine blade 2 on the suction surface 5 side to 0.24 times Cax, and the maximum depth of the recess is 5% Cax; a recessed area is set from 0.80 times to 1.0 times Cax on the suction surface 5 side, and the maximum depth of the recess is 5% Cax; a recessed area is set from 0.52 times to 0.74 times Cax on the pressure surface 4 side, and the maximum depth of the recess is 7% Cax; at the same time, a convex area is set from 0.10 times to 0.38 times Cax on the pressure surface 4 side to 0.52 times to 0.74 Cax of the suction surface 5 of the adjacent turbine blade 2, and the maximum height of the convex is 7% Cax.

[0018] The cross section of the blade 3 is defined by a cubic polynomial, and the cross section shape remains unchanged at different cross-sectional positions. The size of the blade 3 is defined by the width, which gradually becomes thinner from the thickest in the middle to the two ends, and the maximum thickness is located on the leading edge of the turbine blade 2 slightly biased towards the suction surface 5.

Claims

1. A low-pressure turbine structure in which a non-axisymmetric end wall and a blade are combined, the low-pressure turbine structure comprising a hub and a plurality of turbine blades mounted on the hub, characterized in that: An inclined U-shaped wing blade is provided at the leading edge root of the turbine blade. The wing blade starts from the leading edge of the turbine blade and extends along the pressure surface and suction surface on both sides to the trailing edge, and the height gradually decreases during the extension process; at the same time, different recessed and raised areas are provided in the blade channel on the hub, thereby forming a non-axisymmetric end wall.

2. The low-pressure turbine structure combining a non-axisymmetric end wall and a wing blade according to claim 1, characterized in that: The winglet is highest at the leading edge of the turbine blade, and is 0.2 times the axial chord length away from the end wall of the hub; from the leading edge to the trailing edge, the winglet height gradually decreases, the pressure surface extends to a position 0.2 times the axial chord length away from the leading edge, and the height is reduced by 0.1 times the axial chord length, and the suction surface extends to a position 0.27 times the axial chord length away from the leading edge, and the height is reduced by 0.1 times the axial chord length.

3. The low-pressure turbine structure combining a non-axisymmetric end wall and a wing blade according to claim 1, characterized in that: In a blade channel of the non-axisymmetric end wall, a recessed area is set from the leading edge of the turbine blade on the suction surface side to 0.24 times the axial chord length, and the maximum depth of the recess is 5% of the axial chord length; a recessed area is set from 0.80 times to 1.0 times the axial chord length on the suction surface side, and the maximum depth of the recess is 5% of the axial chord length; a recessed area is set from 0.52 times to 0.74 times the axial chord length on the pressure surface side, and the maximum depth of the recess is 7% of the axial chord length; at the same time, a raised area is set from 0.10 times to 0.38 times the axial chord length on the pressure surface side to 0.52 times to 0.74 times the axial chord length of the suction surface of the adjacent turbine blade, and the maximum height of the raised area is 7% of the axial chord length.

4. The low-pressure turbine structure combining a non-axisymmetric end wall and a wing blade according to claim 1, characterized in that: The cross-section of the blade is defined by a cubic polynomial, and the cross-sectional shape remains unchanged at different cross-sectional positions. The size of the blade is defined by the width, which gradually becomes thinner from the thickest in the middle to the two ends, and the maximum thickness is located at a position slightly biased towards the suction surface on the leading edge of the turbine blade.

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