CN104420888A - Tapered runner transonic turbine blade and turbine with same - Google Patents

Abstract

The invention provides a transonic turbine blade with a tapered channel and a turbine using the same. The surface three-dimensional shape line of the transonic turbine blade with tapered flow channel is formed by stacking N blade shapes along the radial direction, wherein, N≥3; each blade shape in the N blade shapes includes a suction surface shape line and The profile of the pressure surface, the profile of the suction surface of at least one of the N airfoils has a concave profile. The transonic turbine blade with tapered channel of the invention reduces the total aerodynamic loss of the blade, and effectively reduces the flow loss of the transonic turbine in the supersonic region.

Description

Transonic turbine blade with tapered channel and turbine using it

technical field

The invention relates to the field of aerodynamics, in particular to a transonic turbine blade with a tapered channel with a concave suction surface without a cover section and a turbine using the same.

Background technique

Compared with traditional subsonic turbines, high-load transonic turbines can effectively increase the stage load, and have been widely used in high thrust-to-weight ratio aeroengines. Existing high-load transonic turbines (such as GE's ^E3 turbine, etc.) mainly use tapered flow passages. After the airflow reaches the local speed of sound at the throat, it follows a slightly convex or straight suction surface in the uncovered passage. The line continues to accelerate beyond the local speed of sound. The outward and outward extensional shock waves and expansion waves generated by the supersonic airflow at the trailing edge and their respective reflection waves on the suction surface, together with the outward extensional shock waves at the trailing edge, constitute a wave system structure that has a complex relationship with each other. The wave system structure is usually accompanied by a large velocity gradient and entropy increase, which not only produces shock wave loss but also affects the development process of the suction surface boundary layer and wake, thereby changing the aerodynamic loss of the blade. These losses all increase with the increase of turbine stage load and blade exit Mach number.

Contents of the invention

(1) Technical problems to be solved

In view of the above-mentioned technical problems, the present invention provides a transonic turbine blade with a tapered channel and a turbine using the same, so as to reduce the flow loss of the transonic turbine in the supersonic region.

(2) Technical solutions

According to one aspect of the present invention, a tapered flow path transonic turbine blade is provided. The surface three-dimensional shape line of the transonic turbine blade with tapered flow channel is formed by stacking N blade shapes along the radial direction, wherein, N≥3; each blade shape in the N blade shapes includes a suction surface shape line and The profile of the pressure surface, the profile of the suction surface of at least one of the N airfoils has a concave profile.

According to another aspect of the present invention, a turbine is also provided. The turbine comprises: a turbine rotor; and a plurality of the above-mentioned transonic turbine blades with tapered channels, uniformly distributed on the hub surface of the turbine rotor along the circumferential direction.

(3) Beneficial effects

It can be seen from the above technical solutions that in the transonic turbine blade with tapered flow path and the turbine using it in the present invention, since the suction surface profile has a concave profile on its uncovered section, the total aerodynamic loss of the blade is reduced. , the circumferential non-uniformity of the outlet airflow is improved, and the unsteady influence on the boundary layer of the downstream blade row is reduced.

Description of drawings

FIG. 1A and FIG. 1B are three-dimensional perspective views of a transonic turbine blade with a tapered channel in different viewing angles according to an embodiment of the present invention;

Fig. 1C is a three-dimensional airfoil stacking diagram of a transonic turbine blade with a tapered channel according to an embodiment of the present invention;

Fig. 2 is the airfoil diagram of the transonic turbine blade and the adjacent blades in the tapered channel of the present embodiment;

Fig. 3 is the control point distribution diagram of the Bezier curve of the suction surface profile line of a blade profile of a transonic turbine blade with a tapered channel according to an embodiment of the present invention;

Fig. 4 is a three-dimensional perspective view of a turbine according to an embodiment of the present invention.

