An inverse method for solving ice-induced propeller loads based on shafting measurements

Abstract

The present invention relates to an inverse method for inversely solving ice-induced propeller loads based on shafting measurements. The method involves installing a telemetry system and a virtual extended local area network system on the shafting to obtain shafting measurement values. The measurement values ​​are then verified based on these values, and full-scale shafting strain, torque, angular velocity, and other data are measured. The shafting dynamics are analyzed, and a continuous mass model of the shafting and propeller is established. A transfer function is established, and an inverse method for inverse solution is established to obtain the ice-induced propeller loads. Compared to shafting measurement methods that only use a telemetry system, the inverse method of the present invention can significantly reduce measurement interference and noise, thereby improving the accuracy and validity of measurement data. Compared to traditional methods of directly measuring ice-induced propeller loads by installing sensors on propeller blades, the inverse method of the present invention can avoid modifying the relatively fragile propeller blade structure, thereby improving the structural strength and service life of the propeller, and solving the problem of difficulty in measuring ice-induced propeller loads on existing polar icebreakers.

Description

Technical Field

[0001] The invention relates to an inverse method for inversely solving ice-induced propeller loads based on shafting measurement, and belongs to the technical field of propeller measurement. Background Art

[0002] As global warming becomes more widespread, the opening of polar shipping routes becomes possible, and the future center of international shipping is bound to shift to the polar regions. Compared to the southern sea route between the Far East and Europe, the Arctic route can shorten sailing distances by 60%, representing enormous potential economic benefits. Furthermore, the polar regions are rich in natural resources such as oil, natural gas, and coal. Therefore, polar icebreakers will play an increasingly important role in resource exploration, development, transportation, and scientific research in the polar regions.

[0003] When an icebreaker navigates through crushed ice and floating ice, some of the crushed and floating ice slides toward the bottom of the ship and enters the flow field in front of the propeller. Then, under the action of the suction flow, it impacts and cuts the high-speed propeller, causing deformation and damage to the propeller blades. This directly affects the ship's propulsion efficiency and can even cause severe noise and vibration, and reduce speed and economic indicators. Therefore, studying ice-induced propeller loads has important engineering significance and application value for the structural design and strength analysis of propulsion systems for ships in ice-covered areas.

[0004] Currently, the conventional method for obtaining ice-induced propeller loads is based on direct measurement using sensors installed on the propeller. For example, scholars from Harbin Engineering University obtained ice-induced propeller loads using a propeller dynamometer and signal test and analysis system; scholars from the China Ship Science Research Center obtained ice-induced propeller loads by fixing measurement sensors on a hollow propeller hub. Conventional direct measurement methods for ice-induced propeller loads require installing sensors on the propeller blades, which necessitates modifications to the propeller structure to arrange the entire measurement device. However, such modifications to the propeller structure often reduce the structural strength of the propeller, thereby affecting the propeller's aerodynamic and vibration performance. Summary of the Invention

[0005] In order to solve the problem that the ice-induced propeller loads of existing polar icebreakers are difficult to measure, the present invention provides an inverse method for solving the ice-induced propeller loads based on shaft system measurement. The indirect measurement method can avoid the need to modify the relatively fragile propeller blade structure, thereby improving the structural strength and service life of the propeller.

[0006] To achieve the above object, the technical solution of the present invention is: an inverse method for solving ice-induced propeller loads based on shafting measurements, comprising the following steps:

[0007] Step 1: Verify the measured values: Verify the shaft strain, torque, and angular velocity values ​​obtained by the shaft measurement device to ensure the correctness of the measurement method and device and to ensure the measurement accuracy.

[0008] Step 2: Measure full-scale shaft strain, torque, and angular velocity data: Use full-scale measurement to measure and collect shaft strain, torque, and angular velocity data, and obtain dynamic data in all directions of the shaft measurement points to ensure data accuracy.

[0009] Step 3: Analyze the dynamics of the shafting system: Analyze the effects of cavitation and ice impact on the shafting dynamics through time and frequency domains.

[0010] Step 4: Establish continuous mass model of shafting and propeller: Establish continuous modal superposition model of shafting and propeller;

[0011] Step 5: Establish transfer function: Determine the transfer function between the external ice-induced propeller torque and the measured internal shafting torque;

[0012] Step 6: Establish an inverse method for inverse solution: establish an inverse method through singular value decomposition, generalized singular value decomposition and regularization method;

[0013] Step 7. Obtain ice-induced propeller loads: The external ice-induced propeller loads are determined from the shafting measurement data.

