A S2 flow field design method for multi-design point and multi-duct fan

Abstract

The present application belongs to the technical field of S2 flow field design of multi-duct fans of aircraft engines, and specifically relates to a multi-design point, multi-duct fan S2 flow field design method, including: determining the main working design point and multiple important working design points of the multi-duct fan; designing the S2 flow field of the main working design point of the multi-duct fan; designing the S2 flow field of each important working design point of the multi-duct fan; comparing the changes of the S2 flow field of each important working design point of the multi-duct fan with the S2 flow field of the main working design point, and optimizing the angle of attack and the angle of lagging.

Description

Technical Field

[0001] The present application belongs to the technical field of S2 flow field design of multi-duct fans of aircraft engines, and specifically relates to a multi-design point, multi-duct fan S2 flow field design method. Background Art

[0002] Currently, when designing the S2 flow field of an aircraft engine fan, a main working design point is usually selected at the design speed for design, and then numerical or experimental verification is performed at multiple important working points. The design is modified and iterated according to the verification results of the design speed and non-design speed until the modification and iteration meet the design requirements.

[0003] In order to improve the performance of aircraft engine fans, a multi-duct fan configuration is designed, which divides the fan into a front fan and a rear fan, wherein the front fan part includes an inner duct and an outer duct, and a third duct is introduced at the same time. For the S2 flow field design of the multi-duct fan, if the currently conventional method mentioned above is followed, in a design-verification-modification iterative manner, a large number of important working points need to be verified, the design efficiency is low, the cycle is long, and a large amount of manpower and material resources are required.

[0004] This application is proposed in view of the above-mentioned technical defects.

[0005] It should be noted that the disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0006] The purpose of this application is to provide a multi-design point, multi-duct fan S2 flow field design method to overcome or alleviate at least one of the known technical defects.

[0007] The technical solution of this application is:

[0008] A multi-design point, multi-duct fan S2 flow field design method, comprising:

[0009] Determine the main working design points and multiple important working design points of multi-duct fans;

[0010] Design the flow field of the main working design point S2 of the multi-duct fan;

[0011] Design the S2 flow field of each important working design point of the multi-duct fan;

[0012] By comparing the changes in the S2 flow field at each important working design point of the multi-duct fan with the S2 flow field at the main working design point, the angle of attack and the angle of lag are optimized.

[0013] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, the main working design point of the multi-duct fan is selected from the typical operating point with the longest running time or the highest aerodynamic load in the aircraft engine envelope;

[0014] The important working design points of multi-duct fans are selected with the same speed but different flow and pressure ratio as the main working design points.

[0015] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, the design of the multi-duct fan main working design point S2 flow field is specifically:

[0016] According to the aerodynamic design requirements of the main working design points of the multi-duct fan, the S2 flow field is built for design. The aerodynamic design requirements include pressure ratio, meridian flow channel, inner and outer duct flow lines, diversion point, meridian projection of each blade row, spanwise pressure ratio, efficiency, total pressure loss coefficient, and inlet pre-swirl angle.

[0017] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, when the S2 flow field is built for design according to the aerodynamic design requirements of the main working design points of the multi-duct fan, the S2 flow field of the front fan is divided into two parts, the inner part and the outer part, for calculation. After the calculation of the inner part and the outer part is completed, the diversion streamlines are iteratively corrected to make both the inner part and the outer part converge.

[0018] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, when the S2 flow field is constructed for design according to the aerodynamic design requirements of the main working design points of the multi-duct fan, the initial values ​​of the flow lines of the inner and outer parts of the S2 flow field of the front fan are determined in the following manner:

[0019] Calculate the proportion of connotation traffic;

[0020] Build the S2 flow field of the front fan separately, and set the flow ratio of a selected streamline as the implicit flow ratio;

[0021] After the flow field calculation of the front fan S2 converges, the coordinates of the selected streamlines are extracted as the initial values ​​of the diversion streamlines.

[0022] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, when determining the initial values ​​of the inner and outer flow stream lines of the S2 flow field of the front fan, the selected streamline is the second to last streamline from the blade root to the blade tip.

[0023] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, the design of the S2 flow field of each important working design point of the multi-duct fan is specifically as follows:

[0024] On the basis of the S2 flow field construction of the main working design point of the multi-duct fan, the S2 flow field is rebuilt after the fan flow rate is changed, and the calculation stations of the meridian flow channel and the blade row remain the same as the main working design point of the multi-duct fan;

[0025] Re-set the initial value of the front fan diversion streamline, adjust the diversion point position and the calculation station near the diversion point, so that the initial calculation of the S2 flow field converges;

[0026] The outlet pre-swirl angle of the stator blades, the pressure ratio of the rotor blades and the efficiency input are adjusted so that after the S2 flow field calculation converges, the airflow turning angle of each blade is the same as the main working design point of the multi-duct fan.

