A Design Method for a Compressor Rotor with a Small Hub Ratio

Abstract

The present invention discloses a method for designing a small hub ratio compressor rotor, which belongs to the technical field of aero-engine fan / compressor, and includes: step 1, constructing a meridian projection layout of a small hub ratio compressor rotor, including: constructing a meridian projection layout of a small hub ratio compressor rotor according to the meridian projection distribution law of the small hub ratio compressor rotor; wherein, the inlet hub ratio of the small hub ratio compressor is 0.3-0.4; step 2, constructing a blade shape of a small hub ratio compressor rotor, including: constructing a blade shape of a small hub ratio compressor rotor according to at least the density, the dimensionless geometric turning angle of the mid-arc line, the angle of attack and the angle of lagging of the small hub ratio compressor rotor. The technical solution provided by the embodiment of the present invention solves the problem that the aerodynamic design of the existing compressor is not applicable to the aerodynamic design of the compressor with a small hub ratio because the values of its various parameters are within the conventional range.

Description

Technical Field

[0001] The invention belongs to the field of compressor design, and in particular relates to a design method for a compressor rotor with a small hub ratio. Background Art

[0002] Continuously reducing the engine's frontal area is one of the important directions of development in military aviation engine technology. To adapt to this development trend, the development direction of the compression system is to pursue a smaller hub ratio. A small hub ratio inevitably requires the fan compressor to achieve compressor performance in a smaller inlet frontal area.

[0003] The existing compressor inlet hub ratio is usually 0.5-0.75, and the parameter values in its rotor aerodynamic design are within the conventional range. However, the parameter values in this conventional range are not applicable to the aerodynamic design of compressor rotors with small hub ratios. Summary of the Invention

[0004] In view of this, the present invention provides a design method for a compressor rotor with a small hub ratio to solve the technical problem in the aerodynamic design of the existing compressor that the aerodynamic design of the compressor rotor with a small hub ratio is not applicable because the values of its various parameters are within the conventional range.

[0005] A method for designing a compressor rotor with a small hub ratio is provided, comprising:

[0006] Constructing a meridian projection layout of a small hub ratio compressor rotor, wherein the inlet hub ratio of the small hub ratio compressor is 0.3-0.4, and constructing the meridian projection layout of the small hub ratio compressor rotor according to a meridian projection distribution law of the small hub ratio compressor rotor;

[0007] The blade shape of the small hub ratio compressor rotor is constructed based on the meridian projection layout of the small hub ratio compressor rotor, and the design range of the blade shape parameters of the small hub ratio compressor rotor is determined. The shape parameters at least include consistency, dimensionless geometric turning angle of the mid-camber line, angle of attack and angle of lagging.

[0008] The technical beneficial effects of the present invention are:

[0009] The method of this patent redesigns the rotor's shape parameters, which can effectively provide a technical basis for the design of engine compressors that pursue a small frontal area, while taking into account the efficiency and margin of the compressor. The use of this solution can shorten the design cycle, improve design efficiency, and provide a foundation for the next generation of engine design. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] Figure 1 Meridian layout diagram of a compressor rotor with an inlet hub ratio of 0.36 provided in an embodiment of the present invention;

[0012] Figure 2 A graph showing the consistency distribution of a compressor rotor with an inlet hub ratio of 0.36 provided in an embodiment of the present invention;

[0013] Figure 3 A diagram showing the distribution of dimensionless geometric turning angles of the camber line of a compressor rotor with an inlet hub ratio of 0.36 provided by an embodiment of the present invention;

[0014] Figure 4 A diagram showing the distribution of the compressor rotor angle of attack with an inlet hub ratio of 0.36 provided in an embodiment of the present invention;

[0015] Figure 5 A diagram showing the distribution of the lagging angle of the compressor rotor with an inlet hub ratio of 0.36 provided in an embodiment of the present invention;

[0016] Among them: 1 is the compressor rotor, 2 is the blade root flow passage of the compressor rotor with conventional inlet hub ratio, 3 is the blade root flow passage of the compressor rotor with a hub ratio of 0.36, 4 is the inlet leading edge point of the compressor rotor blade root flow passage, 5 is the position point of the first 20% of the blade root axial chord length of the compressor rotor blade root flow passage with conventional inlet hub ratio, 6 is the position point of the first 20% of the blade root axial chord length of the compressor rotor with a hub ratio of 0.36, 7 is the outlet trailing edge point of the blade root flow passage of the compressor rotor with a hub ratio of 0.36, 8 is the outlet trailing edge point of the blade root flow passage of the compressor rotor with conventional inlet hub ratio, 9 is the trailing edge line of the compressor rotor with conventional inlet hub ratio, and 10 is the leading edge line of the compressor rotor with conventional inlet hub ratio. DETAILED DESCRIPTION