[Description of the main component symbols of the present invention]

1-blade shape; 2-suction surface shape line;

3-pressure surface profile; 4-blade leading edge;

5-blade trailing edge; 6-blade channel

7-covered segment; 8-the first sub-segment of the non-covered segment;

9 - the second subsection of the uncovered section; 10 - the third subsection of the uncovered section;

11-uncovered segment; 12-center of gravity;

13 - accumulation line;

A, B, C, D, E-points on the shape line of the suction surface;

F - the end point of the pressure surface profile;

L - the axial length of the unshielded section;

L ₂ - the axial length of the second sub-section of the unshielded section; L ₃ - the axial length of the third sub-section of the unshielded section;

P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , P ₆ , P ₇ - Bezier curve control points.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be noted that, in the drawings or descriptions of the specification, similar or identical parts all use the same figure numbers. Implementations not shown or described in the accompanying drawings are forms known to those of ordinary skill in the art. Additionally, while illustrations of parameters including particular values may be provided herein, it should be understood that the parameters need not be exactly equal to the corresponding values, but rather may approximate the corresponding values within acceptable error margins or design constraints. The directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., are only referring to the directions of the drawings. Therefore, the directional terms used are for illustration and not for limiting the protection scope of the present invention.

The invention provides a transonic turbine blade with a tapered flow channel and a turbine using the concave profile line in the unshielded section of the suction surface. The blade weakens the strong interaction between the reflected wave of the trailing edge extension shock wave and the trailing edge extension shock wave, and reduces the shock wave loss caused by the superposition of the two.

In an exemplary embodiment of the present invention, there is provided a transonic turbine blade with a tapered flow path and a concave suction surface without a shrouded section. FIG. 1A and FIG. 1B are perspective views of a transonic turbine blade with a tapered channel in different viewing angles according to an embodiment of the present invention. Fig. 1C is a three-dimensional airfoil stack-up diagram of a transonic turbine blade with a tapered channel according to an embodiment of the present invention.

Please refer to Fig. 1A, Fig. 1B and Fig. 1C, the surface three-dimensional shape line of the transonic turbine blade with tapered channel of the present embodiment is formed by stacking five blade shapes along the radial direction (r direction), and each blade shape is formed by suction The surface profile 2 and the pressure surface profile 3 are smoothly connected by the arcs of the leading edge and the trailing edge, and the suction surface profile has a concave profile.

The airfoil shape of the transonic turbine blade with tapered flow path in this embodiment will be described in detail below.

Fig. 2 is an airfoil diagram of a transonic turbine blade with a tapered channel and adjacent blades in this embodiment. Please refer to FIG. 2 , the airfoil 1 of the transonic turbine blade with the tapered channel is smoothly connected by the suction surface profile line 2 and the pressure surface profile line 3 through the arcs of the airfoil leading edge 4 and the airfoil trailing edge 5 . Wherein, the radius of the arc is between 0.1 mm and 5 mm.

The profile line 3 of the pressure surface of the transonic turbine blade and the profile line 2 of the suction surface of the adjacent blade form a profile channel 6 whose width gradually decreases. The inlet of the airfoil passage 6 is formed between the leading edge of the transonic turbine blade airfoil of the tapered flow passage and the airfoil of the adjacent blade at the same radial position.

Please continue to refer to Figure 2, the suction surface profile 2 of the airfoil 1 includes along the axial direction (z direction): a cover section 7, which is the part of the suction surface profile 2 located in the airfoil channel, as shown in Figure 2 between point A and point The part between B; the uncovered segment 11 is the part where the suction surface profile line 2 is located outside the airfoil passage, as shown in the part between point B and point E in Figure 2 . The outlet of the airfoil channel 6 is formed between the starting point B of the uncovered section of the transonic turbine blade airfoil of the current tapered flow channel and the end point F of the airfoil pressure surface profile line at the same radius position of the adjacent blade.