[0027] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, the comparison of the changes of the S2 flow field of each important working design point of the multi-duct fan and the S2 flow field of the main working design point is carried out to optimize the angle of attack and the angle of backwardness, specifically:

[0028] Calculate the change in the inlet and outlet airflow angles of the blades between the S2 flow field at each important working design point of the multi-duct fan and the main working design point S2 flow field, and take the angle of attack and angle of lag within the range of change.

[0029] According to at least one embodiment of the present application, the above-mentioned multi-design point, multi-duct fan S2 flow field design method further includes:

[0030] Determine whether the S2 flow field meets the requirements of the specifications. When the S2 flow field does not meet the requirements of the specifications, redesign the S2 flow field of the main working design point of the multi-duct fan and the S2 flow field of each important working design point of the multi-duct fan. Compare the changes of the S2 flow field of each important working design point of the multi-duct fan with the S2 flow field of the main working design point, and optimize the angle of attack and the angle of lagging until the S2 flow field meets the requirements of the specifications.

[0031] According to at least one embodiment of the present application, in the above-mentioned multi-design point, multi-duct fan S2 flow field design method, it is judged whether the S2 flow field meets the specification requirements, specifically, it is judged whether the S2 flow field of the main working design point of the multi-duct fan, the blade row, Mach number, diffusion factor, and airflow turning angle at which the flow rate and pressure ratio of the S2 flow field of each important working design point of the multi-duct fan change meet the specification requirements.

[0032] This application has at least the following beneficial technical effects:

[0033] A multi-design point and multi-duct fan S2 flow field design method is provided, which designs the S2 flow fields of the main working design points and multiple important working design points of the multi-duct fan under the constraints of the same flow channel and blade geometry, that is, the S2 flow field is designed under multiple important working design points, and the range of variation of the inlet and outlet airflow angles of the blades is obtained. The angle of attack and the angle of lag are selected based on this, and the characteristics of the S2 flow fields at multiple working design points are comprehensively considered, so that the design parameters of the S2 flow fields at different working design points are well matched, so that the inner and outer ducts of the fan have good performance at each working design point, and do not need to be iteratively modified repeatedly in subsequent verification, and have high design efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of a multi-design point, multi-duct fan S2 flow field design method provided in an embodiment of the present application;

[0035] Figure 2 It is a schematic diagram of constructing a flow field of a multi-duct fan S2 provided in an embodiment of the present application;

[0036] in:

[0037] VIGV is an imported variable-curvature guide;

[0038] R1 is the first stage rotor blade; S1 is the first stage stator blade;

[0039] R2 is the second-stage rotor blade, and S2 is the second-stage stator blade;

[0040] R3 is the third-stage rotor blade, and S3 is the third-stage stator blade;

[0041] S2B is the third outer duct outlet guide vane.

[0042] In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; in addition, the drawings are used for illustrative purposes, and their positional relationships are limited to illustrative purposes and cannot be understood as limitations on this patent. DETAILED DESCRIPTION

[0043] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be further described in detail in detail and in detail in conjunction with the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0044] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall be the common meanings understood by the general technicians in the field to which this application belongs. The words "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inside", "outside" and other words indicating orientation used in the description of this application are only used to indicate the relative direction or positional relationship, and do not imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, so it cannot be understood as a limitation on this application. The "first", "second", "third" and similar terms used in the description of this application are only used for descriptive purposes to distinguish different components, and cannot be understood as indicating or implying relative importance. The similar words "one", "one" or "the" used in the description of this application should not be understood as an absolute limitation on quantity, but should be understood as the existence of at least one. The similar words "including" or "comprising" used in the description of this application mean that the elements or objects appearing in front of the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0045] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installed", "connected", "connected" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0046] The following is combined with Figure 1 to Figure 2 The multi-design point, multi-duct fan S2 flow field design method provided in this application is further described in detail.

[0047] 1. Determination of the main working design points of multi-duct fans:

[0048] The principle for selecting the main working design point of the multi-duct fan is the typical operating point with the longest running time or the highest aerodynamic load and the greatest design difficulty within the engine envelope, which is generally the point with the highest converted speed and the highest pressure ratio. The final design output of the S2 flow field also uses the S2 flow field calculation result of this design point.

[0049] 2. Determination of important working design points of multi-duct fans

[0050] Select the operating point where the multi-duct fan has the same speed as the main working design point, but the flow rate, pressure ratio and parameters of the main working design point are different as the important working design point of the multi-duct fan. The boundary points of the maximum flow rate variation range should be selected, and the number can be one or more.

