A volute structure for reducing the exciting force of radial flow turbine blades

Abstract

The present invention discloses a volute structure for reducing the exciting force of radial turbine blades, belonging to the technical field of turbochargers, comprising: a turbine rotor, a volute and a casing, a jet tube is arranged between the volute and the casing; the jet tube comprises: an air inlet, an air outlet and an intermediate tube body, the air inlet and the air outlet are located at both ends of the intermediate tube body, the air inlet is located at the inlet section of the volute, and the air outlet is located at the inner wall surface of the casing. By arranging a jet tube between the volute and the casing, the present invention can lead high-pressure gas from the inlet section of the volute to improve the uniformity of the circumferential distribution of the volute outlet pressure without modifying the geometric structure of the volute or the geometric dimensions of the volute tongue, reduce the vibration stress on the turbine blades, suppress the vibration of the turbine blades, and prevent the turbine blades from fatigue damage.

Description

Technical Field

[0001] The invention relates to the technical field of turbochargers, and in particular to a volute structure for reducing the exciting force of radial flow turbine blades. Background Art

[0002] The radial turbine is widely used in aerospace, transportation, energy and chemical industries due to its high efficiency, compact structure and high reliability. It is an important component of turbochargers and small gas turbines. The reliability of turbine blades is crucial to the safe operation of the turbine. However, due to the non-axisymmetric geometry of the volute and the high and low pressure areas near the volute tongue, the circumferential pressure distribution at the outlet of the turbine volute is uneven. Therefore, when the turbine blade passes near the volute tongue, it will be affected by a sudden pressure change, resulting in periodic fluctuations in the surface pressure of the turbine blade, that is, the volute tongue exerts an exciting force on the turbine blade. When the turbine runs at a specific speed, the turbine rotor may cause the turbine blade to resonate under this aerodynamic excitation, causing the turbine blade to be damaged due to high-cycle fatigue. At present, there are two main methods for suppressing the vibration of radial turbine blades: one is to improve the situation by modifying the key parameters of the volute tongue geometry, adjusting the circumferential distribution of the volute cross-sectional area, or improving the uniformity of the circumferential distribution of the volute outlet pressure; the other is to optimize the shape and thickness distribution of the turbine blade to reduce the vibration stress on the turbine blade. However, both methods have many problems.

[0003] First way:

[0004] Limited effect: Although modifying the geometry of the volute and volute tongue can improve the fluid dynamics to a certain extent, because the vibration of the turbine blades is not only affected by the pressure distribution at the volute outlet, but also by many other factors, such as airflow instability, turbulence, and the interaction between the turbine blades and the fluid, such changes often have limited effect on suppressing the vibration of the turbine blades.

[0005] Poor versatility: Different turbine designs have different geometric parameters and operating conditions, so the optimization method for a specific turbine design may not be applicable to other turbine designs. This requires separate optimization for vibration suppression of different turbine designs, which increases the complexity and cost of the design.

[0006] Great influence on aerodynamic performance: Geometric modification of the volute will affect the aerodynamic performance of the turbine, such as increasing flow losses, changing efficiency, etc., thus affecting the performance of the entire system.

[0007] Unable to solve resonance problems of different orders: It is difficult to solve vibration problems at multiple resonant frequencies at the same time by simply modifying the geometric structure of the volute and the volute tongue.

[0008] Second way:

[0009] Limited effect: Although optimizing the shape and thickness distribution of turbine blades can reduce the vibration stress on turbine blades, this method is often only effective for specific vibration modes. For complex vibration modes or multi-order resonances, this optimization method is not sufficient to fully suppress vibration.

[0010] Poor versatility: The optimized design of turbine blades usually depends on specific turbine operating conditions. Different operating points may require different turbine blade designs, which makes it difficult for the optimization scheme to be universal in different turbines or different operating conditions.

