A centrifugal compressor and a method for adjusting the geometry of the internal flow channel of the compressor stage.

Abstract

A centrifugal compressor and a method for adjusting the geometry of the compressor stage internal flow channel are disclosed. The compressor stage internal flow channel includes impeller blades, a diffuser, and the internal flow channel formed by these components. The internal flow channel comprises a compressor stage hub and a compressor stage rim. The hub curve formed by a set of points on the compressor stage hub and the rim curve formed by a set of points on the compressor stage rim are defined on the Z-R plane, respectively satisfying the fitting curve equations for the hub meridional plane and the rim meridional plane. The hub curve and rim curve are rotated about the Z-axis to form the compressor stage hub surface and the compressor stage rim surface, respectively. This invention reduces the number of diffuser blades in the original design, increases the impeller inlet hub radius, and reduces airflow impact losses. Simultaneously, the suction surface separation generated within the diffuser flow channel disappears, the flow tends to stabilize, and the entropy increase of the diffuser is controlled within the blade surface boundary layer. There are no significant losses within the diffuser flow channel, thus improving aerodynamic performance.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic design technology for centrifugal compressors used in expansion refrigerators, and in particular to a centrifugal compressor and a method for adjusting the geometry of the internal flow channel of the compressor stage. Background Technology

[0002] As a key component of the expander compressor and an upstream component of the turbine, the compressor decelerates and pressurizes incoming low-pressure air, driving high-pressure air further into the turbine to complete the expansion and work process. Therefore, the compressor's pressurization capacity directly affects the turbine's work capacity, and consequently, the system performance of the expander compressor. The compressor impeller directly influences the total gas pressure rise within the compressor. Downstream of the impeller, the diffuser recovers kinetic energy and decelerates and diffuses the air. Therefore, a good match between the impeller and diffuser is essential for the compressor stage to achieve high efficiency under design conditions. Traditional compressor stages often have a large number of diffuser blades and a large impeller inlet hub radius, leading to difficulties in blade manufacturing and airflow impact losses at the compressor stage inlet. Suction surfaces are also prone to form within the diffuser channels, resulting in unstable flow and requiring improvement in the compressor stage's aerodynamic performance. Summary of the Invention

[0003] To address the aforementioned problem of unreasonable internal flow channel design in traditional compressor stages, this invention provides a centrifugal compressor and a method for adjusting the geometry of the internal flow channel of the compressor stage. This method reduces the number of diffuser blades in traditional designs and increases the impeller inlet hub radius, thereby reducing the machining difficulty of the impeller blades. It also allows the airflow at the impeller and diffuser inlet positions to conform to the blades as it enters the flow channel, reducing airflow impact losses. At the same time, the suction surface separation generated in the diffuser flow channel disappears, the flow tends to be stable, and the aerodynamic performance of the compressor stage is effectively improved.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a centrifugal compressor, comprising impeller blades and a diffuser and the compressor stage internal flow channel formed therefrom, wherein the compressor stage internal flow channel includes a compressor stage hub and a compressor stage rim, wherein the hub curve formed by the set of points on the compressor stage hub and the rim curve formed by the set of points on the compressor stage rim are defined on the ZR plane, respectively satisfying the hub meridional plane fitting curve equation and the rim meridional plane fitting curve equation;

[0005] The hub curve and rim curve are rotated around the Z-axis to form the compressor stage hub surface and compressor stage rim surface, respectively.

[0006] Preferably, the equation for the fitting curve of the hub meridional plane is:

[0007] R = az 5 +bz 4 +cz 3+dz 2 +ez+f;

[0008] In the formula: a = 3.2E-5, b = -5.6E-3, c = 3.8E-1, d = -1.2E+1, e = 2.0E+2, f = -1.2E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the hub curve point set defined on the ZR plane.

[0009] Preferably, the equation for the fitting curve of the rim meridional surface is:

[0010] R = az 5 +bz 4 +cz 3 +dz 2 +ez+f;

[0011] In the formula: a = 9.7E-5, b = -1.5E-2, c = 9.5E-1, d = -2.9E+1, e = 4.4E+2, f = -2.5E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the rim curve point set defined on the ZR plane.

