Contra-rotating fan with guide vane in middle and optimization design method thereof
By setting guide vanes in the middle of the counter-rotating fan and optimizing the design, the problems of narrow stable operating range and flow sensitivity of the vaneless counter-rotating fan are solved, achieving the effect of high pressure ratio and wide flow margin.
Patent Information
- Application Number
- CN202610309542.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-15
AI Technical Summary
Vaneless counter-rotating fans have a narrow stable operating range, their flow rate is sensitive to changes in operating conditions, their high-efficiency range is narrow, and their performance under varying operating conditions is poor.
A guide vane is set in the middle of the counter-rotating fan. The blade shape of the middle guide vane is roughly the same as that of the outlet guide vane. The axial distance between the middle guide vane and the first and second stage rotors is controlled, and the design is optimized through parametric modeling, CFD simulation and optimization algorithm.
It broadens the stable operating range and flow margin of the counter-rotating fan, maintains the high pressure ratio characteristics, and improves the insulation efficiency and flow tolerance.
Smart Images
Figure CN122040662A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of turbomachinery, and more specifically, to a counter-rotating fan with intermediate guide vanes and its optimized design method. Background Technology
[0002] Counter-rotating fans / compressors have attracted widespread attention due to their ability to achieve high pressure ratios, relatively compact structure, ability to counteract gyroscopic torque, and large thrust-to-weight ratio. However, vaneless counter-rotating fans have the following inherent problems: (1) Narrow stable operating range: The high-speed airflow at the outlet of the first-stage rotor directly enters the second-stage rotor rotating in the opposite direction, resulting in a strong negative pre-swirl at the inlet of the second-stage rotor, a high inlet Mach number, and a large shock wave loss, leading to a low overall efficiency of the second-stage rotor. In addition, when the flow rate of the counter-rotating fan deviates slightly from the design point, it will cause flow separation and deteriorate the flow, that is, the flow rate is extremely sensitive to changes in operating conditions; (2) Sharp high-efficiency region and poor performance under varying operating conditions: Its peak efficiency is high but narrow, and the efficiency is extremely sensitive to changes in flow rate, and the performance degrades rapidly under non-design operating conditions. Summary of the Invention
[0003] This application provides a counter-rotating fan with intermediate guide vanes and its optimized design method, aiming to maintain the high pressure ratio characteristics of the counter-rotating fan while expanding the stable operating range and flow margin of the counter-rotating fan.
[0004] The first aspect of this application provides a counter-rotating fan with intermediate guide vanes, comprising: Casing; The hub is located inside the casing; The hub is provided with an inlet guide vane, a first-stage rotor, a second-stage rotor and an outlet guide vane in sequence along the length of the hub, and the first-stage rotor and the second-stage rotor rotate in opposite directions. The hub is provided with an intermediate guide vane located between the first stage rotor and the second stage rotor, and the blade shape of the intermediate guide vane is approximately the same as that of the outlet guide vane. The axial distance between the leading edge of the intermediate guide vane and the trailing edge of the first-stage rotor is 30%-45% of the average axial chord length of the first-stage rotor; The axial distance between the trailing edge of the intermediate guide vane and the leading edge of the second-stage rotor is 30%-45% of the average axial chord length of the second-stage rotor.
[0005] Optionally, the intermediate guide vane includes a root, a middle section, and a tip along the blade height direction, with the root positioned close to the hub; The inlet metal angles of the intermediate guide vane at the leaf root, leaf middle, and leaf tip are 39.483°, 38.754°, and 34.071°, respectively. The exit metal angles of the intermediate guide vane at the leaf root, leaf middle, and leaf tip are 0.249°, 2.344°, and 4.727°, respectively.
