Test method for testing hydrodynamic performance of composite propeller
By determining the geometric similarity conditions and appropriate test parameters for composite propellers, the problem of test accuracy caused by large deformation of composite propellers under hydrodynamic loads was solved, and efficient and economical hydrodynamic performance testing was achieved.
Patent Information
- Application Number
- CN202511289723.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2025-11-14
AI Technical Summary
Existing technologies cannot effectively address the issue of large deformation of composite material propellers under hydrodynamic loads, which results in the directly scaled model propeller failing to meet geometric similarity conditions and affecting the accuracy of hydrodynamic performance testing.
By determining the geometric similarity conditions between the composite model propeller and the actual propeller under hydrodynamic loads, selecting appropriate model scaling ratios and test condition parameters, conducting open-water tests, obtaining hydrodynamic performance parameters, and fitting open-water characteristic curves, the accuracy of testing under geometric, kinematic, and dynamic similarity conditions is ensured.
It improves the accuracy and reliability of hydrodynamic performance testing of composite propellers, reduces testing costs and time, and requires no additional equipment, making it suitable for accurate prediction of large-scale composite propellers.
Smart Images
Figure CN120947985A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of propeller performance testing technology, and in particular to a test method for hydrodynamic performance testing of composite material propellers. Background Technology
[0002] As the primary propulsion device for ships, the hydrodynamic performance of propellers is crucial for analyzing ship energy consumption. The hydrodynamic performance of conventional metal propellers is typically measured using open-water tests, which require model propellers to exhibit geometric, kinematic, and dynamic similarity to the actual propeller. Obtaining the hydrodynamic performance parameters of the actual propeller through open-water tests on the model propeller serves as the basis for subsequent hydrodynamic performance predictions.
[0003] Because conventional metal propellers experience almost no deformation under hydrodynamic loads, the model propeller formed by directly scaling down a real propeller naturally satisfies geometric similarity during operation. However, composite propellers deform relatively significantly under hydrodynamic loads, and the composite model propeller formed by directly scaling down a real composite propeller does not naturally satisfy geometric similarity. Therefore, the accuracy of hydrodynamic performance tests on composite propellers based on the geometric similarity conditions for conventional metal propellers is low. Currently, there are no conditions that can achieve geometric similarity for composite propellers, which poses a challenge to conducting hydrodynamic performance tests on composite propellers. Summary of the Invention
[0004] This application addresses the aforementioned problems and technical needs by proposing a test method for the hydrodynamic performance of composite material propellers. The technical solution of this application is as follows:
[0005] A test method for hydrodynamic performance of a composite material propeller includes the following steps:
[0006] Determine the geometric similarity conditions between the composite material model propeller and the actual composite material propeller under hydrodynamic loads;
[0007] Determine the model scaling ratio λ, fabricate a composite material model paddle according to the model scaling ratio λ, and arrange the composite material model paddle in the test water tank; the composite material model paddle and the actual composite material paddle are the same in terms of material, layup structure, molding process and connection method.
[0008] Based on multiple sets of full-scale operating parameters of the composite material propeller and the model scaling ratio, under the conditions of geometric similarity, kinematic similarity and dynamic similarity between the composite material model propeller and the actual composite material propeller, multiple sets of different test operating parameters are determined; each set of test operating parameters corresponds one-to-one with each set of full-scale operating parameters.
[0009] Open water tests were conducted on the composite material model propeller according to each set of test conditions to obtain the hydrodynamic performance parameters of the composite material model propeller in multiple open water tests. The open water characteristic curve of the actual composite material propeller was obtained by fitting the hydrodynamic performance parameters in multiple open water tests. The open water characteristic curve indicates the hydrodynamic performance of the actual composite material propeller under different test conditions.
[0010] Hydrodynamic performance of composite material propellers under different real-scale operating parameters was determined based on open-water characteristic curves.
