Volute design method and system of centrifugal compressor and storage medium
By using a volute shell design method that combines multiple segment function relationships in the centrifugal compressor, the problem of uneven performance of volute shells in the working range in the prior art is solved, and the matching of volute shells and stages is achieved, improving the improvement of volute shells and stages The overall performance and efficiency of the compressor.
Patent Information
- Application Number
- CN202411353444.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2024-12-31
AI Technical Summary
The existing centrifugal compressor volute design cannot maintain excellent performance over the entire operating range, resulting in performance degradation in high flow conditions or performance deterioration in small flow conditions, making it difficult to achieve stage (impeller and diffuser) Match with volute.
By establishing the circumferential cross-sectional area distribution function of the volute, using multiple segmented function relationship combinations, the circumferential cross-sectional area of each circumferential angle is calculated according to the performance parameters of the impeller and diffuser, and the styling is carried out to realize the volute shell Better match with the level.
The performance of the centrifugal compressor is improved throughout the working range, the pressure loss of the volute is reduced, and the efficiency and pressure ratio are significantly improved under high flow conditions.
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Figure CN119227268A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of centrifugal compressors, and in particular to a volute design method, system and storage medium for a centrifugal compressor. Background Art
[0002] Centrifugal compressors are widely used in petroleum / coal chemical industry, metallurgy, air separation, aviation and other industrial fields. Centrifugal compressors are impeller machines used to compress gas. The compression of gas and the increase of gas pressure rely on the rotation of the impeller to increase the gas pressure and kinetic energy. The gas flows through the expansion channels such as the impeller and diffuser to achieve pressure increase. It is a general-purpose equipment with high energy consumption. Improving the performance of the compressor and reducing energy consumption are the long-term goals of centrifugal compressor design.
[0003] The stages of a centrifugal compressor can be impeller, impeller + diffuser, impeller + diffuser + volute. In a centrifugal compressor, the volute is used to collect the gas behind the diffuser or impeller and lead it to the gas pipeline or cooler behind the compressor. As the core stationary component of a centrifugal compressor, the quality of its design will directly affect the efficiency and working range of the stage.
[0004] The circumferential cross-sectional area of the existing volute is limited to a single change rule, which makes it difficult for the centrifugal compressor to achieve good performance in the entire operating range when the volute is matched with the stage (impeller and diffuser), either the performance of the centrifugal compressor is excellent in the large flow range, but the performance of the small flow range is sharply reduced; or the performance of the small flow range is excellent, but the performance of the large flow range is sharply deteriorated. Summary of the invention
[0005] The purpose of the present application is to provide a volute design method, system and storage medium for a centrifugal compressor, which can make the volute and the stage (impeller and diffuser) more matched, thereby making the performance of the centrifugal compressor in a better state throughout the entire working range.
[0006] One aspect of the present application provides a method for designing a volute of a centrifugal compressor. The centrifugal compressor includes an impeller, a diffuser and a volute. The method includes: establishing a circumferential cross-sectional area distribution function of the volute based on the airflow flow law of the impeller and the diffuser, wherein the circumferential cross-sectional area distribution function is composed of a plurality of piecewise function relationships, and the plurality of piecewise function relationships are all associated with the circumferential angle of the volute; obtaining the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow and the circumferential component velocity of the diffuser outlet airflow based on the performance parameters of the impeller and the diffuser; obtaining the circumferential cross-sectional area of each circumferential angle of the volute according to the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow and the circumferential component velocity of the diffuser outlet airflow and based on the plurality of piecewise function relationships; shaping according to the circumferential cross-sectional area of each circumferential angle of the volute to obtain the desired volute.
[0007] Furthermore, the method further comprises: pre-dividing the circumferential angle of the volute into a plurality of circumferential angle intervals, wherein different circumferential angle intervals correspond to different piecewise function relationship expressions.
[0008] Furthermore, the method also includes: predetermining an intermediate function about the circumferential angle of the volute, wherein the circumferential cross-sectional area distribution function is a function of the circumferential angle of the volute and the intermediate function, and the relationship between the intermediate functions corresponding to different circumferential angle intervals is different.
[0009] Further, the circumferential cross-sectional area distribution function is expressed as follows:
[0010]
[0011] in, represents the circumferential cross-sectional area distribution function of the volute; represents the intermediate function; is the circumferential angle of the volute; a is a constant; b and c are both constants related to the radius of the diffuser outlet.
