A biomimetic blade for a variable geometry turbine stage with leading and trailing edge and a method of forming the same

Abstract

The application provides a variable geometry turbine stage bionic blade with variable front edges and tail edges and a forming method thereof, and belongs to the technical field of component design of marine gas turbines. The application solves the problems of large blade attack angle variation and low efficiency of the existing ship gas turbine turbine during variable condition operation. The variable geometry turbine stage blade is adopted, the front edges of turbine stage guide vanes and moving vanes adopt the undulating structure of beluga whale fins, and the tail edges adopt the structure of seal whiskers, the front edges of the blade present sinusoidal undulation along the blade height, and the tail edge points, the pressure sides and the suction sides of the tail edges of the blade present sinusoidal undulation along the blade height. The application is mainly applied to the variable geometry turbine blade of the marine gas turbine. Through the combination of the bionic beluga whale fin front edge and the bionic seal whisker tail edge structure design, the loss caused by the positive and negative attack angles of the turbine stage guide vanes and moving vanes under the variable condition is weakened, the unsteady loss caused by the turbine stage blade wake is inhibited, and the performance of the variable geometry turbine stage can be significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of bionic blade and its forming method, belong to ship gas turbine component design technical field. BACKGROUND

[0002] More than 90% of the time, the ship gas turbine is in partial load operation, the thermal parameters of non-design condition are different from that of design condition, which makes the oil consumption rate increase greatly. In the aerodynamic design of ship gas turbine turbine, the variable geometry turbine technology can adjust and optimize the matching relationship between components, so as to improve the acceleration, deceleration characteristics and variable condition performance of the whole unit. The LM1600 ship gas turbine of the United States uses electronic regulation system to adjust the installation angle of the first stage static blade of turbine, which improves the maneuverability of the ship. The WR-21 ship intercooling regenerative gas turbine developed by Rolls-Royce and the United States Navy also uses variable geometry turbine technology. This makes the variable condition performance curve more flat, and the performance of the gas turbine under partial load is further improved. Compared with the simple cycle LM2500 gas turbine, the annual fuel consumption can be reduced by about 30% to 40%, which has become a symbol of the new generation of ship gas turbines.

[0003] The rotation of adjustable guide vanes has a significant impact on the angle of attack of guide vanes and moving vanes. Generally, the impact of guide vane rotation on guide vanes is relatively small, but the impact on moving vanes is larger. The rotation of adjustable guide vanes makes the downstream moving vanes operate in a large range of angle of attack, and large positive angle of attack will cause flow separation on the suction side, which will significantly reduce the efficiency of the turbine. Therefore, when designing the blade profile, not only the angle of attack in the design state should be considered, but also the angle of attack in the non-design state should be considered. When designing the blade profile of variable geometry turbine, taking a negative value of the angle of attack can weaken the negative impact of the positive angle of attack caused by guide vane closure.

[0004] The wake vortex shedding from the trailing edge is an important source of turbine blade loss, and the wake loss accounts for more than 1 / 3 of the profile loss. In addition, the interference between guide vane wake and moving vane will further increase the turbine stage loss. In the research of "DDES analysis of unsteady and loss of high-pressure turbine stage wake" by Lin Dong et al., it is shown that the guide vane wake will cause strong fluctuation of rotor blade load and affect the surface heat transfer of rotor blade; the large eddy simulation results of "High-fidelity simulation study on unsteady flow effects on high-pressure turbine blade performance" by Leggett J et al. show that the unsteady behavior of guide vane wake will significantly affect the performance of the rotor.

[0005] Some flow control methods are used to improve the angle of attack characteristics of the blade and reduce the wake loss. The structure of humpback whale fin has the characteristics of being insensitive to angle of attack, and the humpback whale fin is Figure 7CN105298924A, a bionic static blade of compressor based on humpback whale flipper and its implementation method, applies the humpback whale flipper structure to the leading edge of the compressor, uses a cubic spline curve to construct the wave structure of the leading edge, controls the flow separation of the suction surface of the compressor static blade, and thus improves the aerodynamic performance of the blade; Al-Ghandi et al. in “A novel flow control method for turbine blade vortex shedding” applies a micro balance hole to the trailing edge of the turbine guide vane, improves the base pressure of the trailing edge, and reduces the wake loss; the elliptical trailing edge can delay the separation of the trailing edge boundary layer, weaken the wake intensity, and reduce the trailing edge loss. In the aspect of active flow control, Bernardini et al. in “Effect of pulsed coolant injection downstream of a supersonic trailing edge” use trailing edge pulsed blowing to suppress the trailing edge shedding vortex; the pulsed blowing changes the mode of the shedding vortex but introduces additional loss; the seal whisker is found to be able to suppress the Karman vortex street; the seal whisker structure is as shown in Figure 8 CN114991878B, a turbine pressure side half-split cooling seal whisker trailing edge blade and forming method, applies the seal whisker structure to the split lip and trailing edge of the half-split cooling blade on the pressure side of the aero-engine turbine, improves the trailing edge film cooling efficiency and reduces the wake loss by controlling the split lip and trailing edge shedding vortex.

