Radial flow type turbine design method

Abstract

The invention discloses a radial flow type turbine design method, and relates to the field of turbine design. Aiming at the problems of high cost and low efficiency of a traditional single design, efficient design is realized on the basis of a similarity theory by establishing an impeller model stage library and a guide vane profile library. The method comprises the steps that design parameters are input, the rotating speed is preset, after the specific rotating speed is calculated, the closest model stage in a model stage library is matched, the rotating speed is corrected, and the impeller size is determined by modeling or cutting the model stage; giving an initial value of an outlet airflow angle of the guide vane, iteratively analyzing inlet pressure deviation until error requirements are met, and finally outputting correction parameters to complete design of the impeller and the guide vane. According to the method, through model-level automatic matching and parameter iterative optimization, the design efficiency and precision are remarkably improved, the method is suitable for multi-working-condition and multi-medium scenes, rapid and reliable design of the radial flow turbine is achieved, and the method has the advantages of being high in universality and high in engineering practicability.

Description

Technical Field

[0001] The present invention relates to the field of radial turbine design, and specifically to an efficient radial turbine design method based on similarity theory and a model-level library. The method is suitable for multi-stage radial turbine design in scenarios such as micro gas turbines, solar thermal power generation systems, and natural gas pressure differential energy recovery. Background Art

[0002] As a core component of energy conversion, radial turbines, with their compact structure, ease of manufacturing, and suitability for low-flow conditions, are widely used in micro-gas turbines, solar thermal power generation systems, natural gas differential pressure energy recovery, superchargers, and high-speed micro-expanders. With the diversification of energy sources and the miniaturization of industry, different application scenarios have brought about differentiated requirements for the design parameters of radial turbines, including significant differences in inlet and outlet pressures, temperatures, flow rates, and working media (such as air, gas, steam, and carbon dioxide).

[0003] Traditional radial turbine design relies primarily on a single design model, where aerodynamic calculations, structural design, and performance optimization are performed independently for each specific project. This approach has the following significant drawbacks:

[0004] High R&D costs: Each project must be designed from scratch, requiring significant repetitive calculations, resulting in wasted manpower and time. Statistics show that repetitive basic calculations account for a high proportion of traditional design processes, leading to generally long R&D cycles.

[0005] Low design efficiency: The lack of a standardized design framework requires designers to frequently adjust design parameters and rely on trial and error, making it difficult to quickly respond to diverse scenarios. This is especially true in multi-stage turbine design, where inter-stage matching calculations are complex and traditional methods require multiple iterations, resulting in low efficiency.

[0006] Insufficient design accuracy: A single design is easily affected by the designer's subjective factors, such as differences in model simplification and different choices of empirical formulas, which lead to deviations in the prediction of aerodynamic performance and low actual operating efficiency.

[0007] Poor versatility: Design results from different projects are difficult to reuse, and a standardized design system cannot be formed, which limits the rapid application of radial turbines in emerging fields.

[0008] While there are a few existing modeling design methods based on similarity theory, they suffer from issues such as incomplete model-level libraries, a lack of systematic guide vane profile matching, and unclear speed correction mechanisms. For example, traditional modeling design only targets a single impeller parameter and lacks a model-level library encompassing multi-dimensional performance parameters such as specific speed, speed ratio, and flow coefficient. This results in insufficient matching between the modeled impeller and actual operating conditions. Furthermore, in guide vane design, there is a lack of a blade profile library linked to the impeller model level, requiring separate blade profile aerodynamic optimization, increasing design complexity.

[0009] Therefore, it is urgent to propose a systematic design method. By establishing a standardized model-level library and blade profile library, combined with an automatic parameter matching and correction mechanism, efficient and high-precision design of radial turbines can be achieved, R&D costs can be reduced, and design versatility can be improved. Summary of the Invention

[0010] The present invention aims to overcome the above-mentioned shortcomings of the prior art and provide a radial turbine design method.