[0011] A further technical solution is that each set of real-scale operating parameters for the composite material propeller includes the flow velocity V of the fluid medium acting on the composite material propeller under real-scale operating conditions. Ap Real-scale rotational speed n of composite material propeller p Each set of test parameters includes the flow velocity V of the fluid medium acting on the composite material model paddle during open water testing. Am Model rotational speed n of composite material model propeller m Determining the conditions for geometric similarity includes:
[0012] Based on the geometric similarity between the composite model propeller and the actual composite propeller under the same distributed pressure, and considering that the propeller thrust coefficients are the same for both the model and the actual propellers at the same advance rate, the geometric similarity condition satisfied by the composite model propeller and the actual composite propeller is determined as follows: n p D p =n m D m D m D is the diameter of the composite material model paddle. p It refers to the diameter of the actual composite propeller and the advance coefficient of the composite model propeller. Precipitation coefficient of composite material propeller Distributed pressure represents the hydrodynamic load distributed per unit area.
[0013] A further technical solution is to determine the distributed pressure q of the composite material model paddle. m The distributed pressure q of the composite material solid paddle p Equality determination And combined with the thrust coefficient of the composite material model propeller Thrust coefficient of composite material propeller The geometric similarity condition between the composite model propeller and the actual composite propeller is determined to be: n p D p =n m D m ;T m It is the thrust of the composite material model propeller under test conditions, T pIt is the thrust of the composite material propeller under real-scale operating conditions, and ρ is the density of the fluid medium.
[0014] The further technical solution involves determining the model scaling ratio λ, including:
[0015] Based on the distributed pressure q of the composite material model paddle m The distributed pressure q of the composite material solid paddle p Equal, confirmed
[0016] Based on the fact that the composite material model propeller can be placed intact in the test water tank, and the thrust T generated by the composite material model propeller in the test water tank... m =λ 2 T p Not exceeding the maximum thrust T max The constraints, combined with the composite material model propeller satisfying the Reynolds number, are determined. Dynamic similarity conditions above the critical Reynolds number determine the model scaling ratio λ; T P ′ is the maximum thrust of the composite material propeller under all real-scale operating conditions. It is 0.75D m The chord length of the blade section of the composite material model propeller and It is 0.75D p The chord length of the blade section of the composite material impeller, where ν is the viscosity coefficient of the fluid medium, and the maximum thrust T generated by the composite material model impeller in the test water tank. max These are the experimental performance indicators of the test water cylinder.
[0017] The further technical solution involves determining the parameters for each set of test conditions, including:
[0018] Based on the actual speed n p Based on the model scaling ratio λ, the model rotational speed in the test conditions is determined under the condition that the composite material model propeller and the actual composite material propeller are geometrically similar.
[0019] Based on the actual speed n p and model rotational speed n m The flow velocity V is determined under the kinematic similarity condition that the advance coefficients of the composite material model propeller and the actual composite material propeller are equal. Am =V Ap And the flow rate V of each group of test conditions Am and model rotational speed n m There is at least one difference: the model rotational speed n in each set of test condition parameters. m and flow velocity V Am Satisfying the Reynolds number Dynamic similarity conditions greater than the critical Reynolds number, and the model rotational speed n in each set of test parameters.m All within the model rotational speed range, the flow velocity V in each set of test conditions m All were within the flow rate range of the test water cylinder. It is 0.75D m The chord length of the blade section of the composite material model propeller and It is 0.75D p The chord length of the blade section of the composite material propeller is given by ν, which is the viscosity coefficient of the fluid medium.
[0020] A further technical solution involves fitting the hydrodynamic performance parameters from multiple open-water tests to obtain the open-water characteristic curves of the composite material paddle, including:
[0021] The collected hydrodynamic performance parameters are dimensionlessly processed based on the size parameters of the composite material model propeller and the test condition parameters used in each open water test to obtain the hydrodynamic performance coefficient of the composite material model propeller under the current open water test. The hydrodynamic performance coefficient of the composite material model propeller is used to characterize the hydrodynamic performance of the composite material model propeller under the current advance rate coefficient of the open water test and is independent of the test condition parameters and size parameters.
[0022] Based on the fact that the hydrodynamic performance coefficients of the composite material model propeller and the actual composite material propeller are the same under the same advance rate coefficient, the relationship between the advance rate coefficient and the hydrodynamic performance coefficient in multiple open water tests is curve fitted to obtain the open water characteristic curve of the actual composite material propeller.