[0012] Preferably, the compressor stage blade mounting angle β is defined by a relative flow direction position m along the flow direction relative to a pre-set mid-arc line, including the impeller blade hub position mounting angle β. 叶轮轮毂 The first installation angle function and the impeller blade rim position installation angle β are satisfied. 叶轮轮缘 Meets the second mounting angle function, diffuser rim and / or hub position mounting angle β 扩压器 It conforms to the third installation angle function.

[0013] Preferably, the hub mounting angle and rim mounting angle of the impeller blades respectively include:

[0014] The first installation angle function is:

[0015] β 叶轮轮毂 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0016] In the formula: a = 3.9E+2, b = -9.0E+2, c = 8.3E+2, d = -3.1E+2, e = 5.4E+1 are expressed in scientific notation, and m is the mounting angle β corresponding to the hub curve point set. 叶轮轮毂 The ratio of relative flow direction positions distributed along the flow direction in the middle arc;

[0017] The second installation angle function is:

[0018] β 叶轮轮缘 =am4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0019] In the formula: a = -9.6E+0, b = 3.4E+1, c = 8.2E+1, d = -1.1E+2, e = 6.2E+1 are expressed in scientific notation, and m is the installation angle β corresponding to the set of points on the rim curve. 叶轮轮缘 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

[0020] Preferably, the installation angles at the diffuser rim and hub are consistent, including:

[0021] The third installation angle function is:

[0022] β 扩压器 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0023] In the formula: a = 2.2E+0, b = -6.9E+1, c = 1.1E+0, d = -5.9E+1, e = 7.6E+1, expressed in scientific notation; m is the installation angle β corresponding to the hub or rim curve point set of the diffuser blade. 扩压器 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

[0024] Preferably, the thickness of the impeller blades and diffuser blades is distributed equally on both sides with the central arc as the reference, and the blade thickness distribution includes: the thickness distribution at the impeller blade hub position conforms to a first thickness distribution function, the thickness distribution at the impeller blade rim position conforms to a second thickness distribution function, and the thickness distribution at the diffuser blade hub and rim positions is consistent and conforms to a third thickness distribution function.

[0025] Preferably, the thickness distribution of the impeller blades includes:

[0026] The first thickness distribution function is:

[0027] t 叶轮轮毂 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0028] In the formula: a = -5.8E+0, b = 1.2E+1, c = -9.3E+0, d = 3.1E+0, e = 9.0E+1, t is expressed in scientific notation. 叶轮轮毂 The thickness value of the hub curve point set of the impeller blades, relative to the flow direction position m along the flow direction with the middle arc line as the reference;

[0029] The second thickness distribution function is:

[0030] t 叶轮轮缘 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0031] In the formula: a = -4.0E+0, b = 8.5E+0, c = -6.7E+0, d = 2.3E+0, e = 6.0E-1, t is expressed in scientific notation. 叶轮轮缘 The thickness value of the impeller blade rim curve point set corresponding to the position m relative to the flow direction along the flow direction with the middle arc line as the reference.

[0032] Preferably, the thickness distribution of the diffuser blades includes:

[0033] The third thickness distribution function is:

[0034] t 扩压器 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0035] In the formula: a = 8.7E-2, b = -1.0E+1, c = 1.7E+0, d = 8.7E+0, e = 2.0E-1, t is expressed in scientific notation. 扩压器 The thickness value of the diffuser blade rim and / or hub curve point set corresponding to the relative flow direction position m along the flow direction with the middle arc line as the reference.

[0036] On the other hand, the present invention adopts the following technical solution: a method for adjusting the geometry of the internal flow channel of a compressor stage, comprising the following steps:

[0037] Calculate the pseudo-hub curve and pseudo-rim curve of the internal flow channel of the compressor stage and define the pseudo-hub curve and pseudo-rim curve on the ZR plane;

[0038] The hub curve and the rim curve are approximated by fitting the curve equations of the hub meridional plane and the rim meridional plane respectively. The fitting results are used to determine the hub curve and rim curve of the compressor stage internal flow channel.

[0039] The hub curve and rim curve are rotated about the Z-axis to generate the compressor stage hub surface and compressor stage rim surface, respectively.

