Steady state simulation method and system for rapidly determining liquid level height difference of double oil tanks and medium
By using steady-state simulation methods and converting liquid level differences into pressure differences using volume ratio and hydrostatic pressure formulas, combined with iterative algorithms, the problem of uneven fuel supply in dual fuel tanks of commercial vehicles was solved, improving simulation efficiency and accuracy, and reducing fuel consumption and computational costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-31
AI Technical Summary
Existing technologies struggle to quickly and accurately predict fuel supply imbalances in dual-tank systems for commercial vehicles, resulting in low utilization rates and high computational costs. Traditional methods are fuel-intensive and require significant computational resources.
A steady-state simulation method is adopted. By calculating the volume ratio and static pressure formula, the liquid level difference is converted into a pressure difference and set as the boundary condition of the simulation model. The target pressure value is found by using an iterative algorithm, and the stable liquid level difference and the remaining oil volume in the large oil tank are calculated.
It improves simulation efficiency, reduces computation time and resource consumption, accurately predicts liquid level differences and remaining oil volume in large tanks, and supports the design and optimization of dual-tank systems.
Smart Images
Figure CN121765840A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of commercial vehicle fuel supply technology, specifically involving a steady-state simulation method, system, and medium for rapidly determining the liquid level difference between two fuel tanks. Background Technology
[0002] In commercial vehicles, auxiliary fuel tanks are often equipped to increase fuel carrying capacity and improve driving range, forming a dual-tank system consisting of a main tank (large tank) and an auxiliary tank (small tank). In such parallel fuel supply systems, due to differences in the geometry, installation location, and volume of the two tanks, an imbalance in fuel supply is common when they simultaneously supply fuel to the engine. Specifically, the fuel level in the smaller tank drops significantly faster than in the larger tank, causing the smaller tank to run out of fuel first, while the larger tank still retains a considerable amount of fuel. If this fuel supply imbalance is not accurately predicted and controlled, it will directly reduce the effective utilization rate of the total volume of the two tanks and pose challenges to the matching design of the fuel tank system and the accurate assessment of the vehicle's driving range.
[0003] To address these issues, traditional methods primarily rely on two approaches: First, conducting real-vehicle or bench tests to observe and measure the fuel supply process until the small fuel tank is empty by actually consuming fuel. While intuitive, this method consumes a large amount of fuel, has a long testing cycle, is costly, and is susceptible to environmental and equipment factors, resulting in poor repeatability and making it difficult to widely apply in product design and rapid iteration phases. Second, using computational fluid dynamics (CFD) for transient numerical simulation, attempting to simulate the complete fuel supply process from a full tank to an empty small fuel tank. However, because this process involves two-phase flow of air and fuel, liquid level changes, and a real physical time span of tens of hours (e.g., 25.5 hours), transient simulation requires complex multiphase flow models, small calculation steps, and a huge number of total calculation steps, leading to extremely long simulation times. This places extremely high demands on computing hardware resources (such as CPU / GPU computing power and memory), resulting in huge computational costs and low efficiency, making it difficult to meet the needs of rapid analysis and multi-solution comparison in modern product development.
[0004] Therefore, there is an urgent need in this field for an innovative simulation method that can break away from the traditional long-term transient simulation framework and efficiently and accurately predict the liquid level difference when a dual-tank system reaches a steady state during the fuel supply process and the final amount of remaining oil in the large tank. Summary of the Invention
[0005] In a first aspect, embodiments of this application provide a steady-state simulation method for rapidly determining the liquid level difference between two oil tanks, comprising the following steps: S1. Calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and set the steady state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the net oil flow ratio of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. S2. The liquid level difference corresponding to the steady state is converted into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and the pressure difference is set as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level difference exists. S3. The first net oil flow ratio of the two oil tanks in the initial full state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full are calculated by simulation. When the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. S4. When a stable state is determined to exist, the pressure values corresponding to the initial full oil state and the extreme state are used as an interval. An iterative algorithm is used to find a target pressure value, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. S5. Based on the target pressure value found, the corresponding stable liquid level height difference is calculated using the inverse formula of the static pressure formula.