[0006] For a variable geometry turbine stage, the rotation of the adjustable guide vane causes the guide vane and the moving vane to be in a large range of attack angles, which makes the variable geometry turbine stage have poor variable working condition performance, and the guide vane wake also causes the performance of the turbine stage to decrease significantly. That is, the variable geometry turbine guide vane can be opened or closed to meet the requirements of the turbine on the variable working condition performance. The rotation of the adjustable guide vane changes the attack angles of the guide vane and the moving vane, and the performance of the turbine stage becomes poor. The current variable geometry turbine has no change in the leading edge geometry when being stacked along the span direction, which leads to a large difference between the attack angle and the leading edge angle of the blade.

[0007] Therefore, it is urgent to provide a variable geometry turbine stage bionic blade with variable leading edge and trailing edge and a forming method thereof to solve the above technical problems. SUMMARY

[0008] In view of the deficiencies in the prior art, the present application provides a variable geometry turbine stage bionic blade with variable leading and trailing edges and a forming method thereof. A brief summary of the present application is given below to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not an exhaustive overview of the present application. It is not intended to identify key or important parts of the present application, nor is it intended to limit the scope of the present application.

[0009] Technical scheme of the present application:

[0010] A variable geometry turbine stage bionic blade with variable leading and trailing edges, comprising a convex structure of the leading edge of the blade adopting the front part of the humpback whale fin, and a surface undulating structure of the trailing edge of the blade adopting the mustache of the seal.

[0011] Preferably, the leading edge is close to the pressure side of the blade, and the leading edge is designed to have a better variable attack angle characteristic by a leading edge point along the spanwise sinusoidal undulation.

[0012] The trailing edge is controlled by a trailing edge point, a suction side and a pressure side trailing edge ring control point along the spanwise sinusoidal undulation, so that the bionic turbine stage has the function of controlling the trailing edge shedding vortex.

[0013] Preferably, the amplitude of the leading edge is smaller than the amplitude of the trailing edge.

[0014] Preferably, the blade (variable geometry turbine stage bionic blade) is a guide vane or a moving vane.

[0015] A forming method of a variable geometry turbine stage bionic blade with variable leading and trailing edges, comprising:

[0016] The leading edge sinusoidal undulation is constructed when the blade profile is spanwise accumulated, so that the leading edge has a convex structure similar to the leading edge of the humpback whale, thereby widening the attack angle range of the blade and improving the variable working condition performance of the variable geometry turbine stage.

[0017] The trailing edge sinusoidal undulation along the span is constructed when the blade profile is spanwise accumulated, so that the trailing edge point and the suction side and pressure side control points of the trailing edge ring change sinusoidally along the span, thereby reducing the wake loss of the turbine stage guide vane and moving vane and suppressing the interaction of the guide vane wake and the moving vane. The leading edge wake is an important factor affecting the performance of the variable geometry turbine stage. The present application not only considers the leading edge by imitating the humpback whale fin leading edge and the seal mustache trailing edge when the blade profile is spanwise accumulated, but also improves the performance of the variable geometry turbine stage.

[0018] Preferably, the leading edge forming method comprises the following steps:

[0019] A leading edge cut-off point on the suction side and a leading edge cut-off point on the pressure side are set at one end of the original blade profile, and the original leading edge is between the two leading edge cut-off points.

[0020] The leading edge point of the original leading edge is control point one, and the control curve one of the control point one along the spanwise sinusoidal change is expressed as:

[0021]

[0022] wherein, Δd1 represents the distance of the leading edge control point deviating from the original blade profile leading edge base point, A1 represents the amplitude coefficient, and the value range is 0.05-0.08, d l represents the leading edge circle diameter, and h represents the blade height (along the span direction) position;

[0023] The truncation point forms a truncation line along the span direction;

[0024] The leading edge truncation point and the control point one on the same layer are connected through a third-order Bezier curve, and the blade profile is accumulated in the span direction to form a bionic leading edge.

