Modelica-based FPSO propulsion modeling method

Abstract

The invention belongs to the field of electrical digital data processing, and discloses a modelica-based FPSO propulsion modeling method, which comprises the following steps: S1, modeling a propulsion coefficient model of a propeller, including calculating the following parameters: a thrust coefficient, a thrust moment coefficient, a thrust gain coefficient and a thrust moment gain coefficient; s2, modeling a propeller performance model, including calculating the following parameters: a wake coefficient, a forward number, a thrust loss coefficient and relative rotation efficiency; and S3, according to results of the step S1 and the step S2, the thrust and the thrust moment of the propeller are output, and then the propulsion efficiency of the propeller is obtained. By using the method, the thrust and torque change characteristics of the propeller under different working conditions can be comprehensively simulated through a discrete dynamic modeling method, so that accurate simulation support is provided for dynamic response of an FPSO system in a complex marine environment.

Description

Technical Field

[0001] The invention belongs to the field of electrical digital data processing, and in particular relates to a FPSO propulsion modeling method based on Modelica. Background Art

[0002] Offshore floating production storage and offloading vessels (FPSO) are key facilities for offshore oil development, mainly used for the extraction, processing, storage and transportation of offshore oil, natural gas and other energy sources. FPSO systems usually rely on propeller propulsion systems to achieve ship positioning, navigation and stability control. As the core propulsion device of FPSO, the performance of the propeller directly affects the working efficiency and safety of FPSO in complex marine environments. The FPSO propeller propulsion system needs to cope with complex environmental conditions, such as the combined effects of waves, wind and currents, which makes the dynamic response of the propeller highly nonlinear and time-varying. Therefore, establishing an accurate propeller propulsion system dynamics model is crucial to analyze and optimize the propulsion efficiency and operational stability of FPSO.

[0003] The Modelica language unifies various multi-domain unified modeling mechanisms in principle, directly supports block diagram-based modeling, object-oriented and component-oriented modeling, and enables it to simultaneously describe mechanical, hydraulic and control systems through a generalized Kirchhoff network mechanism based on ports and connections, providing an ideal platform for multi-domain coupled modeling of propulsion systems. Summary of the invention

[0004] The present invention provides a FPSO propulsion modeling method based on Modelica. The method can comprehensively simulate the thrust and torque variation characteristics of the propeller under different working conditions through a discrete dynamic modeling method, thereby providing accurate simulation support for the dynamic response of the FPSO system in a complex marine environment.

[0005] To achieve the above object, the present invention provides the following technical solution: a FPSO propulsion modeling method based on Modelica, the modeling method includes using Modelica language to model a propeller propulsion coefficient model and a propeller performance model, and simulating a propeller propulsion system by modeling the propeller propulsion coefficient model and the propeller performance model; the propulsion modeling method includes the following steps: S1: Modeling the propulsion coefficient model of the propeller, including calculating the following parameters: thrust coefficient, thrust torque coefficient, thrust gain coefficient, thrust torque gain coefficient; S2: Modeling of propeller performance model, including calculation of the following parameters: wake coefficient, advance number, thrust loss coefficient, relative rotation efficiency; S3: According to the results of steps S1 and S2, the thrust and thrust torque of the propeller are output, and then the propulsion efficiency of the propeller is obtained.

[0006] Preferably, the calculation formulas for the thrust coefficient and thrust moment coefficient in step S1 are: (1) (2) in, is the thrust coefficient, is the thrust moment coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, and D is the propeller diameter.

[0007] Preferably, the calculation formulas for the thrust gain coefficient and the thrust torque gain coefficient in step S1 are: (3) (4) (5) (6) in, is the thrust gain coefficient, is the thrust torque gain coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, D is the propeller diameter, Re is the Reynolds number, is an intermediate coefficient based on the propeller geometry, V a is the forward speed of the propeller, n is the rotational speed of the propeller, U is the blade area ratio, and v is the dynamic viscosity of the fluid.