[0040] The hub and rim positions of the impeller blades and diffuser blades are fitted with the corresponding installation angle functions, and the arc installation angles in the hub and rim positions of the impeller blades and diffuser blades are determined by fitting.

[0041] The impeller blades and diffuser blades are based on the central arc line, and the thickness is applied equally on both sides of the central arc line. The thickness distribution is determined by the thickness distribution function corresponding to each position.

[0042] After determining the arc installation angle and thickness distribution of the hub and rim of the impeller blades and diffuser blades, the generated hub curves and rim curves are superimposed to obtain the ruled surfaces of the compressor impeller blades and diffuser blades. The geometry of the internal flow channel of the compressor stage is determined by combining the rim surface and the hub surface.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] This invention reduces the number of diffuser blades in the original design, increases the impeller inlet hub radius, reduces the manufacturing difficulty of the impeller blades, and allows the airflow at the impeller and diffuser inlet positions to enter the flow channel in close contact with the blades, reducing airflow impact losses. At the same time, the suction surface separation generated in the diffuser flow channel disappears, the flow tends to be stable, the entropy increase of the diffuser is controlled within the blade surface boundary layer, there are no significant losses in the diffuser flow channel, and the aerodynamic performance of the original design is improved. Attached Figure Description

[0045] To more clearly illustrate the technical solution, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the meridional view of the compressor stage of the present invention;

[0047] Figure 2 This is a geometrical schematic diagram of the hub curve and rim curve of the compressor stage meridional plane of the present invention;

[0048] Figure 3 This is a schematic diagram of the impeller blade mounting angle distribution along the flow direction according to the present invention;

[0049] Figure 4 This is a schematic diagram showing the distribution of the impeller and diffuser mounting angles along the flow direction according to the present invention;

[0050] Figure 5 This is a schematic diagram of the thickness distribution of the impeller and diffuser along the flow direction according to the present invention;

[0051] Figure 6 This is a schematic diagram of the initial impeller geometry in a traditional technology.

[0052] Figure 7 This is a schematic diagram of the optimized impeller geometry of the present invention;

[0053] Figure 8This is a schematic diagram of the Mach number distribution in the diffuser channel before and after optimization according to the present invention;

[0054] Figure 9 This is a schematic diagram of the initial compressor's efficiency and pressure ratio characteristics at constant speed, using traditional technology.

[0055] Figure 10 This is a schematic diagram of the constant speed efficiency and pressure ratio characteristic curves of the compressor after optimization according to the present invention. Detailed Implementation

[0056] In order to clearly and completely understand the technical solution, the present invention will be further described in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0058] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0059] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0060] Implementation Case 1:

[0061] A centrifugal compressor includes impeller blades and a diffuser, forming an internal flow channel within the compressor stage. The internal flow channel includes a compressor stage hub and a compressor stage rim. The hub curve formed by a set of points on the compressor stage hub and the rim curve formed by a set of points on the compressor stage rim are defined on the ZR plane, as shown below. Figure 1 The compressor stage meridional view shown includes the compressor stage hub curve and compressor stage rim curve, which are defined on the ZR plane to obtain the following... Figure 2 The geometry of the hub curve and rim curve of the compressor stage meridional plane is shown.

[0062] like Figure 2The compressor stage hub curve and rim curve shown are approximated by the hub meridional plane fitting curve equation and the rim meridional plane fitting curve equation, respectively. The specific details are as follows:

[0063] The equation for the fitting curve of the hub meridional plane is:

[0064] R = az 5 +bz 4 +cz 3 +dz 2 +ez+f;

[0065] In the formula: a = 3.2E-5, b = -5.6E-3, c = 3.8E-1, d = -1.2E+1, e = 2.0E+2, f = -1.2E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the hub curve point set defined on the ZR plane.

[0066] The equation for the fitting curve of the rim meridional surface is:

[0067] R = az 5 +bz 4 +cz 3 +dz 2 +ez+f;

[0068] In the formula: a = 9.7E-5, b = -1.5E-2, c = 9.5E-1, d = -2.9E+1, e = 4.4E+2, f = -2.5E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the rim curve point set defined on the ZR plane.