[0051] 3. Flow field design of the main working design point S2 of the multi-duct fan

[0052] According to the aerodynamic design requirements of the main working design points, including the determination of the design pressure ratio, the design of the meridian flow channel, the determination of the inner and outer flow lines and the diversion points, as well as the meridian projection and spanwise pressure ratio of each blade row, efficiency, total pressure loss coefficient and inlet pre-swirl angle distribution, the S2 flow field is built for design;

[0053] For the front fan S2 flow field, the calculation is divided into two parts: the inner part and the outer part. After the calculation of each part is completed, the diversion streamline is iteratively corrected, and finally the inner part and the outer part converge.

[0054] Theoretically, the initial values ​​of the flow lines of the inner and outer parts of the S2 flow field of the front fan do not affect the final convergence results. However, for the important working design point where the third outer duct is relatively small, the flow rate of the outer duct is small, and the flow lines are close to the flow line of the casing. The calculation convergence is sensitive to the initial position of the flow lines. If the initial value of the flow lines deviates slightly, the S2 flow field iteration is prone to dead loop and stop calculation. The initial value of the flow lines is determined by the following method:

[0055] Calculate the proportion of the internal flow. For example, when the bypass ratio of the third external bypass is 0.03, the internal flow accounts for 0.97%;

[0056] The S2 flow field of the front fan is built separately, and the flow ratio of a certain streamline is selected to be set to 0.97 of the implicit flow ratio. Specifically, the flow ratio of the second-to-last streamline from the blade root to the blade tip is set to 0.97;

[0057] After the calculation of the flow field of the front multi-duct fan S2 converges, the coordinates of the selected streamlines are taken as the initial values ​​of the diversion streamlines. The initial values ​​are close to the final converged values, and the numerical process is easier to converge.

[0058] 4. S2 flow field design of important working design points of multi-duct fans

[0059] On the basis of the S2 flow field construction of the main working design point of the multi-duct fan, the S2 flow field is rebuilt after the fan flow rate is changed, and the calculation stations of the meridian flow channel and the blade row remain the same as the main working design point of the multi-duct fan;

[0060] Re-set the initial value of the front fan diversion streamline, adjust the diversion point position and the calculation station near the diversion point, so that the initial calculation of the S2 flow field converges;

[0061] Adjust the outlet pre-rotation angle of the corresponding stator blades, the pressure ratio and efficiency input of the rotor blades to make the S2 flow field calculation converge. After the calculation converges, the airflow turning angle of all blades and the main working design point of the multi-duct fan, because when the fan flow is changed by adjusting the stator, the geometric characteristics of the blades remain unchanged. However, the design input of the S2 flow field is the pressure ratio or circulation, and the output is the airflow angle. It is impossible to accurately guarantee that the airflow turning angle remains unchanged. In specific operations, it is sufficient to ensure that the airflow angle error of the key section or average section is less than the error range given by the designer.

[0062] 5. Comparison of S2 flow field changes at important working design points and main working design points of multi-duct fans

[0063] After completing the S2 flow field construction of the important working design points of the multi-duct fan, compare the S2 calculation results with the results of the main working design points of the multi-duct fan, pay attention to the blade rows where the flow rate and pressure ratio change, and check whether the Mach number, diffusion factor, airflow turning angle and other parameters meet the specification requirements. If not, redesign is required;

[0064] The changes in the inlet and outlet airflow angles of the relevant blade rows between the important working design points and the main working design points of the multi-duct fan are calculated, so that the changes in the blade angle of attack caused by the flow change can be understood in the S2 flow field design stage, and then the flow field characteristics of different working design points can be considered when selecting the angle of attack and the trailing angle, without having to wait until the verification to do this work, which can reduce the number of design iterations.

[0065] 6. Optimization of attack angle and trailing angle

[0066] Combined with the calculation of the angle of attack characteristics of the primitive blade profile of the S1 flow surface, the angle of attack and angle of lag of the adjustable blades and blades with changed working conditions are optimized so that these blades can adapt to the flow field changes introduced by the flow change.

[0067] 7 Design Output

[0068] Output the S2 flow field calculation results of the main working design points of the multi-duct fan as input data for blade shaping.

[0069] The above-mentioned multi-design point, multi-duct fan S2 flow field design method designs the S2 flow field of the main working design point and multiple important working design points of the multi-duct fan during the design process, and provides a basis for the selection of the angle of attack and the angle of fall by calculating the changes in the inlet and outlet airflow angles of the relevant blade rows between the important working design points and the main working design points. The design requirements of multiple working design points are considered in the design stage, and there is no need to assess whether the design requirements are met in the verification stage. The design of multiple working design points is targeted, which improves the design accuracy and efficiency and can greatly shorten the design cycle.