[0017] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0018] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0019] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0020] The background art has already explained that the inlet hub ratio of existing compressors is typically 0.5-0.75, and the values of the various parameters in the aerodynamic design of their rotors are within a conventional range. However, the parameter values within this conventional range are not applicable to the aerodynamic design of compressor rotors with small hub ratios. In response to the increasingly smaller inlet hub ratios of compression components, the embodiments of the present invention study the aerodynamic design of compressor rotors with small hub ratios and propose a design method for compressor rotors with small hub ratios. This method enables the designed compressor to meet the requirements of high efficiency and high stability margins over a wide range of operating conditions. Furthermore, the method provided by the embodiments of the present invention can shorten the design cycle, improve design efficiency, and continuously enhance the thrust-to-weight ratio of the engine.

[0021] like Figure 1 The design method for a small hub-ratio compressor rotor is intended to address the problem in existing compressor aerodynamic design that is not applicable to small hub-ratio compressor rotors due to the conventional range of various parameter values. The method includes:

[0022] S101: constructing a meridian projection layout of a small hub ratio compressor rotor, where the inlet hub ratio of the small hub ratio compressor is 0.3-0.4, and constructing the meridian projection layout of the small hub ratio compressor rotor based on a meridian projection distribution law of the small hub ratio compressor rotor;

[0023] S102: Constructing a blade shape for the small hub ratio compressor rotor based on the meridian projection layout of the small hub ratio compressor rotor, and determining a design range of blade shape parameters for the small hub ratio compressor rotor, where the shape parameters include at least density, dimensionless geometric turning angle of the mid-camber line, angle of attack, and angle of lagging.

[0024] According to the traditional 0.5-0.75 hub ratio setting, the compressor rotor design with a hub ratio of 0.3-0.4 cannot be adapted, and surge is prone to occur. Moreover, at the same speed, the tangential speed of the rotor root is reduced, resulting in a weakening of the work capacity of the rotor root, resulting in a reduction in the efficiency of the entire compressor. This case aims to redesign the density, the dimensionless geometric turning angle of the mid-arc line, the angle of attack and the angle of lag, so that the compressor with a hub ratio of 0.3-0.4 can work efficiently. Therefore, the position point (6) of the first 20% of the blade root axial chord length of the blade root flow channel (3) of the small hub ratio compressor rotor is relative to the position point (5) of the first 20% of the blade root axial chord length of the blade root flow channel (2) of the conventional inlet hub ratio compressor rotor, and the radial blade height of the conventional inlet hub ratio compressor rotor leading edge line (10) is reduced by 0.5%-3%, and

[0025] The outlet trailing edge point (7) of the blade root flow passage (3) of the small hub ratio compressor rotor is raised by 3% to 10% of the radial blade height of the conventional inlet hub ratio compressor rotor trailing edge line (9) relative to the outlet trailing edge point (8) of the blade root flow passage (2) of the conventional inlet hub ratio compressor rotor, and

[0026] The radial height of the small hub increases smoothly from the position point (6) of the blade root axial chord length of the first 20% of the blade root flow passage (3) of the compressor rotor to the outlet trailing edge point (7);

[0027] The blade shape of the small hub ratio compressor rotor is constructed based on the adjusted rotor meridian projection layout, and the corresponding relationship between the increase in rotor blade root density, the increase in rotor blade root angle of attack, the increase in rotor blade root trailing angle and the inlet hub ratio of the small hub ratio compressor is determined.

[0028] As a specific implementation method provided in this case, the consistency of the root section of the compressor rotor with a small hub ratio is 2.4-3.0, and the consistency of the compressor rotor with a small hub ratio smoothly transitions from the root to the tip to a first preset value, and the first preset value is the same as the consistency of the tip section of the compressor rotor with a conventional hub ratio.