[0023] A further technical solution involves determining the hydrodynamic performance of the composite material impeller under any real-scale operating parameters based on the open-water characteristic curve, including:
[0024] The hydrodynamic performance coefficients of the composite material propeller under the current real-scale operating conditions are determined by using the open-water characteristic curve of the composite material propeller.
[0025] Based on the hydrodynamic performance coefficients of the composite material propeller under the current real-scale operating conditions at the corresponding advance coefficient, and combined with the real-scale operating conditions parameters, the hydrodynamic performance parameters of the composite material propeller under the current real-scale operating conditions are determined.
[0026] The further technical solution is that the hydrodynamic performance parameters include thrust and torque, and the hydrodynamic performance coefficients of the composite material model propeller in each open-water test are obtained as follows:
[0027] The composite material model propeller is controlled to rotate at a speed n according to the test conditions parameters. m Rotate, and use the test water cylinder at a flow rate V according to the test conditions parameters. mFlow generation; the thrust T of the composite material model propeller under the test conditions was measured using a propeller force gauge mounted on the composite material model propeller. m and torque Q m And the hydrodynamic performance coefficients, including the thrust coefficient, were calculated. Torque coefficient and propeller efficiency ρ is the density of the fluid medium.
[0028] The beneficial technical effects of this application are:
[0029] This application discloses a test method for hydrodynamic performance testing of composite material propellers. It establishes a hydrodynamic similarity criterion for hydrodynamic performance testing of composite material propellers and provides a design method for test conditions and operating modes. This method can be used to guide the hydrodynamic performance testing of composite material propellers, effectively improving the accuracy of test results. Furthermore, this method requires no additional experimental equipment or operations, reducing testing time and economic costs.
[0030] By analyzing the characteristic that the relative deformation of composite propellers with the same material and ply structure but different scales is only proportional to the hydrodynamic load they are subjected to, the geometric similarity conditions between composite model propellers and actual composite propellers are derived. This effectively solves the problem that traditional model testing methods, which directly scale down actual composite propellers, cannot meet the geometric similarity conditions due to the large deformation of the composite material. Especially for large-scale composite propellers, the deformation of the scaled composite model propeller under hydrodynamic loads increases significantly. The method in this application can significantly improve the reliability and accuracy of hydrodynamic performance test results, which is of great significance for the accurate prediction of the hydrodynamic performance of actual composite propellers in the future.
[0031] When designing the model scale ratio and test conditions for composite material propellers, considering the unique geometric similarity conditions of composite material propellers compared to conventional metal propellers, the hydrodynamic performance testing method of this application only requires the selection of appropriate model scale ratio and test conditions, which helps to reduce the difficulty of hydrodynamic performance testing and improve the efficiency and accuracy of model tests. Attached Figure Description
[0032] Figure 1 This is a flowchart of the hydrodynamic performance testing method. Detailed Implementation
[0033] The specific embodiments of this application will be further described below with reference to the accompanying drawings.
[0034] This application discloses a test method for hydrodynamic performance testing of composite material propellers, which can be used to guide the hydrodynamic performance testing of composite material propellers. Please refer to [the relevant documentation]. Figure 1 The flowchart shown illustrates the specific steps of this method:
[0035] Step 1: Determine the geometric similarity conditions between the composite material model propeller and the actual composite material propeller under hydrodynamic loads.
[0036] Since conventional metal propellers exhibit almost no deformation under hydrodynamic loads, the model propeller formed by directly scaling down a real propeller naturally satisfies the geometric similarity conditions during operation. However, composite propellers deform relatively more under hydrodynamic loads, and the composite model propeller formed by directly scaling down a real composite propeller does not naturally satisfy the geometric similarity conditions during operation. Therefore, the test parameters of the metal propeller cannot be directly used for model testing. Thus, it is first necessary to determine the geometric similarity conditions between the composite model propeller and the real composite propeller under hydrodynamic loads.