[0011] The technical solution adopted in the present invention is as follows:

[0012] A radial turbine design method comprises the following steps:

[0013] S1: establishing a radial turbine impeller model level library, wherein each model level in the model level library is associated with corresponding performance data, including specific speed, and each model level has a corresponding number;

[0014] S2: Establish a guide vane profile library. Different guide vanes in the profile library are associated with corresponding performance parameters, including inlet airflow angle. Each guide vane has a corresponding number.

[0015] S3: Determine the radial turbine design input parameters, including inlet and outlet pressures, temperatures, flow rates, working medium, set stages, and preliminarily preset speeds;

[0016] S4: According to the initial preset speed, calculate the corresponding specific speed of each level. The calculation formula of the specific speed is: Where w is the angular velocity of rotation; Q3 is the outlet volume flow rate; ΔHs is the isentropic enthalpy drop;

[0017] S5: According to the specific speed, the model level with the closest specific speed is searched in the impeller model level library and selected;

[0018] S6: According to the selected model level, the preliminary preset speed is modified to determine the final design speed;

[0019] S7: Calculate the final design specific speed of each stage according to the final design speed;

[0020] S8: If a model level with the same specific speed as the final design specific speed of the stage exists in the model level library, the modularization ratio is calculated, and the size of the impeller after modularization is calculated based on the modularization ratio; if it does not exist, a model level with a similar specific speed is selected, the model level is cut according to the cutting ratio, and the modularization ratio of the cut model level is calculated, and the size of the impeller after modularization is calculated based on the modularization ratio;

[0021] S9: Based on the impeller size, the initial value of the guide vane outlet airflow angle is given, and the single-stage analysis program module is called to perform analysis and calculation to determine whether the deviation between the analyzed inlet pressure and the given inlet pressure is less than the allowable error value;

[0022] S10: If the deviation value is less than the allowable error value, the corrected speed, selected model level, modeling ratio, cutting ratio, geometric dimensions, and aerodynamic parameters are output; if not, the guide vane outlet airflow angle is corrected and the single-stage analysis program module is called again until the deviation value is less than the allowable error value and the corresponding parameters are output;

[0023] S11: Complete the design of the final impellers and guide vanes at each stage according to the output parameters to realize the design of the entire radial turbine.

[0024] Furthermore, the performance data associated with each model level in the impeller model level library also includes speed ratio, flow coefficient, and average reaction degree.

[0025] Furthermore, the performance parameters associated with different guide vanes in the guide vane profile library also include outlet airflow angles.

[0026] Furthermore, in the step of correcting the preliminary preset rotational speed according to the selected model level, the corrected final design rotational speed is the same rotational speed for each level.

[0027] Furthermore, the modeling ratio is calculated based on the similarity theory and is used to scale the impeller size at the model level to the impeller size required for the design.

[0028] Furthermore, the cutting ratio is determined based on the difference between the final design specific speed of the stage and the specific speed of the selected approximate model stage, and the impeller of the approximate model stage is cut to match the design requirements.

[0029] Furthermore, the analysis calculation of the single-stage analysis program module includes calculation of the deviation value between the inlet pressure and the given inlet pressure, and the error allowable value is a preset pressure deviation threshold.

[0030] Furthermore, the geometric dimensions include the guide vane inlet radius, the guide vane outlet radius, the blade height, the impeller inlet top radius, the impeller inlet width, the impeller outlet root radius, the impeller outlet top radius, the impeller outlet middle radius and the impeller shaft width.

[0031] Furthermore, the radius of the middle of the impeller outlet satisfies R 3m =(R 3h +R 3t ) / 2; R 3m / R2<0.7;R 3h / R 3t >0.4, where R 3m is the radius of the middle part of the impeller outlet, R 3h is the impeller outlet root radius, R3t R2 is the impeller inlet top radius and R is the impeller outlet top radius.