[0011] Great impact on aerodynamic performance: Changes in the shape and thickness of the turbine blades may affect the aerodynamic performance of the turbine, such as changing the lift and drag characteristics of the turbine blades, thereby affecting the efficiency of the turbine.

[0012] Unable to solve the resonance problem of rotors of different orders: The shape and thickness distribution of general turbine blades are usually only effective for a certain order of vibration, and frequent modifications are required to solve the vibration problem at multiple resonant frequencies.

[0013] Therefore, it is necessary to design a volute structure for reducing the exciting force of the radial flow turbine blades to effectively solve the problem of turbine blade leading edge vibration caused by rotor resonance. Summary of the invention

[0014] The present invention provides a volute structure for reducing the exciting force of radial flow turbine blades to solve the above technical problems.

[0015] In order to achieve the above object, the technical solution of the present invention is:

[0016] A volute structure for reducing the exciting force of radial turbine blades comprises: a turbine rotor, a volute and a casing, wherein a jet tube is arranged between the volute and the casing; the jet tube comprises: an air inlet, an air outlet and an intermediate tube body, wherein the air inlet and the air outlet are located at two ends of the intermediate tube body, the air inlet is located at the inlet section of the volute, and the air outlet is located at the inner wall surface of the casing.

[0017] Preferably, three jet tubes are provided.

[0018] Preferably, the center plane of the jet tube passes through the axis of the turbine rotor, and the three jet tubes respectively correspond to the incident deflection angle α 1 =45°、α 2 =60°、α 3 =75°, the three jet tubes correspond to the air bleed position angle β 1 =51°, β 2 =36°, β 3 =21°.

[0019] Preferably, along the center line direction of the inlet section of the volute: the distance M between the center of the air inlet corresponding to the three jet tubes and the inlet end face of the volute is 1 =0.2L, M 2 =0.3L, M 3 =0.4L; Along the axis of the turbine rotor: the distance between the center of the air inlet corresponding to the three jet pipes and the center line of the inlet section of the volute N 1 =0.2W, N 2 =0.3W, N 3 =0.4W;

[0020] Wherein, L represents the distance from the lower edge of the inlet end face of the volute to the center line of the inlet section of the volute, and W represents the distance from the side edge of the inlet end face of the volute to the center line of the inlet section of the volute.

[0021] Preferably, along the axis direction of the turbine rotor: the center of the air outlet is located at 25%-40%H of the trailing edge of the turbine blade of the turbine rotor, and the distance between the center of the air outlet and the leading edge of the turbine rotor is δ=2T-4T;

[0022] Wherein, H represents the length of the blade root of the turbine blade from the leading edge to the trailing edge along the axial direction of the turbine rotor, and T represents the leading edge thickness of the turbine rotor.

[0023] Preferably, the air outlet is arranged along the radial direction of the turbine rotor, and the center line of the air outlet forms an angle θ with a plane perpendicular to the axis of the turbine rotor, and the value of θ is 46°-54°.

[0024] Preferably, the inner holes of the jet tubes are arranged with equal cross-sections, and the relative flow area A re =A / A 0 5%-10%, where A represents the cross-sectional area of ​​the air inlet, A 0 Represents the zero cross-sectional area of ​​the volute.

[0025] Preferably, the inner hole diameter of the jet tube is less than or equal to 3 mm.

[0026] Preferably, the intermediate tube body comprises: an air inlet straight section, an intermediate arc section and an air outlet straight section, and the axes of the air inlet straight section and the air outlet straight section are respectively tangent to the center line of the intermediate arc section.

[0027] Preferably, the bleed air straight section is perpendicular to the axis of the turbine rotor, and the curvature radius of the middle arc section is 30 mm.

