Method for evaluating energy-saving effect of energy-saving device in waves

Abstract

The invention discloses a method for evaluating the energy-saving effect of an energy-saving device in waves, test evaluation is performed through a ship model and the energy-saving device, the ship model is equipped with a self-propulsion power system, and a self-propulsion method in waves commonly adopted at present is replaced by a load self-propulsion method in still water, so that the energy-saving effect of the energy-saving device in the waves is evaluated. The method solves the problems of high uncertainty, high test cost and the like when a self-propulsion model test is directly carried out in waves at present, and achieves more accurate and efficient evaluation of the energy-saving effect of the energy-saving device in the waves under the condition of more controllable test conditions through a load self-propulsion method. According to the method, the energy-saving effect of the energy-saving device under the real marine navigation condition can be reflected, the energy-saving device can play the best effect under different marine conditions through design optimization, the ship can meet the strict requirements of environmental protection laws and regulations, the fuel cost in the operation cost can be remarkably reduced, and the energy-saving effect of the energy-saving device is improved. And long-term economic benefits are brought to ship owners.

Description

Technical Field

[0001] The invention relates to a method for evaluating the energy-saving effect of an energy-saving device in waves, and belongs to the technical field of ship performance evaluation. Background Art

[0002] As the International Maritime Organization (IMO) continues to raise its requirements for ship energy efficiency and carbon emission standards, the shipping industry faces major challenges in reducing greenhouse gas emissions and improving energy efficiency. Ship energy-saving devices have emerged and have been increasingly widely used in recent years. Energy-saving devices achieve the goal of energy conservation and emission reduction by improving the hydrodynamic performance of ships and the efficiency of propulsion systems. They not only help ships meet strict environmental regulations, but also significantly reduce fuel costs in operating costs, thereby bringing long-term economic benefits to shipowners.

[0003] At present, the design and effect verification of energy-saving devices are usually carried out in a still water environment. This is because the still water environment provides a relatively stable and easy-to-control basic condition, which is convenient for evaluating the basic performance of energy-saving devices. However, there are certain limitations to the energy-saving effect evaluation based on still water, which is mainly reflected in the complex and changeable marine environment. Ships will inevitably encounter the impact of wind and waves during actual navigation. Tests in still water cannot fully simulate the dynamic environment under these real conditions, resulting in the actual performance of energy-saving devices may be quite different from the model test results. Therefore, it is of great significance to verify the effect of energy-saving devices in wave environments, which can more accurately evaluate the performance of energy-saving devices under real navigation conditions, and then through design optimization, the energy-saving devices can play the best effect under different sea conditions.

[0004] There are two existing methods that can be used to evaluate the energy-saving effect of energy-saving devices in waves:

[0005] (1) The computational fluid dynamics (CFD) method is used to perform numerical simulation of the ship's self-propulsion in waves. The power required for propulsion with and without the energy-saving device is obtained, and the effect of the energy-saving device is determined by the difference between the two.

[0006] Disadvantages: The CFD numerical simulation method for self-propulsion in waves is not mature, and the calculation results are greatly affected by the quality of the grid, turbulence mode, time step, etc. The credibility of the conclusion is low without model test verification. In addition, the amount of calculation for CFD simulation is huge. It usually takes several days to carry out a working condition calculation. It can take several months to fully evaluate the performance of energy-saving devices in waves, and the time cost is too high. In summary, the CFD numerical simulation method is currently limited to research.

[0007] (2) Evaluation is carried out by conducting a self-propulsion model test of a ship model in waves. This method is to simulate the wave environment directly in a wave-making pool and conduct a self-propulsion test of a ship model in waves. The propeller speed and torque with and without the energy-saving device are obtained, thereby obtaining the power required for propulsion. The effect of the energy-saving device is judged by the power difference.