[0037] In one embodiment, based on the characteristic that the composite material model propeller and the actual composite material propeller satisfy geometric similarity under the same distributed pressure, and combined with the characteristic that the propeller thrust coefficient of the composite material model propeller and the actual composite material propeller is the same under the same advance rate coefficient, the geometric similarity condition satisfied by the composite material model propeller and the actual composite material propeller is determined to be: n p D p =n m D m D m D is the diameter of the composite material model paddle. p It refers to the diameter of the actual composite propeller and the advance coefficient of the composite model propeller. Precipitation coefficient of composite material propeller V Ap n is the flow velocity of the fluid medium acting on the composite material impeller under real-scale operating conditions. p It is the real-scale rotational speed of the composite material propeller, V. Am n is the velocity of the fluid medium acting on the composite material model paddle during open-water testing. m The model rotational speed is the composite material model propeller; the distributed pressure represents the hydrodynamic load distributed per unit area. The specific derivation of this geometric similarity condition is as follows:
[0038] According to the theory of lath beams, the expression for the deformation curve of a lath beam fixed at one end under uniformly distributed pressure is shown in Equation (1), and the expression for the maximum deformation is shown in Equation (2):
[0039]
[0040] Where K is the bending stiffness of the lath beam and E is the modulus of the lath beam, t is the thickness of the lath beam, and μ is Poisson's ratio. It is a uniformly distributed pressure, representing the pressure that is uniformly distributed per unit area on the lath beam. l is the length of the lath beam, and x is the coordinate along the length of the lath beam. One end of the lath beam is fixed as the fulcrum, and this fulcrum is the origin of the coordinate system. Generally, the left end of the lath beam is taken as the fulcrum, and the positive direction of the coordinate axis is along the length of the lath beam.
[0041] Substituting the bending stiffness K into the deformation curve formula (1) and the maximum deformation formula (2), we get:
[0042]
[0043] For the same material, its modulus E and Poisson's ratio μ are constants. Rearranging formula (3), we obtain the expression for the deformation curve u as follows:
[0044]
[0045] Where c is a constant term related to material parameters and L is a one-dimensional geometric scale-dependent variable and
[0046] As can be seen from formula (5), for a lath beam of a specified material, its deformation under uniform pressure is related to the uniformly distributed pressure it experiences. It is positively correlated with the product of the one-dimensional geometric scale L. Further normalizing the deformation curve u using the one-dimensional geometric scale L yields... This indicates that the relative deformation of a lath beam of different sizes is only proportional to the uniformly distributed pressure it is subjected to.
[0047] Based on this, it can be proved using the finite element method that for composite propellers of the same material and the same layup scheme, the relative deformation of composite propellers of different scales is different. It is only proportional to the hydrodynamic load it is subjected to, that is D is the diameter of the composite material propeller.
[0048] Since the composite model propeller and the actual composite propeller have the same materials and layup schemes, and differ only in scale, the composite model propeller and the actual composite propeller satisfy the characteristic of geometric similarity under the same distributed pressure.
[0049] Because the hydrodynamic load varies at different locations on a composite propeller, the hydrodynamic load distributed per unit area is not the same at different locations. The distributed pressure q is a position-dependent field quantity. The integral of the distributed pressure q over the entire propeller disk surface yields the propeller thrust T. The area of the propeller disk surface is...
[0050] Therefore, based on the distributed pressure q of the composite material model propeller m The distributed pressure q of the composite material solid paddle p If they are equal, then we can determine that:
[0051]
[0052] When the composite model propeller and the actual composite propeller are geometrically similar, the propeller's hydrodynamic performance depends only on the advance coefficient J, and the thrust coefficient is the same for the same advance coefficient J. Based on the thrust coefficient of the composite model propeller... Thrust coefficient of composite material propeller Equal, we get:
[0053]
[0054] Among them, T m It is the thrust of the composite material model propeller under test conditions, T p It is the thrust of the composite material propeller under real-scale working conditions, where ρ is the density of the fluid medium, which is usually water.
[0055] Combining formulas (6) and (7), the geometric similarity condition satisfied by the composite material model propeller and the actual composite material propeller is determined as follows: n p D p =n m D m .
[0056] Step 2: Determine the model scale ratio λ, fabricate the composite material model paddle according to the model scale ratio λ, and arrange the composite material model paddle in the test water tank. The composite material model paddle and the actual composite material paddle are identical in material, layup structure, molding process, and connection method.
[0057] Because composite propellers deform significantly, a suitable scaling ratio must be selected to facilitate model preparation and ensure accurate experimental results.
