Method for distributing the pitch angle of the blades of a ring propeller based on the angle of attack of the profile
Patent Information
- Application Number
- CN202611368073.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-04
- Publication Date
- 2026-10-09
AI Technical Summary
[0007]本发明旨在针对现有环形螺旋桨由于结构形式复杂、前后桨叶水动力耦合强、螺距角分布设计困难，导致难以快速获得高效初始构型的问题，提出一种基于翼型攻角的环形螺旋桨桨叶螺距角分布方法
[0040]（1）本发明针对环形螺旋桨的复杂构型，提出基于翼型攻角的螺距角分布设计方法，通过分别计算前桨叶、后桨叶及过渡段的螺距角，能够快速、系统地建立完整的环形螺旋桨几何模型，大幅缩短初始构型设计周期。
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Figure CN122886065A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ship propulsion technology, specifically relating to a method for the pitch angle distribution of annular propeller blades based on airfoil angle of attack. Background Technology
[0002] With the increasing demands for low noise, low vibration, and high stealth performance in underwater vehicles and ship propulsion systems, traditional open-type propellers have gradually revealed their limitations in terms of cavitation noise, unsteady excitation force, and efficiency. To address these issues, annular propellers, as a novel type of underwater propulsion device, have attracted widespread attention in recent years due to their annular blades connected at both ends.
[0003] Compared to conventional propellers, annular propellers, by replacing a rigid blade with an annular blade rigidly connected at both ends, effectively suppress tip leakage vortices due to the smooth transition section, significantly reducing noise and energy loss caused by tip vortices. Simultaneously, the annular structure provides some constraint on the flow field, helping to reduce the development of cavitation on the blade surface, lowering cavitation noise levels, and improving the anti-cavitation performance of the propulsion system to some extent. Furthermore, annular propellers exhibit smaller periodic load fluctuations during operation, which helps reduce the excitation forces acting on the propulsion system and its supporting structure. Therefore, they show promising application prospects in underwater vehicles and ship propulsion applications where stealth performance is crucial.
[0004] However, due to the significant differences in structure and hydrodynamic characteristics between annular propellers and traditional propellers, their design process faces numerous challenges. First, a single blade of an annular propeller typically consists of a front blade, a rear blade, and a transition section connecting them. Significant hydrodynamic interaction exists between the front and rear blades, resulting in a highly unsteady and nonlinear induced velocity field and load distribution, making the selection of blade geometry more complex. Second, the pitch angle distribution of the front and rear blades not only affects their individual thrust and efficiency but also influences overall propulsion performance through flow field coupling. Existing design methods based on traditional propeller experience are difficult to directly apply to annular propellers.
[0005] Furthermore, the transition section connecting the front and rear blades typically features spatial curved surfaces and torsional structures, and its geometry significantly impacts flow continuity, local flow separation, and structural stress. The way the blade cross-section attitude changes within the transition section, especially the distribution of the pitch angle, can easily cause local flow turbulence if poorly designed. This weakens the advantages of the annular structure in noise reduction and cavitation resistance, leading to decreased propulsion efficiency. It can even directly cause intersecting surfaces in the three-dimensional model of the annular propeller, making it impossible to form a solid model and consequently hindering calculation and fabrication.
[0006] In summary, although annular propellers have significant potential in reducing noise, minimizing excitation force, and improving cavitation resistance, the complex hydrodynamic coupling mechanism of their front and rear blades and the difficulty in designing the pitch angle distribution mean that there is currently a lack of a systematic and feasible blade pitch angle distribution design method that addresses the overall structural characteristics of annular propellers. This has hindered the engineering design and application of high-efficiency annular propellers. Summary of the Invention
[0007] This invention addresses the challenge of quickly achieving an efficient initial configuration in existing annular propellers due to their complex structure, strong hydrodynamic coupling between the front and rear blades, and difficulties in designing the pitch angle distribution. It proposes a method for annular propeller blade pitch angle distribution based on airfoil angle of attack. This method introduces the concept of airfoil angle of attack prediction during the design phase, establishing a correlation between the incoming flow conditions and the pitch angle distribution between the front and rear blades. This enables a systematic and feasible design of the pitch angles of the front, rear, and transition sections of the annular propeller, providing a reliable foundation for geometric modeling and performance optimization of the annular propeller.