[0029] As a specific embodiment provided in this case, the dimensionless geometric turning angle of the mid-arc line within the range of (0.3-0.5) times the axial chord length of the small hub ratio compressor rotor root section blade exceeds 0.7, and the dimensionless geometric turning angle of the mid-arc line is Δβ x , and satisfy:

[0030] Among them, the total bending angle of the compressor rotor blade is Δβ k , the inlet geometric angle of the leading edge of the blade is β k1 , the geometric angle at a certain midline position on the median arc is β kx ;

[0031] The dimensionless geometric turning angle of the mid-arc within the range of 0.4 times the axial chord length increases, and the dimensionless geometric turning angle of the mid-arc after 0.4 times the axial chord length increases gently to 1.

[0032] As a specific implementation method provided in this case, the angle of attack of the root section of the compressor rotor with a small hub ratio is 2-4 degrees, and the angle of attack of the compressor rotor with a small hub ratio smoothly transitions from the root to the tip to a second preset value, which is the same as the angle of attack of the tip section of the compressor rotor with a conventional hub ratio.

[0033] As a specific implementation method provided in this case, the lag angle of the small hub to the compressor rotor blade root section is 7.5-8.5 degrees, and the lag angle of the small hub to the compressor rotor smoothly transitions from the root to the tip to the third preset value, and the third preset value is the same as the lag angle of the conventional hub to the compressor rotor blade tip section.

[0034] like Figure 1As shown in the meridian layout diagram of a compressor rotor with an inlet hub ratio of 0.36 provided by a specific embodiment of the present invention, it can be seen that the radial height of the position point 6 of the first 20% of the blade root axial chord length of the compressor rotor blade root flow channel 3 of the inlet hub ratio of 0.36 is reduced by 0.003 meters relative to the position point 5 of the first 20% of the blade root axial chord length of the compressor rotor blade root flow channel 2 of the conventional inlet hub ratio, which is equivalent to reducing the radial blade height of the compressor rotor leading edge line 10 of the conventional inlet hub ratio by 1.3%. In addition, the radial height of the outlet trailing edge point 7 of the compressor rotor blade root flow channel 3 of the small hub ratio is raised by 0.0117 meters relative to the outlet trailing edge point 8 of the compressor rotor blade root flow channel 2 of the conventional inlet hub ratio, which is equivalent to raising the radial blade height of the compressor rotor trailing edge line 9 of the conventional inlet hub ratio by 5.5%. The radial height of the compressor rotor blade root flow channel 3 of the small hub ratio increases smoothly from the position point 6 of the first 20% of the blade root axial chord length to the outlet trailing edge point 7. Research has found that when the inlet hub ratio reaches 0.3-0.4, it is more appropriate for the small hub ratio to reduce the radial blade height of the compressor rotor leading edge line 10 by 0.5%-3% relative to the conventional inlet hub ratio at the position point 6 of the blade root axial chord length of the first 20% of the compressor rotor blade root flow channel 3, relative to the conventional inlet hub ratio at the position point 5 of the blade root axial chord length of the first 20% of the compressor rotor blade root flow channel 2. It is more appropriate for the small hub ratio to raise the radial blade height of the compressor rotor trailing edge line 9 by 3%-10% relative to the conventional inlet hub ratio at the point 7 of the outlet trailing edge of the compressor rotor blade root flow channel 3, relative to the conventional inlet hub ratio at the point 8 of the outlet trailing edge of the compressor rotor blade root flow channel 2. The radial height of the small hub ratio from the position point 6 of the blade root axial chord length of the first 20% of the compressor rotor blade root flow channel 3 to the outlet trailing edge point 7 increases smoothly. In this way, both performance and strength vibration are taken into account, ensuring safe and reliable operation of the rotor.

[0035] After completing the meridional projection layout of the compressor rotor, it is necessary to design the blade shape of the compressor rotor. The following is a detailed description of the design of the compressor rotor blade shape.

[0036] The first step is the consistency design. The consistency is the ratio of the blade chord length to the blade pitch. It is a parameter that measures the density of the blades. For small hub ratio compressors, due to the low radius of the rotor root, the consistency of the rotor blade root will be relatively large while ensuring the consistency of the rotor blade tip. Usually, it is acceptable as long as it is within a suitable range. Generally, the root section consistency of the compressor rotor with a conventional inlet hub ratio is selected to be 1.9-2.1. As the compressor inlet hub ratio decreases, the consistency is developing in a larger direction. Studies have found that the relative increase in the consistency of the rotor blade root is related to the compressor inlet hub ratio. The smaller the hub ratio, the greater the relative increase in the consistency of the rotor blade root. When the imported hub ratio reaches 0.3-0.4, it is more appropriate to select the consistency of the rotor blade root section in the range of 2.4-3.0. Compared with the conventional imported hub ratio compressor rotor, the relative increase in the consistency of the blade root section is 20%-50%. The consistency of the blade tip section of the small hub ratio compressor rotor is equivalent to the consistency of the blade tip section of the conventional imported hub ratio compressor rotor. The consistency of the small hub ratio compressor rotor has a smooth transition from root to tip.