[0032] Furthermore, the aerodynamic parameters include speed ratio, flow coefficient, and average reaction degree, where: the speed ratio is χ = U2 / C0, U2 is the rotational linear velocity of the outer edge of the impeller inlet, C0 is the isentropic velocity; the flow coefficient is Φ = C m3 / U2,C m3 is the impeller outlet meridian velocity;

[0033] The average reaction rate is h2 is the static enthalpy at the impeller inlet, h3 is the static enthalpy at the impeller outlet, H1 is the total enthalpy at the stage inlet, and H3 is the total enthalpy at the stage outlet.

[0034] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0035] The present invention builds a standardized model-level library and blade profile library, combined with automatic parameter matching and iterative optimization mechanisms, to significantly improve the efficiency, accuracy, and versatility of radial turbine design:

[0036] Improved design efficiency: By reusing core parameters from the impeller model-level library, duplicate calculations and design work are avoided, significantly shortening the R&D cycle. In multi-stage design scenarios, each stage can be quickly matched to the model level, enabling inter-stage collaborative optimization. Furthermore, automated screening and speed correction algorithms replace manual trial and error, making the design process more standardized and efficient.

[0037] Improved design accuracy and reliability: Using dimensionless specific speed as the core matching parameter, combined with multi-dimensional aerodynamic parameters, the model-level performance closely matches the target operating conditions, ensuring impeller design accuracy. Automatic, iterative correction of the guide vane outlet airflow angle precisely controls inlet pressure deviation, effectively improving operational efficiency and design compatibility.

[0038] Strong versatility and scalability: Applicable to a variety of working conditions, and can be easily adapted to emerging media through model-level library expansion.

[0039] Outstanding economical and practical performance: Reducing repetitive design reduces R&D costs, while modular design and cutting technology reduce test piece processing costs. Geometric dimensional constraints ensure a reasonable impeller structure, reducing the number of structural optimizations and improving project implementation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure is a general flow chart of a radial turbine design method in the present invention.

[0041] Figure 2 The schematic diagram of radial turbine dimensions is completed for the design.

[0042] Figure 3Schematic diagram of single-stage impeller flow path at different specific speeds. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below with reference to the accompanying drawings.

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] In this embodiment, a radial turbine design method includes the following steps:

[0046] S1: establishing a radial turbine impeller model level library, wherein each model level in the model level library is associated with corresponding performance data, including specific speed, and each model level has a corresponding number;

[0047] S2: Establish a guide vane profile library. Different guide vanes in the profile library are associated with corresponding performance parameters, including inlet airflow angle. Each guide vane has a corresponding number.

[0048] S3: Determine the radial turbine design input parameters, including inlet and outlet pressures, temperatures, flow rates, working medium, set stages, and preliminarily preset speeds;

[0049] S4: According to the initial preset speed, calculate the corresponding specific speed of each level. The calculation formula of the specific speed is: Where w is the angular velocity of rotation; Q3 is the outlet volume flow rate; ΔHs is the isentropic enthalpy drop;

[0050] S5: According to the specific speed, the model level with the closest specific speed is searched in the impeller model level library and selected;

[0051] S6: According to the selected model level, the preliminary preset speed is modified to determine the final design speed;

[0052] S7: Calculate the final design specific speed of each stage according to the final design speed;

[0053] S8: If a model level with the same specific speed as the final design specific speed of the stage exists in the model level library, the modularization ratio is calculated, and the size of the impeller after modularization is calculated based on the modularization ratio; if it does not exist, a model level with a similar specific speed is selected, the model level is cut according to the cutting ratio, and the modularization ratio of the cut model level is calculated, and the size of the impeller after modularization is calculated based on the modularization ratio;

[0054] S9: Based on the impeller size, the initial value of the guide vane outlet airflow angle is given, and the single-stage analysis program module is called to perform analysis and calculation to determine whether the deviation between the analyzed inlet pressure and the given inlet pressure is less than the allowable error value;

[0055] S10: If the deviation value is less than the allowable error value, the corrected speed, selected model level, modeling ratio, cutting ratio, geometric dimensions, and aerodynamic parameters are output; if not, the guide vane outlet airflow angle is corrected and the single-stage analysis program module is called again until the deviation value is less than the allowable error value and the corresponding parameters are output;

[0056] S11: Complete the design of the final impellers and guide vanes at each stage according to the output parameters to realize the design of the entire radial turbine.