[0069] The fitted curves are shown in the table below:

[0070]

[0071]

[0072] The hub curve and rim curve are obtained by fitting the above-mentioned curve equation. The hub curve and rim curve are rotated with the Z-axis as the rotation axis to form the compressor stage hub surface and compressor stage rim surface, respectively.

[0073] In this implementation case, the number of compressor impeller blades after fitting and optimization is 17, and the number of diffuser blades is reduced to 13 compared with the traditional compressor. This reduces the number of diffuser blades in the original design, increases the impeller inlet hub radius, and reduces the difficulty of impeller blade processing.

[0074] In this embodiment, the compressor stage blade installation angle β is defined relative to a pre-set mid-curve line along the flow direction at a flow direction position m, such as... Figure 3 and 4As shown, in this embodiment, the installation angle of the mid-arc line along the flow direction of the impeller blades and diffuser blades at the rim and hub positions is defined by... Figure 3 A schematic diagram of the impeller blade mounting angle distribution along the flow direction is given, showing the variation of the mounting angle along the flow direction. Figure 4 A schematic diagram of the impeller and diffuser mounting angles along the flow direction is given.

[0075] Specifically, the installation angle of the impeller blade at the inlet hub position is close to 55°. Within the relative flow direction range of 0.3-0.4, its installation angle reaches its minimum value of approximately 15°. Afterward, the installation angle at the impeller hub position increases, reaching 58° at the impeller outlet hub position. In this embodiment, the impeller blade hub position installation angle β... 叶轮轮毂 It conforms to the first installation angle function, which is:

[0076] β 叶轮轮毂 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0077] In the formula: a = 3.9E+2, b = -9.0E+2, c = 8.3E+2, d = -3.1E+2, e = 5.4E+1 are expressed in scientific notation, and m is the mounting angle β corresponding to the hub curve point set. 叶轮轮毂 The ratio of relative flow direction positions distributed along the flow direction in the middle arc;

[0078] The installation angle at the inlet rim of the impeller blades is approximately 62°; it reaches a minimum of approximately 31° within the 0.5-0.6 relative flow direction range, after which the installation angle increases, reaching 58° at the outlet rim. In this embodiment, the installation angle β at the impeller blade rim is... 叶轮轮缘 It conforms to the second installation angle function, which is:

[0079] β 叶轮轮缘 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0080] In the formula: a = -9.6E+0, b = 3.4E+1, c = 8.2E+1, d = -1.1E+2, e = 6.2E+1 are expressed in scientific notation, and m is the installation angle β corresponding to the set of points on the rim curve. 叶轮轮缘 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

[0081] The installation angle functions of the arc lines at the hub and rim positions of the impeller blades are shown in the table below:

[0082]

[0083] The installation angle distribution of the diffuser blades' rim and hub arcs remains consistent. At the diffuser inlet, the installation angle is close to 76°. A minimum installation angle exists within the 0.5-0.6 relative flow direction position range; a maximum installation angle exists within the 0.7-0.8 relative flow direction position range. In this embodiment, the installation angle β at the diffuser rim and / or hub positions is... 扩压器 It conforms to the third installation angle function, which is:

[0084] β 扩压器 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0085] In the formula: a = 2.2E+0, b = -6.9E+1, c = 1.1E+0, d = -5.9E+1, e = 7.6E+1, expressed in scientific notation; m is the installation angle β corresponding to the hub or rim curve point set of the diffuser blade. 扩压器 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

[0086] The mounting angle function of the arc at the diffuser rim and / or hub position is shown in the table below:

[0087]

[0088]

[0089] Therefore, the arc installation angle of the impeller blades and diffuser blades in this embodiment is determined.

[0090] In this embodiment, the thickness of the impeller blades and diffuser blades is evenly distributed on both sides of the mid-curve as a reference. The thickness is applied equally on both sides of the mid-curve to complete the blade thickness distribution design. The thickness variation along the flow direction is as follows: Figure 5 The diagram shows the thickness distribution of the impeller and diffuser along the flow direction.