[0025] Preferably, the tail edge forming method comprises the following steps:

[0026] Tail edge truncation points are respectively arranged on both sides of the other end of the original blade profile, and the original tail edge is between the two tail edge truncation points;

[0027] The end and the two sides of the original tail edge are respectively provided with control point two, control point three on the pressure side, and control point four on the suction side;

[0028] The expression of the control point two changing along the span direction is:

[0029]

[0030] wherein, Δd2 represents the distance of the tail edge control point two deviating from the original blade profile tail edge base point, A2 represents the amplitude coefficient, and the value range is 0.1-0.12, d t represents the tail edge (along the span direction) thickness;

[0031] The expression of the control point three and the control point four is:

[0032]

[0033] wherein, Δd 3 / 4 represents the distance of the control point three and the control point four deviating from the original blade profile tail edge base point, A 3 / 4 represents the amplitude coefficient, and the value range is 0.03-0.04;

[0034] The tail edge truncation point, the control point four, and the control point three on the same layer are connected through a third-order Bezier curve, the control point four, the control point two, and the control point three are connected through an elliptic curve, and the blade profile is accumulated in the span direction to form a bionic tail edge.

[0035] Preferably, the control points form a control curve along the span direction, a sine curve formed by the control points three and the control points four is consistent in phase, and the troughs of the control curve three and the control curve four correspond to the peaks of the control curve two.

[0036] Preferably, the variable geometry turbine stage biomimetic blade is manufactured by a lost wax casting method.

[0037] First, a ceramic material is used to shape an inner core model, and then a plurality of layers of ceramic slurry are wrapped outside to form a casting shell; after a drying and heating process, the internal wax model is melted away to form a cavity; a nickel-based high-temperature alloy material is poured into the cavity, and after the alloy cools and solidifies, the ceramic shell is destroyed to take out the casting; the casting-shaped blade is subjected to preliminary mechanical processing to remove burrs and excess metal, so that the size of the blade is close to the final requirement; and then finishing and surface treatment are performed to obtain the biomimetic blade.

[0038] The present application has the following beneficial effects:

[0039] The biomimetic fin leading edge structure of the present application widens the angle of attack range of the blade through the wave-like structure in the span direction, so that the turbine stage efficiency of the variable geometry turbine stage under variable working conditions is improved; the leading edge stagnation point of the variable geometry turbine stage under variable working conditions is closer to the leading edge point;

[0040] The seal whisker trailing edge structure of the present application suppresses the trailing edge shedding vortex and reduces the interaction between the wake and the moving blade; the seal whisker biomimetic trailing edge reduces the wake loss and improves the turbine stage efficiency;

[0041] The present application combines the design of the fin leading edge of the beluga whale and the trailing edge of the seal whisker to weaken the loss caused by the positive and negative angles of attack of the turbine stage guide vane and the moving blade under variable working conditions, suppresses the unsteady loss caused by the turbine stage blade wake, and can significantly improve the performance of the variable geometry turbine stage, and improve the turbine stage efficiency of the variable geometry turbine stage under different working conditions by 1.42% to 2.41%. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a perspective view of a variable geometry turbine stage biomimetic blade with a leading edge and a trailing edge;

[0043] Figure 1 (a) is a guide vane view;

[0044] Figure 1 (b) is a moving blade view;

[0045] Figure 1 (c) is a guide vane leading edge pressure side view;

[0046] Figure 1 (d) is a guide vane leading edge suction side view;

[0047] Figure 1 (e) is a trailing edge pressure side view of the guide vane;

[0048] Figure 1 (f) is a trailing edge suction side view of the guide vane.

[0049] Figure 2 is a schematic of the blade profile;

[0050] Figure 2 (a) is a schematic of the blade profile;

[0051] Figure 2 (b) is a leading edge pressure side view;

[0052] Figure 2 (c) is a leading edge suction side view;

[0053] Figure 2 (d) is a trailing edge pressure side view;

[0054] Figure 2 (e) is a trailing edge suction side view;

[0055] Figure 2 (f) is a control map.