[0028] Beneficial effect: The present application discloses a volute structure for reducing the exciting force of radial flow turbine blades. By arranging a jet tube between the volute and the casing, it is possible to draw out high-pressure gas from the inlet section of the volute to improve the uniformity of the circumferential distribution of the volute outlet pressure, reduce the vibration stress on the turbine blades, suppress the vibration of the turbine blades, and prevent fatigue damage to the turbine blades without modifying the volute geometric structure or the volute tongue geometric dimensions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 A schematic structural diagram of a volute structure for reducing the exciting force of radial flow turbine blades disclosed in the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of a volute structure for reducing the exciting force of radial flow turbine blades disclosed in the present invention, in which the turbine rotor is hidden;

[0032] Figure 3 A side view of a volute structure for reducing the exciting force of radial flow turbine blades disclosed in the present invention;

[0033] Figure 4 for Figure 3 Sectional view of AA in the middle;

[0034] Figure 5 A radial view of an air inlet straight section and an air outlet straight section of a volute structure for reducing the exciting force of radial flow turbine blades disclosed in the present invention;

[0035] Figure 6 The present invention discloses a meridian plane schematic diagram of a volute structure jet tube for reducing the exciting force of radial flow turbine blades.

[0036] 1. Turbine rotor; 11. Turbine blades; 2. Volute; 21. Inlet section; 3. Casing; 4. Jet pipe; 41. Air inlet; 42. Air outlet; 43. Intermediate tube body; 431. Air inlet straight section; 432. Intermediate arc section; 433. Air outlet straight section. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] A volute structure for reducing the exciting force of radial turbine blades, combined with Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, it comprises: a turbine rotor 1, a volute 2 and a casing 3, a jet tube 4 is arranged between the volute 2 and the casing 3; the jet tube 4 comprises: an air inlet 41, an air outlet 42 and an intermediate tube body 43, the air inlet 41 and the air outlet 42 are located at both ends of the intermediate tube body 43, the air inlet 41 is located at the inlet section 21 of the volute 2, and the air outlet 42 is located at the inner wall surface of the casing 3. By arranging the jet tube 4 between the volute 2 and the casing 3, during the rotation of the turbine rotor 1, the high-pressure gas of the inlet section 21 of the volute 2 is introduced into the upstream of the volute tongue through the jet tube 4 to eliminate the low static pressure area, significantly improve the uniformity of the static pressure distribution near the volute tongue, so that when the turbine blade 11 passes near the volute tongue, the static pressure difference fluctuation amplitude of the pressure surface and the suction surface is reduced, and the exciting force of the radial turbine blade 11 is reduced. The present application can lead high-pressure gas from the inlet section 21 of the volute 2 to improve the uniformity of the circumferential distribution of the volute outlet pressure without modifying the geometric structure of the volute or the geometric size of the volute tongue, reduce the vibration stress on the turbine blades 11, suppress the vibration of the turbine blades 11, and prevent fatigue damage to the turbine blades 11. At the same time, the jet tube 4 has little effect on the aerodynamic performance of the turbine, and the overall effect of the jet tube 4 can be ignored compared to the vibration suppression effect on the turbine blades 11.

[0039] Specifically, the air outlet 42 is located on the inlet side of the turbine rotor 1 of the inner wall surface of the casing 3, that is, the side where the leading edge of the turbine blade 11 is located, so that the jet tube 4 can act on the large diameter of the turbine rotor 1, avoiding the weakening of the vibration suppression effect due to the jet tube 4 being far away from the inlet of the turbine rotor 1.

[0040] Preferably, three jet tubes 4 are provided. Airflow excitation is an important cause of the vibration of the turbine blade 11. When the airflow excitation frequency matches the natural frequency of the turbine blade 11, resonance will occur, causing the vibration amplitude of the turbine blade 11 to increase sharply. Resonances of different orders correspond to different natural frequencies, so resonances of different orders will cause vibration responses of different parts of the turbine blade 11. And in actual situations, the situation that causes the turbine blade 11 to be damaged generally only occurs in lower-order vibration modes, generally the first three orders. If it is the first and second orders, two jet tubes 4 can be arranged at the same time to suppress vibration respectively. Setting three jet tubes 4 can solve the problem of vibration of the leading edge of the turbine blade 11 (i.e., the major diameter of the turbine blade 11) caused by resonances of different orders in actual situations. This makes the present application have the advantages of high versatility, almost negligible impact on the aerodynamic performance of the turbine, and no need to optimize the blade shape and thickness distribution.