[0091] Specifically, the thickness distribution at the impeller blade hub and rim is similar, with minimum values ​​at the leading and trailing edges, and minimal variation within the relative flow direction range of 0.2-0.8. The thickness distribution at the impeller blade hub conforms to a first thickness distribution function, which is:

[0092] t 叶轮轮毂 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0093] In the formula: a = -5.8E+0, b = 1.2E+1, c = -9.3E+0, d = 3.1E+0, e = 9.0E+1, t is expressed in scientific notation. 叶轮轮毂 The thickness value of the hub curve point set of the impeller blades, relative to the flow direction position m along the flow direction with the middle arc line as the reference;

[0094] The thickness distribution at the impeller blade rim conforms to a second thickness distribution function, which is:

[0095] t 叶轮轮缘 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0096] In the formula: a = -4.0E+0, b = 8.5E+0, c = -6.7E+0, d = 2.3E+0, e = 6.0E-1, t is expressed in scientific notation. 叶轮轮缘 The thickness value of the impeller blade rim curve point set corresponding to the position m relative to the flow direction along the flow direction with the middle arc line as the reference.

[0097] The thickness distribution functions at the hub and rim positions of the impeller blades are shown in the table below:

[0098]

[0099]

[0100] The thickness distribution of the diffuser blades is completely consistent at the rim and hub positions, and conforms to the third thickness distribution function, which is:

[0101] t 扩压器 =am 4 +bm 3 +cm 2 +dm+e, m∈[0,1];

[0102] In the formula: a = 8.7E-2, b = -1.0E+1, c = 1.7E+0, d = 8.7E+0, e = 2.0E-1, t is expressed in scientific notation. 扩压器 The thickness value of the diffuser blade rim and / or hub curve point set corresponding to the relative flow direction position m along the flow direction with the middle arc line as the reference.

[0103]

[0104] This implementation reduces the number of diffuser blades in the original design. The airflow at the impeller and diffuser inlet position adheres to the blades as it enters the flow channel, reducing airflow impact losses. At the same time, the suction surface separation generated in the diffuser flow channel disappears, the flow tends to be stable, and the aerodynamic performance of the traditional design scheme is effectively improved.

[0105] Implementation Case 2:

[0106] Based on the centrifugal compressor in Case Study 1, a method for adjusting the geometry of the internal flow channel of a compressor stage is provided, including the following steps:

[0107] The pseudo-hub curve and pseudo-rim curve of the compressor stage internal flow channel are calculated and defined on the ZR plane. The hub curve and the rim curve are approximated by fitting the curve equation of the hub meridional plane and the curve equation of the rim meridional plane respectively. The hub curve and the rim curve of the compressor stage internal flow channel are obtained by fitting. The hub curve and the rim curve are rotated about the Z axis to generate the compressor stage hub surface and the compressor stage rim surface respectively.

[0108] The hub and rim positions of the impeller blades and diffuser blades are fitted with the corresponding installation angle functions, and the arc installation angles in the hub and rim positions of the impeller blades and diffuser blades are determined by fitting.

[0109] The impeller blades and diffuser blades are based on the central arc line, and the thickness is applied equally on both sides of the central arc line. The thickness distribution is determined by the thickness distribution function corresponding to each position.

[0110] After determining the arc installation angle and thickness distribution of the hub and rim of the impeller blades and diffuser blades, the generated hub curves and rim curves are superimposed to obtain the ruled surfaces of the compressor impeller blades and diffuser blades. The geometry of the internal flow channel of the compressor stage is determined by combining the rim surface and the hub surface.

[0111] This implementation case optimizes the traditional technical solution. The optimized impeller blade geometric reference is as follows: Figure 6 The initial impeller geometry shown and as Figure 7 The optimized impeller geometry shown has the same number of blades as the initial impeller geometry in the traditional scheme and the optimized impeller geometry in this embodiment, but the hub diameter D at the inlet position of the optimized impeller is different. hopt Increase the original hub diameter D hori This is about twice the size of the blade hub, which increases the pitch at the impeller inlet hub position and effectively reduces the machining difficulty at the blade hub position.

[0112] like Figure 8As shown, the Mach number distribution in the diffuser channel of the centrifugal compressor under design conditions is shown. The number of diffuser blades is reduced after optimization, and there is no obvious low Mach number region in the channel. This indicates that the optimized diffuser in this embodiment can ensure that the incoming air adheres to the blade surface when entering the channel and does not generate suction surface separation during the downstream flow process, while avoiding unnecessary losses in the channel.