[0012] Furthermore, the method also includes: preselecting a separation angle; dividing the circumferential angle of the volute into a first circumferential angle interval and a second circumferential angle interval through the separation angle, wherein when the circumferential angle of the volute is located in the first circumferential angle interval, the intermediate function has a first relationship; when the circumferential angle of the volute is located in the second circumferential angle interval, the intermediate function has a second relationship, and the first relationship is different from the second relationship.
[0013] Furthermore, the relational expression of the intermediate function is expressed as follows:
[0014]
[0015] Wherein, d and e are constants; R5 is the radius of the diffuser outlet; C u5 is the circumferential velocity component of the diffuser outlet airflow; Q v5 is the volume flow rate of the diffuser outlet airflow.
[0016] Furthermore, the separation angle is within the range of 80° to 120°.
[0017] Furthermore, the separation angle is 100°. When the separation angle is 100°, the relational expression of the intermediate function is as follows:
[0018]
[0019] The values of a, b, and c are as follows: a = 3.356; c = 6.712R5.
[0020] Another aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method for designing a volute of a centrifugal compressor as described above are implemented.
[0021] Another aspect of the present application provides a volute design system for a centrifugal compressor, wherein the system comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the volute design method for a centrifugal compressor as described above when executing the computer program.
[0022] The volute design method, system and storage medium of the centrifugal compressor in one or more embodiments of the present application adopt a method of combining a plurality of piecewise function relationships to design the circumferential cross-sectional area distribution function of the volute, and control the circumferential cross-sectional area distribution rule of the volute through these piecewise function relationships, so that the designed volute can be better matched with the stages (impeller and diffuser) of the centrifugal compressor, thereby making the performance of the centrifugal compressor in a better state throughout the entire working range. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 A schematic diagram of the circumferential cross-sectional area distribution of a volute designed using an existing volute design method.
[0024] Figure 2 A schematic diagram of a volute model and its circumferential angle.
[0025] Figure 3 A flow chart of a method for designing a volute of a centrifugal compressor according to an embodiment of the present application.
[0026] Figure 4A schematic diagram of the circumferential interface marking of a volute.
[0027] Figure 5 A schematic diagram of the distribution of the circumferential cross-sectional area of the volute according to an embodiment of the present application.
[0028] Figure 6 This is a comparison curve of stage efficiency and stage pressure ratio for centrifugal compressors matching different volutes.
[0029] Figure 7 A curve diagram showing the reduction in pressure loss of a volute in a volute designed using the volute design method of the present application for matching a centrifugal compressor.
[0030] Figure 8 A schematic block diagram of a volute design system for a centrifugal compressor according to an embodiment of the present application. DETAILED DESCRIPTION
[0031] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.
[0032] Figure 1 The present invention discloses a schematic diagram of the circumferential cross-sectional area distribution of a volute designed using an existing volute design method. Figure 1 As shown in the figure, the existing volute design methods mainly include: equal circulation method, equal velocity method and the design method of controlling the distribution of volute cross-sectional area based on the above methods. In the existing volute design methods, the volute cross-sectional area is limited to a change rule, that is, It can be a constant, gradually increasing, or gradually decreasing. Where A represents the circumferential cross-sectional area of the volute; Indicates the circumferential angle of the volute; the superscript ' indicates that A is The first derivative of . Figure 2 A model of a volute and a schematic diagram of its circumferential angle are disclosed. Figure 2 As shown, the circumferential asymmetric characteristics of the volute make it difficult for a single volute circumferential cross-sectional area control law to match the stage (impeller and diffuser) in the entire operating range.
[0033] In view of this, the present application provides an improved volute design method for a centrifugal compressor.
[0034] The following is a detailed description of the centrifugal compressor volute design method, system and storage medium of the present application in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.
[0035] Figure 3 A flow chart of a method for designing a volute of a centrifugal compressor according to an embodiment of the present application is disclosed. The centrifugal compressor includes an impeller, a diffuser and a volute. Figure 3 As shown, a volute design method for a centrifugal compressor according to an embodiment of the present application may include steps S11 to S14.
[0036] In step S11, a circumferential cross-sectional area distribution function of the volute is established based on the airflow law of the impeller and the diffuser.