[0006] The second aspect of this application provides an optimized design method for a counter-rotating fan with intermediate guide vanes, applied to a counter-rotating fan with intermediate guide vanes provided in the first aspect of this application, characterized in that the design method includes: Parametric modeling is performed on the meridional flow channel and each row of blades of the counter-rotating fan. The meridional flow channel is controlled by several control points. The air inlet angle and air outlet angle of each row of blades along the blade root section, blade middle section, and blade tip section are used as independently adjustable design parameters. Different three-dimensional blade shapes are generated by combining and adjusting the air inlet angle and air outlet angle parameters. Build an automated simulation process that integrates parametric geometry, mesh generation, and CFD solving; The optimization problem is defined with the goal of maximizing efficiency and the constraints of pressure ratio and flow rate. The optimization goal and constraints can be selected according to the design requirements. An initial sample set is generated by sampling within the design space. Sample performance data is obtained through the automated simulation process. A proxy model of the input and output relationship between design variables and aerodynamic performance is constructed. Global optimization is performed based on the proxy model to obtain the initial scheme. The initial scheme is verified by CFD, and the accuracy and precision of the proxy model are judged based on the verification results. Then, the proxy model is adaptively updated. After establishing a new proxy model, the above steps are repeated until the optimal scheme that satisfies all indicators and optimization objectives is obtained. In the optimal solution, the contra-rotating fan has an inlet guide vane, a first-stage rotor, a second-stage rotor, and an outlet guide vane arranged sequentially along the length of the hub; an intermediate guide vane is arranged on the hub between the first-stage rotor and the second-stage rotor, and the blade shape of the intermediate guide vane is approximately the same as that of the outlet guide vane. The axial distance between the leading edge of the intermediate guide vane and the trailing edge of the first-stage rotor is 30%-45% of the average axial chord length of the first-stage rotor; The axial distance between the trailing edge of the intermediate guide vane and the leading edge of the second-stage rotor is 30%-45% of the average axial chord length of the second-stage rotor.
[0007] Optionally, the mass flow rate constraint in the definition of the optimization problem is greater than or equal to 210 kg / s, and the total pressure ratio constraint is greater than 2.2.
[0008] Optionally, in the steps of sampling and generating an initial sample set within the design space, obtaining sample performance data through the automated simulation process, constructing a surrogate model of the input-output relationship between design variables and aerodynamic performance, and performing global optimization based on the surrogate model to obtain an initial scheme, the design method includes: Initial sample points are generated using Latin hypercube sampling; A surrogate model was constructed using response surface methodology and genetic algorithms. A multi-objective optimization algorithm is used to perform global optimization based on the surrogate model to obtain an initial solution.
[0009] Optionally, the control points of the meridional channel include seven control points in a coordinate system established with respect to the axial and radial directions of the hub; The axial coordinate of the control point is fixed, while the radial coordinate is adjustable.
[0010] Optionally, in the step of performing CFD verification on the initial scheme, judging the precision and accuracy of the surrogate model based on the verification results, adaptively updating the surrogate model, establishing a new surrogate model, and repeating the above steps until the optimal scheme that satisfies all indicators and optimization objectives is obtained, the design method further includes: If the initial scheme does not meet the requirements, new sampling points are added near the optimal prediction solution or in areas with high model uncertainty, based on the prediction error distribution of the current proxy model. When the predicted performance established by the surrogate model is inaccurate, the parameters that have a significant impact on the performance of the counter-rotating fan are reselected, the range of the selected design variables is redefined, and a new surrogate model is constructed.