[0058] In one embodiment, determining the model scaling ratio λ includes:
[0059] Based on the distributed pressure q of the composite material model paddle m The distributed pressure q of the composite material solid paddle p Equal, confirmed
[0060] Based on the fact that the composite material model propeller can be placed intact in the test water tank, and the thrust T generated by the composite material model propeller in the test water tank... m =λ 2 T p Not exceeding the maximum thrust T maxThe constraints, combined with the composite material model propeller satisfying the Reynolds number, are determined. Dynamic similarity conditions above the critical Reynolds number determine the model scaling ratio λ; T P ′ is the maximum thrust of the composite material propeller under all real-scale operating conditions. It is 0.75D m The chord length of the blade section of the composite material model propeller and It is 0.75D p The chord length of the blade section of the composite material impeller, where ν is the viscosity coefficient of the fluid medium, and the maximum thrust T generated by the composite material model impeller in the test water tank. max This refers to the experimental performance indicators of the test water tank, which reflect its testing capabilities and are quantities known in advance. The thrust of the composite material paddle under various real-scale operating conditions can be calculated in advance through finite element simulation.
[0061] Based on the fact that the size of the composite material model paddle is smaller than the size of the test water tank, and the thrust T generated by the composite material model paddle in the test water tank... m =λ 2 T p ′ <T max This allows us to determine the maximum value of the model scaling ratio λ. Furthermore, the model test of the composite material propeller also needs to satisfy the dynamic similarity condition, namely the Reynolds number. V can be determined based on geometric similarity conditions and kinematic similarity conditions. Am and n m D m The value, therefore according to The minimum value of the model scaling ratio λ can be determined. λ within the range of both minimum and maximum values satisfies the experimental requirements. In practical applications, to ensure the convenience of model preparation and the accuracy of experimental results, a larger model scaling ratio λ is usually selected within this range.
[0062] Based on geometric similarity requirements, the shape of the composite material model propeller is made by scaling down the shape of the actual composite material propeller. The material, layup structure, molding process, and connection method of the composite material model propeller are consistent with those of the actual composite material propeller. The completed composite material model propeller also needs to undergo shape accuracy testing in accordance with the "Technical Conditions for Marine Metal Propellers" (GB / T 12916-2024) to ensure that the shape accuracy meets the Level 2 requirements. The specific shape accuracy testing methods are conventional techniques and will not be elaborated in this application.
[0063] Step 3: Based on the multiple sets of full-scale operating condition parameters of the composite material propeller and the model scaling ratio, determine multiple sets of different test operating condition parameters under the conditions of geometric similarity, kinematic similarity and dynamic similarity between the composite material model propeller and the composite material propeller. Each set of test operating condition parameters corresponds one-to-one with each set of full-scale operating condition parameters. The full-scale operating condition parameters are predetermined according to the design requirements.
[0064] Each set of real-scale operating parameters for the composite material propeller includes the flow velocity V of the fluid medium acting on the composite material propeller under real-scale operating conditions. Ap Real-scale rotational speed n of composite material propeller p Each set of test parameters includes the flow velocity V of the fluid medium acting on the composite material model paddle during open water testing. Am Model rotational speed n of composite material model propeller m During model testing, the advance speed of the composite material model paddle can be controlled by adjusting the flow rate of the fluid medium in the test water tank.
[0065] The test conditions for the composite material model propeller are determined based on hydrodynamic similarity conditions such as geometric similarity, kinematic similarity, and dynamic similarity. In one embodiment, the parameters for each set of test conditions include:
[0066] Based on the actual speed n p Based on the model scaling ratio λ, the model rotational speed in the test conditions is determined under the condition that the composite model propeller and the actual composite propeller are geometrically similar.
[0067] Based on the actual speed n p and model rotational speed n m The flow velocity V is determined under the kinematic similarity condition that the advance coefficients of the composite material model propeller and the actual composite material propeller are equal. Am =V Ap And the flow rate V of each group of test conditions Am and model rotational speed n m There is at least one difference: the model rotational speed n in each set of test condition parameters. m and flow velocity V Am Satisfying the Reynolds number Dynamic similarity conditions greater than the critical Reynolds number, and the model rotational speed n in each set of test parameters. m All within the model rotational speed range, the flow velocity V in each set of test conditions m All were within the flow rate range of the test water cylinder.