[0008] Disadvantages: Due to the influence of wave quality and ship model motion on force measurement accuracy, the uncertainty of evaluating the effect of energy-saving devices directly in waves is large, and the uncertainty of test results usually exceeds 10%, while the energy-saving effect of existing energy-saving devices is generally around 5%. Therefore, a large number of repetitive tests need to be carried out very carefully to reliably obtain the real energy-saving effect of energy-saving devices in waves. In addition, it is expensive to carry out self-propelled model tests with energy-saving devices directly in waves. A series of self-propelled model tests in different regular waves are required. After each test in waves, it takes a long time to wait for the water surface to calm before the next test can be carried out. Therefore, although the self-propelled model test method in waves is more reliable than CFD numerical simulation and is the only publicly available method that can be used to evaluate the energy-saving effect of energy-saving devices in waves and has engineering feasibility, it is still limited by problems such as low test accuracy, poor result reliability, and long test cycle, and needs further improvement and improvement. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a method for evaluating the energy-saving effect of an energy-saving device in waves, which replaces the currently commonly used self-propulsion method in waves with a load self-propulsion method in still water. Under more controllable test conditions, the energy-saving effect of the energy-saving device in waves can be evaluated more accurately and efficiently.

[0010] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0011] The present invention provides a method for evaluating the energy-saving effect of an energy-saving device in waves, and a test evaluation is performed through a ship model and an energy-saving device, wherein the ship model is equipped with a self-propulsion power system, and comprises the following steps:

[0012] Determine the speed V to be evaluated s and sea conditions to be assessed;

[0013] Speed ​​to be evaluated V s Under the conditions, the resistance of the ship model in still water was measured with and without the energy-saving device.

[0014] The rapid self-propulsion test in still water was carried out on ships with and without energy-saving devices to obtain the speed V to be evaluated. s The following two correspond to the propeller speed and propeller torque of the actual ship at the self-propulsion point;

[0015] Conduct wave resistance increase model tests on ships with energy-saving devices and ships without energy-saving devices respectively to obtain the average wave resistance increase of the two ships under the sea conditions to be evaluated;

[0016] Speed ​​to be evaluated V s Under the conditions of wave resistance increase, the corresponding average wave resistance increase loads were applied to the ship models with and without energy-saving devices, and rapid self-propulsion tests in still water were carried out to obtain the propeller speed and propeller torque corresponding to the real ship self-propulsion point under the wave resistance increase effect.

[0017] Based on the above experimental results, the power difference between the ship model with and without energy-saving devices is calculated to obtain an evaluation of the energy-saving effect.

[0018] Preferably, the wave resistance increase model test includes the following steps: simulating irregular waves under the sea conditions to be evaluated in a water tank; measuring the forces on the ship model when it is moving at the speed to be evaluated; taking the difference between the average value of the force when the force is applied and the resistance of the ship model in still water as the average wave resistance increase of the ship in the sea conditions to be evaluated.

[0019] Preferably, the sea condition to be evaluated is determined by the significant wave height Hs and the wave average zero-crossing period Tz.

[0020] Preferably, the load is applied via a trailer and a pulley mechanism fixed to the trailer.

[0021] Furthermore, the trailer is connected to the ship model via an airworthiness instrument mechanism.

[0022] Furthermore, the seakeeping instrument mechanism is a four-degree-of-freedom seakeeping instrument, and the ship model can move freely in four degrees of freedom, namely, surge, heave, pitch and roll, through the seakeeping instrument mechanism.

[0023] Furthermore, the airworthiness instrument mechanism is connected to the ship model via a single-component force balance.

[0024] Preferably, the self-propelled power system includes a servo motor, a propeller and a self-propelled power meter, the servo motor drives the propeller to rotate at a specified speed, and the self-propelled power is arranged between the servo motor and the propeller to measure the propeller torque.

[0025] Preferably, the ship model with the energy-saving device is at a speed V to be evaluated. s The expression of power during sailing is:

[0026] P W1 =2πλ 3 (n W1 Q W1 -n SW1 Q SW1 );

[0027] Ship model without energy-saving device to be evaluated for speed V s The expression of power during sailing is:

[0028] P W0 =2πλ 3 (n W0 Q W0 -n SW0 Q SW0 );

[0029] Where λ is the scale ratio selected for the model test, that is, the ratio of the length of the actual ship to the length of the ship model; n w1 n is the propeller speed of the ship model with energy-saving device when self-propulsion under load; sw1 n is the propeller speed of the ship model with energy-saving device when it is self-propelled in still water; w0 The propeller speed of the ship model without energy-saving device when the load is applied; n sw0 Q is the propeller speed of the ship model without energy-saving device when it is self-propelled in still water; w1 Q is the propeller torque of the ship model with energy-saving device when the load is applied; sw1 Q is the propeller torque of the ship model with energy-saving device when it is self-propelled in still water; w0 Q is the propeller torque of the ship model without energy-saving device when the load is applied; sw0 It is the propeller torque of the ship model without energy-saving device when it is self-propelled in still water.