[0008] Preferably, the calculation formula of the wake coefficient in step S2 is: (7) (8) (9) (10) (11) Where w is the wake coefficient, The captain, The width of the ship, The stern draft, is the longitudinal center of buoyancy position, is the resistance correction factor, is the ship type factor, is the friction coefficient, It is a single-paddle stern shape. is the rhombus coefficient, is the midship section coefficient, is the square coefficient, is the wetted surface area, is the propeller diameter, and and and is the intermediate coefficient.

[0009] Preferably, the calculation formula for the forward number in step S2 is: (12) (13) Where J is the advance number, is the forward speed, n is the propeller speed, D is the propeller diameter, V is the ship's speed, and w is the wake coefficient.

[0010] Preferably, the calculation formula of the thrust loss coefficient in step S2 is: (14) in, is the thrust loss coefficient, The captain, The width of the ship, is the propeller diameter, The stern draft, is the rhombus coefficient, is the longitudinal center of buoyancy position, It is a single-paddle stern shape.

[0011] Preferably, the calculation formula of the relative rotation efficiency in step S2 is: (15) in, is the relative rotation efficiency, U is the blade area ratio, is the rhombus coefficient, is the longitudinal center of buoyancy position.

[0012] Preferably, the calculation formula for outputting the thrust and thrust torque of the propeller in step S3 is: (16) (17) Where Q is the thrust torque, T is the thrust, is the thrust torque coefficient, is the thrust coefficient, n is the propeller speed, D is the propeller diameter, is the density of water, is the thrust loss coefficient.

[0013] Preferably, the calculation formula of the propeller propulsion efficiency in step S3 is: (18) in, is the propulsion efficiency of the propeller, Q is the thrust torque, T is the thrust, n is the propeller speed, is the relative rotational efficiency, It is the forward speed.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention accurately calculates the thrust and thrust loss of the propeller based on input parameters such as propeller structural parameters and ship speed, and uses formula modeling to calculate the thrust loss coefficient, which can better simulate the propeller propulsion efficiency, reduce modeling errors, and calculate and fit multiple performance parameters. By calculating the thrust coefficient, thrust moment coefficient, and relative rotation efficiency and other performance parameters, a detailed analysis basis is provided for the performance of the propeller under different speeds and load conditions, ensuring the optimal design of the propulsion system; 2. The present invention defines the input and output parameters of the standardized interface, making the model easy to expand, maintain and reuse, thereby reducing the workload and complexity of subsequent development and application; 3. The present invention constructs a multi-domain coupling model of the propeller propulsion coefficient model and the propeller performance model through the Modelica language, realizes the dynamic simulation and optimization of the propeller propulsion system, and comprehensively simulates the thrust and torque change characteristics of the propeller under different working conditions, thereby providing accurate simulation support for the dynamic response of the FPSO system in a complex marine environment. DETAILED DESCRIPTION

[0015] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The present invention provides a technical solution: a FPSO propulsion modeling method based on Modelica, the modeling method includes using Modelica language to model a propeller propulsion coefficient model and a propeller performance model, and simulating a propeller propulsion system by modeling the propeller propulsion coefficient model and the propeller performance model; the propeller propulsion modeling method includes the following steps: S1: Modeling the propulsion coefficient model of the propeller, including calculating the following parameters: thrust coefficient, thrust torque coefficient, thrust gain coefficient, thrust torque gain coefficient; In the propulsion coefficient modeling in the propeller propulsion system model, the propulsion coefficient is one of the key parameters, which includes the thrust coefficient, thrust torque coefficient, thrust gain and thrust torque gain. These parameters can be accurately calculated by interpolation method under different forward numbers, pitch ratios, number of blades and propeller diameter and other related parameters. The thrust gain and thrust torque gain are also interpolated with the Reynolds number. The calculation formulas for thrust coefficient and thrust moment coefficient are: (1) (2) in, is the thrust coefficient, is the thrust moment coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, and D is the propeller diameter.

