Centrifugal fan type spectrum planning method and system based on specific diameter definition

Abstract

The invention discloses a centrifugal fan type spectrum planning method and system based on specific diameter definition. The method comprises the steps that design point dimensionless performance parameters of a centrifugal fan are calculated according to summarized high efficiency; according to a similarity criterion, a definition method for the dimensionless performance parameter specific diameter Ds of the centrifugal fan is provided and calculated; analyzing according to the calculated dimensionless performance parameters of the design points of the high-efficiency backward centrifugal fans; based on the specific diameter Ds, reasonability verification analysis of design point flow coefficient phi selection is carried out; performing comprehensive fitting effect evaluation by using the decision coefficient R and the root mean square error RMSE; finally, a dimensionless performance parameter combination of the specific diameter Ds, the flow coefficient phi and the energy head coefficient psi is obtained, and the backward centrifugal fan type spectrum planning based on the specific diameter is completed. According to the method, the relationship between the design point specific diameter and the specific speed is deeply researched, so that the rapid conversion between the design point specific diameter and the specific speed is realized, and a priority number system is better combined, so that the profile spectrum planning layout is realized.

Description

Technical Field

[0001] The present invention relates to the field of centrifugal fan design, and in particular to a centrifugal fan model spectrum planning method and system based on specific diameter definition. Background Art

[0002] Centrifugal fans, as essential impeller machines widely used in the energy, chemical, and other fields, enjoy a huge market demand. However, their operation is often accompanied by significant energy consumption. With the advancement of my country's industrialization and the promotion of a low-carbon economy, higher requirements are being placed on the efficiency and energy efficiency of centrifugal fans. However, current domestic centrifugal fan products suffer from generally low efficiency, complex model structures, and a lack of systematic layout planning, hindering the overall energy-saving and efficient development of the industry.

[0003] In response to the above problems, the traditional centrifugal fan design method relies on designing each unit one by one, which has the disadvantages of huge calculation amount, long design cycle and high cost. The test phase is often restricted by actual working conditions and it is difficult to achieve the ideal design performance. To overcome these limitations, a spectrum planning method based on similarity principle is usually adopted. Through a model machine with excellent performance, a series design is carried out with dimensionless performance parameters. However, the existing spectrum planning mostly uses the design point specific speed as the main parameter for layout. In actual application, there is a problem of limited accuracy, which may lead to large errors in the design phase, increased costs in the test phase, and it is difficult for the actual operating performance to reach the expected target. Both specific diameter and specific speed can be used as important dimensionless performance parameters for spectrum planning. At present, there are large differences and ambiguities in the definition of specific diameter, which leads to large deviations in actual application and affects the accuracy of spectrum planning based on specific diameter. Summary of the Invention

[0004] The purpose of the present invention is to further improve the accuracy and design efficiency of spectrum planning. A centrifugal fan spectrum planning method and system based on the definition of specific diameter is proposed, and a fitting relationship between the design point specific diameter and the flow coefficient is constructed based on this. By deeply studying the relationship between the design point specific diameter and the specific speed, a rapid conversion of the design point specific diameter and the specific speed is achieved, and the spectrum planning layout is realized by better combining the priority number system. The spectrum planning based on the design point specific diameter has higher accuracy, can shorten the design cycle, reduce development costs, effectively meet the diverse market needs, and promote the development of centrifugal fan products towards standardization, serialization, energy saving and high efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A centrifugal fan model spectrum planning method based on specific diameter definition includes:

[0007] 1) Calculate the dimensionless performance parameters of the design point based on the summarized high-efficiency backward centrifugal fan, including flow coefficient φ, energy head coefficient ψ, specific speed ω s According to the similarity criterion, a dimensionless performance parameter ratio of centrifugal fan to diameter D is proposed. s The definition method is used to calculate the design point dimensionless performance parameters of each high-efficiency backward centrifugal fan, and the specific speed ω of the design point is analyzed. s and specific diameter D s As the horizontal axis, the flow coefficient φ of the design point is plotted as the vertical axis to obtain the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s Scatter plot with discharge coefficient φ;