[0006] Furthermore, the specific steps of step S1 are as follows: S11. Obtain the volume of the large fuel tank. and the capacity of the small fuel tank Calculate the volume ratio using the following formula. : ; S12. Define the net oil flow rate of the large oil tank as... The net oil flow rate of the small oil tank is The condition for setting a steady state is the net oil flow rate ratio. equal to volume ratio .
[0007] Furthermore, the specific steps of step S2 are as follows: S21. Set the liquid level difference corresponding to the steady state as... ; S22. According to the static pressure formula The difference in liquid level Converted into pressure difference ,in, For fuel density, It is the acceleration due to gravity; S23. In the simulation model, the pressure inlet pressure corresponding to the large oil tank is set as the reference value. The pressure inlet pressure corresponding to the small oil tank is and order This will reduce the pressure difference. Set as simulation boundary conditions.
[0008] Furthermore, the specific steps of step S3 are as follows: S31. In the simulation model, set the pressure boundary condition of the small oil tank as follows: , Simulating an initial full oil condition, the net oil flow rate of the small oil tank under the initial full oil condition was calculated. Net fuel flow rate from large fuel tank And calculate the first net oil flow rate ratio. ; S32. In the simulation model, set the pressure boundary condition of the small oil tank as follows: Simulating the extreme condition of an empty small fuel tank and a full large fuel tank, the net fuel flow rate of the small fuel tank under extreme conditions was calculated. Net fuel flow rate from large fuel tank And calculate the second net oil flow rate ratio. ;in, This refers to the height of the small fuel tank. S33. Determine the volume ratio Does it meet the following conditions: or ; If the conditions are met, a steady state is determined to exist, and the pressure value corresponding to the initial full oil state is recorded. and the pressure value corresponding to extreme conditions Proceed to step S4; If the conditions are not met, it is determined that there is no stable state, and the process ends.
[0009] Furthermore, the iterative algorithm in step S4 employs a binary search method; The specific steps of step S4 are as follows: S41. Set the lower bound of the iterative search interval and upper limit Initial command , ,in and These are the pressure values corresponding to the initial full oil state and the pressure values corresponding to the extreme state, as recorded in step S3. S42. Calculate the pressure at the midpoint of the interval. : ; S43. In the simulation model, the pressure boundary condition of the small oil tank is set as the pressure at the midpoint of the interval. The net oil flow rate of the small oil tank under the pressure boundary conditions was calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S44. Compare the current net oil flow rate ratio with volume ratio : like Then let ; like Then let ; If the current net oil output flow rate is... equal Or approximate within the preset tolerance range Then the current midpoint pressure will be... As the target pressure value And end the iteration; S45. Repeat steps S42 to S44 until the target pressure value is found. .
[0010] Furthermore, the iterative algorithm in step S4 employs the finite difference method; The specific steps of step S4 are as follows: S41A. Set the first test pressure value And set the initial value of the first test pressure value to the pressure value corresponding to the initial full oil state. Pressure values corresponding to extreme conditions Select from the defined interval; S42A. In the simulation model, the pressure boundary condition of the small oil tank is set to the current first test pressure value, and the net oil flow rate of the small oil tank under the pressure boundary condition is calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S43A. Compare the current net oil flow rate ratio with volume ratio : like If the current pressure difference setting is determined to be too small, a new test pressure value that is reduced according to preset rules will be generated. To increase the current pressure difference; like If the current pressure difference setting is determined to be too large, a new test pressure value that is increased according to preset rules will be generated. To reduce the current pressure difference; S44A. New test pressure value Assign the value to the first test stress value And repeat steps S42A to S43A; S45A. Repeat the iterative process until the current net oil flow rate ratio is reached. Equal to or approaching the volume ratio within a preset tolerance range Then the first test pressure value at this time As the target pressure value Then, the iteration ends.