[0017] Thrust coefficient It is the ratio of the thrust generated by the propeller to its geometric parameters and water flow conditions. is the coefficient related to the torque generated by the propeller and its operating conditions. Interp is an interpolation function. The specific interpolation function is to create an interpolation table in the CombiTable1D component in the modelica standard library to store the corresponding values ​​of variables J (number of advances), P / D (pitch ratio), z (number of blades) and D (propeller diameter). and Each row of data represents a unique combination of input values ​​for these variables and the corresponding thrust coefficients. Or thrust torque coefficient Finally, we can get the interpolation result by calling CombiTable1D output and to meet the requirements of formulas (1) and (2).

[0018] The calculation formulas for thrust gain coefficient and thrust torque gain coefficient are: (3) (4) (5) (6) in, is the thrust gain coefficient, is the thrust torque gain coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, D is the propeller diameter, Re is the Reynolds number, is an intermediate coefficient based on the propeller geometry, V a is the forward speed of the propeller, n is the rotational speed of the propeller, U is the blade area ratio, and v is the dynamic viscosity of the fluid.

[0019] Thrust gain factor It is a further correction to the thrust coefficient, which reflects the change in propeller thrust under specific flow conditions. It is a correction to the thrust torque coefficient, taking into account the torque characteristics of the propeller under different fluid conditions. The specific interpolation function here is to create an interpolation table in the CombiTable1D component in the modelica standard library to store the corresponding values ​​of variables J (number of advances), P / D (pitch ratio), z (number of blades), D (propeller diameter), and Re (Reynolds number). and Each row of data represents a unique combination of input values ​​for these variables and the corresponding thrust coefficients. Or thrust torque coefficient Finally, we can get the interpolation result by calling CombiTable1D output and to meet the requirements of formulas (3) and (4).

[0020] S2: Modeling of propeller performance model, including calculation of the following parameters: wake coefficient, advance number, thrust loss coefficient, relative rotation efficiency; The calculation of the wake coefficient w is based on the geometric parameters of the ship and the characteristics of the propeller. The specific formula is: (7) (8) (9) (10) (11) Where w is the wake coefficient, The captain, The width of the ship, The stern draft, is the longitudinal center of buoyancy position, is the resistance correction factor, is the ship type factor, is the friction coefficient, It is a single-paddle stern shape. is the rhombus coefficient, is the midship section coefficient, is the square coefficient, is the wetted surface area, is the propeller diameter, and and and These parameters are defined as input variables in Modelica. By inputting the geometric parameters of the hull and propeller, the system will automatically calculate the wake coefficient w and use it for subsequent propeller thrust and efficiency calculations.

[0021] The advance number mainly involves the time and distance required for the ship to reach a stable speed after starting the main engine in a stationary state. These parameters are of great significance to the ship's maneuverability and navigation efficiency. The specific calculation formula is: (12) (13) Where J is the advance number, is the forward speed, n is the propeller speed, D is the propeller diameter, V is the ship's speed, and w is the wake coefficient.

[0022] The thrust loss coefficient is one of the key parameters to describe the propulsion efficiency of a propeller. It mainly reflects the thrust loss caused by the propeller's resistance in the water flow. The specific calculation formula is: (14) in, is the thrust loss coefficient, The captain, The width of the ship, is the propeller diameter, The stern draft, is the rhombus coefficient, is the longitudinal center of buoyancy position, The thrust loss coefficient formula also depends on the geometric parameters of the ship and the characteristics of the propeller. Through this formula, the thrust loss coefficient can be accurately calculated and combined with the wake coefficient for the evaluation of propeller thrust and efficiency.

[0023] Relative rotational efficiency is an important parameter that affects the actual working efficiency of the propeller. It reflects the difference between the actual working state of the propeller and its design theory. The specific calculation formula is: (15) in, is the relative rotation efficiency, U is the blade area ratio, is the rhombus coefficient, is the longitudinal center of buoyancy position.

[0024] S3: According to the results of steps S1 and S2, the thrust and thrust torque of the propeller are output, and then the propulsion efficiency of the propeller is obtained.