[0057] Database creation: Historically mature impeller designs are classified and stored in a model-level library by parameters such as specific speed (0.2-1.0) and speed ratio (0.5-0.8), with each model level labeled with a unique ID; guide vanes are classified and stored by outlet airflow angle (10°-30°), with the blade type ID labeled. Parameter input: Input the design parameters of a natural gas turbine (inlet and outlet pressures, flow rates, and medium is methane) and preset the initial speed. Specific speed calculation: Call the formula Generate the current stage specific speed value. Model level matching: The system automatically searches the model level library and selects the model level with the smallest specific speed difference. Speed correction: Based on the historical speed of the selected model level, adjust the initial speed according to the similarity theory to ensure that the speed of each level is unified (avoid multi-stage differential speed transmission). Modulation / cutting decision: If the target specific speed is exactly the same as the model level, directly scale the size according to the modulating ratio; if there is a deviation (such as the difference > 0.05), call the cutting algorithm to adjust the impeller flow channel size. Guide vane iteration: Initially set the guide vane outlet angle to 30°, run the single-stage analysis module, if there is a deviation in the inlet pressure (such as the deviation > 0.01), automatically correct the outlet angle (such as 30°→29°) until it meets the standard. Output design: Generate a design file containing the model level ID, corrected speed, impeller size (such as R1=50mm), and guide vane ID.

[0058] Reduce repeated calculations through standardized database construction and automatic matching.

[0059] Furthermore, the performance data associated with each model level in the impeller model level library also includes speed ratio, flow coefficient, and average reaction degree.

[0060] When matching the model level library, in addition to the specific speed, the speed ratio, flow coefficient, etc. are synchronously checked for deviations from the corresponding parameters of the selected model level (such as deviation <1%) to ensure similar aerodynamic performance.

[0061] Multi-parameter matching improves modeling accuracy and controls efficiency prediction deviation within a smaller range.

[0062] Furthermore, the performance parameters associated with different guide vanes in the guide vane profile library also include outlet airflow angles.

[0063] When matching the guide vanes, according to the impeller inlet airflow angle (determined by the model level, such as 23°), the guide vanes with an outlet angle within the range of ±5° are selected from the blade profile library, and the outlet angle parameters of the guide vane blade profile library (such as an outlet angle of 20°) are called as the initial value of the iteration.

[0064] The guide vanes are linked to the impeller aerodynamic parameters to reduce inter-stage flow losses.

[0065] Furthermore, in the step of correcting the preliminary preset rotational speed according to the selected model level, the corrected final design rotational speed is the same rotational speed for each level.

[0066] In a multi-stage design, each stage is matched based on the same model-level library, and the corrected speed is forced to be unified (for example, the first-stage matching speed is 52,000 rpm, and the secondary synchronization adopts this speed), avoiding the complexity of the multi-stage transmission structure.

[0067] Unified speed simplifies shaft system design and improves unit reliability.

[0068] Furthermore, the modeling ratio is calculated based on the similarity theory and is used to scale the impeller size at the model level to the impeller size required for the design.

[0069] When the model stage is fully matched, the size is scaled according to the modularization ratio (e.g. the model stage impeller diameter is 100 mm, the modularization ratio is 1.2, and the design impeller diameter is 120 mm), and the aerodynamic parameters such as the number of model stage blades and inlet and outlet angles are retained.