[0008] 2) According to the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s The data were fitted with the scatter plot of the flow coefficient φ and the speed ω was compared. s The flow coefficient φ is linearly fitted and the upper and lower limits are determined using a 95% confidence level prediction band. s The power function is used to fit the flow coefficient φ and the upper and lower limits are determined using the prediction band with 95% confidence. The determination coefficient R and root mean square error RMSE are used to evaluate the comprehensive fitting effect. The existing high-efficiency backward centrifugal fan experimental data are combined to perform the calculation based on the specific diameter D. s Conduct rationality verification analysis on the selection of design point discharge coefficient φ;

[0009] 3) The design point is larger than the diameter D s As the abscissa, the design point specific speed ω s The data were plotted as the vertical axis, and the power function was used for fitting and the prediction band with 95% confidence level was used to determine the upper and lower limits. The determination coefficient R and root mean square error RMSE were used to evaluate the comprehensive fitting effect.

[0010] 4) Compare the speed ω according to the priority number system of [GB / T321-2005] s Select the corresponding ratio based on the design point diameter D s The fitting relationship between the specific speed and the lower and upper limits is close to the center line as the selection basis to obtain different specific speeds ω s Corresponding specific diameter D s , based on the design point diameter D s The fitting relationship between the flow coefficient φ and the flow coefficient φ is within the upper and lower limits, close to the center line as the selection basis, and the flow coefficient φ corresponding to different specific diameters is obtained. s The calculation formula is used to obtain the corresponding energy head coefficient ψ, and finally a set of specific diameters D is obtained. sThe dimensionless performance parameter combination of flow coefficient φ and energy head coefficient ψ is used to complete the backward centrifugal fan model spectrum planning based on specific diameter.

[0011] A further improvement of the present invention is that the dimensionless performance parameters of the centrifugal fan in step 1) are defined as follows:

[0012] Flow coefficient:

[0013] Energy head coefficient:

[0014] Where Q is the volume flow rate, D is the impeller diameter, ω is the impeller angular velocity, and h is the impeller angular velocity. pol is the unit mass work of the fan;

[0015] The rotational angular velocity of the model fan when it is a standard fan is defined as the specific speed:

[0016] When the model fan is a standard fan, the impeller outer diameter is defined as the specific diameter:

[0017] Where D′ is the outer diameter of the model fan impeller.

[0018] A further improvement of the present invention is that, in step 2), the design point specific speed and flow coefficient and the design point specific diameter and flow coefficient are fitted respectively, and the fitting relationship is obtained as follows:

[0019] φ=0.1436ω s -0.0340;

[0020] φ=0.7037D s -1.7992 ;

[0021] To evaluate the comprehensive effect, the coefficient of determination R and the root mean square error RMSE are used, which are defined as follows:

[0022] Coefficient of determination:

[0023] Root mean square error:

[0024] Among them, y i is the ith actual value, is the i-th predicted value, is the average of the actual values, N is the total number of data points, and p is the number of unknown parameters in the regression model.

[0025] A further improvement of the present invention is that, in step 3), the design point specific diameter and specific speed are fitted to obtain the following fitting relationship:

[0026] ωs =2.8949D s -0.9885 .

[0027] The present invention is further improved in that, in step 4), the performance parameters of the backward centrifugal fan are planned based on the specific diameter spectrum, the specific diameter D s The range is 1.87 to 10.21, the flow coefficient φ ranges from 0.01 to 0.229, and the energy head coefficient ψ ranges from 0.392 to 0.72.

