Ice load analysis method based on interaction of free crushed ice and propeller

Abstract

The invention discloses an ice load analysis method for interaction of free crushed ice and a propeller, and relates to the technical field of water power and safety evaluation of ship propellers in ice areas, and the method comprises the following steps: obtaining a propeller model ice-water mixed load measurement device according to the structural design of the ship propeller; and arranging the mixed load in a test pool paved with a free floating crushed ice model, and carrying out a multi-component load measurement test under a target test working condition to obtain mixed load time calendar data. In the test pool without the crushed ice model, an open water test is carried out under the target test working condition, and hydrodynamic load time calendar data are obtained. And determining ice load time-calendar data according to the mixed load time-calendar data and the hydrodynamic load time-calendar data, performing statistical analysis, and determining ice load characteristic parameters of interaction between the propeller and the free crushed ice. The problem that a traditional method can only analyze ice load characteristics of interaction of constraint ice and a propeller is solved.

Description

Technical Field

[0001] The present application relates to the technical field of hydrodynamics and safety assessment of ship propellers in ice areas, and in particular to an ice load analysis method for the interaction between free crushed ice and a propeller. Background Art

[0002] When polar ships sail in ice areas, the propellers will inevitably collide and interact with ice. The propellers are not only subject to the hydrodynamic loads of the fluid, but also to the ice loads of the ice-propeller contact. Therefore, analyzing the ice load characteristics of the interaction between the propeller and ice is of great significance for the safety assessment of propellers in ice areas.

[0003] At present, the simulation of the interaction between propeller and ice at home and abroad usually uses a model experiment of milling action between a constrained ice model and a propeller, supplemented by synchronous shooting with a high-speed camera to analyze the data. This method can measure the ice load data of the interaction between constrained ice and propeller. However, since there is often a large amount of free-floating broken ice on the water surface, the contact position, speed, ice size and crushing method of the ice propeller during the high-speed rotation of the propeller make the ice load of the ice propeller contact disordered and random as a whole. Therefore, this method cannot accurately obtain the ice load characteristics of the interaction between the propeller and ice. Summary of the invention

[0004] In view of the above problems and technical requirements, this application proposes an ice load analysis method for the interaction between free ice and propeller. The technical solution of this application is as follows:

[0005] An ice load analysis method for interaction between free crushed ice and a propeller comprises the following steps:

[0006] A propeller model ice-water mixed load measuring device is obtained according to the structural design of the ship propeller, and the propeller model ice-water mixed load measuring device includes a single blade;

[0007] Spreading a crushed ice model in a test water pool so that the crushed ice model floats freely on the surface of the test water pool, arranging a propeller model ice-water mixed load measuring device in the test water pool, controlling the propeller model ice-water mixed load measuring device to drive the blades to rotate under target test conditions to carry out a multi-component load measurement test, and obtaining mixed load time history data;

[0008] In a test pool without a crushed ice model, the propeller model ice-water mixed load measuring device is controlled to conduct an open water test under target test conditions, and the hydrodynamic load time history data is obtained;

[0009] Determine ice load time history data according to mixed load time history data and hydrodynamic load time history data, wherein the ice load time history data is the ice load received by a single blade in an ice-water mixed load measuring device of a propeller model at different moments during the rotation process;

[0010] The ice load time history data were statistically analyzed to determine the ice load characteristic parameters of the interaction between the propeller and free ice in the ship propulsion system.

[0011] A further technical solution is to statistically analyze the ice load history data to determine the ice load characteristic parameters of the interaction between the propeller and the free ice in the ship propeller, including:

[0012] According to the blade rotation speed under the target test conditions, the ice load history data during the period when the blade contacts the crushed ice model in each rotation cycle is selected as the single blade ice load data in each rotation cycle;

[0013] The ice load characteristic parameters are determined by statistical analysis of the single blade ice load data in each rotation cycle.

[0014] A further technical solution is to statistically analyze the ice load data of a single blade in each rotation cycle to determine the ice load characteristic parameters including:

[0015] The peak value of the single blade ice load data in each rotation cycle is determined, and the peak value of the single blade ice load data in each rotation cycle is statistically analyzed to determine the ice load characteristic parameters. The ice load characteristic parameters include single blade ice load distribution parameters and blade-ice collision parameters. The blade-ice collision parameters indicate the collision of a single blade with the crushed ice model in each rotation cycle.