[0011] Beneficial effects: This application provides a counter-rotating fan with intermediate guide vanes and its optimized design method. The counter-rotating fan includes a casing, a hub, and inlet guide vanes, a first-stage rotor, a second-stage rotor, and an outlet guide vane disposed on the hub. An intermediate guide vane is disposed between the first-stage rotor and the second-stage rotor on the hub. The blade profile of the intermediate guide vane is approximately the same as that of the outlet guide vane. The axial distance between the leading edge of the intermediate guide vane and the trailing edge of the first-stage rotor is 30%-45% of the average axial chord length of the first-stage rotor. The axial distance between the trailing edge of the intermediate guide vane and the leading edge of the second-stage rotor is also 30%-45% of the average axial chord length of the second-stage rotor. By distributing the intermediate guide vane between the first-stage rotor and the second-stage rotor and controlling the distance between the intermediate guide vane and the first-stage rotor and the second-stage rotor, the stable operating range and flow margin of the counter-rotating fan can be widened while maintaining the high pressure ratio characteristics of the counter-rotating fan. Attached Figure Description
[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0013] Figure 1 This is a schematic diagram of the structure of a counter-rotating fan with guide vanes in the middle, according to an embodiment of this application; Figure 2 This is a schematic diagram of the three-dimensional blades of a counter-rotating fan with guide vanes in the middle, according to an embodiment of this application, rotating around the Z-axis. Figure 3 This is a schematic diagram of the speed triangle principle of a counter-rotating fan with guide vanes in the middle, according to an embodiment of this application. Figure 4 This is a comparison chart showing the thermal efficiency of a counter-rotating fan with intermediate guide vanes proposed in an embodiment of this application and a counter-rotating fan in related technologies as a function of reduced flow rate at the design speed. Figure 5 This is a comparison chart showing the total pressure ratio as a function of reduced flow rate at the design speed of a counter-rotating fan with intermediate guide vanes proposed in an embodiment of this application and a counter-rotating fan in related technologies; Figure 6 This is a comparison diagram of the Mach number along the blade height of the second-stage rotor inlet of a counter-rotating fan with intermediate guide vanes proposed in an embodiment of this application and a counter-rotating fan in the related art. Figure 7 This is a flowchart illustrating an optimized design method for a counter-rotating fan with intermediate guide vanes according to an embodiment of this application. Figure 8 This is a schematic diagram of the meridional plane of a counter-rotating fan in an optimized design method for a counter-rotating fan with guide vanes in the middle, as proposed in an embodiment of this application.
[0014] Explanation of reference numerals in the attached diagram: 1. Hub; 2. Inlet guide vane; 3. First-stage rotor; 4. Intermediate guide vane; 5. Second-stage rotor; 6. Outlet guide vane. Detailed Implementation
[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0016] Reference Figure 1 and Figure 2As shown, this application discloses a counter-rotating fan with guide vanes in the middle, which includes a casing and a hub 1.
[0017] Specifically, the hub 1 is disposed within the casing. Along the length of the hub 1, an inlet guide vane 2, a first-stage rotor 3, a second-stage rotor 5, and an outlet guide vane 6 are sequentially arranged. It can be understood that the airflow enters the counter-rotating fan from the end where the inlet guide vane 2 is located, and after passing through the inlet guide vane 2, the first-stage rotor 3, the second-stage rotor 5, and the outlet guide vane 6 in sequence, it exits the counter-rotating fan. In this embodiment, the first-stage rotor 3 and the second-stage rotor 5 rotate in opposite directions, and from the perspective of the airflow inlet direction, the first-stage rotor 3 rotates clockwise, while the second-stage rotor 5 rotates counter-clockwise.
[0018] At the same time, refer to Figure 2 As shown in the embodiment of this application, an intermediate guide vane 4 is provided on the hub 1 between the first stage rotor 3 and the second stage rotor 5. The blade shape of the intermediate guide vane 4 is approximately the same as that of the outlet guide vane 6. Specifically, the blade thickness, mounting angle and chord length of the intermediate guide vane 4 are designed with reference to the outlet guide vane 6.
[0019] Furthermore, in this embodiment, the axial mounting position of the intermediate guide vane 4 on the hub 1 is as follows: the axial distance between the leading edge of the intermediate guide vane 4 and the trailing edge of the first-stage rotor 3 is 30%-45% of the average axial chord length of the first-stage rotor 3; the axial distance between the trailing edge of the intermediate guide vane 4 and the leading edge of the second-stage rotor 5 is 30%-45% of the average axial chord length of the second-stage rotor 5. For example, the axial distance between the leading edge of the intermediate guide vane 4 and the trailing edge of the first-stage rotor 3 is 30% of the average axial chord length of the first-stage rotor 3, and the axial distance between the trailing edge of the intermediate guide vane 4 and the leading edge of the second-stage rotor 5 is 30% of the average axial chord length of the second-stage rotor 5; or, the axial distance between the leading edge of the intermediate guide vane 4 and the trailing edge of the first-stage rotor 3 is 45% of the average axial chord length of the first-stage rotor 3, and the axial distance between the trailing edge of the intermediate guide vane 4 and the leading edge of the second-stage rotor 5 is 45% of the average axial chord length of the second-stage rotor 5.