[0113] like Figure 9 and Figure 10 As shown in the figure, the isotropic efficiency and pressure ratio characteristic curves of the compressor under standard inlet conditions (total inlet pressure: 1 atm; total inlet temperature: 15℃) are compared. The information in the figure shows that the isentropic efficiency at the design point is near the maximum value of the characteristic curve, indicating that the compressor aerodynamic design is reasonable and has good aerodynamic performance at the design point. Figure 9 The initial compressor constant speed efficiency and pressure ratio characteristic curves are shown. Figure 10 The optimized compressor constant speed efficiency and pressure ratio characteristic curves for this implementation case show that the pressure ratio of the optimized compressor is slightly reduced, but it fully meets the pressure ratio requirements under the design conditions. At the same time, its isentropic efficiency increases by 2.5% and power consumption decreases by 1.44 kW.

[0114] Compared to traditional compressors, the diffuser blades in this implementation case are circumferentially uniformly distributed, meaning the consistency is consistent in the circumferential direction. The radial diffuser blades are aerodynamic blades, with the leading edge tip and root at the same position in the radial direction. The diffuser blades can be tightly connected to the outer casing without any gaps.

[0115] This implementation reduces the number of diffuser blades in the original design, increases the impeller inlet hub radius, reduces the manufacturing difficulty of the impeller blades, and allows the airflow at the impeller and diffuser inlet positions to adhere to the blades before entering the flow channel, reducing airflow impact losses. At the same time, the suction surface separation generated in the diffuser flow channel disappears, the flow tends to be stable, the entropy increase of the diffuser is controlled within the blade surface boundary layer, there are no significant losses in the diffuser flow channel, and the aerodynamic performance of the original design is improved.

[0116] The above disclosures are merely one or more preferred embodiments of the present invention, intended to help understand the inventive concept of the technical solution, and are not intended to limit the present invention in any other way. Any other equivalent or conventional substitution schemes made by those skilled in the art based on the features defined by the present invention shall still fall within the scope of the present invention.

Claims

1. A centrifugal compressor, comprising impeller blades and a diffuser, and the compressor stage internal flow channel formed therefrom, characterized in that: The compressor stage internal flow channel includes a compressor stage hub and a compressor stage rim. The hub curve formed by the set of points on the compressor stage hub and the rim curve formed by the set of points on the compressor stage rim are defined on the ZR plane, respectively satisfying the hub meridional plane fitting curve equation and the rim meridional plane fitting curve equation. The hub curve and rim curve are rotated around the Z-axis to form the compressor stage hub surface and compressor stage rim surface, respectively. The equation for the fitting curve of the hub meridional plane is: R = az 5 +bz 4 +cz 3 +dz 2 +ez+f; In the formula: a=3.2E-5, b=-5.6E-3, c=3.8E-1, d=-1.2E+1, e=2.0E+2, f=-1.2E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the hub curve point set defined on the ZR plane, respectively. Alternatively, the equation for the fitting curve of the rim meridional surface may be: R = az 5 +bz 4 +cz 3 +dz 2 +ez+f; In the formula: a=9.7E-5, b=-1.5E-2, c=9.5E-1, d=-2.9E+1, e=4.4E+2, f=-2.5E+3 are expressed in scientific notation, and R and z are the coordinate values ​​of the rim curve point set defined on the ZR plane.

2. A centrifugal compressor according to claim 1, characterized in that: The compressor stage blade mounting angle β is defined by a relative flow direction position m along the flow direction relative to a pre-defined mid-arc line, including the impeller blade hub position mounting angle β. 叶轮轮毂 The first installation angle function and the impeller blade rim position installation angle β are satisfied. 叶轮轮缘 Meets the second mounting angle function, diffuser rim and / or hub position mounting angle β 扩压器 It conforms to the third installation angle function.

