Implementation method of a low-noise pre-deformed composite propeller

Abstract

The present invention relates to the technical field of the actual ship application of ship composite propellers, and specifically to a method for realizing a low-noise pre-deformed composite propeller. The present invention includes a method for generating and analyzing a virtual simulated pre-assembled propeller, a method for verifying a scaled-down model, a method for manufacturing a physical object, and a method for testing and analyzing the manufactured physical object. The present invention ensures the probability that the final propeller meets various performance indicators, reduces the manufacturing risk and development investment, and improves the efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of the application of ship composite propellers in actual ships, and specifically relates to a method for realizing a low-noise pre-deformed composite propeller. Background Art

[0002] As an energy conversion device for ship propulsion, the propeller is also the main source of vibration and noise. At present, most ship propellers are numerically controlled and manufactured from manganese-nickel-aluminum-copper (MAB) or nickel-aluminum-bronze (NAB) alloys. Although they have high precision and good stability, as rigid rotating blades, their limitations in the coupling adaptability to the flow field, poor damping performance of metal materials, and noise reduction measures limited to geometric profile optimization have restricted the rapid development of ship propellers. In recent years, composite propellers have become a new research object for improving the performance of ship propellers due to their material design advantages internationally. From the basic properties of the composite structure, the advantages of composite propellers are mainly reflected in: reducing weight and load; being easy to form and suitable for mass production; being heterogeneous and designable; having high damping and reducing vibration; changing frequencies and avoiding resonance; resisting impact and increasing service life; having low magnetism and promoting concealment. Among them, composite propellers adapt to the non-uniform wake flow field through bending-torsion coupling deformation to improve the unsteady hydrodynamic pulsation characteristics, and at the same time, the high damping characteristics weaken the vibration source, showing great potential in ship vibration and noise reduction.

[0003] A composite propeller is a propeller propulsion device made of reinforced fiber composites, which can have various configurations. It can be a continuous laying of carbon / glass fibers, or a composite skin covering a high-damping core material, or a high-damping material skin covering a composite core material, etc. Compared with traditional metal propellers, composite propellers have obvious self-adaptive hydroelastic characteristics. To make reasonable use of this characteristic, the rapidity can be ensured without loss through pre-deformation design, and the pressure pulsation and vibration noise of the propeller can be effectively reduced through low-noise design.

[0004] At present, domestic research on composite propellers focuses on small-scale model propellers, mainly numerical calculations and theoretical research, lacking the whole-process development experience of optimization methods, manufacturing and onshore detection. Especially for the development of low-noise pre-deformed composite propellers, the engineering application field is still blank. Therefore, this patent proposes a method for realizing the optimization, manufacturing and detection of pre-deformed composite propellers with the goal of vibration and noise reduction. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for realizing a low-noise pre-deformed composite propeller. The present invention includes a method for generating and analyzing a virtual simulated pre-assembled propeller, a method for verifying a scaled model, a method for manufacturing a physical object, and a method for testing and analyzing the manufactured physical object. The present invention ensures the probability that the final propeller meets various performance indicators, reduces the manufacturing risk and development investment, and improves the efficiency.

[0006] To achieve the above object, the present invention provides a method for realizing a low-noise pre-deformed composite propeller, which includes three stages, and the specific process is as follows:

[0007] Stage 1: A method for generating and analyzing a virtual simulated pre-assembled propeller