[0041] Preferably, the center plane of the jet tube 4 passes through the axis of the turbine rotor 1, and the incident deflection angles α corresponding to the three jet tubes 4 are 1 =45°、α 2 =60°、α 3 =75°, the three jet tubes 4 correspond to the air bleed position angle β 1 =51°, β 2 =36°, β 3 =21°. The incident deflection angle is defined as the angle between the center plane of the jet tube 4 and the plane passing through the center line of the inlet section 21 of the volute 2 and parallel to the axis of the turbine rotor 1. The air bleed position angle is defined as the angle between the center plane of the jet tube 4 and the plane formed by the profile of the tip of the volute tongue and the axis of the turbine rotor 1. The fluid spin will affect the pressure distribution on the turbine blade 11, which may increase the local load on the turbine blade 11 and increase the stress level of the turbine blade 11. The fluid spin dissipation will cause the pressure difference between the suction surface and the pressure surface of the turbine blade 11 to decrease, affecting the work capacity of the turbine. In addition, the fluid spin dissipation will cause part of the kinetic energy of the fluid to be converted into heat energy, thereby reducing the available energy of the fluid, which will reduce the efficiency of the turbine. The incident deflection angles of the three jet tubes 4 are separated by 15°, and the incident deflection angles between 45° and 75° can ensure good flow, avoid a large turn when the high-pressure airflow enters the jet tube 4 at a smaller incident angle, and generate a recirculation zone, thereby avoiding a large pressure loss caused by fluid spin dissipation.

[0042] Specifically, the turbine rotor 1 is coaxially arranged inside the volute 2, and a plurality of radial turbine blades 11 are evenly distributed in the circumference of the turbine rotor 1. The three jet tubes 4 are located at 21° to 51° relative to the volute tongue in the opposite direction of the rotation of the turbine rotor 1. The three jet tubes 4 are named the third jet tube, the second jet tube and the first jet tube in the opposite direction of the rotation of the turbine rotor 1. The incident deflection angle of the first jet tube is α1 , the air bleed position angle is β 1 , the incident deflection angle of the second jet tube is α 2 , the air bleed position angle is β 2 , the incident deflection angle of the third jet tube is α 3 , the air bleed position angle is β 3 The fluid pressure value at the inlet section 21 of the volute 2 meets the vibration suppression requirement within the angular radiation range of the air inlet 41 of the three jet pipes 4. A small amount of high-pressure gas in this area is introduced to the leading edge of the turbine blade 11 through the jet pipe 4, improving the pressure fluctuation near the turbine blade 11 and the load distribution of the turbine blade 11, suppressing the pressure difference between the pressure surface and the suction surface of the turbine blade 11, and thus reducing the exciting force of the turbine blade 11.

[0043] Preferably, along the centerline direction of the inlet section 21 of the volute 2: the distance M between the center of the air inlet 41 corresponding to the three jet tubes 4 and the inlet end surface of the volute 2 is 1 =0.2L, M 2 =0.3L, M 3 = 0.4L; along the axial direction of the turbine rotor 1: the distance N between the center of the air inlet 41 corresponding to the three jet tubes 4 and the center line of the inlet section 21 of the volute 2 1 =0.2W, N 2 =0.3W, N 3 =0.4W;

[0044] Wherein, L represents the distance from the lower edge of the inlet end surface of the volute 2 to the center line of the inlet section 21 of the volute 2, and W represents the distance from the side edge of the inlet end surface of the volute 2 to the center line of the inlet section 21 of the volute 2. The air inlet 41 of the first jet pipe corresponds to M 1 and N 1 The air inlet 41 of the second jet tube corresponds to M 2 and N 2 The air inlet 41 of the third jet tube corresponds to M 3 and N 3 The inlet section 21 of the volute 2 is gradually contracted, and the pressure increases as it goes backwards. The front and rear heights of the air inlets 41 corresponding to the three jet tubes 4 are inconsistent, which can better guide the highest pressure fluid in the corresponding local area. The lateral positions of the air inlets 41 corresponding to the three jet tubes 4 are staggered, which can prevent the front jet tube 4 from interfering with the fluid flowing through the rear jet tube 4.