[0020] In this embodiment, the inlet and outlet metal angles of the intermediate guide vane 4 along the blade height direction are determined based on the outlet airflow angle of the first-stage rotor 3 and the inlet airflow angle of the second-stage rotor 5, and are continuously iteratively optimized according to the flow field. In one embodiment, the intermediate guide vane 4 includes a root, a middle section, and a tip along the blade height direction, with the root located close to the hub 1; the inlet metal angles of the intermediate guide vane 4 at the root, middle section, and tip are 39.483°, 38.754°, and 34.071°, respectively; the outlet metal angles of the intermediate guide vane 4 at the root, middle section, and tip are 0.249°, 2.344°, and 4.727°, respectively.
[0021] Figure 3 A schematic diagram of the velocity triangle principle of this counter-rotating fan is given. From left to right in the diagram, the components are the first-stage rotor 3, the intermediate guide vane 4, and the second-stage rotor 5. Figure 2 As shown, The values represent relative speeds, with subscripts 1, 2, 3, and 4 indicating the inlet and outlet of the first and second rows of rotors, respectively. For absolute velocity, the subscripts 1, 2, and 3 represent the inlet of the first row of rotors, the interface between the first and second rows of rotors, and the outlet of the second row of rotors, respectively. The velocity is tangential, and the subscripts 1 and 2 represent the rotational linear velocities of the first and second rows of rotors, respectively. and These represent the changes in relative velocity and tangential velocity, respectively; subscripts , For the front rotor and the rear rotor; subscript (shock) and (turning) indicates the change in tangential velocity caused by the turning of shock waves and airflow.
[0022] pass Figure 3 It can be seen that the velocity triangle of the first-stage rotor 3 is the first part, the middle guide vane 4 is the middle part, and the velocity triangle of the second-stage rotor 5 is the last part. Figure 3 As shown, after rectification by the intermediate guide vane 4, the airflow direction at the second-stage rotor inlet is... It is closer to the axial direction.
[0023] In this embodiment of the application, the first-stage rotor 3 and the second-stage rotor 5 have the same rotational speed, both 6500 r / min. The outlet of the counter-rotating fan retains stator blades responsible for changing the absolute airflow velocity direction to be close to the axial airflow.
[0024] To verify the beneficial technical effects of this application, the inventors of this application conducted relevant experiments on the counter-rotating fan in the related art and the counter-rotating fan provided in the embodiments of this application. The main design parameters of the two counter-rotating fans under design conditions are shown in Table 1, and the aerodynamic performance of the two counter-rotating fans under design conditions is shown in Table 2.
[0025] Table 1
[0026] Table 2
[0027] The graph showing the relationship between the total pressure ratio and adiabatic efficiency of the counter-rotating fan as a function of mass flow rate provided in this embodiment is as follows: Figure 4 , Figure 5As shown.
[0028] Furthermore, the specific implementation process for the numerical calculation of the two types of counter-rotating fans is as follows: 1. Mesh generation and calculation are implemented using Ansys Turbogrid and CFX. Mesh generation is performed using Turbogrid, and the entire region is meshed using OH type mesh. The mesh near the wall is refined to meet the mesh independence verification.
[0029] 2. Numerical calculations were performed using CFX, with the Reynolds-averaged Navier-Stokes (NS) equations selected as the governing equations, and the Sheer Stress Transport Model (SST) chosen as the turbulence model. Boundary conditions were set as the inlet total temperature... Imported total pressure The axial inlet boundary condition, the outlet boundary condition is the given outlet static pressure, the solid boundary adopts the adiabatic wall no-slip boundary, the inter-blade interface parameter transfer adopts the mixed plane method, and the computational fluid domain side adopts periodic boundary conditions.
[0030] 3. The results of the numerical calculation are as follows: Figure 4 , Figure 5 , Figure 6 As shown, under design conditions, compared with the counter-rotating fan in the related technology (counter-rotating fan without guide vanes in the figure), under the same inlet conditions and approximately equal flow rates, the counter-rotating fan (counter-rotating fan with guide vanes in the figure) provided in this application embodiment has a flow margin of 2.23% and a stable operating range of 2.26%, while the counter-rotating fan in the related technology has a flow margin of 6.22% and a stable operating range of 6.32%.