[0068] Step 4: Conduct open-water tests on the composite material model propeller according to each set of test conditions to obtain the hydrodynamic performance parameters of the composite material model propeller in multiple open-water tests; fit the hydrodynamic performance parameters from multiple open-water tests to obtain the open-water characteristic curve of the composite material propeller, which indicates the hydrodynamic performance of the composite material propeller under different test conditions.
[0069] The advance rate coefficient is the same for each set of test operating parameters as for the actual scale operating parameters. Therefore, the obtained open water characteristic curve is a curve about the advance rate coefficient. During multiple open water tests, the flow velocity V can be changed. Am Or the model rotation speed n m To change the advance coefficient, this application controls the model speed n. m The flow rate V remains constant, but is varied during each open-water test. Am To change the test conditions. In one embodiment, fitting the hydrodynamic performance parameters from multiple open-water tests to obtain the open-water characteristic curve of the composite material paddle includes:
[0070] (1) The collected hydrodynamic performance parameters are dimensionless based on the size parameters of the composite material model propeller and the test conditions used in each open water test to obtain the hydrodynamic performance coefficient of the composite material model propeller under the current open water test. The hydrodynamic performance coefficient of the composite material model propeller is used to characterize the hydrodynamic performance of the composite material model propeller under the current advance coefficient of the open water test and is independent of the test conditions and size parameters. The size parameters of the composite material model propeller include the diameter of the composite material model propeller and the chord length of the blade section at each position along the diameter direction.
[0071] Hydrodynamic performance parameters include thrust and torque. The hydrodynamic performance coefficients of the composite material model propeller in each open-water test are obtained as follows:
[0072] Controlling the model propeller of the composite material according to the model rotation speed n under test conditions m Rotate, and use the test water cylinder according to the flow rate V of the test conditions. m Flow generation; the thrust T of the composite material model propeller under the test conditions was measured using a propeller force gauge mounted on the composite material model propeller. m and torque Q m And the hydrodynamic performance coefficients, including the thrust coefficient, were calculated. Torque coefficient and propeller efficiency ρ is the density of the fluid medium.
[0073] (2) Based on the characteristic that the hydrodynamic performance coefficients of the composite material model propeller and the actual composite material propeller are the same under the same advance rate coefficient, the relationship between the advance rate coefficient and the hydrodynamic performance coefficient in multiple open water tests is curve fitted to obtain the open water characteristic curve of the actual composite material propeller. Among them, any existing curve fitting method can be used for curve fitting, such as the least squares curve fitting method, the specific details of which will not be elaborated in this application.
[0074] Step 5: Determine the hydrodynamic performance of the composite material paddle under different real-scale operating parameters based on the open water characteristic curve.
[0075] In one embodiment, determining the hydrodynamic performance of the composite material propeller under any real-scale operating condition based on the open-water characteristic curve includes: using the open-water characteristic curve of the composite material propeller to determine the hydrodynamic performance coefficient of the composite material propeller under the advance coefficient corresponding to the current real-scale operating condition; and based on the hydrodynamic performance coefficient of the composite material propeller under the advance coefficient corresponding to the current real-scale operating condition, combined with the real-scale operating condition parameters of the current real-scale operating condition, determining the hydrodynamic performance parameters of the composite material propeller under the current real-scale operating condition.
[0076] This application illustrates this with a specific example, where the diameter D of the composite material solid paddle is... p = 2.438m, design advance coefficient J p =0.9, actual speed n p =281rpm, T obtained in advance through finite element simulation p =160kN. A composite material model propeller was prepared using T700 carbon fiber reinforced epoxy resin matrix composite material with a layup scheme of [0 / ±60]ns, and resin transfer molding (RTM) process. The working section diameter of the test water tank was 0.8m, the flow velocity range was 3m / s to 20m / s, and the test thrust limit was T. max =1200N. The model scaling ratio is selected based on geometric similarity conditions. At this time (T) m =λ 2 T p ′=989N)<(T max =1200N), meeting the test thrust limit, and the Reynolds number Re is calculated. m =2.1×10 6 >3.0×10 5 The dynamic similarity conditions are satisfied. Determine the diameter D of the composite material model propeller. m=0.1875m. According to geometric similarity requirements, the model propeller's geometry is directly scaled down from the actual propeller at a 1:13 ratio. The material is T700 carbon fiber reinforced epoxy resin composite material, with a layup scheme of [0 / ±60]ns. It is formed using resin transfer molding (RTM) to maintain consistency with the actual propeller. Geometric accuracy is tested after the model propeller is manufactured.