[0016] A further technical solution is to select the ice load history data during the period when the blade contacts the crushed ice model in each rotation cycle as the single blade ice load data in each rotation cycle, including:

[0017] The contact time t of a single blade with the crushed ice model in each rotation cycle is determined according to the blade rotation speed under the target test conditions, and the single blade ice load data in each rotation cycle is screened out from the ice load history data according to the contact time t.

[0018] A further technical solution is to select single blade ice load data in each rotation cycle from the ice load history data according to the contact time t, including:

[0019] The rotation period T is determined according to the blade speed under the target test conditions, and the contact time of a single blade with the crushed ice model in each rotation period is determined in combination with the number of blades Z included in the ship propeller.

[0020] Filter out the nth rotation cycle within the time period The ice load time history data in is used to obtain the single blade ice load data in the nth rotation cycle, where n is an integer parameter.

[0021] A further technical solution is to statistically analyze the peak values ​​of the single blade ice load data in each rotation cycle to determine the single blade ice load distribution parameters including:

[0022] The maximum value of the peak values ​​of the single blade ice load data in all rotation cycles is determined to obtain the maximum ice load, and / or the distribution of the peak values ​​of the single blade ice load data in each rotation cycle in different value intervals is counted.

[0023] A further technical solution is to statistically analyze the peak value of the ice load data of a single blade in each rotation cycle to determine the ice load characteristic parameters, and further include:

[0024] The peak values ​​of ice load data of a single blade in each rotation cycle when a single blade collides with the crushed ice model are statistically analyzed to determine the distribution of the peak values ​​of ice load data of a single blade in each rotation cycle when a single blade collides with the crushed ice model in different value ranges.

[0025] A further technical solution is to statistically analyze the peak values ​​of ice load data of a single blade in each rotation cycle to determine the parameters of blade-ice collision, including:

[0026] When the peak value of the ice load data of a single blade in a rotation cycle reaches k times the peak value of the hydrodynamic load, a blade-ice collision condition parameter indicating that the blade has collided with the crushed ice model in the rotation cycle is obtained, otherwise a blade-ice collision condition parameter indicating that the blade has not collided with the crushed ice model in the rotation cycle is obtained, and the hydrodynamic load peak value is the peak value in the hydrodynamic load time history data;

[0027] The parameters of the propeller-ice collision in each rotation cycle are counted to determine the number and proportion of collisions between the propeller blade and the crushed ice model.

[0028] A further technical solution is to process the hydrodynamic load time history data F water The average hydrodynamic load is obtained by averaging According to the mixed load history data F hybrid and the average hydrodynamic load Ice load history data for determining the ice load on a single blade of a propeller model in contact with a free ice model

[0029] A further technical solution is to divide the value intervals according to multiples of the hydrodynamic load peak value when the peak value of the single blade ice load data in each rotation cycle is distributed in different value intervals.

[0030] The beneficial technical effects of this application are:

[0031] The present application proposes an ice load analysis method for the interaction between free crushed ice and a propeller. By obtaining mixed load time history data through a multi-component load measurement test in a test pool spread with a free-floating crushed ice model, and performing statistical analysis on the mixed load time history data obtained from an open water test, the characteristic parameters of the ice load for the interaction between the propeller and the free crushed ice can be effectively determined, which solves the limitation problem that the traditional method can only analyze the ice load for the interaction between constrained ice and the propeller.

[0032] By subtracting the hydrodynamic load time history data from the mixed load time history data to eliminate the influence of the hydrodynamic load, the ice load time history data of the interaction between the propeller and the free ice can be analyzed more accurately, and the ice load characteristic parameters with scientific and regularity can be obtained, making the ice load characteristic parameters more valuable for guidance. By statistically analyzing the parameters of the ice load distribution of a single blade and the parameters of the propeller-ice collision, technical support is provided for the safety assessment of propellers when ships are sailing in ice areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of ice load analysis method.

[0034] Figure 2 It is a single blade mixed load time history data curve.

[0035] Figure 3 It is a curve diagram of single blade ice load time history data.