[0030] Furthermore, the ship model with the energy-saving device and without the energy-saving device at the speed to be evaluated V s The power difference during down sailing is obtained by the following formula:

[0031] P ES =P W0 -P W1 .

[0032] The method for evaluating the energy-saving effect of an energy-saving device in waves provided by the present invention has the following advantages:

[0033] The method for evaluating the energy-saving effect of the energy-saving device in waves of the present invention solves the problems of high uncertainty and high test cost in the current self-propulsion model test directly in waves. Through the load self-propulsion method, the energy-saving effect of the energy-saving device in waves can be evaluated more accurately and efficiently under more controllable test conditions. The proposed method helps to reflect the energy-saving effect of the energy-saving device under real sailing conditions at sea, and then through design optimization, the energy-saving device can play the best effect under different sea conditions, which not only helps ships meet strict environmental protection regulations, but also significantly reduces the fuel cost in operating costs, bringing long-term economic benefits to ship owners. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A method flow chart of a method for evaluating the energy-saving effect of an energy-saving device in waves according to the present invention;

[0035] Figure 2 A schematic diagram of a load self-propulsion test method of a method for evaluating the energy-saving effect of an energy-saving device in waves according to the present invention;

[0036] Figure 3 Schematic diagram of the load self-propulsion test data analysis method Figure 1 ;

[0037] Figure 4 Schematic diagram of the load self-propulsion test data analysis method Figure 2 ;

[0038] In the figure:

[0039] 1-ship model; 2-self-propulsion power system; 21-servo motor; 22-propeller; 23-self-propulsion dynamometer; 3-trailer; 4-pulley mechanism; 5-load counterweight; 6-airworthiness instrument mechanism; 7-single-component force balance. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without creative work are within the scope of protection of the present invention.

[0041] The energy-saving device of the present invention is used to evaluate the energy-saving effect in a water pool by cooperating with a ship model 1 equipped with a self-propelled power system 2. The self-propelled power system 2 includes a servo motor 21, a propeller 22 and a self-propelled power meter 23. The servo motor 21 is installed on the ship model 1 to drive the propeller 22 to rotate at a specified speed. The self-propelled power is installed between the servo motor 21 and the propeller 22 to measure the thrust and torque of the propeller 22. In this embodiment, the use of the self-propelled power system 2 is a prior art and will not be described in detail.

[0042] Reference Figure 1 , a method for evaluating the energy-saving effect of an energy-saving device in waves designed by the present invention comprises the following steps;

[0043] S1, determine the ship speed and sea conditions to be evaluated, where the sea conditions to be evaluated are determined by two parameters: significant wave height Hs and wave average zero-crossing period Tz.

[0044] S2, speed to be evaluated V sUnder the condition of the above, a resistance test in still water is carried out to obtain the resistance of the ship model 1 in still water when the ship model 1 is with and without the energy-saving device.

[0045] S3, a rapid self-propulsion test in still water is carried out on ships with and without energy-saving devices, and the speed V to be evaluated is measured by a self-propulsion power instrument 23. s The following two correspond to the rotation speed of the propeller 22 and the torque of the propeller 22 at the actual ship's self-propulsion point.

[0046] S4, wave resistance increase model tests were carried out on ships with energy-saving devices and ships without energy-saving devices, irregular waves under the sea conditions to be evaluated were simulated in the water tank, and the speed V of the ship model 1 to be evaluated was measured. s The force during the forward movement is the average force R. w The difference between the resistance of the ship model 1 in still water obtained in step S1 is used as the average wave resistance increase of the ship in the sea condition to be evaluated.