[0014] Further: the shafting measurement device in step 1 includes a telemetry system and a virtual extended local area network system.

[0015] Further: Step 2 measures the full-scale shafting strain, torque, and angular velocity data, including the following four different input settings:

[0016] Setting 2.1, input angular deformation of sensor 1;

[0017] Setting 2.2, input the angular deformation of sensor 1 and the angular velocity of sensor 2;

[0018] Setting 2.3, input the angular deformation of sensor 1 and sensor 2;

[0019] Setting 2.4, input the angular deformation of sensor 1 and sensor 2, and the angular velocity of sensor 3.

[0020] Further: Each sensor contains 8 strain gauges, 4 of which measure the maximum shear stress on the outer surface of the shaft system, and are arranged at a 45° angle relative to the horizontal midplane of the shaft; the other 4 strain gauges measure the axial strain of the shaft, 2 of which are arranged parallel to the horizontal midplane of the shaft, and 2 perpendicular to the horizontal midplane of the shaft.

[0021] Further: The continuous mass model established in step 4 relies on the concept of modal superposition. By superimposing the modal vibration shapes, the angular displacement, velocity and acceleration along the axis with infinite degrees of freedom are calculated. The following relationship exists within the unit length of the drive shaft:

[0022]

[0023] Among them, J0 represents the mass moment of inertia per unit length of the transmission shaft, represents angular displacement, Q represents the internal torque of the transmission shaft, and M represents the external torque applied to the transmission shaft.

[0024] Further: Step 6 establishes an inverse method for inverse solution, including the following sub-steps:

[0025] Step 6.1. Input the measured shafting strain, torque, and angular velocity: Input the strain, torque, angular velocity, and other data obtained from full-scale shafting measurements;

[0026] Step 6.2, filter signal processing: remove interference and noise from the input measurement signal;

[0027] Step 6.3: Establish the inverse shafting sub-model: correct the strain, torque, and angular velocity of the shafting dynamics;

[0028] Step 6.4: Establish the inverse propeller submodel: Correct the shaft torque calculated at the end connected to the propeller for propeller dynamics.

[0029] Step 6.5. Output the ice-induced propeller loads obtained by the inverse solution: Finally, output the ice-induced propeller loads obtained by the inverse solution;

[0030] Further: The inverse shafting submodel in step 6.3 calculates the torque Q at the boundary based on the collected measurement data s (t) and angular velocity The formula is:

[0031]

[0032] Among them, Q s,1 (t) represents the torque at the end of the high-elastic coupling, Q s,2 (t) represents the torque at the connected propeller end, and the constant J s , c s , k s denote the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L];

[0033] Drive shaft angular displacement It can be expressed as the orthogonal mode shape Y n and time-varying generalized coordinates η n Sum of products:

[0034]

[0035] Further: The inverse propeller submodel in step 6.4 is different from the inverse shafting submodel. It only considers the rigid body discretization and output torque. According to the torque Q output by the inverse shafting sub-model s,2 (t) and angular acceleration Calculated, specifically the torque Q s,2 (t) minus propeller inertia moment Jp and angular acceleration The product of the first-order derivatives of is:

[0036]

[0037] The present invention has the following beneficial effects:

[0038] This invention proposes an inverse method for calculating ice-induced propeller loads based on shafting measurements. This method addresses the difficulty in measuring ice-induced propeller loads on existing polar icebreakers. Compared to traditional methods that directly measure ice-induced propeller loads by installing sensors on propeller blades, this method avoids modifying the fragile propeller blade structure, thereby improving the propeller's structural strength and service life. This method utilizes a shafting measurement method that combines a telemetry system with a virtual extended local area network. Compared to shafting measurement methods that rely solely on telemetry, this method significantly reduces measurement interference and noise, improving the accuracy and validity of the measured data. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Flowchart of the inverse method for solving ice-induced propeller loads based on shafting measurements

[0040] Figure 2 Flowchart of the inverse method for reverse solution

[0041] Figure 3 Structure and flow chart for shafting measurement

[0042] Figure 4 Schematic diagram of strain gauge arrangement in shafting measurement DETAILED DESCRIPTION

[0043] The following combination Figures 1 to 4 The specific embodiment of the present invention is described as follows: The embodiment of the present invention proposes an inverse method for solving ice-induced propeller loads based on shaft system measurement, such as Figure 1 As shown, the following steps are included:

[0044] Step 1: Verify the measured values: Verify the measured values ​​of shaft strain, torque, angular velocity, etc. obtained by the shaft measurement device to ensure the correctness of the measurement method and device and to ensure the measurement accuracy;

[0045] Step 2: Measure full-scale shafting strain, torque, angular velocity and other data: Use full-scale measurement to measure and collect shafting strain, torque, angular velocity and other data, and obtain dynamic data in all directions of the shafting measurement points to ensure data accuracy;

[0046] Step 3: Analyze the dynamics of the shafting system: Analyze the effects of cavitation and ice impact on the shafting dynamics through time and frequency domains.

[0047] Step 4: Establish continuous mass model of shafting and propeller: Establish continuous modal superposition model of shafting and propeller;

[0048] Step 5: Establish transfer function: Determine the transfer function between the external ice-induced propeller torque and the measured internal shafting torque;

[0049] Step 6: Establish an inverse method for inverse solution: establish an inverse method through singular value decomposition, generalized singular value decomposition and regularization method;

[0050] Step 7: Obtain ice-induced propeller loads: The external ice-induced propeller loads are determined from shafting measurement data.

[0051] Preferably: Step 6 establishes an inverse method for inverse solution, such as Figure 2 As shown, it includes the following sub-steps:

[0052] Step 6.1. Input the measured shafting strain, torque, and angular velocity: Input the strain, torque, angular velocity, and other data obtained from full-scale shafting measurements;

[0053] Step 6.2, filter signal processing: remove interference and noise from the input measurement signal;

[0054] Step 6.3: Establish the inverse shafting sub-model: correct the strain, torque, and angular velocity of the shafting dynamics;

[0055] Step 6.4: Establish the inverse propeller submodel: Correct the shaft torque calculated at the end connected to the propeller for propeller dynamics.

[0056] Step 6.5. Output the ice-induced propeller loads obtained by the inverse solution: Finally, output the ice-induced propeller loads obtained by the inverse solution;

[0057] Preferably, step 2 of measuring full-size shafting strain, torque, angular velocity and other data includes the following four different input settings:

[0058] Setting 2.1, input angular deformation of sensor 1;

[0059] Setting 2.2, input the angular deformation of sensor 1 and the angular velocity of sensor 2;

[0060] Setting 2.3, input the angular deformation of sensor 1 and sensor 2;

[0061] Setting 2.4, input the angular deformation of sensor 1 and sensor 2, and the angular velocity of sensor 3.

[0062] like Figure 3 As shown, the shaft system measurement device includes a telemetry system and a virtual extended local area network system.

[0063] like Figure 4 As shown, each sensor contains 8 strain gauges (strain gauges 1 to 8, of which strain gauges 1 to 4 measure the maximum shear stress on the outer surface of the shaft system and are arranged at a 45° angle relative to the horizontal midplane of the shaft; in addition, strain gauges 5 to 8 measure the axial strain of the shaft, of which two are arranged parallel to the horizontal midplane of the shaft and two are arranged perpendicular to the horizontal midplane of the shaft.

[0064] The continuous mass model relies on the concept of modal superposition. By superimposing the modal shapes, the angular displacement, velocity, and acceleration along the axis with infinite degrees of freedom are calculated. The following relationship exists per unit length of the drive shaft:

[0065]

[0066] Among them, J0 represents the mass moment of inertia per unit length of the transmission shaft, represents angular displacement, Q represents the internal torque of the transmission shaft, and M represents the external torque applied to the transmission shaft.

[0067] The inverse shafting sub-model calculates the torque Q at the boundary based on the collected measurement data s (t) and angular velocity The formula is:

[0068]

[0069] Among them, Q s,1 (t) represents the torque at the end of the high-elastic coupling, Q s,2 (t) represents the torque at the connected propeller end, and the constant J s , c s , k s denote the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L];

[0070] Drive shaft angular displacement It can be expressed as the orthogonal mode shape Y n and time-varying generalized coordinate η n Sum of products:

[0071]

[0072] The inverse propeller sub-model is different from the inverse shafting sub-model. It only considers the rigid body discretization and output torque. According to the torque Q output by the inverse shafting sub-model s,2 (t) and angular acceleration Calculated, specifically the torque Q s,2 (t) minus propeller moment of inertia J p and angular acceleration The product of the first-order derivatives of is:

[0073]

[0074] This embodiment is only an illustrative description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto. As long as they do not exceed the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. An inverse method for solving ice-induced propeller loads based on shafting measurements, characterized in that: The following steps are involved: Step 1: Verify the measured values: Verify the shaft strain, torque, and angular velocity values ​​obtained by the shaft measurement device to ensure the correctness of the measurement method and device and to ensure the measurement accuracy. Step 2: Measure full-scale shaft strain, torque, and angular velocity data: Use full-scale measurement to measure and collect shaft strain, torque, and angular velocity data, and obtain dynamic data in all directions of the shaft measurement points to ensure data accuracy. Step 3: Analyze the dynamics of the shafting system: Analyze the effects of cavitation and ice impact on the shafting dynamics through time and frequency domains. Step 4: Establish continuous mass model of shafting and propeller: Establish continuous modal superposition model of shafting and propeller; Step 5: Establish transfer function: Determine the transfer function between the external ice-induced propeller torque and the measured internal shafting torque; Step 6: Establish an inverse method for inverse solution: establish an inverse method through singular value decomposition, generalized singular value decomposition and regularization method; Step 7. Obtain ice-induced propeller loads: The external ice-induced propeller loads are determined from the shafting measurement data.

2. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 1 is characterized in that: The shafting measurement device in step 1 includes a telemetry system and a virtual extended local area network system.

3. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 1 is characterized by: The measurement of full-scale shafting strain, torque, and angular velocity data in step 2 includes the following four different input settings: Setting 2.1, input angular deformation of sensor 1; Setting 2.2, input the angular deformation of sensor 1 and the angular velocity of sensor 2; Setting 2.3, input the angular deformation of sensor 1 and sensor 2; Setting 2.4, input the angular deformation of sensor 1 and sensor 2, and the angular velocity of sensor 3.

4. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 3 is characterized by: Each sensor contains 8 strain gauges, 4 of which measure the maximum shear stress on the outer surface of the shaft system and are arranged at a 45° angle relative to the horizontal midplane of the shaft; the other 4 strain gauges measure the axial strain of the shaft, 2 of which are arranged parallel to the horizontal midplane of the shaft and 2 perpendicular to the horizontal midplane of the shaft.

5. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 1 is characterized by: The continuous mass model established in step 4 relies on the concept of modal superposition. By superimposing the modal vibration shapes, the angular displacement, velocity, and acceleration along the axis with infinite degrees of freedom are calculated. The following relationship exists within the unit length of the drive shaft: Among them, J0 represents the mass moment of inertia per unit length of the transmission shaft, represents angular displacement, Q represents the internal torque of the transmission shaft, and M represents the external torque applied to the transmission shaft.

6. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 1 is characterized by: Step 6: Establishing the inverse method for the inverse solution includes the following sub-steps: Step 6.

1. Input the measured shafting strain, torque, and angular velocity: Input the strain, torque, angular velocity, and other data obtained from full-scale shafting measurements; Step 6.2, filter signal processing: remove interference and noise from the input measurement signal; Step 6.3: Establish the inverse shafting sub-model: correct the strain, torque, and angular velocity of the shafting dynamics; Step 6.4: Establish the inverse propeller submodel: Correct the shaft torque calculated at the end connected to the propeller for propeller dynamics. Step 6.5: Output the ice-induced propeller loads obtained by the inverse solution: Finally, output the ice-induced propeller loads obtained by the inverse solution.

7. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 6 is characterized by: The inverse shafting submodel in step 6.3 calculates the torque Q at the boundary based on the collected measurement data. s (t) and angular velocity The formula is: Among them, Q s,1 (t) represents the torque at the end of the high-elastic coupling, Q s,2 (t) represents the torque at the connected propeller end, and the constant J s , c s , k s denote the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L]; Drive shaft angular displacement Expressed as orthogonal mode shape Y n and time-varying generalized coordinates η n Sum of products:

8. The inverse method for calculating ice-induced propeller loads based on shafting measurements according to claim 6 is characterized by: The inverse propeller submodel in step 6.4 is different from the inverse shafting submodel. It only considers the rigid body discretization and outputs the torque. According to the torque Q output by the inverse shafting sub-model s,2 (t) and angular acceleration Calculated, specifically the torque Q s,2 (t) minus propeller moment of inertia J p and angular acceleration The product of the first-order derivatives of is:

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