[0031] It can be seen that by adding a row of intermediate guide vanes 4 between the first-stage rotor 3 and the second-stage rotor 5, the flow margin of the counter-rotating fan can be increased, and the stable operating range can be expanded. The counter-rotating fan provided in this embodiment has an adiabatic efficiency of 87.6% and a total pressure ratio of 2.267 at the design point. Figure 4 , Figure 5 As shown. Furthermore, due to the rectifying effect of the intermediate guide vane 4, the Mach number of the counter-rotating fan provided in this embodiment of the application decreases along the blade height at the inlet of the second-stage rotor 5.
[0032] The definitions of flow margin and stable operating range are as follows:
[0033]
[0034] In the formula, Indicates the design point. Indicates the near-stall point. Indicates the point of near blockage. This represents the equivalent mass flow rate.
[0035] The counter-rotating fan with guide vanes proposed in this invention not only has a high total pressure ratio and adiabatic efficiency, but also ensures the feasibility and operability of the counter-rotating structure.
[0036] Reference Figure 7 As shown in the embodiments of this application, an optimized design method for a counter-rotating fan with intermediate guide vanes is also provided, applied to the counter-rotating fan with intermediate guide vanes as provided in the embodiments of this application. The design method includes: Step S1: Parametric modeling of the meridional flow channel and each row of blades of the counter-rotating fan. The meridional flow channel is controlled by several control points. The inlet and outlet angles of each row of blades along the blade root section, blade middle section, and blade tip section are used as independent and adjustable design parameters. Different three-dimensional blade shapes are generated by combining and adjusting the inlet and outlet angle parameters.
[0037] Specifically, in this application, the meridional channel of the counter-rotating fan adopts a constant outer diameter design, and the hub 1 profile of the counter-rotating fan is a Bézier curve defined by seven control points. These seven control points are located in a coordinate system established with respect to the axial and radial directions of the hub 1. The axial coordinates of the seven control points are fixed, while the radial coordinates are adjustable design parameters. Different hub 1 profiles can be generated by adjusting different radial coordinates. The meridional channel parameterization diagram is shown below. Figure 8 As shown in the figure, the control points are 7-13 on the meridional plane. The blade profiles of each row of blades of the counter-rotating fan (including the inlet guide vane 2, the first-stage rotor 3, the middle guide vane 4, the second-stage rotor 5, and the outlet guide vane 6) are generated by superimposing the thickness of the middle arc line. The thickness of the blade is a fixed value. The inlet and outlet angles of the blade root section, the blade middle section, and the blade tip section are independently adjustable design parameters. Different three-dimensional blade shapes are generated by combining and adjusting the inlet and outlet angle parameters. This application has a total of 28 design variables.
[0038] This application utilizes the aforementioned parametric modeling method to condense the complex three-dimensional fan geometry model into key design variables centered on the radial coordinates of the control points of the hub's Bezier curve and the inlet and outlet metal angles of the blades at each characteristic cross-section. This parametric method, while ensuring design freedom that decisively influences fan aerodynamic performance, significantly reduces the dimensionality of the optimization design space. It overcomes the drawbacks of high computational cost and difficulty in convergence inherent in traditional multivariate global optimization processes, thereby enabling efficient and accurate optimization of the aerodynamic performance of counter-rotating fans.
[0039] Step S2: Construct an automated simulation process that integrates parametric geometry, mesh generation, and numerical (CFD) solution.
[0040] Specifically, the Ansys-Workbench platform integrates a parametric geometry module, a mesh generation module (Turbogrid), a CFD solver (CFX), and a post-processing module to build a simulation working module that can automatically execute design points and optimize the design process.
[0041] Step S3: Define an optimization problem with the goal of maximizing efficiency and with pressure ratio and flow rate as constraints. The optimization goal and constraints can be selected according to the design requirements.