Please continue to refer to Fig. 2, the uncovered segment 11 includes again along the axial direction (z direction): a first sub-section 8 protruding towards the outside of the blade, as shown in Fig. 2 between point B and point C; the second sub-section 8 Segment 9, which is concave toward the inside of the blade, is the above-mentioned concave profile, such as the part between point C and point D in Figure 2; and the third sub-section 10 is convex or straight toward the outside of the blade, such as The part between point D and point E in Figure 2.

Please refer to FIG. 2 and FIG. 3 , the first subsection 8 and the second subsection 9 are connected. The curvature of the connection point of the first subsection 8 and the second subsection 9 is 0, and the first subsection 8 and the second subsection 9 on both sides of the connection point have curvatures with opposite signs. The second subsection 9 and the third subsection 10 are connected. The curvature of the connection point of the second subsection 9 and the third subsection 10 is 0, and the second subsection 9 and the third subsection 10 on both sides of the connection point have curvatures with opposite signs.

In this embodiment, the shape line of the suction surface is generated by a Bezier curve with 7 control points. Fig. 3 is a distribution diagram of the control points of the Bezier curve of the suction surface profile of a blade profile of a transonic turbine blade with a tapered channel according to an embodiment of the present invention. Please refer to Figure 3, the control points P ₁ , P ₂ and P ₃ are located on the outside of the suction surface profile line 2, the control points P ₄ , P ₅ and P ₆ are located on the inside of the suction surface profile line 2, and the control point P ₇ is located on the suction surface On the profiled line 2, a concave profiled line 9 with an axial length of L2 is constructed on the uncovered section 11 with an axial length of _L.

In this embodiment, the shape line of the suction surface of the airfoil is constructed by a Bezier curve with 7 control points. It should be clear to those skilled in the art that the number of control points of the Bezier curve can range from 4 to innumerable. Get 4～innumerable Bezier curves for this control point, it needs to meet the following conditions, just can constitute the suction surface profile line of the transonic turbine blade of the present invention's taper channel:

(1) At least one of the control points of the axial front end portion is located outside the suction surface molded line;

(2) At least one of the control points in the middle section is located inside the shape line of the suction surface;

(3) The control point of the axial rear end part is located on the shape line of the suction surface or outside the shape line of the suction surface.

It should be clear to those skilled in the art that the determination of the shape line of the suction surface by the Bezier curve is only one of the implementations of the present invention, and those skilled in the art can also use other spline curves or arc curves with at least second-order continuous curvature, etc. To construct the suction surface profile of the present invention, it should also be within the protection scope of the present invention, and will not be repeated here.

Please refer to FIG. 2 and FIG. 3 , the axial length L of the uncovered section accounts for 30.2% of the axial length of the airfoil 1 . Among them, in the uncovered section, the axial length (LL ₂ -L ₃ ) of the first subsection accounts for 4.2% of the axial length of airfoil 1; the axial length L ₂ of the second subsection accounts for 4.2% of the axial length of airfoil 1. 22.0% of the length. The axial length L ₃ of the third subsection accounts for 4.0% of the axial length of the airfoil 1 .

It should be clear to those skilled in the art that the shape and size of the uncovered segment can be designed as desired. In other embodiments of the present invention, the axial length L of the uncovered section 11 accounts for about 14-55% of the axial length of the airfoil 1 . Wherein, the axial length (LL ₂ -L ₃ ) of the first sub-section 8 accounts for 2-10% of the axial length of the airfoil 1; the axial length L ₂ of the second sub-section 9 accounts for 2% of the axial length of the airfoil 1 10-30%. The axial length L ₃ of the third subsection 10 accounts for 2-15% of the axial length of the airfoil 1 .

In this embodiment, the ratio of the outlet pitch of the airfoil to the outlet width (geometric throat width) of the airfoil channel 6 is between 1.1 and 3.5, and the geometric throat width of the airfoil channel is the small circle of the airfoil trailing edge. The diameter is 8 to 15 times, the airflow angle (axial) of the inlet and outlet of the blade type is arbitrarily selected between 0 and 90 degrees, and the Mach number of the blade type outlet is 1.1 to 1.5. The airfoil outlet pitch is the distance between the trailing edges of the airfoil at the same radius position of two adjacent blades.