[0056] Figure 3 is the blade surface pressure distribution of the biomimetic moving blade at 5 degrees of guide vane setting;

[0057] Figure 3 (a) is the original blade profile;

[0058] Figure 3 (b) is the biomimetic blade profile.

[0059] Figure 4 is the control effect of the biomimetic turbine stage on the wake vortex at design conditions;

[0060] Figure 4 (a) is the original control effect;

[0061] Figure 4 (b) is the biomimetic turbine stage control effect.

[0062] Figure 5 is the original blade profile of a variable geometry turbine stage.

[0063] Figure 6 is an embodiment of a variable geometry biomimetic turbine stage with leading edge mimic beluga fin and trailing edge mimic seal mustache in a cascade flow field.

[0064] Figure 7 is a schematic of a beluga fin.

[0065] Figure 8 is a schematic of a seal mustache.

[0066] In the figure: 1 - guide vane leading edge, 2 - guide vane trailing edge, 3 - rotor leading edge, 2 - rotor trailing edge. DETAILED DESCRIPTION

[0067] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be described below by means of specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of well-known structures and techniques is omitted to avoid unnecessary confusion of the concept of the present application.

[0068] DETAILED DESCRIPTION Figure 1 In this embodiment, a variable geometry turbine stage biomimetic blade with a variable leading edge and trailing edge on the blade uses the convex structure of the front part of the beluga fin and the surface undulating structure of the seal mustache; the variable geometry turbine stage biomimetic blade of the present application applies the structure of the beluga fin and the structure of the seal mustache to the leading edge and trailing edge of the guide vane and rotor of the variable geometry turbine stage, respectively, for improving the performance of the variable geometry turbine stage, using flow control method to improve the variable working condition performance of the turbine stage and reduce the wake loss;

[0069] The leading edge and the wake are important factors affecting the performance of the variable geometry turbine stage. The leading edge is close to the pressure side of the blade. The leading edge has better variable attack angle characteristics through the sinusoidal undulation design of the leading edge point along the spanwise. The present application constructs the sinusoidal undulation of the leading edge when the blade profile is spanwise accumulated, so that the leading edge has a convex structure similar to the leading edge of the beluga, thereby widening the attack angle range of the blade and improving the variable working condition performance of the variable geometry turbine stage;

[0070] The trailing edge is controlled by the trailing edge point, the suction side and the pressure side trailing edge ring control point along the spanwise sinusoidal undulation, so that the biomimetic turbine stage has the function of controlling the trailing edge shedding vortex. The present application not only considers the sinusoidal change of the leading edge geometry along the spanwise when the blade profile is spanwise accumulated, but also constructs the sinusoidal undulation of the trailing edge along the spanwise, so that the trailing edge point and the control points of the suction side and the pressure side of the trailing edge ring change sinusoidally along the spanwise, thereby reducing the wake loss of the guide vane and the rotor of the turbine stage and suppressing the interaction of the guide vane wake and the rotor; through the beluga fin leading edge and the seal mustache trailing edge, the ability to improve the performance of the variable geometry turbine stage is achieved;

[0071] The amplitude of the leading edge is smaller than the amplitude of the trailing edge;

[0072] The blade (variable geometry turbine stage biomimetic blade) is a guide vane or a rotor; for example Figure 1(a), (b) show the three-dimensional space structure of the variable geometry turbine stage biomimetic guide vane and biomimetic moving vane blade of the leading edge of the humpback whale fin and the trailing edge of the seal mustache; the variable geometry turbine stage is composed of adjustable guide vane blades and moving vane blades, and by adjusting the guide vane installation angle, the through-flow area can be controlled to be opened and closed, so that the turbine has the variable working condition operation capability; as shown in Figure 1 (c) and Figure 1 (d) show that the leading edge of the biomimetic turbine stage guide vane and moving vane imitates the convex structure of the front part of the humpback whale fin, and by designing the leading edge point to be sinusoidal in the spanwise direction, the blade has better variable attack angle characteristics; as shown in Figure 1 (e) and Figure 1 (f) show that the trailing edge of the biomimetic turbine stage guide vane and moving vane is designed by imitating the surface undulation of the seal mustache, and by controlling the trailing edge point, the suction side and the pressure side trailing edge ring control point to be sinusoidal in the spanwise direction, the biomimetic turbine stage has the function of controlling the trailing edge shedding vortex;

[0073] The blade design of the application can be applied to the turbine stage of a ship gas turbine; the undulating structure of the humpback whale fin has the characteristic of being insensitive to the attack angle, and the seal mustache structure has the characteristic of suppressing the shedding vortex; the influence of the opening and closing of the guide vane of the variable geometry turbine on the blade attack angle and the wake loss, the application of the undulating structure of the humpback whale fin to the leading edge of the guide vane and the moving vane of the variable geometry turbine stage for widening the attack angle range of the blade profile, and the application of the seal mustache biomimetic trailing edge to the trailing edge of the guide vane and the moving vane of the variable geometry turbine stage for reducing the wake loss, the combination of the two, thereby improving the efficiency of the variable geometry turbine stage under different working conditions.