[0037] The imported hub ratio of this solution is 0.36. Figure 2 It can be seen that the consistency of the blade root section is selected at 2.7, which is about 0.7 larger than the consistency of the conventional imported hub rotor blade root section, with a relative increase of 35%. This selection can take into account the efficiency and margin of the compressor, allowing the rotor to work in the most comfortable area and meet the performance design requirements.

[0038] The second step is to design the dimensionless geometric turning angle of the rotor's mid-arc line. It is known that the total bending angle of the compressor rotor blade is Δβ_k, the inlet geometric angle of the blade leading edge is β_k1, and the geometric angle of a certain midline position on the mid-arc line is β_kx. The dimensionless geometric turning angle of the mid-arc line is defined as the ratio of the geometric bending angle of a point on the blade mid-arc line relative to the blade leading edge position to the total bending angle. Therefore, the dimensionless geometric turning angle of the mid-arc line Δβ can be obtained. x . Its mathematical expression is:

[0039]

[0040] After dimensionless processing, the camber line geometric angle distribution of the rotor's elementary blade profile is standardized between 0 and 1 (except for negative bends) even for blade profiles with different geometric bend angles. This allows us to intuitively determine the geometric characteristics of each center line: the dimensionless geometric turning angle of the camber line of a certain section blade profile changes uniformly along the axial direction, indicating that the maximum deflection position of the elementary blade profile is near 0.5 times the axial chord length; the dimensionless geometric turning angle of the camber line of a certain section blade profile changes slowly in the first half and rapidly in the second half. Some of the changes are faster, indicating that the blade type belongs to the backward curved blade type with the maximum deflection position after 0.5 times the axial chord length, the installation angle increases, and the blade type is in a state of being biased to be closed, which is suitable for compressors with larger or larger inlet hubs than normal; the dimensionless geometric turning angle of the arc line of a certain section of the blade changes faster in the first half and changes slower in the second half, indicating that the blade type belongs to the forward curved blade type with the maximum deflection position before 0.5 times the axial chord length, the installation angle decreases, and the blade type is in a state of being biased to be open, which is suitable for compressors with smaller inlet hubs. The dimensionless geometric turning angle of the arc line of the blade type of the conventional inlet hub is basically uniformly biased along the axial direction, and the blade type of the rotor root section is 0.4 times the axial chord length (i.e. Figure 4 The dimensionless geometric turning angle of the mid-arc line within the range of point c) is within the range of 0.4-0.6. Research has found that when the inlet hub ratio reaches 0.3-0.4, the dimensionless geometric turning angle of the mid-arc line within the range of 0.4 times the axial chord length of the rotor root section blade exceeds 0.7, the dimensionless geometric turning angle of the mid-arc line within the range of 0.4 times the axial chord length increases rapidly, and the dimensionless geometric turning angle of the mid-arc line after 0.4 times the axial chord length increases gently. The advantage of this distribution pattern is that the blade profile in the front half is more curved, the blade installation angle is reduced, and the blade is in an open state, eliminating the problem of reduced compressor flow capacity caused by increased rotor blade root density, while also being able to give a good balance between efficiency and stability margin.

[0041] The inlet hub ratio of the compressor in this scheme is 0.36. Figure 3 It can be seen that the dimensionless geometric turning angle of the mid-arc line at 0.4 times the axial chord length is 0.73, which is 0.16 larger than the dimensionless geometric turning angle of the mid-arc line of the conventional imported hub and stator. This selection takes into account the efficiency and margin of the compressor, allowing the rotor to operate in the most comfortable area and meet the performance design requirements.

