A real-time energy-saving effect method for a marine bubble drag reduction system

Abstract

A method for calculating the real-time energy-saving effect of a ship-mounted bubble drag reduction system, monitoring the navigation and environmental parameters of a ship equipped with a bubble drag reduction system, real-time calculation of the propulsion characteristics of a ship equipped with a bubble drag reduction system, real-time calculation of the energy consumption of the bubble drag reduction system, and real-time calculation of the energy-saving effect of the bubble drag reduction system. The present invention can be effectively applied to obtain real-time calculations of energy-saving effects of bubble drag reduction systems for actual ship applications. The established environmental parameter correction method effectively eliminates the influence of environmental conditions on the calculation results, and ensures the reliability of the calculation results. The entire set of calculation methods is simple to operate, has high calculation efficiency, and has good economy. It has been verified by actual ship applications that the real-time calculation method for energy-saving effects of bubble drag reduction systems established by the present invention has high accuracy and can be reliably applied to any ship equipped with a bubble drag reduction system.

Description

Technical Field

[0001] The invention belongs to the field of ship construction and design, and in particular relates to a real-time energy-saving effect method of a ship-used bubble drag reduction system. Background Art

[0002] Bubble drag reduction technology is an innovative energy-saving and emission-reduction technology for ships that continuously injects air into the bottom of the hull to form and maintain a certain air layer, thereby reducing the resistance of the ship during navigation and achieving energy saving and consumption reduction.

[0003] Regarding the evaluation of the energy-saving effect of the bubble drag reduction system, existing technical solutions mostly focus on the calculation of its contribution in the calculation process of the ship energy efficiency design index (EEDI). As a normally open system during the actual navigation of the ship, the bubble drag reduction system itself often works in non-EEDI assessment conditions. At this time, the energy saving situation needs to be comprehensively calculated based on various environmental conditions and system operation conditions. However, there is no reliable technical method for calculating the real-time energy-saving effect of the bubble drag reduction system at this stage. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a real-time energy-saving method for a marine bubble drag reduction system, and the technical solution adopted is:

[0005] A real-time energy-saving effect method for a marine bubble drag reduction system, the specific method is as follows:

[0006] S1: Monitor the real-time data of ship navigation and environment when the bubble drag reduction system is in normal operation, including: ship speed over ground Vs, main engine power Pe, displacement Δ, bow draft T f , stern draft T a , relative wind speed AWS, relative wind direction AWA, water depth Dp, wave height H WAVE , Yonggao H SWELL , flow velocity Vc, flow direction Dc, seawater temperature Tem_w, seawater density ρ S , temperature Tem_a, air pressure P_a, air density ρ A ;

[0007] S2: Using the navigation and environmental real-time data obtained in step S1 when the bubble drag reduction system is in normal operation as the calculation input, the speed Vs of the ship under this environmental condition without turning on the bubble drag reduction system is obtained. corr and power Pe corr , the specific method is as follows:

[0008] S2.1: Through the still water ship model test, the different ground speeds Vs_id of the ship equipped with the bubble drag reduction system under the conditions of no wind, no waves, no current and infinite water depth at the design draft, structural draft and ballast draft are obtained.i and the corresponding host power Pe_id i , (i=1,2,…,n), that is, the speed and power characteristics of the ship equipped with the bubble drag reduction system when it is in an ideal state;

[0009] S2.2: The environmental wind, wave, surge, seawater temperature, density, and displacement parameters obtained in step S1 when the bubble drag reduction system is in normal operation are converted into the increase or decrease value ΔP of the main engine power when the ship equipped with the bubble drag reduction system is in an ideal state. The calculation formula is as follows:

[0010]

[0011] Where η Did is the propulsion efficiency coefficient at the current draft and speed Vs when the ship equipped with the bubble drag reduction system is in an ideal state,

[0012] ξ P is the load factor, which can be obtained through still water ship model test.

[0013] ΔR is the resistance R caused by the ambient wind AA , resistance R caused by waves and surges WL , the resistance R caused by seawater temperature and density AS and the resistance R caused by displacement ADIS sum:

[0014] ΔR=R AA +R WL +R AS +R ADIS

[0015] Among them, the resistance caused by the ambient wind is R AA The calculation formula is as follows:

[0016]

[0017] In the formula, A XV It is the transverse projection area above the waterline of the ship equipped with the bubble drag reduction system, including the superstructure.