[0074] Specific implementation method two: combined with Figures 1-6 This embodiment describes a forming method of a variable geometry turbine stage biomimetic blade with a leading edge and a trailing edge, which is mainly applied to the variable geometry turbine blade of a ship gas turbine; the design process of the variable geometry turbine stage biomimetic guide vane is as shown in Figure 2 The design process of the moving vane is consistent with that of the guide vane, as shown in Figure 2 (a) The red line of the blade profile is the area of the original blade profile modification, the biomimetic leading edge / trailing edge is divided at the cut-off point, and the blade profile after the cut-off point is consistent with the original type, including:

[0075] By constructing the leading edge sinusoidal undulation in the blade profile spanwise stacking, the leading edge has a convex structure similar to the leading edge of the humpback whale, thereby widening the attack angle range of the blade and improving the variable working condition performance of the variable geometry turbine stage;

[0076] The leading edge forming method includes the following steps:

[0077] As shown in Figure 2As shown in (a), the leading edge cutoff point on the suction side and the leading edge cutoff point on the pressure side are set at one end of the original blade profile. The distance between the leading edge cutoff point on the suction side and the leading edge is 0.2-0.25 times the axial chord length, and the distance between the leading edge cutoff point on the pressure side and the leading edge is 0.15-0.2 times the axial chord length. The area between the two leading edge cutoff points is the original leading edge.

[0078] The leading edge point of the original leading edge is control point 1, and the expression of the control curve 1 that changes sinusoidally along the span direction of control point 1 is:

[0079]

[0080] Where Δd1 represents the distance between the leading edge control point and the original blade leading edge base point, A1 represents the amplitude coefficient, which can be in the range of 0.05-0.08, and d l represents the leading edge circle diameter, h represents the blade height (along the span direction);

[0081] The truncation point forms a truncation line along the span direction;

[0082] like Figure 2 As shown in (b) and 2(c), the leading edge cutoff point and control point 1 on the same level are connected by a third-order Bezier curve, and the blade profile is stacked in the span direction to form a bionic leading edge;

[0083] By constructing a spanwise sinusoidal undulation of the trailing edge when the blade profiles are stacked, the trailing edge point and the suction and pressure side control points of the trailing edge circle vary sinusoidally along the spanwise direction, thereby reducing the wake loss of the turbine stage guide vanes and rotor blades and suppressing the interaction between the guide vane wake and the rotor blades. The leading edge wake is an important factor affecting the performance of the variable geometry turbine stage. The present invention not only considers the leading edge when stacking the blade profiles in the spanwise direction, but also achieves the ability to improve the performance of the variable geometry turbine stage by imitating the leading edge of the humpback whale fin and the trailing edge of the seal whisker.

[0084] The trailing edge forming method comprises the following steps:

[0085] The geometric changes of the trailing edge in the span direction are controlled by using the control points 2, 3 and 4; Figure 2 As shown in (a), the trailing edge cutoff points are set on both sides of the other end of the original blade profile, ensuring that the original blade trailing edge area is minimally modified and a sufficient distance between the cutoff points and the control points is left for transition. The cutoff points on the suction side and the pressure side are more appropriately 1.5 times the diameter away from the trailing edge point. Control point two is located at the end point of the trailing edge. Control points three and four are 0.5 times the diameter away from the trailing edge point to better control the trailing edge separation boundary layer. The profile line between the leading edge cutoff point and the trailing edge cutoff point remains unchanged.