[0042] Specifically, a design optimization problem that satisfies the performance indicators of a specific aircraft is defined: Based on the parameterized geometric model established in steps S1 and S2, the following optimization problem with clear objectives and specific constraints is defined, aiming to provide a highly efficient aerodynamic optimization design method for the counter-rotating fan of a specific short takeoff / vertical landing fighter (such as the F-35B).
[0043] Firstly, the core optimization objective is to maximize the isentropic efficiency of the counter-rotating fan at the design point. To meet the comprehensive performance requirements of a specific aircraft, multiple constraints can be set during the optimization process based on actual needs. The first constraint is the design point pressure ratio: the counter-rotating fan must achieve the target total pressure ratio determined by the lift system under design conditions. This total pressure ratio is greater than 2.2, ensuring the fan has the required boosting capacity. The second constraint is the flow rate: during optimization, the flow rate of the counter-rotating fan must be greater than 210 kg / s. This constraint ensures the required intake performance of the fan.
[0044] This optimization process operates on the parameterized model established in steps S1 and S2 and the automated multi-condition simulation process. It continuously performs collaborative optimization on the inlet and outlet blade angles of the first-stage rotor 3, intermediate guide vane 4, and second-stage rotor 5 along the blade height to maximize efficiency while meeting the design specifications. The definition of the fan optimization objective is as follows.
[0045] Objective function for optimizing a rotating fan:
[0046] Constraints:
[0047]
[0048]
[0049] In the formula, It is a vector of design variables (such as geometric parameters); Mass flow rate, unit is ; The total pressure ratio, and These are the upper and lower limits of the design variable, respectively.
[0050] Step S4: Sample and generate an initial sample set within the design space, obtain sample performance data through the automated simulation process, construct a proxy model of the input and output relationship between design variables and aerodynamic performance, and perform global optimization based on the proxy model to obtain the initial scheme.
[0051] Specifically, based on the completion of geometric parametric modeling (steps S1-S2) and the definition of the optimization problem (step S3), this application adopts a closed-loop optimization method based on a surrogate model and adaptive sampling to efficiently and automatically find an aerodynamic layout scheme that meets the design specifications. This method specifically includes the following steps: Step S4.1: Generate initial sample points using Latin hypercube sampling.
[0052] Specifically, the Latin hypercube sampling method is used at the design point of the counter-rotating fan. Within the design space composed of all geometric design parameters, by observing the flow field, several design parameters that have the greatest impact on the performance of the counter-rotating fan are selected to generate a set of initial sample points.
[0053] Step S4.2: Construct a surrogate model using response surface methodology and genetic algorithm.
[0054] Specifically, the three-dimensional geometric model corresponding to each sample point is automatically meshed and subjected to CFD simulation to accurately obtain its macroscopic performance indicators, including but not limited to: total pressure ratio, isentropic efficiency, and mass flow rate. Based on this dataset, an initial aerodynamic performance surrogate model is constructed using the response surface methodology. This surrogate model can achieve rapid mapping from any given combination of geometric parameters to its predicted performance indicators with extremely low computational cost.
[0055] Step S4.3: Use a multi-objective optimization algorithm to perform global optimization based on the surrogate model to obtain an initial solution.
[0056] Specifically, based on the surrogate model constructed in step S4.2, the optimization problem defined in step S3 is solved on this model. A multi-objective optimization algorithm is used to perform global optimization within the design space represented by the surrogate model, and an initial solution is obtained. This process can quickly filter out a large number of potential solutions and output a Pareto optimal solution set.
[0057] Step S5: Perform CFD verification on the initial scheme, and determine the accuracy and precision of the proxy model based on the verification results. Then, adaptively update the proxy model. After establishing a new proxy model, repeat the above steps until the optimal scheme that satisfies all indicators and optimization objectives is obtained.