[0070] Standardized modeling reduces the number of trials and lowers manufacturing costs.

[0071] Furthermore, the cutting ratio is determined based on the difference between the final design specific speed of the stage and the specific speed of the selected approximate model stage, and the impeller of the approximate model stage is cut to match the design requirements.

[0072] When there is no completely matching model level, select an approximate model level (such as a model with a specific speed of 0.52 matching 0.5), and calculate the impeller flow channel cutting amount according to the cutting law.

[0073] Cutting technology expands the scope of model-level applicability and improves versatility.

[0074] Furthermore, the analysis calculation of the single-stage analysis program module includes calculation of the deviation value between the inlet pressure and the given inlet pressure, and the error allowable value is a preset pressure deviation threshold.

[0075] The single-stage analysis module has a built-in pressure deviation threshold. It automatically compares the calculated pressure with the design pressure in each iteration. When the limit is exceeded, the guide vane outlet angle correction (such as + / -1°) is triggered until the deviation threshold is met and the output is output.

[0076] Automated iteration reduces manual intervention and improves accuracy.

[0077] Furthermore, the geometric dimensions include the guide vane inlet radius, the guide vane outlet radius, the blade height, the impeller inlet top radius, the impeller inlet width, the impeller outlet root radius, the impeller outlet top radius, the impeller outlet middle radius and the impeller shaft width.

[0078] Furthermore, the radius of the middle of the impeller outlet satisfies R 3m =(R 3h +R 3t ) / 2; R 3m / R2<0.7;R 3h / R 3t >0.4, where R 3m is the radius of the middle part of the impeller outlet, R 3h is the impeller outlet root radius, R 3t R2 is the impeller inlet top radius and R is the impeller outlet top radius.

[0079] Furthermore, the aerodynamic parameters include speed ratio, flow coefficient, and average reaction degree, where: the speed ratio is χ = U2 / C0, U2 is the rotational linear velocity of the outer edge of the impeller inlet, and C0 is the stage isentropic speed;

[0080] When designing the impeller size, it is mandatory to check R 3m / R2<0.7(such as R 3m =60mm, R2=90mm, ratio 0.67), ensure the outlet flow channel converges; check R 3h / R 3t >0.4 (such as 0.45) to avoid root blockage.

[0081] Geometric constraints ensure structural rationality and reduce strength issues.

[0082] The flow coefficient is Φ = C m3 / U2,C m3 is the impeller outlet meridian velocity;

[0083] The average reaction rate is h2 is the static enthalpy at the impeller inlet, h3 is the static enthalpy at the impeller outlet, H1 is the total enthalpy at the stage inlet, and H3 is the total enthalpy at the stage outlet.

[0084] When calculating aerodynamic parameters, the speed ratio χ is determined by the ratio of the impeller outer edge linear velocity to the isentropic velocity, the flow coefficient Φ is based on the ratio of the outlet meridian velocity to the linear velocity, and the reaction degree R m Through enthalpy drop difference calculation, the three are synchronously verified to ensure that they are within the model-level empirical range.

[0085] Multi-parameter collaborative optimization improves level efficiency.

[0086] The above description is only a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the invention should be included in the scope of protection of the invention.