[0070] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A multi-design point, multi-duct fan S2 flow field design method, characterized in that: include: Determine the main working design points and multiple important working design points of multi-duct fans; Design the flow field of the main working design point S2 of the multi-duct fan; Design the S2 flow field of each important working design point of the multi-duct fan; Compare the changes of S2 flow field at each important working design point of multi-duct fan with the flow field at the main working design point S2, and optimize the angle of attack and angle of lag; The main working design points of multi-duct fans are selected from the typical operating points with the longest operating time or the highest aerodynamic load within the aircraft engine envelope; The important working design points of multi-duct fans are selected from the working points with the same speed as the main working design points but different flow rates and pressure ratios; The design of the flow field of the main working design point S2 of the multi-duct fan is specifically as follows: According to the aerodynamic design requirements of the main working design points of the multi-duct fan, the S2 flow field is built for design. The aerodynamic design requirements include pressure ratio, meridian flow channel, inner and outer duct flow lines, diversion point, meridian projection of each blade row, spanwise pressure ratio, efficiency, total pressure loss coefficient, and inlet pre-swirl angle. The design of the flow field of each important working design point S2 of the multi-duct fan is specifically as follows: On the basis of the S2 flow field construction of the main working design point of the multi-duct fan, the S2 flow field is rebuilt after the fan flow rate is changed, and the calculation stations of the meridian flow channel and the blade row remain the same as the main working design point of the multi-duct fan; Re-set the initial value of the front fan diversion streamline, adjust the diversion point position and the calculation station near the diversion point, so that the initial calculation of the S2 flow field converges; Adjust the outlet pre-swirl angle of the stator blades, the pressure ratio of the rotor blades and the efficiency input so that after the S2 flow field calculation converges, the airflow turning angle of each blade is the same as the main working design point of the multi-duct fan; The comparison of the flow field of each important working design point S2 of the multi-duct fan and the flow field of the main working design point S2 optimizes the angle of attack and the angle of lag, specifically: Calculate the change in the inlet and outlet airflow angles of the blades between the S2 flow field at each important working design point of the multi-duct fan and the main working design point S2 flow field, and take the angle of attack and angle of lag within the range of change.

2. The multi-design point, multi-duct fan S2 flow field design method according to claim 1, characterized in that: According to the aerodynamic design requirements of the main working design points of the multi-duct fan, when the S2 flow field is built for design, the S2 flow field of the front fan is divided into two parts, the inner part and the outer part, for calculation. After the calculation of the inner part and the outer part is completed, the diversion streamline is iteratively corrected to make both the inner part and the outer part converge.

3. The multi-design point, multi-duct fan S2 flow field design method according to claim 2, characterized in that: According to the aerodynamic design requirements of the main working design points of the multi-duct fan, when the S2 flow field is constructed for design, the initial values ​​of the flow lines of the inner and outer parts of the S2 flow field of the front fan are determined in the following manner: Calculate the proportion of connotation traffic; Build the S2 flow field of the front fan separately, and set the flow ratio of a selected streamline as the implicit flow ratio; After the flow field calculation of the front fan S2 converges, the coordinates of the selected streamlines are extracted as the initial values ​​of the diversion streamlines.

4. The multi-design point, multi-duct fan S2 flow field design method according to claim 3, characterized in that: When determining the initial values ​​of the inner and outer flow streams of the S2 flow field of the front fan, the selected stream line is the second to last stream line from the blade root to the blade tip.

5. The multi-design point, multi-duct fan S2 flow field design method according to claim 4, characterized in that: Also includes: Determine whether the S2 flow field meets the requirements of the specifications. When the S2 flow field does not meet the requirements of the specifications, redesign the S2 flow field of the main working design point of the multi-duct fan and the S2 flow field of each important working design point of the multi-duct fan. Compare the changes of the S2 flow field of each important working design point of the multi-duct fan with the S2 flow field of the main working design point, and optimize the angle of attack and the angle of lagging until the S2 flow field meets the requirements of the specifications.

6. The multi-design point, multi-duct fan S2 flow field design method according to claim 5, characterized in that: Determine whether the S2 flow field meets the requirements of the specifications, specifically, determine whether the S2 flow field at the main working design point of the multi-duct fan, the blade row where the flow rate and pressure ratio of the S2 flow field at each important working design point of the multi-duct fan change, the Mach number, the diffusion factor, and the airflow turning angle meet the requirements of the specifications.

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