[0018] C AA ·(AWA) and C AA (0) are the drag coefficients when the relative wind direction is 0 degrees and AWA, respectively;

[0019] Resistance R caused by waves and surges WL The calculation formula is as follows:

[0020]

[0021] Where g is the acceleration due to gravity,

[0022] B is the width of the ship equipped with the bubble drag reduction system.

[0023] L BWL The distance from the bow of the ship equipped with the bubble drag reduction system to 95% of the maximum width of the waterline,

[0024] H 1 / 3 For the significant wave height:

[0025] Resistance R caused by ambient seawater temperature and density AS The calculation formula is as follows:

[0026]

[0027]

[0028]

[0029] In the formula, ρ S0 is the density of seawater under standard conditions. The standard condition is that the water temperature is 15°C and the density is 1026 kg / m 3 ,

[0030] R T0 is the total resistance in the reference state,

[0031] R F is the friction resistance of the ship equipped with the bubble drag reduction system in the current state,

[0032] S is the wet surface area of ​​the ship equipped with the bubble drag reduction system,

[0033] C T0 is the total resistance coefficient under standard conditions,

[0034] C F0 is the friction coefficient under standard conditions,

[0035] C F is the friction resistance coefficient of the ship equipped with the bubble drag reduction system in the current state,

[0036] C T0 , C F0 , C F It can be obtained through still water ship model test;

[0037] Resistance R caused by displacement ADIS The calculation formula is as follows:

[0038]

[0039] Where Δ0 is the displacement corresponding to the design draft, structural draft and ballast draft in the still water ship model test, which is closest to the current displacement Δ of the ship equipped with the bubble drag reduction system.

[0040] R T0 The total resistance of a ship equipped with a bubble drag reduction system at the above draft can be obtained through a still water ship model test;

[0041] (3) The flow velocity, flow direction, and water depth parameters obtained in S1 when the bubble drag reduction system is in normal operation are converted to the increase or decrease value ΔV of the ground speed compared to the ideal state of the ship equipped with the bubble drag reduction system. The calculation formula is as follows:

[0042] ΔV=ΔV c +ΔV d

[0043] Among them, the increase or decrease value of the ground speed caused by the flow velocity and flow direction is ΔV c The calculation is as follows:

[0044] The flow velocity Vc and the flow direction Dc are vector-decomposed along the sailing direction of the ship to obtain the component Vcx of the flow velocity Vc along the sailing direction of the ship equipped with the bubble drag reduction system and the component Vcy perpendicular to the sailing direction.

[0045] Where Vcx is the increase or decrease in the ground speed caused by the flow velocity and flow direction, ΔV c =Vcx;

[0046] The increase or decrease in speed over ground caused by water depth ΔV d The calculation is as follows:

[0047] Calculate the water depth correction threshold h according to the following formula:

[0048]

[0049] If the water depth Dp is greater than the correction threshold h, the water depth has no effect on the speed over the ground, that is, ΔV d =0,

[0050] If the water depth Dp is less than the correction threshold h, the increase or decrease in speed over the ground caused by the water depth needs to be calculated using the following formula:

[0051]

[0052] In the formula, A M is the area below the waterline of the mid-section of the ship equipped with the bubble drag reduction system,

[0053] The speed Vs when the ship equipped with the bubble drag reduction system is placed in the same environmental conditions as those monitored in step S1 and the bubble drag reduction system is not turned oncorr and power Pe corr The calculation is as follows:

[0054] V Scorr =V S +ΔV

[0055] P ecorr =P e +ΔP;

[0056] S3: Calculate the real-time energy consumption required for the operation of the bubble drag reduction system, including at least: all energy consumption P of the air compressor required to open and maintain the bubble layer air , the system monitors and controls all energy consumption P generated by the unit ctrl , and then convert the above energy consumption into the host power equivalent value P sump ,

[0057]

[0058] In the formula, SFC ge The fuel consumption corresponding to the rated power of the ship generator equipped with the bubble drag reduction system,

[0059] SFC me The fuel consumption of the generator of the ship equipped with the bubble drag reduction system when the power is Pe;