[0036] Figure 4 is the single blade ice load distribution diagram. DETAILED DESCRIPTION

[0037] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0038] This application proposes an ice load analysis method for interaction between free crushed ice and propeller, which can determine the ice load characteristic parameters of interaction between propeller and free crushed ice. Please refer to Figure 1 The ice load analysis method flow chart is shown in the figure. The specific steps are as follows:

[0039] Step 1: According to the structural design of the ship propeller, a propeller model ice-water mixed load measuring device is obtained. The propeller model ice-water mixed load measuring device includes a single blade. For the specific structure of the propeller model ice-water mixed load measuring device, please refer to patent 201810648934.4 applied for by the applicant.

[0040] Step 2: Spread the crushed ice model in the test pool so that the crushed ice model floats freely on the surface of the test pool, and place the propeller model ice-water mixed load measurement device in the test pool to simulate the real crushed ice area channel. Control the propeller model ice-water mixed load measurement device to drive the blade to rotate under the target test conditions to carry out multi-component load measurement tests, and obtain the mixed load time history data of the interaction between a single blade and the free crushed ice model to obtain the mixed load on a single blade at different times. The mixed load includes a mixed load of multiple directional components, with the axial component F x Take the example to illustrate that the axial force F x The single blade mixed load time history data is as follows Figure 2 shown.

[0041] Step 3: In a test pool without a crushed ice model, control the propeller model ice-water mixed load measurement device to perform an open water test under the target test conditions, and obtain the hydrodynamic load history data to obtain the hydrodynamic load on a single blade at different times. The target experimental conditions of the open water test are the same as the target test conditions of the multi-component load measurement test in step 2.

[0042] Step 4: determine ice load history data according to the mixed load history data and the hydrodynamic load history data. The ice load history data is the ice load received by a single blade in the propeller model ice-water mixed load measuring device at different moments during the rotation process.

[0043] Since the mixed loads on a single blade during rotation mainly include ice loads caused by blade-ice contact and hydrodynamic loads caused by blade-water contact, in one embodiment, the hydrodynamic load time history data F water The average hydrodynamic load is obtained by averaging According to the mixed load history data F hybrid and the average hydrodynamic load Ice load history data for determining the ice load on a single blade of a propeller model in contact with a free ice model

[0044] Step 5: Statistically analyze the ice load history data to determine the ice load characteristic parameters of the interaction between the propeller and the free ice in the ship's propeller.

[0045] In one embodiment, a specific method for determining ice load characteristic parameters of the interaction between the propeller and free crushed ice is as follows:

[0046] (1) According to the blade rotation speed under the target test conditions, the ice load history data during the period when the blade contacts the crushed ice model in each rotation cycle is selected as the single blade ice load data in each rotation cycle.

[0047] In one embodiment, the contact time t of a single blade with the crushed ice model in each rotation cycle is determined according to the blade speed under the target test condition, and the ice load data of a single blade in each rotation cycle is screened out from the ice load history data according to the contact time t. The specific screening method is: the rotation cycle T is determined according to the blade speed under the target test condition, and the contact time t of a single blade with the crushed ice model in each rotation cycle is determined in combination with the number of blades Z included in the ship propeller. Filter out the nth rotation cycle within the time period The ice load time history data in the above table are used to obtain the single blade ice load data within the nth rotation period, where n is an integer parameter representing the number of propeller rotation periods of the ship propeller.

[0048] The propeller model ice-water mixed load measurement device of the present application is manufactured according to the specific geometry and structural characteristics of the propeller and the ice load measurement requirements of the propeller contact. Therefore, the blade speed is consistent with the propeller speed of the actual ship's propeller, which is 3r / s, and the rotation period T=0.33s can be calculated. The propeller of the ship's propeller is a 7-blade large side-skew propeller, so it is determined that the contact time t=0.047s of a single blade with the crushed ice model in each rotation cycle, and the ice load time history data of a single blade in contact with the crushed ice model in each rotation cycle is extracted to obtain the single blade ice load data of each rotation cycle, such as Figure 3 shown.

[0049] (2) Statistical analysis is performed on the single blade ice load data in each rotation cycle to determine the ice load characteristic parameters.