[0086] Control point 2 is set at the end and both sides of the original trailing edge, control point 3 on the pressure side, and control point 4 on the suction side respectively;

[0087] The expression of the control point two along the spanwise change is:

[0088]

[0089] In the formula, Δd2 represents the distance of the tail edge control point two deviating from the tail edge base point of the original blade profile, A2 represents an amplitude coefficient, and the value range is 0.1-0.12, d t represents the tail edge (along the spanwise) thickness;

[0090] The expression of the control point three and the control point four is:

[0091]

[0092] In the formula, Δd 3 / 4 is the distance of the control point three and the control point four deviating from the tail edge base point of the original blade profile, A 3 / 4 is an amplitude coefficient, and the value range is 0.03-0.04;

[0093] As shown in (d) and (e), the tail edge truncation point, the control point four and the control point three on the same layer are connected through a third-order Bezier curve, the control point four, the control point two and the control point three are connected through an elliptic curve, and the blade profile is accumulated in the spanwise direction to form a bionic tail edge; Figure 2 As shown in (f), the control points form control curves along the spanwise direction, the control curve three formed by the control point three and the control curve four formed by the control point four are consistent in phase, the control curve two formed by the control point two and the control curve one formed by the control point one have no corresponding relationship in phase, and the troughs of the control curve three and the control curve four are correspondingly arranged with the peak of the control curve two;

[0094] Figure 2 The present application improves the turbine stage efficiency of the variable geometry turbine stage under different working conditions by 1.42% to 2.41%, as shown in Table 1; the bionic beluga fin leading edge structure widens the attack angle range of the blade through the spanwise undulating structure, so that the turbine stage efficiency of the variable geometry turbine stage under variable working conditions is improved; the leading edge stagnation point of the variable geometry turbine stage under variable working conditions is closer to the leading edge point, as shown in (g); the seal whisker tail edge structure suppresses the tail edge shedding vortex, reduces the interaction between the wake and the moving blade, as shown in (h); the seal whisker bionic tail edge improves the turbine stage efficiency by reducing the wake loss; through the design of the bionic beluga fin leading edge and the seal whisker tail edge structure, the performance of the variable geometry turbine stage can be significantly improved;

[0095] The present application improves the turbine stage efficiency of the variable geometry turbine stage under different working conditions by 1.42% to 2.41%, as shown in Table 1; the bionic beluga fin leading edge structure widens the attack angle range of the blade through the spanwise undulating structure, so that the turbine stage efficiency of the variable geometry turbine stage under variable working conditions is improved; the leading edge stagnation point of the variable geometry turbine stage under variable working conditions is closer to the leading edge point, as shown in (g); the seal whisker tail edge structure suppresses the tail edge shedding vortex, reduces the interaction between the wake and the moving blade, as shown in (h); the seal whisker bionic tail edge improves the turbine stage efficiency by reducing the wake loss; through the design of the bionic beluga fin leading edge and the seal whisker tail edge structure, the performance of the variable geometry turbine stage can be significantly improved; Figure 3 Figure 4 Table 1 Efficiency comparison of the original turbine stage and the bionic turbine stage under different working conditions

[0096]

[0097] ​​​

[0098] The variable geometry turbine stage blades with leading edges imitating humpback whale fins and trailing edges imitating seal whiskers are designed based on the original blade profile; the original turbine stage is a variable geometry turbine stage with adjustable guide vanes, which can rotate around the center of rotation, such as Figure 5 As shown in the figure, the counterclockwise rotation of the guide vane is the positive direction, at which point the guide vane channel is enlarged; the clockwise rotation of the guide vane is the negative direction, at which point the guide vane angle is reduced. Tables 2 and 3 give the geometric parameters of the guide vane cascade and the moving blade cascade of the variable geometry turbine stage.

[0099] Table 2 Geometric characteristics of guide vane cascade

[0100]

[0101]

[0102] Table 3 Geometric characteristics of moving blade cascade

[0103]

[0104] The specific implementation scheme provided for the variable geometry bionic turbine stage with the leading edge imitating the humpback whale fin and the trailing edge imitating the seal beard is as follows:

[0105] The humpback whale fin-like leading edge structure and seal whisker-like trailing edge structure are applied to the leading and trailing edges of the original variable geometry turbine stage guide vanes and rotor blades. A flow channel is intercepted under the design working condition. Figure 6 As shown; the guide vane is rotated 5° counterclockwise to enlarge the channel, and rotated 5° clockwise to reduce the flow channel, respectively implementing the bionic turbine stage scheme; the airflow inlet and outlet conditions and the rotating speed of the moving blades are implemented according to the corresponding working conditions of the variable geometry turbine stage; when the ship gas turbine turbine operates under variable working conditions, the blade angle of attack changes little and the efficiency is high.