[0060] S4: Take the speed power characteristics of the ship installed with the bubble drag reduction system in the ideal state obtained in step S2.1 as the reference value, and the speed Vs under the same environmental conditions calculated in step S2 (4) as the reference value. corr and power Pe corr The characteristic value is taken as the eigenvalue, and the reference value is corrected by the least square method to obtain the speed power characteristic Vs_off when the bubble drag reduction system is turned off under the environmental conditions monitored in step S1. i -Pe_off i , (i=1,2,…,n);

[0061] Then, the above speed power characteristic Vs_off i -Pe_off i is the data to be interpolated, and Vs monitored in step S1 is used as the interpolation point coordinates. The main engine power P when the speed of the ship equipped with the bubble drag reduction system is Vs is obtained by applying the spline curve interpolation method. e_int At this time, deduct the real-time equivalent energy consumption P of the bubble drag reduction system obtained in step S3 sump The real-time energy saving effect of the bubble drag reduction system can be obtained. save ,

[0062] Psave =P e_int -P e -P sump .

[0063] The above-mentioned method for real-time energy saving effect of a marine bubble drag reduction system, further, in step S2.2, C AA ·(AWA) and C AA (0) Available through the STA-JIP database.

[0064] The above-mentioned method for real-time energy saving effect of a marine bubble drag reduction system, further, in step S2, C T0 , C F , C F0 , R T0 , η Did , P Can be obtained through ship model testing.

[0065] The present invention can be effectively applied to obtain real-time calculation of the energy-saving effect of the bubble drag reduction system applied on a real ship. The established environmental parameter correction method effectively eliminates the influence of environmental conditions on the calculation results, and ensures the reliability of the calculation results. The whole set of calculation methods is simple to operate, has high calculation efficiency, and has good economy. It has been verified by actual ship application that the real-time calculation method of the energy-saving effect of the bubble drag reduction system established by the present invention has high accuracy and can be reliably applied to any ship equipped with a bubble drag reduction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 This is a step diagram of the method;

[0067] Figure 2 It is a schematic diagram of the speed and power of the ship under the environmental conditions of step S1 when the bubble drag reduction system is not turned on;

[0068] Figure 3 The speed and power characteristics Vs_off of the ship equipped with the bubble drag reduction system under the environmental conditions monitored in step S1 when the bubble drag reduction system is turned off i -Pe_off i , (i=1,2,…,n) schematic diagram. DETAILED DESCRIPTION

[0069] The present invention will be further described in conjunction with the accompanying drawings.

[0070] like Figure 1 As shown, a real-time energy-saving effect method of a marine bubble drag reduction system comprises:

[0071] S1: Monitor the real-time data of ship navigation and environment when the bubble drag reduction system is in normal operation, including: ship speed over ground Vs, main engine power Pe, displacement Δ, bow draft T f , stern draft T a , relative wind speed AWS, relative wind direction AWA, water depth Dp, wave height H WAVE , Yonggao H SWELL , flow velocity Vc, flow direction Dc, seawater temperature Tem_w, seawater density ρ S , temperature Tem_a, air pressure P_a, air density ρ A .

[0072] S2: Using the navigation and environmental real-time data obtained in S1 when the bubble drag reduction system is in normal operation as the calculation input, a certain calculation method is applied to convert the speed and power of the ship under this environmental condition without turning on the bubble drag reduction system, such as Figure 2 As shown, specifically:

[0073] S2.1: Through the still water ship model test, the ship equipped with the bubble drag reduction system is tested in the state of no wind, no waves, no current, and infinite water depth, and the different ground speeds Vs_id when it is at the design draft, structural draft, and ballast draft. i Corresponding host power Pe_id i , (i=1,2,…,n) refers to the speed and power characteristics of the ship equipped with the bubble drag reduction system when it is in an ideal state.