[0008] First, determine the reference profile of the composite propeller with reference to the profile of the metal propeller, optimize the overall configuration, determine the composition of the connecting and positioning parts such as the composite propeller blade, metal hub, metal key and bolt, etc., optimize the metal key, hub end cover plate, bolt, etc., and perform virtual assembly. Then, calculate the equal-thrust condition according to the self-propulsion design point, evaluate the blade load-bearing and preliminary material selection system, perform multi-angle sweep calculations on the fiber material, and evaluate its anisotropic deformation characteristics and stiffness levels of different material selections. Then, based on the non-uniform wake field behind the ship, analyze the hydrodynamic periodic change characteristics of a single propeller blade, adopt the transient fluid-structure interaction algorithm and the vibration reduction and noise reduction optimization algorithm, comprehensively consider factors such as hydrodynamics, noise, cavitation, strength, and vibration, and take reducing the unsteady bearing force as the goal to carry out iterative refinement optimization of the hydrodynamic and structural performance, and form technical design solutions such as the material selection, ply angle, and geometric configuration of each material of the composite propeller. Finally, form the design solution of the composite propeller, which specifically includes: a hydrodynamic numerical simulation calculation technical solution, a noise numerical simulation calculation technical solution, a cavitation numerical simulation calculation technical solution, a strength numerical simulation verification technical solution, a high-damping optimization solution, and a pre-deformation optimization method.

[0009] Stage 2: A method for verifying a scaled model and a method for manufacturing a physical object

[0010] First, perform scaled conversion of geometry, materials, working conditions, etc. according to the optimization solution of the composite propeller, carry out virtual optimization and preparation work, and process a scaled model for carrying out hydrodynamic and noise test verification of the composite propeller model behind the ship in the water tank. Then, on the basis of the model test verification, correct and slightly adjust and optimize the optimization method of the low-noise pre-deformed composite propeller. Finally, carry out the processing technology design and manufacturing of the low-noise pre-deformed composite propeller. When manufacturing a single blade, use the hot press autoclave forming process with male and female molds for curing and forming, and use five-axis numerical control machining for forming the hub and metal key. Assemble all the propeller blades and hubs.

[0011] Stage 3: A method for testing and analyzing the manufactured physical object

[0012] First, conduct precision inspection to evaluate the processing and assembly quality such as the forming precision, internal damage, static and dynamic balance of the low-noise pre-deformed composite propeller. Then, conduct stiffness and strength tests, customize relevant test tooling, and measure the performance such as the static loading deformation and strength limit of the low-noise pre-deformed composite propeller. Finally, conduct vibration characteristic tests, customize relevant test tooling, measure the dry and wet modes and vibration responses of the low-noise pre-deformed composite propeller, and conduct comparative analysis with the relevant data of the benchmark metal propeller.

[0013] Specifically, during material selection in Phase I, for the propeller hub and metal insert keys, use the metal materials used for the benchmark metal propeller, generally nickel-aluminum bronze alloy; for the propeller blades, lay carbon / glass fiber throughout, or use composite material skin to cover high-damping core material, or use high-damping material skin to cover composite material core.

[0014] Specifically, during the optimization design of the propeller hub in Phase I, keep the external dimensions of the propeller hub consistent with those of the benchmark metal propeller hub.

[0015] Specifically, during the hydrodynamic numerical simulation calculation in the scheme design of Phase I, first conduct the steady-state fluid-structure interaction panel method calculation based on potential flow theory, and then conduct the transient fluid-structure interaction calculation based on viscous flow theory.

[0016] Specifically, during the noise numerical simulation calculation technical scheme in the scheme design of Phase I, first conduct the near-field self-noise numerical simulation calculation, and then conduct the far-field radiation noise numerical simulation calculation.

[0017] Specifically, during the cavitation numerical simulation calculation technical scheme in the scheme design of Phase I, verify the accuracy of the numerical calculation method through standard model tests, and based on this, conduct the cavitation characteristic calculation of the composite propeller under specific working conditions and analyze its cavitation action mechanism.

[0018] Specifically, during the strength numerical simulation check in the scheme design of Phase I, use the composite propeller strength check and damage failure assessment method based on structural finite element numerical simulation calculation to conduct the composite propeller strength check.

[0019] Specifically, during the pre-deformation design in the scheme design of Phase I, use the method of multiple iterations to ensure the pre-deformation precision, and finally determine the profile parameters of the composite propeller, the structural form and connection method of the composite material or internal core material, and complete the design work of the composite propeller.

