Inverse method for reversely solving ice-induced propeller load based on shafting measurement

Abstract

The invention relates to an inverse method for reversely solving an ice-induced propeller load based on shafting measurement, which comprises the following steps of: acquiring a shafting measurement value by installing a telemetering system and a virtual extended local area network system on a shafting, verifying the measurement value according to the shafting measurement value, measuring data such as strain, torque and angular velocity of a full-size shafting, analyzing the dynamic condition of the shafting, and calculating the load of the ice-induced propeller. And establishing a shaft system and propeller continuous mass model, establishing a transfer function, establishing an inverse solution inverse method, and obtaining the ice-induced propeller load. Compared with a shafting measurement mode only adopting a telemetering system, the inverse method provided by the invention has the advantages that the interference and noise of measurement can be obviously reduced, and the accuracy and effectiveness of measured data are improved; compared with a traditional method for directly measuring the ice-induced propeller load by installing a sensor on a propeller blade, the method has the advantages that transformation of a relatively fragile propeller blade structure can be avoided, so that the structural strength of the propeller is improved, the service life of the propeller is prolonged, and the problem that the ice-induced propeller load of an existing polar icebreaker is difficult to measure is solved.

Description

Technical Field

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

[0002] As the global climate gradually warms, the opening of polar routes becomes possible, and the center of international shipping will inevitably shift to the polar regions in the future. Compared with the southern sea route between the Far East and Europe, the Arctic route can shorten the sailing distance by 60%, which means there are huge potential economic benefits. In addition, 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 the exploration, development, transportation and scientific research of resources in the polar regions.

[0003] When an icebreaker sails in an area of ​​broken ice and floating ice, some of the broken ice and floating ice slide to the bottom of the ship and enter the flow field in front of the propeller. Then, under the action of the suction flow, they impact and cut the high-speed rotating propeller, causing the propeller blades to deform and damage, directly affecting the propulsion efficiency of the ship, and even causing serious noise, vibration, speed and economic indicators to decline. Therefore, the study of ice-induced propeller loads has very important engineering significance and application value for the structural design and strength analysis of ship propellers in ice areas.

[0004] At present, the conventional method of obtaining ice-induced propeller loads is based on a direct measurement method by installing sensors on the propeller. For example, scholars from Harbin Engineering University obtained ice-induced propeller loads through propeller dynamometers and signal test and analysis systems; scholars from the China Ship Science Research Center obtained ice-induced propeller loads by fixing measurement sensors on the hollow hub. The conventional direct measurement method of ice-induced propeller loads requires the installation of sensors on the propeller blades, so the propeller structure needs to be modified to arrange the entire measurement device. However, this modification of the propeller structure often reduces the structural strength of the propeller, thereby affecting the aerodynamic performance and vibration performance of the propeller. Summary of the invention

[0005] In order to solve the problem that it is difficult to measure the ice-induced propeller load of existing polar icebreakers, the present invention provides an inverse method for inversely solving the ice-induced propeller load based on shaft system measurement. The indirect measurement method can avoid the modification of 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 shaft system measurement, comprising the following steps:

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

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

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

[0010] Step 4: Establish continuous mass model of shaft system and propeller: Establish continuous modal superposition model for shaft system 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 shaft system measurement device in step 1 includes a telemetry system and a virtual extended local area network system.

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

[0016] Setting 2.1, input the 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, of which 4 strain gauges measure the maximum shear stress on the outer surface of the shaft system, and are arranged at an angle of 45° relative to the horizontal midplane of the shaft; the other 4 strain gauges measure the axial strain of the shaft, and are arranged 2 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 transmission shaft:

[0022]

[0023] Wherein, 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 the inverse method of the inverse solution including the following sub-steps:

[0025] Step 6.1. Input the measured shaft strain, torque and angular velocity: Input the strain, torque, angular velocity and other data obtained by measuring the full-size shaft system;

[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 sub-model: for propeller dynamics, correct the shaft system torque calculated at the end connected to the propeller;

[0029] Step 6.5, output the ice-induced propeller load obtained by the inverse solution: Finally, output the ice-induced propeller load 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 They represent the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L];

[0033] Angular displacement of drive shaft It can be expressed as the orthogonal mode vibration shape Y n With the time-varying generalized coordinate 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 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] The present invention proposes an inverse method for inversely solving ice-induced propeller loads based on shafting measurement, which solves the problem that ice-induced propeller loads of existing polar icebreakers are difficult to measure, and provides an inverse method for inversely solving ice-induced propeller loads based on shafting measurement. Compared with the traditional method of directly measuring ice-induced propeller loads by installing sensors on propeller blades, it can avoid modifying the relatively fragile propeller blade structure, thereby improving the structural strength and service life of the propeller. The method adopts a shafting measurement method combining a telemetry system and a virtual extended local area network, which can significantly reduce the interference and noise of the measurement and improve the accuracy and effectiveness of the measurement data compared with the shafting measurement method using only a telemetry system. 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 inverse solution