[0008] To achieve the above objectives, the present invention adopts the following technical solution:
[0009] A method for distributing the pitch angle of an annular propeller blade based on airfoil angle of attack, wherein the annular propeller blade includes a front blade, a rear blade, and a transition section connecting the front and rear blades arranged sequentially along the fluid flow direction, the method comprising:
[0010] The incoming flow angle of the airfoil profile at each radial position of the front blade is calculated based on the design advance parameters of the fluid medium. The first pitch angle distribution of the front blade at each radial position is determined based on the incoming flow angle and the design angle of attack of the airfoil profile at each radial position.
[0011] Based on the acceleration effect of the front blade on the fluid medium, the axial incoming velocity at the airfoil section of the rear blade is corrected; based on the corrected axial incoming velocity, the incoming angle of the airfoil section of the rear blade at each radial position is calculated; based on the incoming angle of the airfoil section of the rear blade at each radial position and the design angle of attack, the second pitch angle distribution of the rear blade at each radial position is determined.
[0012] Within the transition section, the second pitch angle distribution is adjusted based on geometric continuity constraints to obtain the complete target pitch angle distribution.
[0013] Furthermore, the first pitch angle distribution is determined based on the following method:
[0014] Based on the design advance speed parameters and design rotational speed parameters of the annular propeller, the inflow angle of the airfoil profile at each radial position of the front blade is calculated;
[0015] The design angle of attack of the airfoil profile is determined based on the airfoil lift characteristic curve.
[0016] The inflow angle of the airfoil profile at each radial position of the front blade is superimposed with the design angle of attack to obtain the first pitch angle distribution of the front blade at each radial position.
[0017] Furthermore, the formula for calculating the first pitch angle is:
[0018]
[0019] in, The first pitch angle; The design angle of attack for the airfoil profile is the angle of attack corresponding to the peak lift coefficient in the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the front blade is calculated using the following formula:
[0020]
[0021] in, The design advance rate for the annular propeller. , The design speed of the aircraft carrier. For the accompanying flow fraction; Radius position The rotational linear velocity of the airfoil section, , The design speed of the annular propeller, Indicates the radius of the airfoil profile. With the total radius of the annular propeller The ratio of .
[0022] Furthermore, the second pitch angle distribution is determined based on the following method:
[0023] Based on the axial inflow velocity at the modified rear blade airfoil profile and the design rotational speed parameters of the annular propeller, the inflow angle of the airfoil profile at each radial position of the rear blade is calculated.
[0024] The design angle of attack of the airfoil profile is determined based on the airfoil lift characteristic curve.
[0025] The inflow angle of the airfoil profile at each radial position of the rear blade is superimposed with the design angle of attack to obtain the second pitch angle distribution of the rear blade at each radial position.
[0026] Furthermore, the formula for calculating the second pitch angle is:
[0027]
[0028] in, This is the second pitch angle; The design angle of attack for the airfoil profile is the angle of attack corresponding to the peak lift coefficient in the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the rear blade is calculated using the following formula:
[0029]
[0030] in, The axial inflow velocity at the modified rear blade airfoil profile; Radius position The rotational linear velocity of the airfoil section, , The design speed of the annular propeller.
[0031] Furthermore, the correction of the axial inflow velocity at the rear blade airfoil profile based on the acceleration effect of the front blade on the fluid medium includes:
[0032] Based on the acceleration effect of the front blade on the fluid medium, the design advance coefficient of the rear blade is corrected and updated.
[0033] The axial inflow velocity of the rear blade is calculated based on the updated rear blade design advance coefficient.
[0034] Furthermore, the axial inflow velocity at the modified rear blade airfoil profile as follows:
[0035]
[0036] in, The diameter of the annular propeller; The updated rear blade design advance coefficient is based on the baseline design advance coefficient of the front blade. and acceleration correction factor Sure, , , .
[0037] Furthermore, within the transition section, the pitch angle of the airfoil section on the rear blade side is adjusted to 1 to 1.05 times the pitch angle of the airfoil section at the corresponding radial position on the front blade side, in order to ensure the continuity of the blade geometry in the transition section.
[0038] Furthermore, the front blades and the rear blades This serves as the transition segment.
[0039] The beneficial effects of this invention are:
[0040] (1) This invention proposes a pitch angle distribution design method based on airfoil angle of attack for the complex configuration of annular propellers. By calculating the pitch angles of the front blade, rear blade and transition section respectively, a complete geometric model of annular propeller can be established quickly and systematically, which greatly shortens the initial configuration design cycle.