[0025] The calculation formula for the thrust and thrust torque of the output propeller is: (16) (17) Where Q is the thrust torque, T is the thrust, is the thrust torque coefficient, is the thrust coefficient, n is the propeller speed, D is the propeller diameter, is the density of water, is the thrust loss coefficient.

[0026] The formula for calculating the propulsion efficiency of a propeller is: (18) in, is the propulsion efficiency of the propeller, Q is the thrust torque, T is the thrust, n is the propeller speed, is the relative rotational efficiency, It is the forward speed.

[0027] Finally, according to the results of the propeller propulsion coefficient model and the propeller performance model, the propeller thrust T and thrust torque Q are calculated. Finally, the propulsion efficiency is obtained based on the propeller thrust and thrust torque. According to the results, it is judged whether the propeller has good thrust and propulsion efficiency under the current speed and operating conditions. Then, the designer can further optimize the propeller geometry or adjust the operating conditions based on these data to improve the propulsion performance.

[0028] Example: A detailed propeller propulsion system simulation is performed based on the propeller propulsion coefficient model and the propeller performance model. By inputting the geometric parameters of the FPSO ship, the propeller design parameters and the operating conditions, the model will output the propeller thrust, thrust torque, propulsion efficiency and other performance indicators. This implementation case will explain in detail the steps, data input, model operation and result interpretation in the simulation process.

[0029] When analyzing the propulsion performance of a propeller used by a ship at a specific speed and operating conditions, the present invention simulates and calculates the thrust coefficient, thrust moment coefficient, thrust gain, thrust moment gain, and thrust and thrust moment of the propeller, and finally evaluates the propulsion efficiency of the propeller.

[0030] In the simulation, the parameters we need to input include: Vessel geometry parameters ; Geometric parameters of ship propellers ; Ship speed V, propeller speed n; Fluid characteristic parameters ; These parameters are passed into the propeller thrust model as input, and the parameters are calculated according to the following steps, and finally the thrust, thrust torque and propulsion efficiency are output.

[0031] 1. Calculate the thrust coefficient using the interpolation method based on the propeller's forward number, pitch ratio, number of blades, and propeller diameter. Also use the interpolation method to obtain the thrust torque coefficient; 2. Considering the Reynolds number Re, correct the thrust coefficient and thrust torque coefficient, and obtain the thrust and thrust torque gain coefficient according to the Reynolds number and interpolation method; 3. Calculate the propeller wake coefficient based on the hull geometry parameters and propeller design parameters; 4. Calculate the thrust loss coefficient through hull and propeller parameters; 5. Calculate the relative rotation efficiency by combining the propeller parameters and the longitudinal center of buoyancy of the ship; 6. According to the results of the propeller propulsion coefficient model and the propeller performance model, the propeller thrust and thrust torque Q are calculated, and finally the propulsion efficiency is obtained based on the propeller thrust and thrust torque.