[0020] Specifically, during the processing and manufacturing in Phase II, it is necessary to conduct hydrodynamic tests, cavitation tests and noise tests on the scaled model, verify the design method and then fine-tune the design scheme before manufacturing the full-scale composite propeller.

[0021] Specifically, in the second-stage processing and manufacturing, according to the size and material selection of the composite propeller, the RTM molding process or the prepreg compression molding process can be adopted, but the S-class standard must be met according to specifications such as ISO 484S-class.

[0022] Specifically, in the second-stage processing and manufacturing, considering the taper of the hub, virtual assembly must be carried out first to ensure the feasibility and accuracy of the assembly.

[0023] Specifically, in the third-stage onshore inspection, the forming accuracy and static and dynamic balance inspection are carried out in the same way as that of conventional metal propellers.

[0024] Specifically, in the third-stage onshore inspection, the static load during the stiffness inspection needs to match the equal thrust during the navigation condition, and based on this, the ability of the pre-deformed propeller to deform to the shape of the metal propeller after bearing the load is evaluated.

[0025] Specifically, in the third-stage onshore inspection, the dynamic load during the vibration characteristic inspection needs to match the hydrodynamic unsteady force during the navigation condition, and based on this, the vibration response of the composite propeller is evaluated.

[0026] The present invention has the following beneficial effects: It guides the realization of a low-noise pre-deformed composite propeller for the whole process and can be applied to engineering practice. By implementing Steps 1 to 9, it can ensure that the propeller after pre-assembly can be detected in time when it does not meet the requirements, and after optimization, it re-enters the model or physical test, thereby ensuring the probability that the final propeller meets various performance indicators, reducing the manufacturing risk and development investment, and improving the efficiency. The propeller realized by the present invention has a propulsion performance equivalent to that of a metal propeller of the same size, while the weight is significantly reduced, and it has obvious noise reduction advantages in aspects such as self-noise and radiated noise. The low-noise pre-deformed composite propeller designed according to the present invention ensures that the open-water efficiency of the composite propeller is equivalent to that of the metal propeller under the design condition through pre-deformation design, and is superior to the metal propeller under non-design conditions; through low-noise design, it ensures the reduction of the low-frequency excitation force and mid-high frequency vibration response of the propeller, thereby reducing the radiated noise of the propeller. The low-noise pre-deformed composite propeller designed according to the present invention can meet high-precision requirements in aspects such as hydrodynamic performance prediction and forming precision, and is the key to realizing the design goal of the low-noise pre-deformed composite propeller. Description of the Drawings

[0027] Figure 1 It is a method for realizing a low-noise pre-deformed composite propeller. Detailed Embodiments

[0028] The following provides a detailed description of the present invention in combination with specific embodiments.

[0029] As Figure 1As shown in the figure, it is a method for realizing a low-noise pre-deformed composite propeller, and the specific implementation steps are as follows:

[0030] Step 1, virtual simulation pre-assembly of the geometric shape and overall configuration of the composite propeller. Refer to the profile values of the benchmark metal propeller, generate the blade geometry through the chord length, pitch, rake, skew, thickness, camber, and sectional profile values at each radius, generate the hub geometry according to the hub size, generate a helical metal spline according to the pitch at the blade root, pre-assemble the blade and hub geometries, and design bolts for fastening.

[0031] Step 2, analyze the open-water performance of the pre-assembled propeller through virtual simulation. Adopt a propeller open-water performance calculation method based on the panel method to analyze the open-water performance of the propeller at each advance coefficient and evaluate the force level on the blade. First, conduct a mechanical analysis of the rigid propeller, and thus predict what elastic modulus of composite material needs to be used. Therefore, Step 2 is preferably placed before Step 3.