[0028] A centrifugal fan model spectrum planning system based on specific diameter definition, comprising:

[0029] The calculation unit calculates the dimensionless performance parameters of the design point based on the summarized high-efficiency backward centrifugal fan, including the flow coefficient φ, energy head coefficient ψ, specific speed ω s According to the similarity criterion, a dimensionless performance parameter ratio of centrifugal fan to diameter D is proposed. s The definition method is used to calculate the design point dimensionless performance parameters of each high-efficiency backward centrifugal fan, and the specific speed ω of the design point is analyzed. s and specific diameter D s As the horizontal axis, the flow coefficient φ of the design point is plotted as the vertical axis to obtain the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s Scatter plot with discharge coefficient φ;

[0030] Verify the analysis unit, according to the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s The data were fitted with the scatter plot of the flow coefficient φ and the speed ω was compared. s The flow coefficient φ is linearly fitted and the upper and lower limits are determined using a 95% confidence level prediction band. s The power function is used to fit the flow coefficient φ and the upper and lower limits are determined using the prediction band with 95% confidence. The determination coefficient R and root mean square error RMSE are used to evaluate the comprehensive fitting effect. The existing high-efficiency backward centrifugal fan experimental data are combined to perform the calculation based on the specific diameter D. s Conduct rationality verification analysis on the selection of design point discharge coefficient φ;

[0031] Effect evaluation unit, the design point is compared with the diameter D s As the abscissa, the design point specific speed ω s The data were plotted as the vertical axis, and the power function was used for fitting and the prediction band with 95% confidence level was used to determine the upper and lower limits. The determination coefficient R and root mean square error RMSE were used to evaluate the comprehensive fitting effect.

[0032] Centrifugal fan model planning unit, according to the priority number system [GB / T321-2005] to compare the speed ω s Select the corresponding ratio based on the design point diameter D s The fitting relationship between the specific speed and the lower and upper limits is close to the center line as the selection basis to obtain different specific speeds ω s Corresponding specific diameter D s , based on the design point diameter D s The fitting relationship between the flow coefficient φ and the flow coefficient φ is within the upper and lower limits, close to the center line as the selection basis, and the flow coefficient φ corresponding to different specific diameters is obtained. s The calculation formula is used to obtain the corresponding energy head coefficient ψ, and finally a set of specific diameters D is obtained. s The dimensionless performance parameter combination of flow coefficient φ and energy head coefficient ψ is used to complete the backward centrifugal fan model spectrum planning based on specific diameter.

[0033] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0034] The present invention clearly proposes a centrifugal fan spectrum planning method and system based on the definition of specific diameter, which solves the problem that the important dimensionless parameter specific diameter was difficult to be widely and accurately used in engineering due to its unclear definition in the past. It makes it feasible to use the design point specific diameter as a parameter for centrifugal fan performance analysis and prediction.

[0035] The present invention establishes a functional fitting relationship between the design point specific diameter and the flow coefficient through a large amount of fan experimental data, and determines the 95% confidence interval of the fitting function as the basis for selecting the design point flow coefficient. Statistical analysis shows that compared with the existing commonly used spectrum selection method using specific speed as a parameter, the fitting function of the present invention has significantly higher fitting accuracy, can be used to predict and infer the flow coefficient of unknown design points, and has good predictive ability. In the spectrum planning process of actual engineering applications, by applying the fitting relationship constructed by the present invention, designers can accurately and quickly determine the corresponding optimal flow coefficient after determining the design point specific diameter of the centrifugal fan, which can effectively avoid the design selection deviation caused by the poor specific speed fitting effect in the existing method, significantly improve the accuracy and reliability of fan selection, reduce the experimental cost and design cycle in the design process, accelerate the development speed of centrifugal fan spectrum, and improve the efficiency and economy of product development.