[0050] In one embodiment, a specific method for performing statistical analysis on single blade ice load data is as follows: determining a peak value of the single blade ice load data within each rotation cycle, performing statistical analysis on the peak value of the single blade ice load data within each rotation cycle to determine ice load characteristic parameters, the ice load characteristic parameters including single blade ice load distribution parameters and blade-ice collision parameters, the blade-ice collision parameters indicating the collision of a single blade with a crushed ice model within each rotation cycle.

[0051] The specific method for determining the single blade ice load distribution parameters by statistically analyzing the peak values ​​of the single blade ice load data in each rotation cycle is as follows:

[0052] The value intervals are divided according to the multiples of the hydrodynamic load peak value, and the distribution of the peak values ​​of the single blade ice load data in each rotation cycle in different value intervals is analyzed. The specific analysis includes the following two aspects:

[0053] (1) Determine the maximum value of the peak values ​​of the ice load data of the single blade in all rotation cycles to obtain the maximum ice load, and / or, count the distribution of the peak values ​​of the ice load data of the single blade in each rotation cycle in different value intervals.

[0054] (2) A statistical analysis is performed on the peak values ​​of the ice load data of the single blade in each rotation cycle when the single blade collides with the crushed ice model to determine the distribution of the peak values ​​of the ice load data of the single blade in each rotation cycle when the single blade collides with the crushed ice model in different value ranges.

[0055] The specific method for determining the propeller-ice collision parameters by statistically analyzing the peak values ​​of the single blade ice load data in each rotation cycle is as follows:

[0056] When the peak value of the single blade ice load data within a rotation cycle reaches k times the peak value of the hydrodynamic load, a blade-ice collision condition parameter is obtained, indicating that the blade has collided with the crushed ice model within the rotation cycle; otherwise, a blade-ice collision condition parameter is obtained, indicating that the blade has not collided with the crushed ice model within the rotation cycle; the hydrodynamic load peak value is the peak value in the hydrodynamic load time history data, k is a positive number greater than or equal to 1, and the specific value of k can be determined according to actual conditions. In this application, k=2; the blade-ice collision condition parameters in each rotation cycle are counted to determine the number of times and proportions of collisions between the blade and the crushed ice model.

[0057] This application uses the max function of the script program to extract the peak values ​​of the single blade ice load data and the hydrodynamic load history data, and uses the sorting function to sort the single blade ice load data. The multiples of the hydrodynamic load peak value are used as different value intervals, and the distribution of the peak value of the single blade ice load data in each value interval is counted, such as Figure 4 The peak value of the hydrodynamic load shown is 18N, and the value ranges are 0-1 times, 1-2 times, 2-3 times, 3-4 times, 4-5 times, and 6-7 times the peak value of the hydrodynamic load. Among them, the single blade ice load is mainly distributed between 18N-90N. There is a 4% probability of generating a strong ice load during the rotation of the propeller, which is distributed in the value range of 108N-126N. The difference in the size of the single blade ice load within the value range is mainly due to the size of the crushed ice model and the different positions and speeds of the propeller-ice contact. Since the peak value of the single blade ice load data is 1 times or more of the hydrodynamic load peak, it can be determined that the blade has collided with the crushed ice model during the rotation cycle. Therefore, Figure 4 It can be seen that the number of propeller-ice collisions is 65% of the total number of propeller rotations.

[0058] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A method for analyzing ice loads of free crushed ice interacting with a propeller, characterized in that: The ice load analysis method comprises: A propeller model ice-water mixed load measuring device is obtained according to the structural design of the ship propeller, and the propeller model ice-water mixed load measuring device includes a single blade; Spreading a crushed ice model in a test water pool so that the crushed ice model floats freely on the surface of the test water pool, arranging a propeller model ice-water mixed load measuring device in the test water pool, controlling the propeller model ice-water mixed load measuring device to drive the blades to rotate under target test conditions to carry out a multi-component load measurement test, and obtaining mixed load time history data; In a test water pool without a crushed ice model, controlling the propeller model ice-water mixed load measuring device to perform an open water test under the target test conditions, and obtaining hydrodynamic load time history data; Determine ice load time history data according to the mixed load time history data and the hydrodynamic load time history data, wherein the ice load time history data is the ice load received by a single blade in a propeller model ice-water mixed load measuring device at different moments during the rotation process; The ice load time history data is statistically analyzed to determine ice load characteristic parameters of the interaction between the propeller and free ice in the ship propeller.