[0041] (2) This invention determines the optimal design angle of attack by introducing the airfoil lift characteristic curve and considers the acceleration effect of the front blade on the incoming flow of the rear blade to correct the axial incoming flow velocity, so that both the front and rear blades work near the peak value of the lift coefficient. Compared with conventional methods, the designed annular propeller has significantly improved thrust coefficient, torque coefficient and open water efficiency, effectively improving propulsion performance.
[0042] (3) This invention corrects the pitch angle of the rear blade transition section for the key area of the transition section, so that it transitions smoothly with the front blade side, avoiding the problem of surface intersection or model breakage caused by sudden torsion, ensuring that the three-dimensional solid model can be generated smoothly, and further improving the propeller propulsion efficiency. Attached Figure Description
[0043] Figure 1 This is a flowchart of a method for distributing the pitch angle of an annular propeller blade based on the airfoil angle of attack in an embodiment of the present invention.
[0044] Figure 2 This is an airfoil profile at each radius position of a single blade of a ring propeller and a regional distribution diagram of each part of the single blade, established in an embodiment of the present invention.
[0045] Figure 3 This is a schematic diagram of the annular propeller established in an embodiment of the present invention.
[0046] Figure 4 This is a schematic diagram of the velocities, incoming flow angles, and pitch angles at the airfoil cross-section in an embodiment of the present invention.
[0047] Figure 5 This is a schematic diagram of the airfoil lift characteristic curve in an embodiment of the present invention.
[0048] Figure 6 This is a comparison chart of the open-water performance of the annular propeller established in this embodiment of the invention and the annular propeller established by conventional methods.
[0049] Figure 7 This is a comparison diagram of the efficiency before and after adjusting the pitch angle of the annular propeller transition section in an embodiment of the present invention.
[0050] In the figure: 1. Front blade; 2. Rear blade; 3. Airfoil profile at each radius position; 4. Front blade transition section; 5. Rear blade transition section; 6. Blade profile chord; 7. Plane of rotation. Detailed Implementation
[0051] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The embodiments of the present invention are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operating procedures are given. However, the scope of protection of the present invention is not limited to the following embodiments.
[0052] This embodiment provides a method for the pitch angle distribution of annular propeller blades based on airfoil angle of attack, such as... Figure 2 and Figure 3 As shown, the blades of the annular propeller are integral curved blades consisting of a front blade 1, a rear blade 2, and a transition section connecting the front and rear blades (composed of a front blade transition section 4 and a rear blade transition section 5); Figure 1 As shown, the method for distributing the pitch angle of the annular propeller specifically includes the following steps:
[0053] Step S100: Based on the design speed of the vehicle and the calculated wake fraction, calculate the design advance speed of the annular propeller.
[0054] In this embodiment, the design speed of the vehicle is used as the basis. (m / s) and the wake fraction calculated using CFD methods Calculate the design advance rate of the annular propeller (m / s) is used to characterize the equivalent incoming flow velocity at the surface of the annular propeller disk.
[0055] Step S200: Calculate the design advance coefficient of the front blade based on the design advance speed of the front blade of the annular propeller.
[0056] In this embodiment, the diameter of the annular propeller is determined according to the geometric constraints of the aircraft. (m); The design speed of the annular propeller is selected based on the critical Reynolds number requirement. (rps); combined with the propeller design advance rate obtained in step S100 Calculate the design advance coefficient of the front blade of the annular propeller. It is used to characterize the working state of a propeller under design conditions.
[0057] Step S300: Calculate the incoming flow angle of the airfoil profile at each radius position of the front blade, and determine the front blade pitch angle distribution, i.e., the first pitch angle distribution, in combination with the airfoil lift characteristic curve.
[0058] First, based on the design speed of the annular propeller, calculate the front blade at different radius positions. linear velocity of rotation at the airfoil profile :
[0059] (1)
[0060] in, Indicates the radius of the airfoil profile. With the total radius of the annular propeller The ratio, .
[0061] Subsequently, the design advance rate of the annular propeller's front blades was combined with... Calculate the incoming flow angle of airfoil section 3 at each radius position of the front blade. :
[0062] (2)
[0063] Referring then to the lift characteristic curve of the selected airfoil, the angle of attack corresponding to the peak lift coefficient is determined. The design angle of attack for the airfoil profile was determined. This allows for the determination of the pitch angle of the airfoil profile at each radial position of the front blade. :
[0064] (3)
[0065] In this embodiment, the angular velocity is 88.4 rad / s, and the total radius of the annular propeller is... m, the design angle of attack of the airfoil profile deg, the radial positions of the front blades The incoming flow angle of the airfoil profile at each radius position of the front blade. The rotational linear velocity of the airfoil profile at different radius positions of the front blade Pitch angle of the airfoil profile at each radius position of the front blade As shown in Table 1.