[0036] The present invention determines the functional fitting relationship between the design point specific diameter and the specific speed, and proposes a fast conversion method. Through this functional relationship, the accurate conversion between the specific speed and the design point specific diameter can be quickly realized, and the design point specific diameter value suitable for model spectrum planning can be determined. Then, the flow coefficient of each design point can be quickly and accurately selected using the aforementioned functional relationship between the design point specific diameter and the flow coefficient, and finally the corresponding energy head coefficient can be determined according to the centrifugal fan performance calculation formula. This method significantly improves the problems of uneven model distribution, redundant parameter overlap, and limited coverage in traditional fan model spectrum planning, and achieves coverage of a wider and more comprehensive performance requirement with a more streamlined model machine series. The design process is clear, the steps are concise, and it is easy to implement, which promotes the standardization and universalization of fan products and plays an important role in promoting the realization of the overall energy conservation and consumption reduction goals of the centrifugal fan industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 It is the fitting relationship diagram between the specific speed and the discharge coefficient at the design point;

[0039] Figure 2 is the fitting relationship diagram between the design point specific diameter and the discharge coefficient;

[0040] Figure 3 This is the relationship between the specific diameter and flow coefficient under multiple working conditions of a series of fans;

[0041] Figure 4 It is the fitting relationship diagram of the specific diameter and specific speed of the design point;

[0042] Figure 5 This is a structural block diagram of a centrifugal fan model planning system based on specific diameter definition according to the present invention. DETAILED DESCRIPTION

[0043] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0044] In the description of the present invention, it is to be understood that when used in this specification and the appended claims, the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0045] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present 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.

[0046] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0047] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0048] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0049] Example 1

[0050] The present invention provides a centrifugal fan model spectrum planning method based on specific diameter definition, comprising:

[0051] The calculation formulas for the dimensionless performance parameters flow coefficient φ and energy head coefficient ψ used in the present invention are as follows:

[0052]

[0053] Where Q is the volume flow rate, D is the impeller diameter, ω is the impeller angular velocity, and h is the impeller angular velocity. pol is the unit mass work of the fan.

[0054] The dimensionless performance parameter specific speed ω used in the present invention is s The definition is: the rotational angular velocity when the model fan is a standard fan (flow rate is 1, energy head is 1). The calculation formula is as follows:

[0055]

[0056] Where ω′ is the angular velocity of the model fan.

[0057] The present invention proposes a specific diameter D s Definition: The impeller outer diameter of the model fan is a standard fan (flow rate is 1, energy head is 1), which is consistent with the definition of specific speed. The calculation formula used is as follows:

[0058]

[0059] Where D′ is the outer diameter of the model fan impeller.

[0060] Since the present invention is mainly based on dimensionless performance parameters, formula (3) and formula (4) can be written based on dimensionless performance parameters as follows:

[0061]

[0062] The dimensionless parameters of the high-efficiency backward centrifugal fan model summarized in this invention are from the two books "Air Dynamic Outlines and Characteristic Curves of Fans" and "Fan Handbook", and the relevant dimensionless performance parameters are calculated. Based on the summarized dimensionless performance parameters of the design points of each high-efficiency backward centrifugal fan model, the design point specific speed and specific diameter are used as independent variables, and the design point flow coefficient is used as the dependent variable for analysis. The specific speed and flow coefficient are approximately linearly related (φ = aω s +b), the fitted image is as follows Figure 1 As shown, the fitting function φ=0.1436ω s -0.0340, the specific diameter and the flow coefficient are approximately in a power function relationship (φ=aD s b ), the fitted image is as Figure 2 As shown, the fitting function φ=0.7037D s -1.7992 , a prediction band with 95% confidence level is used to determine a reasonable selection interval with upper and lower limits. From the figure, it can be determined that the flow coefficient basically falls within the corresponding prediction band. Compared with the specific speed, the data points are more in line with the design point specific diameter and flow coefficient fitting curve. For the above two different fitting functions, the present invention uses the determination coefficient R and the root mean square error RMSE to evaluate the comprehensive fitting effect. The closer the determination coefficient R is to 1, the smaller the root mean square error RMSE, and the better the fitting effect of the data. It shows a higher fitting accuracy in the existing experimental data set. At the same time, it can be used to predict and infer the flow coefficient of the unknown design point, reflecting better prediction ability or promotion performance. The calculation formula used is as follows:

[0063]

[0064] Among them, y iis the ith actual value, is the i-th predicted value, is the average of the actual values, N is the total number of data points, and p is the number of unknown parameters in the regression model.