[0058] Specifically, for the initial scheme predicted by the surrogate model obtained in step S4.2, the generated initial scheme is verified by three-dimensional CFD simulation, and the error between the result generated by the surrogate model and the result obtained by the numerical simulation of the original model is judged. The judgment criterion is the coefficient of determination. To determine the accuracy of the proxy model, where The expression is as follows:
[0059] Step S5 further includes: Based on the results calculated in the above steps, the following adaptive closed-loop process is executed: If the initial scheme meets the design requirements, the initial scheme is determined as the optimal scheme, and the optimization process ends; if it does not meet the requirements, the surrogate model update and iterative optimization process is started. The initial scheme that does not meet the requirements and its accurate CFD data can be added as new sample points to the original sample library; or, based on the prediction error distribution of the current database and the surrogate model, new sampling points are strategically added near the optimal prediction solution or in areas with high model uncertainty. Alternatively, model reconstruction and re-optimization can be performed. Based on the flow field, the design variables that have a significant impact on the performance of the counter-rotating fan can be reselected within all design optimization variables, or the range of values for the design variables can be adjusted to make the surrogate model's predictions more accurate. Then, based on this updated model, the optimization steps in S4.3 are repeated to obtain new, more reliable, and accurate candidate solutions. Finally, the new candidate solutions are substituted back into the original model for CFD verification.
[0060] The optimal design scheme of the counter-rotating fan in this application embodiment can be obtained through the above optimization design method. Under this optimal scheme, the hub 1 of the counter-rotating fan is provided with an inlet guide vane 2, a first-stage rotor 3, a second-stage rotor 5 and an outlet guide vane 6 in sequence along the length direction of the hub 1; an intermediate guide vane 4 is provided on the hub 1 between the first-stage rotor 3 and the second-stage rotor 5, and the blade shape of the intermediate guide vane 4 is approximately the same as that of the outlet guide vane 6; The axial distance between the leading edge of the intermediate guide vane 4 and the trailing edge of the first-stage rotor 3 is 30%-45% of the average axial chord length of the first-stage rotor 3; The axial distance between the trailing edge of the intermediate guide vane 4 and the leading edge of the second-stage rotor 5 is 30%-45% of the average axial chord length of the second-stage rotor 5.
[0061] The counter-rotating fan and its optimized design method provided in the embodiments of this application can expand the stable operating range and flow margin of the counter-rotating fan while maintaining its high pressure ratio characteristics.
[0062] Furthermore, the counter-rotating fan provided in this application embodiment can be applied to short takeoff / vertical landing aircraft; for example, the counter-rotating fan can be used in the lift fan system of SVTOL / VTOL aircraft, and its margin can ensure smooth operation under transition conditions. Compared with a vaneless counter-rotating fan, under the same inlet conditions and inlet flow, the fan can expand the flow margin and stable operating range from 2.23% and 2.26% of the vaneless fan to 6.22% and 6.32%, respectively.
[0063] The counter-rotating fan provided in this application embodiment can also be applied to a compressor to pressurize the rotating machinery; or, it can be applied to a gas pressurization device for ground / ship gas turbines, industrial gas compressors and chemical machinery, mining machinery, and indoor ventilation devices. These devices require a core compressor stage with a high pressure ratio and a wide operating range to improve the overall performance and operational flexibility of the entire power system.
[0064] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0065] It should also be noted that, in this document, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. In the absence of further restrictions, an element defined by the phrase "includes a..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.
[0066] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, for those skilled in the art, there will be different forms of changes in the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, and obvious changes or modifications derived therefrom are still within the protection scope of this application.
Claims
1. A counter-rotating fan with guide vanes in the middle, characterized in that, include: Casing; The hub is located inside the casing; The hub is provided with an inlet guide vane, a first-stage rotor, a second-stage rotor and an outlet guide vane in sequence along the length of the hub, and the first-stage rotor and the second-stage rotor rotate in opposite directions. The hub is provided with an intermediate guide vane located between the first stage rotor and the second stage rotor, and the blade shape of the intermediate guide vane is approximately the same as that of the outlet guide vane. The axial distance between the leading edge of the intermediate guide vane and the trailing edge of the first-stage rotor is 30%-45% of the average axial chord length of the first-stage rotor; The axial distance between the trailing edge of the intermediate guide vane and the leading edge of the second-stage rotor is 30%-45% of the average axial chord length of the second-stage rotor.