[0037] Since the circumferential cross-sectional area distribution of the volute is composed of a variety of variation rules, the circumferential cross-sectional area distribution function of the volute can be composed of a plurality of piecewise function relationship equations, and the plurality of piecewise function relationship equations are all associated with the circumferential angle of the volute.
[0038] In step S12, the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow, and the circumferential component velocity of the diffuser outlet airflow are obtained based on the performance parameters of the impeller and the diffuser.
[0039] In step S13, the circumferential cross-sectional area of the volute at each circumferential angle is obtained according to the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow and the circumferential component velocity of the diffuser outlet airflow obtained in step S12 and based on the multiple piecewise function relationship established in step S11.
[0040] In step S14, the circumferential cross-sectional areas of the volute at various circumferential angles obtained in step S13 are shaped, so that the desired volute can be obtained.
[0041] The following will describe in detail how the present application establishes the circumferential cross-sectional area distribution function of the volute.
[0042] Given the impeller and diffuser, the design flow rate Q is given m Since the diffuser is known, the radius R5 of the diffuser outlet can be obtained. The density ρ5 of the diffuser outlet airflow and the circumferential velocity C of the diffuser outlet airflow can be obtained by three-dimensional CFD (Computational Fluid Dynamics). u5 ; or if the target performance parameters are known, the density ρ5 of the diffuser outlet airflow and the circumferential velocity C of the diffuser outlet airflow can also be obtained by iterative calculation of the thermal parameters. u5 .
[0043] Assuming that the airflow flows freely in the volute, the airflow follows the law of the equal annular flow pattern. In the equal annular flow pattern, the flow parameters of the fluid satisfy a certain relationship. Specifically, the circumferential component velocity C of the fluid u The product of the radius R (i.e. the velocity circulation) is a constant, i.e. RC u = constant. This relationship shows that in the equal annular flow pattern, the fluid maintains a constant velocity circulation during the rotation process, thus achieving the stability of the fluid flow. Therefore, according to the law that the free flow of air in the volute follows the equal annular flow pattern, the following formula can be obtained:
[0044] R i C ui =R5C u5
[0045] Among them, R i is the radius of a circumferential section of the volute, C ui is the circumferential component velocity of the fluid flowing through a circumferential section of the volute.
[0046] Then we have:
[0047]
[0048] in, is the volume flow rate of air flowing through a circumferential section of the volute, is the angle of a circumferential section of the volute (i.e., circumferential angle), such as Figure 2 As shown, the circumferential angle of the volute ranges from 0 to 360°.
[0049] The calculation formula of the volume flow rate flowing through a circumferential section of the volute is as follows:
[0050]
[0051] Among them, A i It is the circumferential cross-sectional area of a circumferential section of the volute.
[0052] Figure 4 A schematic diagram of a circumferential interface mark of a volute is disclosed. Figure 4 , calculate the airflow when the radius R changes from R5 to R t The cumulative effect of flow in the process is:
[0053]
[0054] Where b is Figure 4 The length of the rectangle shown is divided into approximate rectangles during integration.
[0055] but,
[0056]
[0057] again
[0058]
[0059] in, Indicates the circumferential angle of the volute The corresponding radius.
[0060] but,
[0061]
[0062] When solving the above integral equation, simplifying the cross section to a circle, we can get the following:
[0063]
[0064] By the above and The relationship can be solved as follows:
[0065]
[0066] Then the basic calculation formula for the circumferential cross-sectional area of the volute can be obtained as follows:
[0067]
[0068] Since the circumferential cross-sectional area of the volute is composed of different variation rules. Therefore, in some embodiments, the volute design method of the present application further includes: according to the variation rule of the circumferential cross-sectional area of the volute, pre-dividing the circumferential angle of the volute into a plurality of circumferential angle intervals. Among them, different circumferential angle intervals correspond to different piecewise function relationships. Different variation rules of the circumferential cross-sectional area of the volute are represented by different piecewise function relationships.
[0069] In some embodiments, the volute design method of the present application further includes: predetermining an intermediate function about the circumferential angle of the volute Among them, the circumferential cross-sectional area distribution function is the circumferential angle of the volute and intermediate functions The circumferential cross-sectional area distribution function can be expressed as follows:
[0070]
[0071] In order to reflect the different changes in the circumferential cross-sectional area of the volute, the intermediate functions corresponding to different circumferential angle intervals are The relationship is different.