[0065] Therefore, the calculation results show that the coefficient of determination R of the specific speed and flow coefficient fitting curve is 0.8958, and the root mean square error (RMSE) is 0.0219. The coefficient of determination R of the specific diameter and flow coefficient fitting curve is 0.9818, and the root mean square error (RMSE) is 0.0092. Based on these calculation results, the coefficient of determination R and the root mean square error (RMSE) of the specific diameter have been significantly improved, resulting in a better fitting effect and more accurate selection of the design point flow coefficient. Compared with the specific speed, it can more accurately reflect the changing trend of the flow coefficient, which helps to obtain more accurate results. The fitting function form is not complex, making the confirmation of the flow coefficient based on the design point specific diameter simple and feasible.

[0066] In addition, based on actual experiments on a series of fans, it was found that under various working conditions, the specific diameter and flow coefficient of different models of fans are also approximately in a power function relationship, and are almost concentrated on a curve, such as Figure 3 The results show that the rationality of the flow coefficient fitting relationship based on specific diameter is verified. Compared with specific speed, specific diameter is more consistent with the actual law under various fan types and different operating conditions. When selecting the flow coefficient based on specific diameter, the design point should be within the prediction band and close to the centerline.

[0067] According to the performance parameters of the high-efficiency centrifugal fan models, the specific speed is used as the independent variable and the specific diameter is used as the dependent variable for analysis. The specific diameter and the specific speed are approximately in a power function relationship (ω s =aD s b ), the fitted image is as Figure 4 As shown, a 95% confidence prediction band is used to determine a reasonable selection interval with upper and lower limits, and the fitting function ω s =2.8949D s -0.9885 The coefficient of determination (R) of the fitting curve for specific diameter and specific speed is 0.9684, and the root mean square error (RMSE) is 0.0797, indicating a good fit. This functional relationship allows for rapid conversion between specific diameter and specific speed. When selecting specific speed based on specific diameter, the design point should be within the prediction band and close to the centerline.

[0068] According to the priority number system of [GB / T321-2005], the corresponding common ratio is selected, and then the number of fans corresponding to the model planning is determined. Due to the distribution characteristics of the specific diameter, a large number of model fans are required in the high specific diameter area to ensure comprehensive parameter coverage, so it is impossible to directly use the priority number system for the comparison diameter. This invention uses the fitting relationship between the above-mentioned specific diameter and specific speed. First, the speed is selected using the R10 priority number system specified in [GB / T321-2005], and then converted to the specific diameter. Using the fitting relationship between the specific diameter and the flow coefficient, the flow coefficient close to the fitting curve within a reasonable range is selected. The energy head coefficient is obtained by the calculation formula (6) of the specific diameter. Thus, a set of dimensionless performance parameter combinations of specific diameter, flow coefficient, and energy head coefficient is obtained, which is the model planning of the backward centrifugal fan based on the specific diameter. The dimensionless parameter distribution of the model planning of the backward centrifugal fan based on the specific diameter obtained by the present invention is shown in the following table:

[0069]

[0070] Example 2

[0071] like Figure 5 As shown, the present invention provides a centrifugal fan model spectrum planning system based on specific diameter definition, including:

[0072] The calculation unit calculates the dimensionless performance parameters of the design point based on the summarized high-efficiency backward centrifugal fan, including the flow coefficient φ, energy head coefficient ψ, specific speed ω s According to the similarity criterion, a dimensionless performance parameter ratio of centrifugal fan to diameter D is proposed. s The definition method is used to calculate the design point dimensionless performance parameters of each high-efficiency backward centrifugal fan, and the specific speed ω of the design point is analyzed. s and specific diameter D s As the horizontal axis, the flow coefficient φ of the design point is plotted as the vertical axis to obtain the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s Scatter plot with discharge coefficient φ;