[0045] Preferably, along the axis direction of the turbine rotor 1: the center of the air outlet 42 is located at 25%-40%H of the trailing edge of the turbine blade 11 of the turbine rotor 1, and the distance between the center of the air outlet 42 and the leading edge of the turbine rotor 1 is δ=2T-4T;

[0046] Among them, H represents the length of the blade root of the turbine blade 11 from the leading edge to the trailing edge along the axial direction of the turbine rotor 1, and T represents the leading edge thickness of the turbine rotor 1. When the turbine blade 11 is designed, the sizes of H and T are determined, and then the position of the air outlet 42 is defined by H and T.

[0047] Preferably, the air outlet 42 is arranged along the radial direction of the turbine rotor 1, and the center line of the air outlet 42 forms an angle θ with the plane perpendicular to the axis of the turbine rotor 1, which is the outlet pitch angle of the jet tube 4, and θ is 46°-54°. Because within a vibration cycle of the turbine blade 11, there must be an optimal opening position that can offset the excitation effect of the volute tongue; similarly, within a vibration cycle of the turbine blade 11, there must be a moment when a reverse force is applied to the turbine blade 11, which can weaken the vibration of the turbine blade 11 or the excitation effect of the volute tongue to the greatest extent. Therefore, for the third-order harmonic component (EO3) of the volute tongue excitation force, there must be three optimal opening positions on the circumference of the inner wall on the inlet side of the casing 3, which can weaken or even offset the excitation effect of the volute tongue. The positions of the outlets 42 of the three jet tubes 4 determined by the above parameters can better suppress the excitation force generated by the circumferential flow field distortion of the first three orders of the volute tongue, significantly reduce the surface vibration stress of the turbine blades 11, and prevent the turbine blades 11 from being damaged by the excitation force. For the EO3 working condition, the excitation stress decreased by 30%.

[0048] Specifically, the center of the air outlet 42 is located at a distance H1 =H-δtanθ from the leading edge of the turbine blade 11 of the turbine rotor 1 .

[0049] Preferably, the inner holes of the jet tube 4 are arranged with equal cross-sections, and the relative flow area A re =A / A 0 is 5%-10%, wherein A represents the cross-sectional area of ​​the air inlet 41, and A 0 The zero cross-sectional area of ​​the volute is an important reference for evaluating the flow state of the fluid before it enters the volute 2 from the inlet section 21 of the volute 2. Ideally, the flow of the fluid at the zero cross-sectional area of ​​the volute should be irrotational. re When controlled at 5%-10%, the jet tube 4 has a better effect of suppressing the exciting force of the turbine blade 11. By adding the jet tube 4 structure, high-pressure gas is introduced from the inlet section 21 of the volute 2 to improve the uniformity of the static pressure distribution near the volute tongue, and the outlets 42 of the three jet tubes 4 are at different incident angles, and the relative flow area of ​​the jet tubes 4 is controlled, which has a very significant suppressing effect on the exciting force of the turbine blade 11.

[0050] Preferably, the inner diameter of the jet tube 4 is less than or equal to 3 mm to avoid backflow when the diameter of the jet tube 4 exceeds 3 mm due to the pressure value of the inlet section 21 of the volute 2 being lower than the pressure value near the downstream of the volute tongue. In this embodiment, the diameter of the jet tube is 1.5-3 mm.