3. A centrifugal compressor according to claim 2, characterized in that, The hub mounting angle and rim mounting angle of the impeller blades respectively include: The first installation angle function is: b 叶轮轮毂 = am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = 3.9E+2, b = -9.0E+2, c = 8.3E+2, d = -3.1E+2, e = 5.4E+1 are expressed in scientific notation, and m is the mounting angle β corresponding to the hub curve point set. 叶轮轮毂 The ratio of relative flow direction positions distributed along the flow direction in the middle arc; The second installation angle function is: b 叶轮轮缘 = am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = -9.6E+0, b = 3.4E+1, c = 8.2E+1, d = -1.1E+2, e = 6.2E+1 are expressed in scientific notation, and m is the installation angle β corresponding to the set of points on the rim curve. 叶轮轮缘 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

4. A centrifugal compressor according to claim 2, characterized in that, The installation angles at the rim and hub of the diffuser are consistent, including: The third installation angle function is: b 扩压器 = am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = 2.2E+0, b = -6.9E+1, c = 1.1E+0, d = -5.9E+1, e = 7.6E+1, expressed in scientific notation; m is the installation angle β corresponding to the hub or rim curve point set of the diffuser blade. 扩压器 The ratio of relative flow direction positions distributed along the flow direction in the middle arc.

5. A centrifugal compressor according to claim 2, characterized in that: The thickness of the impeller blades and diffuser blades is equally distributed on both sides with the central arc as the reference. The blade thickness distribution includes: the thickness distribution at the impeller blade hub position conforms to the first thickness distribution function; the thickness distribution at the impeller blade rim position conforms to the second thickness distribution function; and the thickness distribution at the hub and rim positions of the diffuser blades is consistent and conforms to the third thickness distribution function.

6. A centrifugal compressor according to claim 5, characterized in that, The thickness distribution of the impeller blades includes: The first thickness distribution function is: t 叶轮轮毂 =am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = -5.8E+0, b = 1.2E+1, c = -9.3E+0, d = 3.1E+0, e = 9.0E+1, t is expressed in scientific notation. 叶轮轮毂 The thickness value of the hub curve point set of the impeller blades, relative to the flow direction position m along the flow direction with the middle arc line as the reference; The second thickness distribution function is: t 叶轮轮缘 =am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = -4.0E+0, b = 8.5E+0, c = -6.7E+0, d = 2.3E+0, e = 6.0E-1, t is expressed in scientific notation. 叶轮轮缘 The thickness value of the impeller blade rim curve point set corresponding to the position m relative to the flow direction along the flow direction with the middle arc line as the reference.

7. A centrifugal compressor according to claim 5, characterized in that: The thickness distribution of the diffuser blades includes: The third thickness distribution function is: t 扩压器 =am 4 +bm 3 +cm 2 +dm+e,m∈[0,1]; In the formula: a = 8.7E-2, b = -1.0E+1, c = 1.7E+0, d = 8.7E+0, e = 2.0E-1, t is expressed in scientific notation. 扩压器 The thickness value of the diffuser blade rim and / or hub curve point set corresponding to the relative flow direction position m along the flow direction with the middle arc line as the reference.

8. A method for adjusting the geometry of the internal flow channel of a compressor stage, characterized in that... Includes the following steps: Calculate the pseudo-hub curve and pseudo-rim curve of the compressor stage internal flow channel and define the pseudo-hub curve and pseudo-rim curve on the ZR plane; The hub curve and the rim curve are approximated by fitting the curve equations of the hub meridional plane and the rim meridional plane respectively. The fitting results are used to determine the hub curve and rim curve of the compressor stage internal flow channel. The hub curve and rim curve are rotated about the Z-axis to generate the compressor stage hub surface and compressor stage rim surface, respectively. The hub and rim positions of the impeller blades and diffuser blades are fitted with the corresponding installation angle functions, and the arc installation angles in the hub and rim positions of the impeller blades and diffuser blades are determined by fitting. The impeller blades and diffuser blades are based on the central arc line, and the thickness is applied equally on both sides of the central arc line. The thickness distribution is determined by the thickness distribution function corresponding to each position. After determining the arc installation angle and thickness distribution of the hub and rim of the impeller blades and diffuser blades, the generated hub curves and rim curves are superimposed to obtain the ruled surfaces of the compressor impeller blades and diffuser blades. The geometry of the internal flow channel of the compressor stage is determined by combining the rim surface and the hub surface.

Images