[0032] The specific parameter calculation and modeling process are as follows: Vessel parameters: Length L = 100m, width B = 15m, stern draft T A =7m, ship speed V=12knots (about 6.17m / s), longitudinal center of buoyancy position =0.05; Propeller parameters: Propeller diameter D = 4.5m, number of blades z = 4, pitch ratio P / D = 0.85, speed n = 150RPM, blade area ratio U = 0.65; Fluid parameters: The dynamic viscosity of water is v=1.14*10 -6 m 2 / s, water density ρ = 1025kg / m 3; Thrust coefficient k t Calculation: The thrust coefficient k is calculated by interpolation based on the propeller's forward number J, pitch ratio P / D, number of blades z and propeller diameter D. t ; ; According to the interpolation method, we can get: k t =0.12 Thrust torque coefficient k q Calculation: Also through interpolation method, the thrust torque coefficient is obtained: k q =0.025 Thrust gain factor and thrust torque gain factor Calculation: After considering the Reynolds number Re and other factors, the thrust coefficient and thrust torque coefficient are corrected: ; Interpolation calculation is performed based on the Reynolds number to obtain the gain coefficient: ; According to the hull geometry parameters and propeller design parameters, the propeller wake coefficient w is calculated: ; Thrust loss coefficient Calculation: Calculate the thrust loss coefficient from the hull and propeller parameters: ; Relative rotation efficiency Calculation: Combining the propeller parameters and the longitudinal center of buoyancy of the ship, the relative rotation efficiency is calculated: ; Calculation of the advancement number J: The advance number is calculated as follows: ; According to the results of the propeller propulsion coefficient model and the propeller performance model, the propeller thrust and thrust torque are calculated: Thrust T: ; ; Thrust torque Q: ; ; Calculation of propulsion efficiency: Propulsion efficiency The calculation of is as follows: ; ; Simulation results analysis: Through the above simulation steps, the following key results are obtained: ; The results show that the propeller has good thrust and propulsion efficiency at the current speed and operating conditions. Ship designers can further optimize the propeller geometry or adjust the operating conditions based on these data to improve propulsion performance.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A FPSO propulsion modeling method based on Modelica, Features: The modeling method includes modeling a propeller propulsion coefficient model and a propeller performance model using the Modelica language, and simulating a propeller propulsion system by modeling the propeller propulsion coefficient model and the propeller performance model; the propulsion modeling method includes the following steps: S1: Modeling the propulsion coefficient model of the propeller, including calculating the following parameters: thrust coefficient, thrust torque coefficient, thrust gain coefficient, thrust torque gain coefficient; S2: Modeling of propeller performance model, including calculation of the following parameters: wake coefficient, advance number, thrust loss coefficient, relative rotation efficiency; S3: According to the results of steps S1 and S2, the thrust and thrust torque of the propeller are output, and then the propulsion efficiency of the propeller is obtained.

2. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formulas for the thrust coefficient and thrust moment coefficient in step S1 are: （1） （2） in, is the thrust coefficient, is the thrust moment coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, and D is the propeller diameter.

3. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formulas of the thrust gain coefficient and the thrust moment gain coefficient in step S1 are: （3） （4） （5） （6） in, is the thrust gain coefficient, is the thrust torque gain coefficient, Interp is the interpolation function, J is the advance number, P / D is the propeller pitch ratio, z is the number of propeller blades, D is the propeller diameter, Re is the Reynolds number, is an intermediate coefficient based on the propeller geometry, V a is the forward speed of the propeller, n is the rotational speed of the propeller, U is the blade area ratio, and v is the dynamic viscosity of the fluid.

4. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula of the wake coefficient in step S2 is: （7） （8） （9） （10） （11） Where w is the wake coefficient, The captain, The width of the ship, The stern draft, is the longitudinal center of buoyancy position, is the resistance correction factor, is the ship type factor, is the friction coefficient, It is a single-paddle stern shape. is the rhombus coefficient, is the midship section coefficient, is the square coefficient, is the wetted surface area, is the propeller diameter, and and and is the intermediate coefficient.

5. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula of the advance number in step S2 is: （12） （13） Where J is the advance number, is the forward speed, n is the propeller speed, D is the propeller diameter, V is the ship's speed, and w is the wake coefficient.

6. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula of the thrust loss coefficient in step S2 is: （14） in, is the thrust loss coefficient, The captain, The width of the ship, is the propeller diameter, The stern draft, is the rhombus coefficient, is the longitudinal center of buoyancy position, It is a single-paddle stern shape.

7. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula of the relative rotation efficiency in step S2 is: （15） in, is the relative rotation efficiency, U is the blade area ratio, is the rhombus coefficient, is the longitudinal center of buoyancy position.

8. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula for the thrust and thrust torque of the output propeller in step S3 is: （16） （17） Where Q is the thrust torque, T is the thrust, is the thrust torque coefficient, is the thrust coefficient, n is the propeller speed, D is the propeller diameter, is the density of water, is the thrust loss coefficient.

9. The FPSO propulsion modeling method based on Modelica according to claim 1, Features: The calculation formula of the propulsion efficiency of the propeller in step S3 is: （18） in, is the propulsion efficiency of the propeller, Q is the thrust torque, T is the thrust, n is the propeller speed, is the relative rotational efficiency, It is the forward speed.

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