2. The ice load analysis method according to claim 1, characterized in that: The statistical analysis of the ice load history data to determine the ice load characteristic parameters of the interaction between the propeller and the free ice in the ship propeller includes: According to the blade rotation speed under the target test condition, the ice load history data during the period when the blade contacts the crushed ice model in each rotation cycle are selected as the single blade ice load data in each rotation cycle; The ice load characteristic parameters are determined by statistical analysis of the single blade ice load data in each rotation cycle.

3. The ice load analysis method according to claim 2, characterized in that: The statistical analysis of the ice load data of the single blade in each rotation cycle to determine the ice load characteristic parameters includes: The peak value of the single blade ice load data in each rotation cycle is determined, and the peak value of the single blade ice load data in each rotation cycle is statistically analyzed to determine ice load characteristic parameters, wherein the ice load characteristic parameters include single blade ice load distribution parameters and blade-ice collision parameters, and the blade-ice collision parameters indicate the collision condition of a single blade with a crushed ice model in each rotation cycle.

4. The ice load analysis method according to claim 2, characterized in that: The step of selecting the ice load history data during the period when the blade contacts the crushed ice model in each rotation cycle as the single blade ice load data in each rotation cycle includes: The contact time t of a single blade with the crushed ice model in each rotation cycle is determined according to the blade rotation speed under the target test condition, and the single blade ice load data in each rotation cycle is screened out from the ice load history data according to the contact time t.

5. The ice load analysis method according to claim 4, characterized in that: The step of selecting the single blade ice load data in each rotation cycle from the ice load history data according to the contact time t includes: The rotation period T is determined according to the blade speed under the target test condition, and the contact time of a single blade with the crushed ice model in each rotation period is determined in combination with the number of blades Z included in the ship propeller. Filter out the nth rotation cycle within the time period The ice load time history data in is used to obtain the single blade ice load data in the nth rotation cycle, where n is an integer parameter.

6. The ice load analysis method according to claim 3, characterized in that: The peak values ​​of the single blade ice load data in each rotation cycle are statistically analyzed to determine the single blade ice load distribution parameters, including: The maximum value of the peak values ​​of the single blade ice load data in all rotation cycles is determined to obtain the maximum ice load, and / or the distribution of the peak values ​​of the single blade ice load data in each rotation cycle in different value intervals is counted.

7. The ice load analysis method according to claim 3, characterized in that: The ice load characteristic parameters determined by statistical analysis of the peak values ​​of the single blade ice load data in each rotation cycle also include: The peak values ​​of ice load data of a single blade in each rotation cycle when a single blade collides with the crushed ice model are statistically analyzed to determine the distribution of the peak values ​​of ice load data of a single blade in each rotation cycle when a single blade collides with the crushed ice model in different value ranges.

8. The ice load analysis method according to claim 3, characterized in that: The peak values ​​of the single blade ice load data in each rotation cycle are statistically analyzed to determine the parameters of the blade-ice collision condition, including: When the peak value of the ice load data of a single blade in a rotation cycle reaches k times the peak value of the hydrodynamic load, a blade-ice collision condition parameter indicating that the blade has collided with the crushed ice model in the rotation cycle is obtained, otherwise a blade-ice collision condition parameter indicating that the blade has not collided with the crushed ice model in the rotation cycle is obtained, and the hydrodynamic load peak value is the peak value in the hydrodynamic load time history data; The parameters of the propeller-ice collision in each rotation cycle are counted to determine the number and proportion of collisions between the propeller blade and the crushed ice model.

9. The ice load analysis method according to claim 1, characterized in that: The hydrodynamic load time history data F water The average hydrodynamic load is obtained by averaging According to the mixed load history data F hybrid and the average hydrodynamic load Ice load history data for determining the ice load on a single blade of a propeller model in contact with a free ice model 10. The ice load analysis method according to claim 6 or 7, characterized in that: When the peak values ​​of ice load data of a single blade in each rotation cycle are distributed in different value intervals, the value intervals are divided according to the multiples of the peak value of the hydrodynamic load.

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