[0074] S2.2: The environmental wind, wave, surge, seawater temperature, density and displacement parameters obtained in S1 when the bubble drag reduction system is in normal operation are converted into the increase or decrease value ΔP of the main engine power when the ship equipped with the bubble drag reduction system is in an ideal state compared with S2.1. The calculation formula is as follows:

[0075]

[0076] Where η Did is the propulsion efficiency coefficient of the ship equipped with the bubble drag reduction system at the current draft and speed Vs when it is in an ideal state, ξ P is the load factor, which can be obtained through still water ship model test. ΔR is the resistance caused by the ambient wind R AA , resistance R caused by waves and surges WL , the resistance R caused by seawater temperature and density AS and the resistance R caused by displacement ADIS sum:

[0077] ΔR=R AA +R WL +R AS +RADIS

[0078] Among them, the resistance caused by the ambient wind is R AA The calculation formula is as follows:

[0079]

[0080] In the formula, A XV C is the transverse projection area above the waterline of the ship equipped with the bubble drag reduction system, including the superstructure; AA ·(AWA) and C AA (0) are the drag coefficients when the relative wind direction is 0 degrees and AWA, respectively, which can be obtained from the STA-JIP database.

[0081] Resistance R caused by waves and surges WL The calculation formula is as follows:

[0082]

[0083] Where g is the gravitational acceleration, B is the width of the ship equipped with the bubble drag reduction system; L BWL H is the distance from the bow of the ship equipped with the bubble drag reduction system to 95% of the maximum width of the waterline; 1 / 3 For the significant wave height:

[0084] Resistance R caused by ambient seawater temperature and density AS The calculation formula is as follows:

[0085]

[0086]

[0087]

[0088] In the formula, ρ S0 is the density of seawater under standard conditions. The standard condition is that the water temperature is 15°C and the density is 1026 kg / m 3 ; R T0 is the total resistance under the reference state; R F is the friction resistance of the ship equipped with the bubble drag reduction system in the current state; S is the wet surface area of ​​the ship equipped with the bubble drag reduction system; C T0 is the total resistance coefficient under standard conditions, C F is the friction resistance coefficient of the ship equipped with the bubble drag reduction system in the current state, C F0 is the friction resistance coefficient under standard conditions, which can be obtained through still water ship model tests.

[0089] Resistance R caused by displacement ADIS The calculation formula is as follows:

[0090]

[0091] Wherein, Δ0 is the displacement corresponding to the design draft, structural draft and ballast draft in the still water ship model test, which is closest to the current displacement Δ of the ship equipped with the bubble drag reduction system; R T0 The total resistance of the ship equipped with the bubble drag reduction system at the above draft can be obtained through a still water ship model test.

[0092] S2.3: The flow velocity, flow direction and water depth parameters obtained in S1 when the bubble drag reduction system is in normal operation are converted into the increase or decrease value ΔV of the ground speed when the ship equipped with the bubble drag reduction system is in an ideal state as described in S2.1. The calculation formula is as follows:

[0093] ΔV=ΔV c +ΔV d

[0094] Among them, the increase or decrease value of the ground speed caused by the flow velocity and flow direction is ΔV c The calculation is as follows:

[0095] The velocity Vc and the flow direction Dc are vector-decomposed along the sailing direction of the ship to obtain the component Vcx of the velocity Vc along the sailing direction of the ship equipped with the bubble drag reduction system and the component Vcy perpendicular to the sailing direction. Among them, Vcx is the increase or decrease of the ground speed caused by the velocity and flow direction, ΔV c =Vcx.

[0096] The increase or decrease in speed over ground caused by water depth ΔV d The calculation is as follows:

[0097] Calculate the water depth correction threshold h according to the following formula:

[0098]

[0099] If the water depth Dp is greater than the correction threshold h, the water depth has no effect on the speed over the ground, that is, ΔV d =0; if the water depth Dp is less than the correction threshold h, the increase or decrease in speed over ground caused by the water depth needs to be calculated. The calculation formula is:

[0100]

[0101] In the formula, A M It is the area below the waterline of the mid-section of the ship equipped with the bubble drag reduction system.

[0102] S2.4: The speed Vs of the vessel equipped with the bubble drag reduction system when it is in the same environmental conditions as those monitored in S1 and the bubble drag reduction system is not turned on corr and power Pe corr The calculation is as follows:

[0103] V Scorr =V S +ΔV

[0104] P ecorr =P e +ΔP

[0105] S3: Calculate the real-time energy consumption required for the operation of the bubble drag reduction system, including at least: all energy consumption P of the air compressor required to open and maintain the bubble layer air , the system monitors and controls all energy consumption generated by the unit P ctrl , and then convert the above energy consumption into the host power equivalent value P sump , the formula is as follows:

[0106]

[0107] In the formula, SFC ge is the fuel consumption corresponding to the rated power of the ship generator equipped with the bubble drag reduction system, SFC me It is the fuel consumption of the ship generator equipped with the bubble drag reduction system when the power is Pe.