[0072] In some embodiments, the volute design method of the present application further includes: preselecting a separation angle Through this separation angle The circumferential angle of the volute is divided into a first circumferential angle interval and a second circumferential angle interval.
[0073] Among them, when the circumferential angle of the volute is in the first circumferential angle interval, the intermediate function With the first relationship; when the circumferential angle of the volute is in the second circumferential angle interval, the intermediate function has a second relational expression, wherein the first relational expression is different from the second relational expression. Optionally, the first circumferential angle interval is less than or equal to the separation angle The circumferential angle of The second circumferential angle interval is greater than the separation angle The circumferential angle of
[0074] You can remember:
[0075]
[0076] In one embodiment, the intermediate function can be as follows:
[0077]
[0078] Where d and e are constants; R5 is the radius of the diffuser outlet; C u5 is the circumferential velocity component at the diffuser outlet; Q v5 is the volume flow rate at the diffuser outlet.
[0079] Therefore, according to the above formulas (1) to (3), the circumferential cross-sectional area distribution function can be Further expressed as follows:
[0080]
[0081] in, represents the circumferential cross-sectional area distribution function of the volute; represents an intermediate function; is the circumferential angle of the volute; a is a constant; b and c are constants related to the radius of the diffuser outlet.
[0082] Separation Angle It can be calibrated according to the actual situation. For example, the value may be in the range of 80° to 120°. is 100°.
[0083] When the separation angle When the angle is 100°, the intermediate function The relationship can be expressed as follows:
[0084]
[0085] The values of a, b, and c are as follows:
[0086]
[0087] Formula (4) is a more accurate calculation formula for the circumferential cross-sectional area of the volute, based on the actual diffuser outlet radius R5 and the volume flow rate Q of the diffuser outlet airflow. v5 and the circumferential velocity C of the diffuser outlet airflow u5 In combination with the above formula (4), a more accurate circumferential cross-sectional area of each circumferential angle of the volute can be obtained. Then, the volute can be shaped according to the more accurate circumferential cross-sectional area of each circumferential angle, so as to obtain the desired volute.
[0088] Figure 5 The following is a schematic diagram showing the distribution of the circumferential cross-sectional area of a volute according to an embodiment of the present application. Figure 5 As shown, when the circumferential angle is in the first angle interval, that is, When , the circumferential cross-sectional area of the volute adopts the first relational expression in the above formula (3), so that the circumferential cross-sectional area of the volute presents a first variation law; when the circumferential angle is in the second angle interval, that is, When , the circumferential cross-sectional area of the volute adopts the second relationship in the above formula (3), so that the circumferential cross-sectional area of the volute presents a second variation law.
[0089] Figure 6 and Figure 7 The performance curve of the final stage of the centrifugal compressor is revealed, where Figure 6 The comparison curves of stage efficiency and stage pressure ratio of centrifugal compressors matching different volutes are revealed. Figure 7 The curve diagram of the reduction of the pressure loss of the volute in the volute designed by the volute design method of the present application is disclosed. Figure 6 In the embodiment, the impeller and the diffuser are completely identical, only the circumferential cross-sectional area design of the volute is different. The dotted line is the volute designed according to the existing equal annular volume method and the solid line is the volute designed using the volute design method of the present application. Figure 6 It can be clearly seen that after matching the volute designed by the volute design method of this application, the performance of the centrifugal compressor at the near-stall operating point remains basically unchanged. In the operating range of more than 70% flow, the pressure ratio and efficiency of the centrifugal compressor begin to improve. The closer to the maximum flow, the more obvious the improvement. Figure 7It is shown in the figure that, in general, the pressure loss in the volute designed by the volute design method of the present application is reduced. Only in the near-stall operating range does the pressure loss increase slightly. In the operating range of more than 63% flow, the pressure loss of the volute is reduced, and the greater the flow, the more the pressure loss is reduced. This also corresponds to the stage performance of the centrifugal compressor. At the design flow, the pressure loss of the volute is reduced by 6.3 kPa and the efficiency is improved by 1.3%.
[0090] The volute design method of the present application adopts a method of combining a plurality of piecewise function relationships to control the circumferential cross-sectional area distribution rule of the volute through these piecewise function relationships, so that the designed volute can be better matched with the stages (impeller and diffuser) of the centrifugal compressor, thereby making the performance of the centrifugal compressor in a better state throughout the entire working range.