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

[0042] Figure 4 This is a schematic diagram of the strain gauge arrangement in shaft measurement. DETAILED DESCRIPTION

[0043] Combine the following Figures 1 to 4 The specific implementation mode of the present invention is described as follows: An inverse method for solving ice-induced propeller loads based on shaft system measurement is proposed in the embodiment of the present invention, 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 the accuracy of the measurement;

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

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

[0047] Step 4: Establish continuous mass model of shaft system and propeller: Establish continuous modal superposition model for shaft system 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, obtaining 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 shaft strain, torque and angular velocity: Input the strain, torque, angular velocity and other data obtained by measuring the full-size shaft system;

[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 sub-model: for propeller dynamics, correct the shaft system torque calculated at the end connected to the propeller;

[0056] Step 6.5, outputting the ice-induced propeller load obtained by the inverse solution: Finally, outputting the ice-induced propeller load 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 includes 8 strain gauges (strain gauge 1 to strain gauge 8, wherein strain gauges 1 to strain gauge 4 measure the maximum shear stress on the outer surface of the shaft system, and are arranged at an angle of 45° relative to the horizontal midplane of the shaft; in addition, strain gauges 5 to strain gauge 8 measure the axial strain of the shaft, and are arranged with 2 parallel to the horizontal midplane of the shaft and 2 perpendicular to the horizontal midplane of the shaft.

[0064] The continuous mass model 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:

[0065]

[0066] Wherein, 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 submodel 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 They represent the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L];

[0070] Angular displacement of drive shaft It can be expressed as the orthogonal mode vibration shape Y n With the time-varying generalized coordinate η n Sum of products:

[0071]

[0072] The inverse propeller submodel is different from the inverse shafting submodel in that 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] The present embodiment is only an exemplary description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit 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 measured values ​​of shaft strain, torque, and angular velocity obtained by the shaft measurement device to ensure the correctness of the measurement method and device and the accuracy of the measurement; Step 2: Measure the full-size shaft strain, torque, and angular velocity data: Use the full-size measurement method to measure and collect the shaft strain, torque, and angular velocity data to obtain dynamic data in all directions of the shaft measurement points to ensure data accuracy; Step 3: Analyze the dynamics of the shaft system: Analyze the effects of cavitation and ice impact on the shaft system dynamics through time and frequency domains; Step 4: Establish continuous mass model of shaft system and propeller: Establish continuous modal superposition model for shaft system 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 inversely solving ice-induced propeller loads based on shafting measurement according to claim 1 is characterized in that: The shaft system measurement device in step 1 includes a telemetry system and a virtual extended local area network system.

3. The inverse method for inversely solving ice-induced propeller loads based on shafting measurement according to claim 1 is characterized in that: The measurement of full-scale shaft strain, torque, and angular velocity data in step 2 includes the following four different input settings: Setting 2.1, input the 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 inversely solving ice-induced propeller loads based on shafting measurement according to claim 3 is characterized in that: Each sensor contains 8 strain gauges, of which 4 strain gauges measure the maximum shear stress on the outer surface of the shaft system, and are arranged at an angle of 45° relative to the horizontal midplane of the shaft; the other 4 strain gauges measure the axial strain of the shaft, and are arranged with 2 parallel to the horizontal midplane of the shaft and 2 perpendicular to the horizontal midplane of the shaft.

5. The inverse method for inversely solving ice-induced propeller loads based on shafting measurement according to claim 1 is characterized in that: 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: Wherein, 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 inversely solving ice-induced propeller loads based on shafting measurement according to claim 1 is characterized in that: Step 6: Establishing the inverse method of the inverse solution includes the following sub-steps: Step 6.

1. Input the measured shaft strain, torque and angular velocity: Input the strain, torque, angular velocity and other data obtained by measuring the full-size shaft system; 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 sub-model: for propeller dynamics, correct the shaft system torque calculated at the end connected to the propeller; 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 inversely solving ice-induced propeller loads based on shafting measurement according to claim 6 is characterized in that: 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 They represent the inertia, damping and stiffness of the transmission shaft, respectively, x = [0, L]; Angular displacement of drive shaft Expressed as orthogonal mode shape Y n With the time-varying generalized coordinate η n Sum of products:

8. The inverse method for inversely solving ice-induced propeller loads based on shafting measurement according to claim 6 is characterized in that: The inverse propeller submodel in step 6.4 is different from the inverse shafting submodel. It only considers 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:

Images