[0066] Table 1. Pitch angle distribution data of the front blade at various radial positions.
[0067]
[0068] Step S400: Correct the incoming flow conditions of the rear blade based on the acceleration effect of the front blade on the fluid, and determine the pitch angle distribution of the rear blade, i.e., the second pitch angle distribution, in combination with the airfoil lift characteristic curve.
[0069] Considering the acceleration effect of the front blade on the fluid medium, the inflow conditions at the rear blade are modified to obtain the design advance coefficient of the rear blade. :
[0070] (4)
[0071] In the formula, The reference design advance coefficient of the nose rotor is calculated in step S200; To accelerate the correction factor, Refer to the definition of the design advance coefficient for the front blade. Establish the design advance coefficient expression for the rear blade. After deformation solving, the blade corrected axial flow velocity is: , That is, the axial inflow velocity at the rear blade airfoil section satisfies This visually demonstrates the axial acceleration effect of the fluid brought about by the front propeller.
[0072] Based on the design speed of the annular propeller, the rotational linear velocity of the airfoil profile at each radius position of the blade was calculated. .
[0073] By combining the axial inflow velocity at the modified rear blade airfoil profile, the inflow angle of the airfoil profile at each radial position of the rear blade is calculated. :
[0074] (5)
[0075] To retrieve the lift characteristic curve of the selected airfoil, see [link / reference]. Figure 5 Take the optimal angle of attack corresponding to the peak lift coefficient. The angle of attack of the rear blade airfoil section is designed as follows. Superimposed inflow angle With design angle The pitch angle of the airfoil profile at each radius position of the rear blade is obtained. .
[0076] In this embodiment, the axial inflow velocity at the modified rear blade airfoil profile =6.6 m / s, the rear blade at different radii. The rotational linear velocity of the airfoil profile at each radius position of the rear blade The incoming flow angle of the airfoil profile at each radial position of the rear blade. Pitch angle of the airfoil profile at each radial position of the rear blade As shown in Table 2.
[0077] Table 2. Distribution data of rear blade pitch angle
[0078]
[0079] Step S500: Under the condition of satisfying the geometric continuity of the transition section, adjust the pitch angle of the airfoil section of the transition section to obtain a complete pitch angle distribution.
[0080] The front blade With the rear blade The section between the two blades serves as a transition zone. The pitch angle of the airfoil profile on the rear blade side is corrected to 1 to 1.05 times the pitch angle of the airfoil profile at the corresponding radius position on the front blade side. This ensures the continuity of the blade geometry in the transition zone, avoiding surface intersections or model breakage problems caused by abrupt torsional changes. This results in a complete and continuous annular propeller pitch angle distribution, thereby improving the propulsion efficiency of the annular propeller. (The corrected airfoil profile pitch angle of the rear blade is shown in the image.) As shown in Table 3.
[0081] Table 3. Pitch angle of the airfoil profile after rear blade correction
[0082]
[0083] In this embodiment, conventional methods (i.e., the pitch angle at each radial position of the front and rear blades is equal to the incoming flow angle of the airfoil section at each radial position of the front blade) are used to determine the data of the pitch angle distribution of the annular propeller blades. The pitch angle distribution of the front blade and the pitch angle distribution of the rear blade are shown in Table 4 and Table 5, respectively.
[0084] Table 4. Determination of front blade pitch angle distribution using conventional methods
[0085]
[0086] Table 5. Determination of rear blade pitch angle distribution using conventional methods
[0087]
[0088] Based on the pitch angle distribution of the annular propeller blades determined by the method of this invention, a three-dimensional modeling method is used to construct a geometric model of the annular propeller; and based on the same parameters (see Table 6, where L is the total wheelbase, l is the wheelbase of the airfoil section; R is the total radius of the annular propeller, r is the radius of the airfoil section; b is the chord length, D is the diameter of the annular propeller; t is the thickness, f is the camber); It measures the oblique angle; X l (where φ is the pitch distance; φ is the outboard angle; and ψ is the roll angle). Using the conventional pitch angle calculation method described above, a geometric model of the annular propeller was established. CFD calculations were performed to compare the open-water performance of the two annular propeller geometric models. The results are as follows: Figure 6 As shown, the annular propeller blade pitch angle distribution method of the present invention has a higher open-water efficiency than the conventional pitch angle method. and thrust coefficient Torque coefficient All have significantly improved; such as Figure 7 As shown, the open water efficiency after transition section adjustment using the method of the present invention There has also been some improvement.