[0108] S4: Take the speed power characteristics of the ship installed with the bubble drag reduction system in the ideal state obtained in S2.1 as the reference value, and the speed Vs under the same environmental conditions calculated by S2.4 corr and power Pe corr The reference value is corrected by the least square method to obtain the speed power characteristics Vs_off when the bubble drag reduction system is turned off under the environmental conditions monitored in S1. i -Pe_off i , (i=1,2,…,n), such as Figure 3 Then, the above speed power characteristic Vs_off i -Pe_off i is the data to be interpolated, and the spline curve interpolation method is used to interpolate the main engine power Pe_int when the speed of the ship equipped with the bubble drag reduction system is Vs, using Vs monitored in S1 as the interpolation point coordinates. At this time, deduct the real-time equivalent energy consumption P of the bubble drag reduction system calculated in S3 sump The real-time energy saving effect of the bubble drag reduction system can be obtained. save , specifically:

[0109] Psave =P e_int -P e -P sump

[0110] This completes the detailed description of the specific embodiments of the present invention.

Claims

1. A real-time energy-saving method for a marine air bubble drag reduction system, characterized in that: The specific method is as follows: S1: Monitor the real-time data of ship navigation and environment when the bubble drag reduction system is in normal operation, including: ship speed over ground Vs, main engine power Pe, displacement Δ, bow draft Tf, stern draft T a , relative wind speed AWS, relative wind direction AWA, water depth Dp, wave height H WAVE , Yonggao H SWELL , flow velocity Vc, flow direction Dc, seawater temperature Tem_w, seawater density ρs, air temperature Tem_a, air pressure P_a, air density ρ A ; S2: Using the navigation and environmental real-time data obtained in step S1 when the bubble drag reduction system is in normal operation as the calculation input, the speed Vs of the ship under this environmental condition without turning on the bubble drag reduction system is obtained. corr and power Pe corr , the specific method is as follows: S2.1: Through the still water ship model test, the different ground speeds Vs_id of the ship equipped with the bubble drag reduction system under the conditions of no wind, no waves, no current and infinite water depth at the design draft, structural draft and ballast draft are obtained. i and the corresponding host power Pe_id i , (i=1, 2, ..., n), i.e., the speed and power characteristics of a ship equipped with a bubble drag reduction system in an ideal state; S2.2: The environmental wind, wave, surge, seawater temperature, density, and displacement parameters obtained in step S1 when the bubble drag reduction system is in normal operation are converted into the increase or decrease value ΔP of the main engine power when the ship equipped with the bubble drag reduction system is in an ideal state. The calculation formula is as follows: Where η Did is the propulsion efficiency coefficient at the current draft and speed Vs when the ship equipped with the bubble drag reduction system is in an ideal state, ξ P is the load factor, which can be obtained through still water ship model test. ΔR is the resistance R caused by the ambient wind AA , resistance R caused by waves and surges WL , the resistance R caused by seawater temperature and density AS and the resistance R caused by displacement ADIS sum: ΔR=R AA +R WL +R AS +R ADIS Among them, the resistance caused by the ambient wind is R AA The calculation formula is as follows: In the formula, A xv It is the transverse projection area above the waterline of the ship equipped with the bubble drag reduction system, including the superstructure. C AA ·(AWA) and C AA (0) are the drag coefficients when the relative wind direction is 0 degrees and AWA, respectively; Resistance R caused by waves and surges WL The calculation formula is as follows: Where g is the acceleration due to gravity, B is the width of the ship equipped with the bubble drag reduction system. L BWL The distance from the bow of the ship equipped with the bubble drag reduction system to 95% of the maximum width of the waterline, H 1 / 3 For the significant wave height: Resistance R caused by ambient seawater temperature and density As The calculation formula is as follows: In the formula, ρ S0 is the density of seawater under standard conditions. The standard condition is that the water temperature is 15°C and the density is 1026 kg / m 3 , R T0 is the total resistance in the reference state, R F is the friction resistance of the ship equipped with the bubble drag reduction system in the current state, S is the wet surface area of ​​the ship equipped with the bubble drag reduction system, C T0 is the total resistance coefficient under standard conditions, C