[0077] The test parameters were determined based on the hydrodynamic similarity criterion; the model rotation speed was determined based on the geometric similarity conditions. Determining the flow velocity V based on motion similarity conditions Am =V Ap =10.29 m / s. An open-water test was conducted according to the experimental operating parameters to obtain the corresponding advance velocity coefficient J. m The thrust coefficient K of the composite material model propeller at 0.9 Tm =0.215, torque coefficient K Qm =0.462 and propeller efficiency η m =66.7%. Based on the characteristic that the hydrodynamic performance coefficients of the composite model propeller and the actual composite propeller are the same at the same advance rate coefficient, the thrust coefficient K of the actual composite propeller can be obtained. Tp Torque coefficient K Qp and propeller efficiency η P Then, the advance coefficient J of the composite material propeller was calculated. p When = 0.9, thrust
[0078] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.
Claims
1. A test method for hydrodynamic performance of a composite material propeller, characterized in that, The hydrodynamic performance testing method includes: Determine the geometric similarity conditions between the composite material model propeller and the actual composite material propeller under hydrodynamic loads; Determine the model scaling ratio λ, fabricate a composite material model paddle according to the model scaling ratio λ, and arrange the composite material model paddle in the test water tank; the composite material model paddle and the actual composite material paddle are the same in terms of material, layup structure, molding process and connection method. Based on multiple sets of full-scale operating parameters of the composite material propeller and the model scaling ratio λ, multiple sets of different test operating parameters are determined under the conditions of geometric similarity, kinematic similarity, and dynamic similarity between the composite material model propeller and the composite material propeller; each set of test operating parameters corresponds one-to-one with each set of full-scale operating parameters. The composite material model propeller was subjected to open-water tests according to each set of test conditions to obtain the hydrodynamic performance parameters of the composite material model propeller in multiple open-water tests; the hydrodynamic performance parameters in multiple open-water tests were fitted to obtain the open-water characteristic curve of the composite material actual propeller, and the open-water characteristic curve indicates the hydrodynamic performance of the composite material actual propeller under different test conditions. Based on the open water characteristic curve, the hydrodynamic performance of the composite material paddle under different real-scale operating parameters was determined.
2. The hydrodynamic performance testing method according to claim 1, characterized in that, Each set of real-scale operating parameters for the composite material propeller includes the flow velocity V of the fluid medium acting on the composite material propeller under real-scale operating conditions. Ap Real-scale rotational speed n of composite material propeller p Each set of test parameters includes the flow velocity V of the fluid medium acting on the composite material model paddle during open water testing. Am Model rotational speed n of composite material model propeller m ; Determining the conditions for geometric similarity includes: Based on the geometric similarity between the composite model propeller and the actual composite propeller under the same distributed pressure, and considering that the propeller thrust coefficients are the same for both the model and the actual propellers at the same advance rate, the geometric similarity condition satisfied by the composite model propeller and the actual composite propeller is determined as follows: n p D p =n m D m D m D is the diameter of the composite material model paddle. p It refers to the diameter of the actual composite propeller and the advance coefficient of the composite model propeller. Precipitation coefficient of composite material propeller Distributed pressure represents the hydrodynamic load distributed per unit area.
3. The hydrodynamic performance testing method according to claim 2, characterized in that, Based on the distributed pressure q of the composite material model paddle m The distributed pressure q of the composite material solid paddle p Equality determination And combined with the thrust coefficient of the composite material model propeller Thrust coefficient of composite material propeller The geometric similarity condition between the composite model propeller and the actual composite propeller is determined to be: n p D p =n m D m ;T m It is the thrust of the composite material model propeller under test conditions, T p It is the thrust of the composite material propeller under real-scale operating conditions, and ρ is the density of the fluid medium.