Please refer to FIG. 1A , FIG. 1B and FIG. 1C , the transonic turbine blade with tapered channel in this embodiment is formed by stacking five blade shapes along the radial direction. Those skilled in the art should know that the number N of airfoils is related to design requirements and process difficulty. Generally, the lower limit of the number N of airfoils is 3, and the upper limit is infinite. In a preferred embodiment of the present invention, the number N of airfoils is between 4 and 100. Preferably, the number N of blade shapes is between 4 and 20. Optimally, the number N of blade shapes can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 50, 100 and so on.

In the transonic turbine blade with tapered channel in this embodiment, the suction surface profiles of the five blade shapes all have concave profiles, but the present invention is not limited thereto. In other embodiments of the present invention, it is also possible that there are concave lines in the profile lines of the airfoil suction surface located in the middle of the blade, or there are concave lines in the profile lines of the airfoil suction surfaces at both ends of the blade, also in the present invention within the scope of protection.

Please refer to Fig. 1C and Fig. 2, among the transonic turbine blades with tapered flow channel in this embodiment, the airfoils 1 with concave contours in the five suction surface contours without covering sections are used to pass the connection line of the center of gravity 12 of each airfoil 1 13 are stacked to obtain a three-dimensional curved surface of the blade surface, that is, the stacking line 13 is a line connecting the centers of gravity of each blade shape and is a straight line, but the present invention is not limited thereto. In other embodiments of the present invention, each airfoil can also be stacked along its center of gravity, leading edge, trailing edge, equal points on the chord line, or equal points on the mid-arc to obtain the span of the tapered flow channel. Three-dimensional contours on the surface of a sonic turbine blade. Moreover, the stacking line can be not only a straight line, but also a space curve of any shape.

In this embodiment, in the supersonic flow region of the transonic turbine airfoil channel, the concave profile increases the curvature of the suction surface profile between the aerodynamic throat and its starting point, so the expansion wave intensity generated by the profile within this range Increase, so that the trailing edge of adjacent blades protruding shock wave surface increases the angle of deflection downstream around the trailing edge. The concave profile reduces the wave front and rear airflow angles (axial) of the inward-extending shock wave reflected by the trailing edge through its own profile, so that the shock wave surface of the reflected wave increases the angle of deflection upstream around the incident point .

The opposite deflection of the above two shock wave fronts pushes back the intersection point of the trailing edge outward shock wave and trailing edge inward shock wave reflection in the flow direction. Since the shock wave is continuously attenuated along the flow direction and the strength of the weaker shock wave superposition is also weaker, the shock wave loss at the pushed back intersection point is also small, that is, the concave profile weakens due to The shock loss caused by the superposition of the trailing edge outward shock wave and the trailing edge inward shock wave reflection. This reduced shock loss results in lower total blade aerodynamic losses, improved circumferential non-uniformity of the outlet airflow, and reduced unsteady effects on the downstream blade row boundary layer.

So far, the introduction of the transonic turbine blade with tapered channel in this embodiment is completed.

In another embodiment of the present invention, there is also provided a turbine using the above-mentioned transonic turbine blade with a tapered channel. The turbine comprises: a turbine rotor and transonic turbine blades with tapered flow passages uniformly distributed on the hub surface of the turbine rotor along the circumferential direction.

It should be clear to those skilled in the art that the number and size of the transonic turbine blades in the turbine of this embodiment can be adjusted according to needs, and will not be repeated here.

So far, the turbine of this embodiment has been introduced.

The present embodiment has been described in detail above with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the transonic turbine blade with tapered channel of the present invention.

In addition, the above definition of each element is not limited to the various specific structures or shapes mentioned in the embodiments, and those skilled in the art can simply replace them with well-known ones.