[0106] The variable geometry turbine stage bionic blades are manufactured using the lost wax casting method;

[0107] First, a ceramic material is used to shape the inner core model, and then multiple layers of ceramic slurry are wrapped on the outside to form a casting shell; after a drying and heating process, the internal wax mold is melted to form a cavity; nickel-based high-temperature alloy material is poured into the cavity, and after the alloy cools and solidifies, the ceramic shell is destroyed to remove the casting; the cast blade is preliminarily machined to remove burrs and excess metal to make the blade size close to the final requirements; then fine machining and surface treatment are performed to obtain the bionic blade.

[0108] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0109] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for forming a turbine-stage bionic blade with variable geometry of leading and trailing edges, characterized by: A variable geometry turbine-stage bionic blade with a leading edge and a trailing edge having a leading edge adopting the convex structure of the front of a humpback whale fin, and a trailing edge adopting the surface undulation structure of a seal's beard; The method comprises: When the blade profile is stacked in the span direction, the leading edge is sinusoidally undulated, giving the leading edge a convex structure similar to the leading edge of a humpback whale. When the blade profile is stacked in the span direction, the trailing edge is constructed to have a sinusoidal fluctuation along the span direction, so that the trailing edge point and the suction side and pressure side control points of the trailing edge circle change sinusoidally along the span direction; The leading edge forming method comprises the following steps: Set the leading edge cutoff point of the suction side and the leading edge cutoff point of the pressure side at one end of the original blade; The leading edge point of the original leading edge is control point 1, and the expression of the control curve 1 that changes sinusoidally along the span direction of control point 1 is: Where, Represents the distance of the control point from the original front edge base point, A 1 represents the amplitude coefficient, represents the leading edge diameter, h Represents the leaf height position; The leading edge cutoff point and the control point 1 are connected by a third-order Bezier curve and overlapped in the span direction to form the leading edge; The suction side leading edge cutoff point is 0.2-0.25 times the axial chord length away from the leading edge, and the pressure side leading edge cutoff point is 0.15-0.2 times the axial chord length away from the leading edge.

2. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 1, characterized in that: The leading edge undulates sinusoidally along the span direction through the leading edge point; The trailing edge fluctuates sinusoidally along the span direction through the trailing edge point, the suction side and the pressure side trailing edge circle control points.

3. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 2, characterized in that: The amplitude of the leading edge is smaller than that of the trailing edge.

4. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 1, characterized in that: The blades are guide vanes or moving blades.

5. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 1, characterized in that: The trailing edge forming method comprises the following steps: Set the trailing edge cutoff points on both sides of the other end of the original blade profile; Control point 2 is set at the end and both sides of the original trailing edge, control point 3 on the pressure side, and control point 4 on the suction side respectively; The expression for the change of control point 2 along the span direction is: Where, Represents the distance of control point 2 from the original trailing edge base point, A 2 represents the amplitude coefficient, represents the thickness of the trailing edge; The expressions for control point three and control point four are: Where, is the distance between control point 3 and control point 4 from the original trailing edge reference point, A 3 / 4 is the amplitude coefficient; The trailing edge truncation point, control point four, and control point three are connected by a third-order Bezier curve, and control point four, control point two, and control point three are connected by an elliptic curve, which are stacked in the span direction to form the trailing edge.

6. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 5, characterized in that: The control points form a control curve along the span direction. The sinusoidal curves of control curve three formed by control point three and control curve four formed by control point four are consistent in phase. The troughs of control curves three and four are set correspondingly to the peaks of control curve two.

7. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 6, characterized in that: The trailing edge cutoff points on the suction side and the pressure side are 1.5 times the diameter away from the trailing edge point, control point two is located at the end point of the trailing edge, and control points three and four are 0.5 times the diameter away from the trailing edge point.

8. The method for forming a turbine-stage bionic blade with variable leading and trailing geometry according to claim 7, characterized in that: The variable geometry turbine stage bionic blades are manufactured using the lost wax casting method; First, a core model is created using ceramic material, then coated with multiple layers of ceramic slurry to form a casting shell. After drying and heating, the wax pattern inside is melted away to form a cavity. A nickel-based high-temperature alloy is poured into the cavity. After the alloy cools and solidifies, the ceramic shell is broken and the casting is removed. The cast blade undergoes preliminary machining to remove burrs and excess metal, bringing the blade to near-final dimensions. The blades are then finished and surface treated.

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