[0073] Verify the analysis unit, according to the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s The data were fitted with the scatter plot of the flow coefficient φ and the speed ω was compared. s The flow coefficient φ is linearly fitted and the upper and lower limits are determined using a 95% confidence level prediction band. sThe power function is used to fit the flow coefficient φ and the upper and lower limits are determined using the prediction band with 95% confidence. The determination coefficient R and root mean square error RMSE are used to evaluate the comprehensive fitting effect. The existing high-efficiency backward centrifugal fan experimental data are combined to perform the calculation based on the specific diameter D. s Conduct rationality verification analysis on the selection of design point discharge coefficient φ;

[0074] Effect evaluation unit, the design point is compared with the diameter D s As the abscissa, the design point specific speed ω s The data were plotted as the vertical axis, and the power function was used for fitting and the prediction band with 95% confidence level was used to determine the upper and lower limits. The determination coefficient R and root mean square error RMSE were used to evaluate the comprehensive fitting effect.

[0075] Centrifugal fan model planning unit, according to the priority number system [GB / T321-2005] to compare the speed ω s Select the corresponding common ratio based on the design point diameter D s The fitting relationship between the specific speed and the lower and upper limits is close to the center line as the selection basis to obtain different specific speeds ω s Corresponding specific diameter D s , based on the design point diameter D s The fitting relationship between the flow coefficient φ and the flow coefficient φ is within the upper and lower limits, close to the center line as the selection basis, and the flow coefficient φ corresponding to different specific diameters is obtained. s The calculation formula is used to obtain the corresponding energy head coefficient ψ, and finally a set of specific diameters D is obtained. s The dimensionless performance parameter combination of flow coefficient φ and energy head coefficient ψ is used to complete the backward centrifugal fan model spectrum planning based on specific diameter.

[0076] In this embodiment, the dimensionless performance parameters of the centrifugal fan in the calculation unit are defined as follows:

[0077] Flow coefficient:

[0078] Energy head coefficient:

[0079] Where Q is the volume flow rate, D is the impeller diameter, ω is the impeller angular velocity, and h is the impeller angular velocity. pol is the unit mass work of the fan;

[0080] The rotational angular velocity of the model fan when it is a standard fan is defined as the specific speed:

[0081] When the model fan is a standard fan, the impeller outer diameter is defined as the specific diameter:

[0082] Where D′ is the outer diameter of the model fan impeller.

[0083] In this embodiment, the verification analysis unit performs fitting on the design point specific speed and flow coefficient, and the design point specific diameter and flow coefficient, respectively, and obtains the following fitting relationship:

[0084] φ=0.1436ω s -0.0340;

[0085] φ=0.7037D s -1.7992 ;

[0086] To evaluate the comprehensive effect, the coefficient of determination R and the root mean square error RMSE are used, which are defined as follows:

[0087] Coefficient of determination:

[0088] Root mean square error:

[0089] Among them, y i is the ith actual value, is the i-th predicted value, is the average of the actual values, N is the total number of data points, and p is the number of unknown parameters in the regression model.

[0090] In this embodiment, the effect evaluation unit performs fitting on the design point specific diameter and specific speed, and obtains the following fitting relationship:

[0091] ω s =2.8949D s -0.9885 .

[0092] In this embodiment, the performance parameters of the backward centrifugal fan based on the diameter spectrum planning in the centrifugal fan spectrum planning unit are the diameter D s The range is 1.87 to 10.21, the flow coefficient φ ranges from 0.01 to 0.229, and the energy head coefficient ψ ranges from 0.392 to 0.72.