[0032] Step 3, determine the material selection of the propeller. According to the self-propulsion design point of the benchmark metal propeller, calculate the wake flow field behind the ship and estimate the equal-thrust condition, calculate the pressure distribution of a single blade accordingly, perform composite material layup modeling on the blade for the material engineering constants of the composite material (reinforcing fiber and resin matrix) to be used, calculate the blade deformation of different material and angle schemes based on the pressure, back-calculate the blade profile parameters and analyze the influence law of different schemes on the profile and open-water performance, and evaluate the blade stiffness of different schemes through the maximum tip deformation to provide regular data support for the subsequent steps.

[0033] Step 4, calculate the steady-state fluid-structure coupling performance of the composite propeller. Adopt a steady-state two-way fluid-structure coupling calculation method for composite propellers that combines potential flow theory and structural finite elements to analyze the coupled open-water performance and coupled structural deformation of composite propellers with different schemes, evaluate the additional stiffness effect of the fluid, and the influence level of the structural coupled deformation on the open-water performance.

[0034] Step 5, calculate the unsteady hydrodynamic forces of the propeller in the wake flow field. Based on the non-uniform wake flow field behind the ship, adopt a transient hydrodynamic algorithm based on viscous flow to analyze the periodic variation characteristics of the thrust and torque of a single blade, and its mechanical mechanism with the wake flow field at each rotational position.

[0035] Step 6, calculate the transient fluid-structure coupling performance of the composite propeller. Adopt a transient two-way fluid-structure coupling calculation method for composite propellers that combines viscous flow theory and structural finite elements to analyze the coupled unsteady forces and the periodic deformation characteristics of the coupled structure of composite propellers with different schemes, and evaluate the influence level of the periodic deformation of composite blades with different schemes on the unsteady forces.

[0036] Step 7, conduct optimization analysis of the low-noise composite propeller. Adopt the transient fluid-structure interaction algorithm and the optimization design method for the ply angle of the composite propeller based on the genetic algorithm. Aiming to reduce the unsteady bearing force, use the fast and efficient coupling algorithm in Step 4 to carry out the iterative refinement design of the hydrodynamic and structural performance, and form the technical design solutions such as the material selection of the composite propeller, the ply angle, the geometric configuration of each material, and the modification of the high-damping material.

[0037] Step 8, conduct optimization analysis of the pre-deformation of the low-noise composite propeller. Under the equal thrust condition, based on the blade coupling deformation field, pre-apply the deformation amount in the reverse direction, and use the fast and efficient coupling algorithm in Step 4 to calculate the hydrodynamic performance of the pre-deformed composite propeller. Through multiple iterations, make the pre-deformation amount converge, and finally determine the profile parameters of the composite propeller, the structural form and connection method of the composite material or the internal core material. Ensure that the thrust and torque of the composite propeller at the designed ship speed are equivalent to the performance of the benchmark metal propeller.

[0038] Step 9, conduct refined performance analysis of the low-noise composite propeller determined in Step 8. Conduct unsteady hydrodynamic numerical simulation calculation, near-field self-noise numerical simulation calculation, far-field radiation noise numerical simulation calculation, cavitation numerical simulation calculation based on the Zwart et al model, and numerical simulation verification calculation of the composite material structure damage failure strength based on the Hoffman criterion for the low-noise pre-deformed composite propeller. Analyze and compare the data in Step 9. If the index requirements are met, proceed to the subsequent steps. If not, re-perform the virtual simulation pre-assembly in Step 1 to the material selection in Step 3, and then re-execute the procedures from Step 4 to Step 9 until the requirements are met.

[0039] Step 10, conduct scale conversion of the low-noise pre-deformed composite propeller according to the propeller determined in Step 8. Considering the scale effect problems of the fluid and the structure, conduct scale conversion of geometry, materials, working conditions, etc. according to the composite propeller design scheme to prepare for the model test.