[0091] The present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for designing a volute of a centrifugal compressor as described above are implemented.
[0092] The present application also provides a volute design system 800 for a centrifugal compressor. Figure 8 A schematic block diagram of a volute design system 800 for a centrifugal compressor according to an embodiment of the present application is disclosed. Figure 8 As shown, a volute design system 800 for a centrifugal compressor according to an embodiment of the present application includes a processor 801, an internal bus 802, a network interface 803, a memory 804, and a non-volatile memory 805, and may also include hardware required for other services. The processor 801 can read the corresponding computer program from the non-volatile memory 805 into the memory 804 and then run it to implement the steps of the volute design method for a centrifugal compressor as described above. Of course, in addition to software implementations, the present application does not exclude other implementations, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic components.
[0093] The volute design system 800 of the centrifugal compressor of the present application can have similar beneficial technical effects as the volute design method of the centrifugal compressor described above, so it will not be described in detail here.
[0094] The above is a detailed introduction to the volute design method, system and storage medium of the centrifugal compressor provided in the embodiment of the present application. This article uses specific examples to illustrate the volute design method, system and storage medium of the centrifugal compressor in the embodiment of the present application. The description of the above embodiments is only used to help understand the core idea of the present application and is not intended to limit the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the spirit and principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications should also fall within the scope of protection of the claims attached to the present application.
Claims
1. A method for designing a volute of a centrifugal compressor, the centrifugal compressor comprising an impeller, a diffuser and a volute, characterized in that: The method comprises: Based on the airflow law of the impeller and the diffuser, a circumferential cross-sectional area distribution function of the volute is established, wherein the circumferential cross-sectional area distribution function is composed of a plurality of piecewise function relationship equations, and the plurality of piecewise function relationship equations are all associated with the circumferential angle of the volute; Based on the performance parameters of the impeller and the diffuser, the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow and the circumferential component velocity of the diffuser outlet airflow are obtained; Obtaining the circumferential cross-sectional area of each circumferential angle of the volute according to the radius of the diffuser outlet, the volume flow rate of the diffuser outlet airflow and the circumferential component velocity of the diffuser outlet airflow and based on the multiple piecewise function relationship expressions; The desired volute is obtained by shaping the volute according to the circumferential cross-sectional area at each circumferential angle of the volute.
2. The method according to claim 1, characterized in that: Also includes: The circumferential angle of the volute is divided into multiple circumferential angle intervals in advance. Among them, different circumferential angle intervals correspond to different piecewise function relationships.
3. The method according to claim 2, characterized in that: Also includes: Predetermine an intermediate function about the circumferential angle of the volute, The circumferential cross-sectional area distribution function is a function of the circumferential angle of the volute and the intermediate function, and different circumferential angle intervals correspond to different relationship expressions of the intermediate function.
4. The method according to claim 3, characterized in that: The circumferential cross-sectional area distribution function is expressed as follows: in, represents the circumferential cross-sectional area distribution function of the volute; represents the intermediate function; is the circumferential angle of the volute; a is a constant; b and c are both constants related to the radius of the diffuser outlet.
5. The method according to claim 4, characterized in that: Also includes: Preselect a separation angle; The circumferential angle of the volute is divided into a first circumferential angle interval and a second circumferential angle interval by the separation angle. Among them, when the circumferential angle of the volute is located in the first circumferential angle interval, the intermediate function has a first relationship; when the circumferential angle of the volute is located in the second circumferential angle interval, the intermediate function has a second relationship, and the first relationship is different from the second relationship.
6. The method according to claim 5, characterized in that: The relational expression of the intermediate function is as follows: Wherein, d and e are constants; R5 is the radius of the diffuser outlet; C u5 is the circumferential velocity component of the diffuser outlet airflow; Q v5 is the volume flow rate of the diffuser outlet airflow.
7. The method according to claim 6, characterized in that: The separation angle is within the range of 80° to 120°.
8. The method according to claim 7, characterized in that: The separation angle is 100°. When the separation angle is 100°, the relational expression of the intermediate function is as follows: The values of a, b, and c are as follows: a=3.356; c=6.712R5。 9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for designing a volute of a centrifugal compressor according to any one of claims 1 to 8 are implemented.
10. A volute design system for a centrifugal compressor, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the volute design method for a centrifugal compressor as described in any one of claims 1 to 8 when executing the computer program.