[0093] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0094] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A centrifugal fan model planning method based on specific diameter definition, characterized in that: include: 1) Calculate the dimensionless performance parameters of the design point based on the summarized high-efficiency backward centrifugal fan, including flow coefficient φ, energy head coefficient ψ, specific speed ω s According to the similarity criterion, a dimensionless performance parameter ratio of centrifugal fan to diameter D is proposed. s The definition method is used to calculate the design point dimensionless performance parameters of each high-efficiency backward centrifugal fan, and the specific speed ω of the design point is analyzed. s and specific diameter D s As the horizontal axis, the flow coefficient φ of the design point is plotted as the vertical axis to obtain the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s Scatter plot with discharge coefficient φ; 2) According to the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s The data were fitted with the scatter plot of the flow coefficient φ and the speed ω was compared. s The flow coefficient φ is linearly fitted and the upper and lower limits are determined using a 95% confidence level prediction band. s The power function is used to fit the flow coefficient φ and the upper and lower limits are determined using the prediction band with 95% confidence. The determination coefficient R and root mean square error RMSE are used to evaluate the comprehensive fitting effect. The existing high-efficiency backward centrifugal fan experimental data are combined to perform the calculation based on the specific diameter D. s Conduct rationality verification analysis on the selection of design point discharge coefficient φ; 3) The design point is larger than the diameter D s As the abscissa, the design point specific speed ω s The data were plotted as the vertical axis, and the power function was used for fitting and the prediction band with 95% confidence level was used to determine the upper and lower limits. The determination coefficient R and root mean square error RMSE were used to evaluate the comprehensive fitting effect. 4) Compare the speed ω according to the priority number system of [GB / T321-2005] s Select the corresponding common ratio based on the design point diameter D s The fitting relationship between the specific speed and the lower and upper limits is close to the center line as the selection basis to obtain different specific speeds ω s Corresponding specific diameter D s , based on the design point diameter D s The fitting relationship between the flow coefficient φ and the flow coefficient φ is within the upper and lower limits, close to the center line as the selection basis, and the flow coefficient φ corresponding to different specific diameters is obtained. s The calculation formula is used to obtain the corresponding energy head coefficient ψ, and finally a set of specific diameters D is obtained. s The dimensionless performance parameter combination of flow coefficient φ and energy head coefficient ψ is used to complete the backward centrifugal fan model spectrum planning based on specific diameter.

2. The centrifugal fan model planning method based on specific diameter definition according to claim 1 is characterized in that: Step 1) The dimensionless performance parameters of the centrifugal fan are defined as follows: Flow coefficient: Energy head coefficient: Where Q is the volume flow rate, D is the impeller diameter, ω is the impeller angular velocity, and h is the impeller angular velocity. pol is the unit mass work of the fan; The rotational angular velocity of the model fan when it is a standard fan is defined as the specific speed: When the model fan is a standard fan, the impeller outer diameter is defined as the specific diameter: Where D′ is the outer diameter of the model fan impeller.

3. The centrifugal fan model planning method based on specific diameter definition according to claim 2 is characterized in that: Step 2) Fitting is performed for the design point specific speed and flow coefficient, as well as the design point specific diameter and flow coefficient, and the fitting relationship is obtained as follows: φ=0.1436ω s -0.0340; φ=0.7037D s -1.7992 ; To evaluate the comprehensive effect, the coefficient of determination R and the root mean square error RMSE are used, which are defined as follows: Coefficient of determination: Root mean square error: Among them, y i is the ith actual value, is the i-th predicted value, is the average of the actual values, N is the total number of data points, and p is the number of unknown parameters in the regression model.

4. The centrifugal fan model planning method based on specific diameter definition according to claim 3 is characterized in that: Step 3) Fitting the design point specific diameter and specific speed, the fitting relationship is as follows: oh s =2.8949D s -0.9885 。 5. The centrifugal fan model planning method based on specific diameter definition according to claim 4 is characterized in that: Step 4) Based on the performance parameters of the backward centrifugal fan planned by the specific diameter spectrum, the specific diameter D s The range is 1.87 to 10.21, the flow coefficient φ ranges from 0.01 to 0.229, and the energy head coefficient ψ ranges from 0.392 to 0.

72.