[0040] Step 11, manufacture the scale model of the low-noise pre-deformed composite propeller determined in Step 8 to obtain the scale model of the composite propeller. To verify the accuracy of the low-noise pre-deformed composite propeller design scheme, manufacture the scale model of the composite propeller blade using the hot press autoclave forming process with male and female molds according to the numerical control machining process flow of the scale model mold and the forming process flow of the composite propeller blade of the scale model, manufacture the scale model of the metal propeller hub using numerical control machining, and complete the assembly of the composite propeller scale model.

[0041] Step 12: Conduct verification tests on the scaled - down model of the composite propeller. Conduct hydrodynamic and noise tests on the composite propeller model behind the ship in the water tank to form a scaled - down model test report and compare it with the simulation calculation results.

[0042] Step 13: Optimize the low - noise pre - deformed composite propeller determined in Step 8. On the basis of the model test verification, correct the design method of the low - noise pre - deformed composite propeller and fine - tune the design scheme to form the final optimized structure of the low - noise pre - deformed composite propeller.

[0043] Step 14: Carry out the processing technology design and manufacturing of the low - noise pre - deformed composite propeller determined in Step 13. Based on the final design scheme of the low - noise pre - deformed composite propeller, according to the numerical control processing technological process of the composite propeller mold, the processing and forming technological process of the composite propeller, and the assembly process of the composite propeller, use the hot - press autoclave forming process with male and female molds to manufacture the composite propeller blades, use numerical control machining to manufacture the metal hub, and complete the assembly of the composite propeller.

[0044] Step 15: Conduct precision inspection on the low - noise pre - deformed composite propeller manufactured in Step 14. According to the provisions of the technical documents, in accordance with the requirements of marine propeller standard S - class and other specifications, conduct factory inspections and formulate inspection plans, specifically including: blade appearance and weight inspection plan, blade profile and dimension inspection plan, hub interface dimension inspection plan, static balance test plan for the whole propeller, appearance quality and penetrant inspection for coloring and other factory test plans, and evaluate the forming precision, internal damage, static and dynamic balance and other processing and assembly qualities of the low - noise pre - deformed composite propeller.

[0045] Step 16: Conduct stiffness and strength tests on the low - noise pre - deformed composite propeller manufactured in Step 14. Customize relevant test tooling, fix the blade and the mold movable block on the reaction frame, equivalently apply a force normal to the local position of the blade in the form of a concentrated load on the blade surface, load in stages, slowly load up to a maximum of 2 times the thrust, and conduct normal deformation and strength tests on specific measuring points of the blade. After reaching the corresponding load in the test, analyze and record the displacement and strain data of the single - blade of the composite propeller, and measure the static loading deformation of the low - noise pre - deformed composite propeller. Gradually increase the blade load until fiber fracture occurs to evaluate the strength limit of the blade.