[0047] S5, speed to be evaluated V s Under the conditions, the corresponding average wave resistance increase load is applied to the ship model 1 with the energy-saving device and the ship model 1 without the energy-saving device, and a rapid self-propulsion test in still water is carried out. The propeller 22 speed and propeller 22 torque corresponding to the real ship self-propulsion point under the wave resistance increase effect are measured by the self-propulsion dynamometer 23.

[0048] Considering that the cost of conducting self-propulsion tests directly in waves is high and the accuracy is low, the present invention applies a load of the same magnitude as the wave resistance increase to the ship model 1 through a set of pulley mechanisms 4, and conducts a self-propulsion model test in still water under this state. Figure 2 In this embodiment, the load of the ship model 1 is preferably applied by the trailer 3 and the pulley mechanism 4 fixed on the trailer 3. The ship model 1 is connected to the trailer 3 through the airworthiness instrument mechanism 6. The trailer 3 tows the ship model 1 to evaluate the speed V s The seaworthiness instrument mechanism 6 is a four-degree-of-freedom seaworthiness instrument. The ship model 1 can freely move in four degrees of freedom, namely, sway, pitch and roll, through the seaworthiness instrument mechanism 6. The seaworthiness instrument mechanism 6 is connected to the ship model 1 through a single-component force balance 7 to measure the force on the ship model 1. By placing a load counterweight block 5 of corresponding weight on the pulley mechanism 4, an additional load equal to the wave resistance increase can be generated on the ship model 1, and the load can be applied to the specified position of the ship model 1 by adjusting the position of the mechanism externally.

[0049] Reference Figure 3 and Figure 4When carrying out the load self-propulsion test, it is necessary to carry out multiple tests at the same propeller 22 speed for the same speed. Based on the tests of different propeller 22 speeds n, the corresponding compulsory force Z measured by the single-component force balance 7 of the airworthiness instrument and the torque Q of the propeller 22 measured by the self-propulsion dynamometer 23 can be obtained. First, according to the compulsory force F corresponding to the actual ship self-propulsion point D The interpolation value is the propeller 22 speed n corresponding to the actual ship self-propulsion point W , and then the propeller 22 torque Q corresponding to the actual ship self-propulsion point is obtained based on the interpolation of the speed W .

[0050] S5, based on the above experimental results, the power value increment of the ship model 1 when sailing with and without the energy-saving device in the self-propulsion state under load is predicted compared with the self-propulsion state in still water, and the difference between the two is used as the basis for evaluating the energy-saving effect of the energy-saving device in waves.

[0051] Specifically, the ship model 1 with the energy-saving device is to be evaluated at a speed V s The expression of power during sailing is:

[0052] p W1 =2πλ 3 (n W1 Q W1 -n SW1 Q SW1 );

[0053] Ship model 1 without energy-saving device to be evaluated for speed V s The expression of power during sailing is:

[0054] P W0 =2πλ 3 (n W0 Q W0 -n SW0 Q SW0 );

[0055] Where, λ is the scale ratio selected for the model test, that is, the ratio of the length of the actual ship to that of the ship model 1; n w1 is the speed of the propeller 22 of the ship model 1 with the energy-saving device when it is self-propelled when the load is applied; n sw1 is the speed of the propeller 22 of the ship model 1 with energy-saving device when it is self-propelled in still water; n w0 is the speed of the propeller 22 of the ship model 1 without the energy-saving device when the load is applied; n sw0 is the speed of the propeller 22 of the ship model 1 without the energy-saving device when it is self-propelled in still water; Q w1 Q is the torque of the propeller 22 of the ship model 1 with the energy-saving device when it is self-propelled when the load is applied; sw1 Q is the torque of the propeller 22 of the ship model 1 with energy-saving device when it is self-propelled in still water; w0Q is the torque of the propeller 22 of the ship model 1 when it is self-propelled without the energy-saving device when the load is applied; sw0 It is the torque of the propeller 22 when the ship model 1 without the energy-saving device is self-propelled in still water.

[0056] Furthermore, the ship model 1 with and without the energy-saving device at the speed V to be evaluated s The power difference during down sailing is obtained by the following formula:

[0057] P ES =P W0 -P W1 .