F0 is the friction coefficient under standard conditions, C F is the friction resistance coefficient of the ship equipped with the bubble drag reduction system in the current state, C T0 , C F0 , C F It can be obtained through still water ship model test; Resistance R caused by displacement ADIS The calculation formula is as follows: Where Δ0 is the displacement corresponding to the design draft, structural draft and ballast draft in the still water ship model test, which is closest to the current displacement Δ of the ship equipped with the bubble drag reduction system. R T0 The total resistance of a ship equipped with a bubble drag reduction system at the above draft can be obtained through a still water ship model test; (3) The flow velocity, flow direction, and water depth parameters obtained in S1 when the bubble drag reduction system is in normal operation are converted to the increase or decrease value ΔV of the ground speed compared to the ideal state of the ship equipped with the bubble drag reduction system. The calculation formula is as follows: ΔV=ΔV c +ΔV d Among them, the increase or decrease value of the ground speed caused by the flow velocity and flow direction is ΔV c The calculation is as follows: The flow velocity Vc and the flow direction Dc are vector-decomposed along the sailing direction of the ship to obtain the component Vcx of the flow velocity Vc along the sailing direction of the ship equipped with the bubble drag reduction system and the component Vcy perpendicular to the sailing direction. Where Vcx is the increase or decrease in the ground speed caused by the flow velocity and flow direction, ΔV c =Vcx; The increase or decrease in speed over ground caused by water depth ΔV d The calculation is as follows: Calculate the water depth correction threshold h according to the following formula: If the water depth Dp is greater than the correction threshold h, the water depth has no effect on the speed over the ground, that is, ΔV d =0, If the water depth Dp is less than the correction threshold h, the increase or decrease in speed over the ground caused by the water depth needs to be calculated using the following formula: In the formula, A M is the area below the waterline of the mid-section of the ship equipped with the bubble drag reduction system, The speed Vs when the ship equipped with the bubble drag reduction system is placed in the same environmental conditions as those monitored in step S1 and the bubble drag reduction system is not turned on corr and power Pe corr The calculation is as follows: V Scorr =V S +ΔV P ecorr =P e +ΔP; S3: Calculate the real-time energy consumption required for the operation of the bubble drag reduction system, including at least: all energy consumption P of the air compressor required to open and maintain the bubble layer air , the system monitors and controls all energy consumption generated by the unit P ctrl , and then convert the above energy consumption into the host power equivalent value P sump , In the formula, SFC ge The fuel consumption corresponding to the rated power of the ship generator equipped with the bubble drag reduction system, SFC me The fuel consumption of the ship generator equipped with the bubble drag reduction system when the power is Pe; S4: Take the speed power characteristics of the ship installed with the bubble drag reduction system in the ideal state obtained in step S2.1 as the reference value, and the speed V under the same environmental conditions calculated in step S2 (4) as the reference value. Scorr and power Pe corr The characteristic value is taken as the eigenvalue, and the reference value is corrected by the least square method to obtain the speed power characteristic Vs_off when the bubble drag reduction system is turned off under the environmental conditions monitored in step S1. i -Pe_off i , (i=1, 2, ..., n); Then, the above speed power characteristic Vs_off i -Pe_off i is the data to be interpolated, and Vs monitored in step S1 is used as the interpolation point coordinates. The main engine power P when the speed of the ship equipped with the bubble drag reduction system is Vs is obtained by applying the spline curve interpolation method. e_int At this time, deduct the real-time equivalent energy consumption P of the bubble drag reduction system obtained in step S3 sump The real-time energy saving effect of the bubble drag reduction system can be obtained. save , P save =P e_int -P e -P sump 。 2. The real-time energy-saving effect method of a marine bubble drag reduction system according to claim 1, characterized in that: In step S2.2, C AA ·(AWA) and C AA (0) Available through the STA-JIP database.

3. The real-time energy-saving effect method of a marine bubble drag reduction system according to claim 1, characterized in that: In step S2, C T0 , C F , C F0 , R T0 , η Did , P Can be obtained through ship model tests.

Images