[0046] Step 17: Conduct vibration characteristic detection on the low-noise pre-deformed composite propeller manufactured in Step 14. Customize relevant test tooling. During the test, fix the blade and the die block on the reaction frame, arrange acceleration sensors to reflect the overall profile of the blade, use a force hammer for excitation, output the vibration acceleration information and vibration nephogram of each point, analyze the dry-mode natural frequency and damping, and evaluate the dry mode of the low-noise pre-deformed composite propeller. Fix the blade in open water, use a waterproof exciter and acceleration sensors to conduct wet-mode measurement tests, and evaluate the wet mode of the low-noise pre-deformed composite propeller. Fix the blade and the die block on the reaction frame, arrange acceleration sensors, use an exciter for excitation, output the acceleration information of each point, analyze the vibration response function, evaluate the vibration response of the low-noise pre-deformed composite propeller, and conduct a comparative analysis with the relevant data of the benchmark metal propeller.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that modifications or equivalent replacements can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for realizing a low-noise pre-deformed composite propeller, characterized in that: it includes the following implementation steps: Step 1, virtual simulation pre-assembly of the geometric shape and overall configuration of the composite propeller. Generate the blade geometry based on the chord length, pitch, rake, skew, thickness, camber, and sectional values at each radius, generate the hub geometry based on the hub size, generate the helical metal insert key based on the pitch at the blade root, pre-assemble the blade and hub geometries, and fasten them with bolts; Step 2, analyze the open-water performance of the virtual simulation pre-assembled propeller; Step 3, determine the material selection of the propeller; Step 4, calculate the steady-state fluid-structure coupling performance of the composite propeller; Step 5, calculate the unsteady hydrodynamic forces of the propeller in the wake flow field; Step 6, calculate the transient fluid-structure coupling performance of the composite propeller; Step 7, carry out optimization analysis of the low-noise composite propeller; Step 8, carry out pre-deformation optimization analysis of the low-noise composite propeller; Step 9, carry out refined performance analysis of the low-noise composite propeller; conduct numerical simulation calculations of hydrodynamic forces, near-field self-noise, far-field radiation noise, cavitation, and strength numerical simulation verification; analyze and compare the data in Step 9. If the index requirements are met, proceed to the subsequent steps. If not, re-perform the virtual simulation pre-assembly in Step 1 to the material selection in Step 3, and then re-execute the procedures from Step 4 to Step 9 until the requirements are met; Step 10, carry out scale conversion of the low-noise pre-deformed composite propeller according to the propeller determined in Step 8; Step 11, manufacture the scale model of the low-noise pre-deformed composite propeller determined in Step 8 to obtain the scale model of the composite propeller; Step 12, carry out experimental verification of the composite propeller scale model; Step 13, optimize the low-noise pre-deformed composite propeller determined in Step 8; Step 14, carry out the processing technology design and manufacture of the low-noise pre-deformed composite propeller determined in Step 13; Step 15, carry out accuracy inspection of the low-noise pre-deformed composite propeller manufactured in Step 14; Step 16, carry out stiffness and strength detection of the low-noise pre-deformed composite propeller manufactured in Step 14; Step 17, carry out vibration characteristic detection of the low-noise pre-deformed composite propeller manufactured in Step 14.

2. The method for realizing a low-noise pre-deformed composite propeller according to claim 1, characterized in that: in Step 1, the hub and the metal insert key are selected as nickel-aluminum bronze alloy; the blade is made of continuous carbon / glass fiber or a composite skin covering a high-damping core or a high-damping material skin covering a composite core.

3. The method for realizing a low-noise pre-deformed composite propeller according to claim 1, characterized in that: in Step 1, the external dimensions of the hub are the same as those of the benchmark metal propeller hub.

4. The method for realizing a low-noise pre-deformed composite propeller according to claim 1, characterized in that: During the pre-deformation optimization analysis in Step 8, the pre-deformation accuracy is ensured by using the method of multiple iterations, and finally the profile parameters of the composite propeller, the structural forms and connection methods of the composite materials or internal core materials are determined.

5. The implementation method of a low-noise pre-deformed composite propeller according to claim 1, characterized in that: During the hydrodynamic numerical simulation calculation in Step 9, first, the steady-state fluid-structure interaction panel method based on the potential flow theory is carried out, and then the transient fluid-structure interaction calculation based on the viscous flow theory is carried out.

6. The implementation method of a low-noise pre-deformed composite propeller according to claim 1, characterized in that: During the noise numerical simulation in Step 9, first, the near-field self-noise numerical simulation calculation is carried out, and then the far-field radiation noise numerical simulation calculation is carried out.

7. The implementation method of a low-noise pre-deformed composite propeller according to claim 1, characterized in that: During the cavitation numerical simulation in Step 9, the accuracy of the numerical calculation method is verified through the standard model test. Based on this, the cavitation characteristics of the composite propeller under specific working conditions are calculated, and its cavitation action mechanism is analyzed.

8. The implementation method of a low-noise pre-deformed composite propeller according to claim 1, characterized in that: During the strength numerical simulation check in Step 9, the strength check of the composite propeller is carried out by using the composite propeller strength check and damage failure assessment method based on the structural finite element numerical simulation calculation.

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