Claims

1. A radial turbine design method, characterized in that: The following steps are involved: S1: establishing a radial turbine impeller model level library, wherein each model level in the model level library is associated with corresponding performance data, the performance data including specific speed, and each model level has a corresponding number; S2: establishing a guide vane profile library, wherein different guide vanes in the profile library are associated with corresponding performance parameters, including an inlet airflow angle, and each guide vane has a corresponding number; S3: Determine radial turbine design input parameters, including inlet and outlet pressures, temperatures, flow rates, working medium, given stages, and preliminarily preset speeds; S4: Calculate the specific speeds corresponding to each level according to the preliminary preset speeds. The specific speed calculation formula is: Where w is the angular velocity of rotation; Q3 is the outlet volume flow rate; ΔHs is the isentropic enthalpy drop; S5: searching for a model level with a closest specific speed in the impeller model level library according to the specific speed and selecting the model level; S6: According to the selected model level, the preliminary preset speed is modified to determine a final design speed; S7: Calculating the final design specific speed of each stage according to the final design speed; S8: If a model level with the same specific speed exists in the model level library as the final design specific speed of the stage, the modularization ratio is calculated, and the size of the impeller after modularization is calculated according to the modularization ratio; if no model level exists, a model level with a similar specific speed is selected, the model level is cut according to the cutting ratio, and the modularization ratio of the cut model level is calculated, and the size of the impeller after modularization is calculated according to the modularization ratio; S9: Based on the impeller size, an initial value of the guide vane outlet airflow angle is given, and a single-stage analysis program module is called to perform analysis and calculation to determine whether a deviation between the analyzed inlet pressure and the given inlet pressure is less than an allowable error value; S10: If the deviation value is less than the allowable error value, the corrected speed, selected model level, modeling ratio, cutting ratio, geometric dimensions, and aerodynamic parameters are output; if not, the guide vane outlet airflow angle is corrected and the single-stage analysis program module is called again until the deviation value is less than the allowable error value and the corresponding parameters are output; S11: Complete the design of the final impellers and guide vanes at each stage according to the output parameters to realize the design of the entire radial turbine.

2. A radial turbine design method according to claim 1, characterized in that: The performance data associated with each model level in the impeller model level library also includes speed ratio, flow coefficient, and average reaction degree.

3. A radial turbine design method according to claim 1, characterized in that: The performance parameters associated with different guide vanes in the guide vane profile library also include outlet airflow angles.

4. A radial turbine design method according to claim 1, characterized in that: In the step of correcting the preliminary preset speed according to the selected model level, the corrected final design speed is the same speed for each level.

5. The radial turbine design method according to claim 1, characterized in that: The calculation of the modulo ratio is based on similarity theory and is used to scale the impeller size of the model stage to the impeller size required for the design.

6. The radial turbine design method according to claim 1, characterized in that: The cutting ratio is determined based on the difference between the final design specific speed of the stage and the specific speed of the selected approximate model stage, and the impeller of the approximate model stage is cut to match the design requirements.

7. The radial turbine design method according to claim 1, characterized in that: The analysis calculation of the single-stage analysis program module includes calculation of the deviation value between the inlet pressure and the given inlet pressure, and the error allowable value is a preset pressure deviation threshold.

8. The radial turbine design method according to claim 1, characterized in that: The geometric dimensions include the guide vane inlet radius, the guide vane outlet radius, the blade height, the impeller inlet top radius, the impeller inlet width, the impeller outlet root radius, the impeller outlet top radius, the impeller outlet middle radius and the impeller shaft width.

9. The radial turbine design method according to claim 1, characterized in that: The central radius of the impeller outlet meets R 3m =(R 3h +R 3t ) / 2; R 3m / R2<0.7;R 3h / R 3t >0.4, where R 3m is the radius of the middle part of the impeller outlet, R 3h is the impeller outlet root radius, R 3t R2 is the impeller inlet top radius and R is the impeller outlet top radius.

10. The radial turbine design method according to claim 1, characterized in that: The aerodynamic parameters include speed ratio, flow coefficient, and average reaction degree, wherein: the speed ratio is χ=U2 / C0, U2 is the rotational linear velocity of the outer edge of the impeller inlet, and C0 is the stage isentropic speed; The flow coefficient is Φ = C m3 / U2,C m3 is the impeller outlet meridian velocity; The average reaction rate is h2 is the static enthalpy at the impeller inlet, h3 is the static enthalpy at the impeller outlet, H1 is the total enthalpy at the stage inlet, and H3 is the total enthalpy at the stage outlet.

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