4. The hydrodynamic performance testing method according to claim 3, characterized in that, Determining the model scaling ratio λ includes: Based on the distributed pressure q of the composite material model paddle m The distributed pressure q of the composite material solid paddle p Equal, confirmed Based on the fact that the composite material model propeller can be placed intact in the test water tank, and the thrust T generated by the composite material model propeller in the test water tank... m =λ 2 T p Not exceeding the maximum thrust T max The constraints, combined with the composite material model propeller satisfying the Reynolds number, are determined. Dynamic similarity conditions above the critical Reynolds number determine the model scaling ratio λ; T P ′ is the maximum thrust of the composite material propeller under all real-scale operating conditions. It is 0.75D m The chord length of the blade section of the composite material model propeller and It is 0.75D p The chord length of the blade section of the composite material impeller, where ν is the viscosity coefficient of the fluid medium, and the maximum thrust T generated by the composite material model impeller in the test water tank. max These are the experimental performance indicators of the test water cylinder.
5. The hydrodynamic performance testing method according to claim 2, characterized in that, The parameters for each test condition group are determined as follows: Based on the actual speed n p Based on the model scaling ratio λ, the model rotational speed in the test conditions is determined under the condition that the composite material model propeller and the actual composite material propeller are geometrically similar. Based on the actual speed n p and model rotational speed n m The flow velocity V is determined under the kinematic similarity condition that the advance coefficients of the composite material model propeller and the actual composite material propeller are equal. Am =V Ap And the flow rate V of each group of test conditions Am and model rotational speed n m There is at least one difference: the model rotational speed n in each set of test condition parameters. m and flow velocity V Am Satisfying the Reynolds number Dynamic similarity conditions greater than the critical Reynolds number, and the model rotational speed n in each set of test parameters. m All within the model rotational speed range, the flow velocity V in each set of test conditions m All were within the flow rate range of the test water cylinder. It is 0.75D m The chord length of the blade section of the composite material model propeller and b 0.75Dp It is 0.75D p The chord length of the blade section of the composite material propeller is given by ν, which is the viscosity coefficient of the fluid medium.
6. The hydrodynamic performance testing method according to claim 5, characterized in that, The process of fitting the hydrodynamic performance parameters from multiple open-water tests to obtain the open-water characteristic curve of the composite material paddle includes: The collected hydrodynamic performance parameters are dimensionlessly processed based on the size parameters of the composite material model propeller and the test condition parameters used in each open water test to obtain the hydrodynamic performance coefficient of the composite material model propeller under the current open water test. The hydrodynamic performance coefficient of the composite material model propeller is used to characterize the hydrodynamic performance of the composite material model propeller under the current advance rate coefficient of the open water test and is independent of the test condition parameters and size parameters. Based on the fact that the hydrodynamic performance coefficients of the composite material model propeller and the actual composite material propeller are the same under the same advance rate coefficient, the relationship between the advance rate coefficient and the hydrodynamic performance coefficient in multiple open water tests is curve fitted to obtain the open water characteristic curve of the actual composite material propeller.
7. The hydrodynamic performance testing method according to claim 6, characterized in that, The hydrodynamic performance of the composite material propeller under any real-scale operating parameters is determined based on the open-water characteristic curve, including: The hydrodynamic performance coefficients of the composite material propeller under the current real-scale operating conditions are determined by using the open-water characteristic curve of the composite material propeller. Based on the hydrodynamic performance coefficients of the composite material propeller under the current real-scale operating conditions at the corresponding advance coefficient, and combined with the real-scale operating conditions parameters, the hydrodynamic performance parameters of the composite material propeller under the current real-scale operating conditions are determined.
8. The hydrodynamic performance testing method according to claim 6, characterized in that, The hydrodynamic performance parameters include thrust and torque. The hydrodynamic performance coefficients of the composite material model propeller in each open-water test are obtained as follows: The composite material model propeller is controlled to rotate at a speed n according to the test conditions parameters. m Rotate, and use the test water cylinder at a flow rate V according to the test conditions parameters. m Flow generation; the thrust T of the composite material model propeller under the test conditions was measured using a propeller force gauge mounted on the composite material model propeller. m and torque Q m And the hydrodynamic performance coefficients, including the thrust coefficient, were calculated. Torque coefficient and propeller efficiency ρ is the density of the fluid medium.