[0058] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for evaluating the energy-saving effect of an energy-saving device in waves, characterized in that: The test evaluation was conducted through a ship model and energy-saving device. The ship model was equipped with a self-propulsion power system, including the following steps; Determine the speed V to be evaluated s and sea conditions to be assessed; Speed ​​to be evaluated V s Under the conditions, the resistance of the ship model in still water was measured with and without the energy-saving device. The rapid self-propulsion test in still water was carried out on ships with and without energy-saving devices to obtain the speed V to be evaluated. s The following two correspond to the propeller speed and propeller torque of the actual ship at the self-propulsion point; Conduct wave resistance increase model tests on ships with energy-saving devices and ships without energy-saving devices respectively to obtain the average wave resistance increase of the two ships under the sea conditions to be evaluated; Speed ​​to be evaluated V s Under the conditions of wave resistance increase, the corresponding average wave resistance increase loads were applied to the ship models with and without energy-saving devices, and rapid self-propulsion tests in still water were carried out to obtain the propeller speed and propeller torque corresponding to the real ship self-propulsion point under the wave resistance increase effect. Based on the above experimental results, the power difference between the ship model with and without energy-saving devices is calculated to obtain an evaluation of the energy-saving effect.

2. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 1, characterized in that: The wave resistance increase model test comprises the following steps: Simulating irregular waves under the sea conditions to be evaluated in a water tank; Measuring the ship model to evaluate the speed V s The forces during the forward movement; Take the average value of the force R when the force is applied w The difference between the resistance of the ship model and the resistance of the ship model in still water is taken as the average wave resistance increase of the ship in the sea state to be evaluated.

3. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 1, characterized in that: The sea condition to be evaluated is determined by the significant wave height Hs and the wave average zero-crossing period Tz.

4. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 1, characterized in that: The load is applied via a trailer and a pulley mechanism fixed to the trailer.

5. A method for evaluating the energy-saving effect of an energy-saving device in waves as claimed in claim 4, characterized in that: The trailer is connected to the ship model via an airworthiness instrument mechanism.

6. A method for evaluating the energy-saving effect of an energy-saving device in waves as claimed in claim 5, characterized in that: The seakeeping instrument mechanism is a four-degree-of-freedom seakeeping instrument, and the ship model can freely move in four degrees of freedom, namely, surge, heave, pitch and roll, through the seakeeping instrument mechanism.

7. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 5, characterized in that: The airworthiness instrument mechanism is connected to the ship model via a single-component force balance.

8. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 1, characterized in that: The self-propulsion power system includes a servo motor, a propeller and a self-propulsion power meter. The servo motor drives the propeller to rotate at a specified speed. The self-propulsion power is arranged between the servo motor and the propeller to measure the propeller torque.

9. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 1, characterized in that: The ship model with the energy-saving device is at a speed V to be evaluated s The expression of power during sailing is: P W1 =2πλ 3 (n W1 Q W1 -n SW1 Q SW1 ); Ship model without energy-saving device to be evaluated for speed V s The expression of power during sailing is: P W0 =2πλ 3 (n W0 Q W0 -n SW0 Q SW0 ); Where λ is the scale ratio selected for the model test, that is, the ratio of the length of the actual ship to the length of the ship model; n w1 n is the propeller speed of the ship model with energy-saving device when self-propulsion under load; sw1 n is the propeller speed of the ship model with energy-saving device when it is self-propelled in still water; w0 The propeller speed of the ship model without energy-saving device when the load is applied; n sw0 Q is the propeller speed of the ship model without energy-saving device when it is self-propelled in still water; w1 Q is the propeller torque of the ship model with energy-saving device when the load is applied; sw1 Q is the propeller torque of the ship model with energy-saving device when it is self-propelled in still water; w0 Q is the propeller torque of the ship model without energy-saving device when the load is applied; sw0 It is the propeller torque of the ship model without energy-saving device when it is self-propelled in still water.

10. The method for evaluating the energy-saving effect of an energy-saving device in waves according to claim 9, characterized in that: The ship model with the energy-saving device and without the energy-saving device at the speed V to be evaluated s The power difference during down sailing is obtained by the following formula: P ES =P W0 -P W1 。

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