[0051] Preferably, the middle tube body 43 comprises: an air-inlet straight section 431, an intermediate arc section 432 and an air outlet straight section 433, and the axes of the air-inlet straight section 431 and the air outlet straight section 433 are respectively tangent to the center line of the intermediate arc section 432. The intermediate arc section 432 realizes the connection and transition between the air-inlet straight section 431 and the air outlet straight section 433.

[0052] Preferably, the bleed air straight section 431 is perpendicular to the axis of the turbine rotor 1, and the curvature radius of the middle arc section 432 is 30 mm.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A volute structure for reducing the exciting force of radial flow turbine blades, characterized in that: include: A turbine rotor (1), a volute (2) and a casing (3), wherein a jet tube (4) is provided between the volute (2) and the casing (3); the jet tube (4) comprises an air inlet (41), an air outlet (42) and an intermediate tube body (43); the air inlet (41) and the air outlet (42) are located at two ends of the intermediate tube body (43); the air inlet (41) is located at an inlet section (21) of the volute (2), and the air outlet (42) is located on an inner wall surface of the casing (3); three jet tubes (4) are provided; the central plane of the jet tube (4) passes through the axis of the turbine rotor (1), and the three jet tubes (4) respectively correspond to incident deflection angles α1=45°, α2=60°, and α3=75°, and the three jet tubes (4) respectively correspond to air inlet position angles β1=51°, β2=36°, and β3=21°.

2. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 1, characterized in that: Along the centerline direction of the inlet section (21) of the volute (2): the distances between the centers of the air inlets (41) respectively corresponding to the three jet tubes (4) and the inlet end surface of the volute (2) are M1=0.2L, M2=0.3L, and M3=0.4L; along the axis direction of the turbine rotor (1): the distances between the centers of the air inlets (41) respectively corresponding to the three jet tubes (4) and the centerline of the inlet section (21) of the volute (2) are N1=0.2W, N2=0.3W, and N3=0.4W; Wherein, L represents the distance from the lower edge of the inlet end surface of the volute (2) to the center line of the inlet section (21) of the volute (2), and W represents the distance from the side edge of the inlet end surface of the volute (2) to the center line of the inlet section (21) of the volute (2).

3. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 1, characterized in that: Along the axial direction of the turbine rotor (1): the center of the air outlet (42) is located at 25%-40%H of the trailing edge of the turbine blade (11) of the turbine rotor (1), and the distance between the center of the air outlet (42) and the leading edge of the turbine rotor (1) is δ=2T-4T; Wherein, H represents the length of the blade root of the turbine blade (11) from the leading edge to the trailing edge along the axial direction of the turbine rotor (1), and T represents the leading edge thickness of the turbine rotor (1).

4. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 3, characterized in that: The air outlet (42) is arranged along the radial direction of the turbine rotor (1), and the center line of the air outlet (42) forms an angle θ with a plane perpendicular to the axis of the turbine rotor (1), and the value of θ is 46°-54°.

5. The volute structure for reducing the exciting force of radial flow turbine blades according to claim 1, characterized in that: The inner holes of the jet tube (4) are arranged with equal cross-sections, and the relative flow area A re =A / A0 is 5%-10%, wherein A represents the cross-sectional area of ​​the air inlet (41), and A0 represents the zero cross-sectional area of ​​the volute.

6. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 5, characterized in that: The inner hole diameter of the jet tube (4) is less than or equal to 3 mm.

7. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 1, characterized in that: The intermediate tube body (43) comprises an air entraining straight section (431), an intermediate arc section (432) and an air outlet straight section (433), wherein the axes of the air entraining straight section (431) and the air outlet straight section (433) are respectively tangent to the center line of the intermediate arc section (432).

8. A volute structure for reducing the exciting force of radial flow turbine blades according to claim 7, characterized in that: The air bleed straight section (431) is perpendicular to the axis of the turbine rotor (1), and the radius of curvature of the middle arc section (432) is 30 mm.

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