To sum up, the present invention provides a transonic turbine blade with a tapered channel and a concave suction surface without a covering section. Due to the concave profile of the suction surface profile on its uncovered section, the total aerodynamic loss of the blade is reduced, the circumferential non-uniformity of the outlet airflow is improved, and the unsteady impact on the boundary layer of the downstream blade row is reduced Influence.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A tapered channel transonic turbine blade, characterized in that its surface three-dimensional profile is formed by stacking N blade profiles along the radial direction, wherein N≥3; Each of the N airfoils includes a suction surface profile and a pressure surface profile, and at least one of the N airfoils has a concave profile in the suction surface profile. 2. The transonic turbine blade with tapered flow path according to claim 1, characterized in that, an airfoil channel whose width gradually decreases is formed between the shape line of the suction surface and the shape line of the pressure surface of the adjacent blade airfoil , the suction surface profile along the axial direction includes: The cover section is a part of the suction surface profile line located in the airfoil channel; The uncovered section is the part of the suction surface line outside the airfoil channel, including: The first subsection protrudes towards the outer direction of the blade; The second sub-section is the concave profile, which is concave toward the inside of the blade; and The third subsection protrudes toward the outside of the blade or is straight. 3. The tapered channel transonic turbine blade according to claim 2, characterized in that, The curvature of the connection point between the first subsection and the second subsection is 0, and the first subsection and the second subsection on both sides of the connection point have curvatures with opposite signs; The curvature of the connection point of the second sub-section and the third sub-section is 0, and the second sub-section and the third sub-section on both sides of the connection point have curvatures with opposite signs. 4 . The transonic turbine blade with tapered flow path according to claim 2 , wherein the shape line of the suction surface is at least second-order continuous spline curve, arc curve or Bezier curve. 5. The tapered channel transonic turbine blade according to claim 4, characterized in that, the shape line of the suction surface is a Bezier curve, and in the Bezier curve: At least one of the control points of the axial front part is located outside the suction surface mold line; At least one of the control points in the middle section is located inside the shape line of the suction surface; The control point of the axial rear end portion is located on or outside the suction surface molded line. 6. The transonic turbine blade with tapered flow path according to claim 2, wherein the axial length of the uncovered section accounts for 14-55% of the axial length of the airfoil, wherein: The axial length of the first subsection accounts for 2-10% of the axial length of the airfoil; The axial length of the second subsection accounts for 10-30% of the axial length of the airfoil; The axial length of the third subsection accounts for 2-15% of the axial length of the airfoil. 7. The tapered channel transonic turbine blade according to any one of claims 1 to 6, characterized in that: The number N of the leaf shapes is between 4 and 100; The profile line of the suction surface and the profile line of the pressure surface are smoothly connected by the arc of the airfoil leading edge and the airfoil trailing edge, wherein the radius of the arc is between 0.1 mm and 5 mm; The ratio of the outlet pitch of the airfoil to the outlet width of the airfoil channel is between 1.1 and 3.5, and the geometric throat width of the airfoil channel is 8 to 15 times the diameter of the small circle at the trailing edge of the airfoil. 8. The transonic turbine blade with tapered flow path according to any one of claims 1 to 6, wherein all of the N airfoils or several airfoils located in the middle of the blade have the concave shape Wire. 9. The tapered channel transonic turbine blade according to any one of claims 1 to 6, wherein said N airfoils are equally divided along its center of gravity, leading edge, trailing edge, and chord. The three-dimensional model line on the surface of the transonic turbine blade of the tapered flow passage is obtained by stacking equal fractions on the point or the mid-arc, and the stacked line is a straight line or a space curve. 10. A turbine comprising the tapered channel transonic turbine blade according to any one of claims 1 to 9, characterized in that it comprises: turbine rotors; and The plurality of transonic turbine blades with tapered channels are evenly distributed on the hub surface of the turbine rotor along the circumferential direction.