[0042] The third step is the angle of attack design. Generally, the angle of attack of the root section of a conventional imported hub-ratio rotor blade is generally between 0 and 1.5 degrees, showing an inverted C-shaped distribution. The angle of attack at the root tip is small, and the angle of attack at the middle section of the blade is large. The small hub-ratio rotor has a high viscosity problem due to its small imported hub ratio. A smaller installation angle is required to ensure the flow capacity of the compressor and keep the rotor blades in an open state. An effective way to reduce the installation angle is to increase the angle of attack. Research has found that the relative increase in the angle of attack of the rotor blade root is related to the compressor inlet hub ratio. The smaller the inlet hub ratio, the greater the relative increase in the angle of attack of the rotor blade root. When the inlet hub ratio reaches 0.3-0.4, it is more appropriate to select the angle of attack of the rotor blade root section in the range of 2 degrees to 4 degrees. Compared with the conventional inlet hub ratio rotor blade root section, the relative increase in the angle of attack is 70%-180%. The angle of attack of the tip section of the small hub ratio compressor rotor is equivalent to the angle of attack of the tip section of the conventional inlet hub ratio compressor rotor. The angle of attack of the small hub ratio compressor rotor transitions smoothly from root to tip.

[0043] The imported hub ratio of this solution is 0.36. Figure 4 It can be seen that the angle of attack of the rotor blade root section is selected at 3.0 degrees, which is about 1.8 degrees higher than that of the conventional imported hub, with a relative increase of 147.5%. This selection takes into account the efficiency and margin of the compressor, allowing the rotor to operate in the most comfortable area and meet the performance design requirements.

[0044] The fourth step is the lagging angle design. Generally, the lagging angle of the root section of the conventional imported hub-ratio rotor blade is generally 6.5 to 7.2 degrees, with a C-shaped distribution. The lagging angle of the root tip section is large, and the lagging angle of the mid-blade section is small. The small hub-ratio rotor has a large viscosity problem due to its small imported hub ratio, so a smaller installation angle is required to ensure the flow capacity of the compressor. Another effective way to reduce the installation angle is to increase the lagging angle. Research has found that the relative increase in the rotor blade root's trailing angle is related to the compressor inlet hub ratio. The smaller the inlet hub ratio, the greater the relative increase in the rotor blade root's trailing angle. When the inlet hub ratio reaches 0.3-0.4, it is more appropriate to select the rotor blade root section's trailing angle in the range of 7.5 to 8.5 degrees. Compared with the conventional inlet hub ratio, the relative increase in the trailing angle of the rotor blade root section is 12%-22%. The trailing angle of the rotor tip section of the small hub ratio compressor is equivalent to the trailing angle of the rotor tip section of the conventional inlet hub ratio compressor. The trailing angle of the small hub ratio compressor rotor has a smooth transition from root to tip.

[0045] The imported hub ratio of this solution is 0.36. Figure 5It can be seen that the trailing angle of the rotor blade root section is selected at 7.80 degrees, which is about 1 degree larger than the trailing angle of the rotor blade root section of the conventional imported hub, and the relative increase is 14.7%. This selection takes into account the efficiency and margin of the compressor, allowing the rotor to operate in the most comfortable area and meet the performance design requirements.

[0046] In summary, this specific embodiment provides a design method for a compressor rotor with an inlet hub ratio of 0.36. By reasonably giving the rotor's meridian projection layout, consistency, mid-arc dimensionless geometric turning angle, angle of attack and lagging angle distribution, the compressor can achieve high efficiency and high stability margin with a small inlet headwind area. This method can be directly used in the design of a compressor rotor with an inlet hub ratio of 0.36, and can effectively reduce the engine inlet headwind area, thereby achieving the purpose of weight reduction.

[0047] The technical solution provided by the embodiment of the present invention belongs to the technical field of aircraft engine fans / compressors. The specific design method of a small hub ratio compressor rotor is mainly aimed at the meridian projection layout design and blade shape design of the imported small hub ratio compressor rotor with a hub ratio of 0.3-0.4. Finally, a relatively general rotor angle of attack, trailing angle distribution law, mid-arc dimensionless geometric turning angle, consistency distribution law, and meridian projection distribution law are obtained. Research results show that the small hub ratio compressor rotor designed using the design method of the present invention can better meet the technical requirements of the engine such as a smaller frontal area and weight reduction.