6. A centrifugal fan model planning system based on specific diameter definition, characterized in that: include: The calculation unit calculates the dimensionless performance parameters of the design point based on the summarized high-efficiency backward centrifugal fan, including the flow coefficient φ, energy head coefficient ψ, specific speed ω s According to the similarity criterion, a dimensionless performance parameter ratio of centrifugal fan to diameter D is proposed. s The definition method is used to calculate the design point dimensionless performance parameters of each high-efficiency backward centrifugal fan, and the specific speed ω of the design point is analyzed. s and specific diameter D s As the horizontal axis, the flow coefficient φ of the design point is plotted as the vertical axis to obtain the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s Scatter plot with discharge coefficient φ; Verify the analysis unit, according to the specific speed ω s Scatter plot of discharge coefficient φ and specific diameter D s The data were fitted with the scatter plot of the flow coefficient φ and the speed ω was compared. s The flow coefficient φ is linearly fitted and the upper and lower limits are determined using a 95% confidence level prediction band. s The power function is used to fit the flow coefficient φ and the upper and lower limits are determined using the prediction band with 95% confidence. The determination coefficient R and root mean square error RMSE are used to evaluate the comprehensive fitting effect. The existing high-efficiency backward centrifugal fan experimental data are combined to perform the calculation based on the specific diameter D. s Conduct rationality verification analysis on the selection of design point discharge coefficient φ; Effect evaluation unit, the design point is compared with the diameter D s As the abscissa, the design point specific speed ω s The data were plotted as the vertical axis, and the power function was used for fitting and the prediction band with 95% confidence level was used to determine the upper and lower limits. The determination coefficient R and root mean square error RMSE were used to evaluate the comprehensive fitting effect. Centrifugal fan model planning unit, according to the priority number system [GB / T321-2005] to compare the speed ω s Select the corresponding common ratio based on the design point diameter D s The fitting relationship between the specific speed and the lower and upper limits is close to the center line as the selection basis to obtain different specific speeds ω s Corresponding specific diameter D s , based on the design point diameter D s The fitting relationship between the flow coefficient φ and the flow coefficient φ is within the upper and lower limits, close to the center line as the selection basis, and the flow coefficient φ corresponding to different specific diameters is obtained. s The calculation formula is used to obtain the corresponding energy head coefficient ψ, and finally a set of specific diameters D is obtained. s The dimensionless performance parameter combination of flow coefficient φ and energy head coefficient ψ is used to complete the backward centrifugal fan model spectrum planning based on specific diameter.

7. The centrifugal fan model planning system based on specific diameter definition according to claim 6, characterized in that: The dimensionless performance parameters of the centrifugal fan in the calculation unit are defined as follows: Flow coefficient: Energy head coefficient: Where Q is the volume flow rate, D is the impeller diameter, ω is the impeller angular velocity, and h is the impeller angular velocity. pol is the unit mass work of the fan; The rotational angular velocity of the model fan when it is a standard fan is defined as the specific speed: When the model fan is a standard fan, the impeller outer diameter is defined as the specific diameter: Where D′ is the outer diameter of the model fan impeller.

8. The centrifugal fan model planning system based on specific diameter definition according to claim 7 is characterized in that: In the verification analysis unit, the design point specific speed and flow coefficient, as well as the design point specific diameter and flow coefficient are fitted respectively, and the fitting relationships are as follows: φ=0.1436ω s -0.0340; φ=0.7037D s -1.7992 ; To evaluate the comprehensive effect, the coefficient of determination R and the root mean square error RMSE are used, which are defined as follows: Coefficient of determination: Root mean square error: Among them, y i is the ith actual value, is the i-th predicted value, is the average of the actual values, N is the total number of data points, and p is the number of unknown parameters in the regression model.

9. The centrifugal fan model planning system based on specific diameter definition according to claim 8, characterized in that: In the effect evaluation unit, the design point specific diameter and specific speed are fitted, and the fitting relationship is as follows: oh s =2.8949D s -0.9885 。 10. The centrifugal fan model planning system based on specific diameter definition according to claim 9, characterized in that: The performance parameters of the backward centrifugal fan based on the diameter spectrum planning in the centrifugal fan spectrum planning unit, the diameter D s The range is 1.87 to 10.21, the flow coefficient φ ranges from 0.01 to 0.229, and the energy head coefficient ψ ranges from 0.392 to 0.72.

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