2. The counter-rotating fan with intermediate guide vanes according to claim 1, characterized in that: The intermediate guide vane includes a root, a middle section, and a tip along the blade height direction, with the root positioned close to the hub. The inlet metal angles of the intermediate guide vane at the leaf root, leaf middle, and leaf tip are 39.483°, 38.754°, and 34.071°, respectively. The exit metal angles of the intermediate guide vane at the leaf root, leaf middle, and leaf tip are 0.249°, 2.344°, and 4.727°, respectively.
3. An optimized design method for a counter-rotating fan with intermediate guide vanes, applied to the counter-rotating fan with intermediate guide vanes as described in any one of claims 1-2, characterized in that, The design method includes: Parametric modeling is performed on the meridional flow channel and each row of blades of the counter-rotating fan. The meridional flow channel is controlled by several control points. The air inlet angle and air outlet angle of each row of blades along the blade root section, blade middle section, and blade tip section are used as independently adjustable design parameters. Different three-dimensional blade shapes are generated by combining and adjusting the air inlet angle and air outlet angle parameters. Build an automated simulation process that integrates parametric geometry, mesh generation, and CFD solving; The optimization problem is defined with the goal of maximizing efficiency and the constraints of pressure ratio and flow rate. The optimization goal and constraints can be selected according to the design requirements. An initial sample set is generated by sampling within the design space. Sample performance data is obtained through the automated simulation process. A proxy model of the input and output relationship between design variables and aerodynamic performance is constructed. Global optimization is performed based on the proxy model to obtain the initial scheme. The initial scheme is verified by CFD, and the accuracy and precision of the proxy model are judged based on the verification results. Then, the proxy model is adaptively updated. After establishing a new proxy model, the above steps are repeated until the optimal scheme that satisfies all indicators and optimization objectives is obtained. In the optimal solution, the contra-rotating fan has an inlet guide vane, a first-stage rotor, a second-stage rotor, and an outlet guide vane arranged sequentially along the length of the hub; an intermediate guide vane is arranged on the hub between the first-stage rotor and the second-stage rotor, and the blade shape of the intermediate guide vane is approximately the same as that of the outlet guide vane. The axial distance between the leading edge of the intermediate guide vane and the trailing edge of the first-stage rotor is 30%-45% of the average axial chord length of the first-stage rotor; The axial distance between the trailing edge of the intermediate guide vane and the leading edge of the second-stage rotor is 30%-45% of the average axial chord length of the second-stage rotor.
4. The optimized design method for a counter-rotating fan with intermediate guide vanes according to claim 3, characterized in that: The mass flow rate constraint in the optimization problem definition is greater than or equal to 210 kg / s, and the total pressure ratio constraint is greater than 2.
2.
5. The optimized design method for a counter-rotating fan with intermediate guide vanes according to claim 3, characterized in that, The design method includes the following steps: generating an initial sample set within the design space, acquiring sample performance data through the automated simulation process, constructing a surrogate model of the input-output relationship between design variables and aerodynamic performance, and performing global optimization based on the surrogate model to obtain an initial solution. Initial sample points are generated using Latin hypercube sampling; A surrogate model was constructed using response surface methodology and genetic algorithms. A multi-objective optimization algorithm is used to perform global optimization based on the surrogate model to obtain an initial solution.
6. The optimized design method for a counter-rotating fan with intermediate guide vanes according to claim 3, characterized in that: The control points of the meridional channel include 7 control points in a coordinate system established with respect to the axial and radial directions of the hub; The axial coordinate of the control point is fixed, while the radial coordinate is adjustable.
7. The optimized design method for a counter-rotating fan with intermediate guide vanes according to claim 3, characterized in that, The design method further includes the following steps: First, CFD validation of the initial solution is performed. Based on the validation results, the accuracy and precision of the surrogate model are determined. Then, the surrogate model is adaptively updated. After establishing a new surrogate model, the above steps are repeated until the optimal solution satisfying all metrics and optimization objectives is obtained. If the initial scheme does not meet the requirements, new sampling points are added near the optimal prediction solution or in areas with high model uncertainty, based on the prediction error distribution of the current proxy model. When the predicted performance established by the surrogate model is inaccurate, the parameters that have a significant impact on the performance of the counter-rotating fan are reselected, the range of the selected design variables is redefined, and a new surrogate model is constructed.