[0048] Technical effect:

[0049] consistency, see Figure 2 The consistency curve of this solution has a smoother transition than the traditional one. The traditional method has a sharp change between 10% and 30%, which reduces the smoothness of the blade and causes more serious separation of the airflow on the blade surface. The structural setting of this solution avoids the phenomenon that the flow channel convergence performance decreases when the inlet flow increases, which causes the airflow to separate at the blade root. When the inlet flow decreases, it can effectively suppress the airflow separation.

[0050] Dimensionless geometric rotation angle, see Figure 3 The blade has a more wavy curve at the root, and the front half of the blade is more curved. When the blade is in the open state, the airflow at the root of the blade increases, that is, the flow rate increases;

[0051] Lag angle, see Figure 5 As shown, the blade tip of this case is relatively flat, which can better control the airflow and prevent separation.

[0052] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A design method for a compressor rotor with a small hub ratio, characterized in that: The method comprises: A meridian projection layout of a small hub ratio compressor rotor is constructed, wherein the inlet hub ratio of the small hub ratio compressor is 0.3-0.4, and the meridian projection layout of the small hub ratio compressor rotor is constructed according to the meridian projection distribution law of the small hub ratio compressor rotor; a blade shape of the small hub ratio compressor rotor is constructed based on the meridian projection layout of the small hub ratio compressor rotor, and a design range of blade shape parameters of the small hub ratio compressor rotor is determined, wherein the shape parameters at least include consistency, dimensionless geometric turning angle of the mid-camber line, angle of attack and angle of lagging, wherein, The position point (6) of the first 20% of the blade root axial chord length of the blade root flow passage (3) of the small hub ratio compressor rotor is relative to the position point (5) of the first 20% of the blade root axial chord length of the blade root flow passage (2) of the conventional inlet hub ratio compressor rotor, and the radial blade height of the conventional inlet hub ratio compressor rotor leading edge line (10) is reduced by 0.5%-3%; The outlet trailing edge point (7) of the blade root flow passage (3) of the small hub ratio compressor rotor is raised by 3%-10% of the radial blade height of the conventional inlet hub ratio compressor rotor trailing edge line (9) relative to the outlet trailing edge point (8) of the blade root flow passage (2) of the conventional inlet hub ratio compressor rotor; The radial height of the small hub increases smoothly from the first 20% of the blade root axial chord length position point (6) to the outlet trailing edge point (7) of the compressor rotor blade root flow passage (3); The blade shape of the small hub ratio compressor rotor is constructed based on the adjusted rotor blade root flow channel (3), and the corresponding relationship between the increase in rotor blade root density, the increase in rotor blade root angle of attack, the increase in rotor blade root trailing angle and the inlet hub ratio of the small hub ratio compressor is determined.

2. The design method of a small hub ratio compressor rotor according to claim 1, characterized in that: The consistency of the small hub ratio compressor rotor blade root section is 2.4-3.0, and the consistency of the small hub ratio compressor rotor smoothly transitions to a first preset value from the root to the tip, and the first preset value is the same as the consistency of the conventional hub ratio compressor rotor blade tip section.

3. The design method of a small hub ratio compressor rotor according to claim 2, characterized in that: The dimensionless geometric turning angle of the center camber line within the range of (0.3-0.5) times the axial chord length of the cross-section blade profile of the compressor rotor root of the small hub ratio exceeds 0.7, and the dimensionless geometric turning angle of the center camber line is , and satisfy: , where the total bending angle of the compressor rotor blade is ∆β k , the inlet geometric angle of the leading edge of the blade is β k1 , the geometric angle at a certain midline position on the median arc is β kx ; The dimensionless geometric turning angle of the mid-arc within the range of 0.4 times the axial chord length increases, and the dimensionless geometric turning angle of the mid-arc after 0.4 times the axial chord length increases gently to 1.

4. The design method for a small hub ratio compressor rotor according to claim 3, characterized in that: The angle of attack of the root section of the small hub ratio compressor rotor is 2-4 degrees, and the angle of attack of the small hub ratio compressor rotor smoothly transitions from the root to the tip to a second preset value, which is the same as the angle of attack of the tip section of the conventional hub ratio compressor rotor.

5. The design method of a small hub ratio compressor rotor according to claim 4, characterized in that: The lag angle of the small hub to the compressor rotor blade root section is 7.5-8.5 degrees, and the lag angle of the small hub to the compressor rotor smoothly transitions from the root to the tip to a third preset value, and the third preset value is the same as the lag angle of the conventional hub to the compressor rotor blade tip section.

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