[0089] Table 6 Other parameters of the annular propeller geometry model
[0090]
[0091] The above description represents a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for distributing the pitch angle of an annular propeller blade based on airfoil angle of attack, wherein the annular propeller blade comprises a front blade, a rear blade, and a transition section connecting the front blade and the rear blade arranged sequentially along the fluid flow direction, characterized in that, include: The incoming flow angle of the airfoil profile at each radial position of the front blade is calculated based on the design advance parameters of the fluid medium. The first pitch angle distribution of the front blade at each radial position is determined based on the incoming flow angle and the design angle of attack of the airfoil profile at each radial position. Based on the acceleration effect of the front blade on the fluid medium, the axial inflow velocity at the airfoil section of the rear blade is corrected. The incoming flow angle of the airfoil profile at each radial position of the rear blade is calculated based on the corrected axial incoming flow velocity. The second pitch angle distribution of the rear blade at each radial position is determined based on the incoming flow angle of the airfoil profile at each radial position and the design angle of attack. Within the transition section, the second pitch angle distribution is adjusted based on geometric continuity constraints to obtain the complete target pitch angle distribution.
2. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 1, characterized in that, The first pitch angle distribution is determined based on the following method: Based on the design advance speed parameters and design rotational speed parameters of the annular propeller, the inflow angle of the airfoil profile at each radial position of the front blade is calculated; The design angle of attack of the airfoil profile is determined based on the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the front blade is superimposed with the design angle of attack to obtain the first pitch angle distribution of the front blade at each radial position.
3. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 2, characterized in that, The formula for calculating the first pitch angle is: in, The first pitch angle; The design angle of attack for the airfoil profile is the angle of attack corresponding to the peak lift coefficient in the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the front blade is calculated using the following formula: in, The design advance rate for the annular propeller. , The design speed of the aircraft carrier. For the accompanying flow fraction; Radius position The rotational linear velocity of the airfoil section, , The design speed of the annular propeller, Indicates the radius of the airfoil profile. With the total radius of the annular propeller The ratio of .
4. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 1, 2, or 3, characterized in that, The second pitch angle distribution is determined based on the following method: Based on the axial inflow velocity at the modified rear blade airfoil profile and the design rotational speed parameters of the annular propeller, the inflow angle of the airfoil profile at each radial position of the rear blade is calculated. The design angle of attack of the airfoil profile is determined based on the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the rear blade is superimposed with the design angle of attack to obtain the second pitch angle distribution of the rear blade at each radial position.
5. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 4, characterized in that, The formula for calculating the second pitch angle is: in, This is the second pitch angle; The design angle of attack for the airfoil profile is the angle of attack corresponding to the peak lift coefficient in the airfoil lift characteristic curve. The inflow angle of the airfoil profile at each radial position of the rear blade is calculated using the following formula: in, The axial inflow velocity at the modified rear blade airfoil profile; Radius position The rotational linear velocity of the airfoil section, , The design speed of the annular propeller.
6. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 5, characterized in that, The correction of the axial inflow velocity at the rear blade airfoil profile based on the acceleration effect of the front blade on the fluid medium includes: Based on the acceleration effect of the front blade on the fluid medium, the design advance coefficient of the rear blade is corrected and updated. The axial inflow velocity of the rear blade is calculated based on the updated rear blade design advance coefficient.
7. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 6, characterized in that, Axial inflow velocity at the modified rear blade airfoil profile as follows: in, The diameter of the annular propeller; The updated rear blade design advance coefficient is based on the baseline design advance coefficient of the front blade. and acceleration correction factor Sure, , , .
8. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 1, characterized in that, Within the transition section, the pitch angle of the airfoil section on the rear blade side is adjusted to 1 to 1.05 times the pitch angle of the airfoil section at the corresponding radial position on the front blade side to ensure the continuity of the blade geometry in the transition section.
9. The method for annular propeller blade pitch angle distribution based on airfoil angle of attack according to claim 1, characterized in that, The front blade and the rear blades This serves as the transition segment.