[0011] Further, in step S43A, a new test pressure value is generated. The rule is: based on the current net oil output ratio with volume ratio The magnitude and direction of the deviation are calculated according to a preset step sequence or interpolation method.
[0012] Furthermore, the specific steps of step S5 are as follows: S51. Obtain the target pressure value Based on the model boundary conditions established in step S2, the target pressure value is... Substituting into the pressure difference calculation formula, we obtain the actual pressure difference under steady-state conditions. : ; S52. In extreme conditions, the fuel level in the small fuel tank is depleted, causing... ,but ; S53. Calculate the actual pressure difference. Substituting into the inverse formula of the hydrostatic pressure equation, the stable liquid level difference can be calculated. :
[0013] S54. Based on the calculated stable liquid level difference The remaining fuel in the large fuel tank when the small fuel tank is depleted is calculated using the following formula. :
[0014] in, This refers to the height of the small fuel tank. This refers to the volume of the large fuel tank.
[0015] Secondly, embodiments of this application also provide a steady-state simulation system for rapidly determining the difference in liquid level between two oil tanks, comprising: The parameter acquisition and criterion definition module is used to calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and to set the stable state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the ratio of the net oil flow rate of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. The boundary condition conversion module is used to convert the liquid level height difference corresponding to the steady state into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and set the pressure difference as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level height difference exists. The state existence judgment module is used to calculate the first net oil flow ratio of the two oil tanks in the initial full oil state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full through simulation. When the value of the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. The pressure iteration solution module is used to find a target pressure value by using the pressure values corresponding to the initial full oil state and the extreme state as an interval when a steady state is determined to exist, through an iterative algorithm, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. The height difference calculation module is used to calculate the corresponding stable liquid level height difference based on the target pressure value found, using the inverse formula of the static pressure formula.
[0016] Thirdly, embodiments of this application also provide a storage medium storing a computer program thereon, wherein when the computer program is executed by a processor, it implements the steps of the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks as described in the first aspect.
[0017] As can be seen from the above technical solutions, this application has the following advantages: The steady-state simulation method, system, and medium for rapidly determining the liquid level difference between two fuel tanks provided in this application transform complex transient simulations into steady-state simulations, avoiding the problems of long calculation times and high resource consumption in traditional transient simulations, thus improving simulation efficiency and shortening calculation time. Through precise mathematical models and iterative algorithms, the liquid level difference and target pressure value under steady-state conditions can be accurately found, providing a basis for the design and optimization of dual-fuel tank systems. This application can effectively solve the problem of uneven fuel supply, improve the effective utilization rate of dual-fuel tank systems, reduce reliance on real vehicle tests or bench tests, reduce fuel consumption and test costs, and avoid the high computational cost of complex multiphase flow models. Attached Figure Description
[0018] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1This is a flowchart illustrating the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to the present invention.
[0020] Figure 2 This is a schematic diagram showing the stable state of the large and small oil tanks of the present invention.
[0021] Figure 3 This is a schematic diagram of the initial full state of the large and small oil tanks of the present invention.
[0022] Figure 4 This is a schematic diagram of the steady-state simulation system for rapidly determining the liquid level difference between two oil tanks according to the present invention. Detailed Implementation
[0023] The various embodiments of this disclosure will be described more fully in the following detailed steps of a steady-state simulation method for rapidly determining the liquid level difference between two oil tanks. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.
[0024] This embodiment provides a steady-state simulation method for quickly determining the liquid level difference between two oil tanks. Through steady-state simulation, the liquid level difference between the two oil tanks can be quickly determined, saving calculation time and resources and improving design efficiency.
[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] Please see Figure 1 The diagram shows a flowchart of a steady-state simulation method for rapidly determining the liquid level difference between two oil tanks in a specific embodiment. The method includes the following steps: S1. Calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and set the steady state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the net oil flow ratio of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. It should be noted that by calculating the volume ratio, key parameters are provided for the simulation calculation. The steady-state condition is defined as the net oil flow rate ratio equal to the volume ratio, which provides the target and judgment basis for the simulation calculation and simplifies the complex problem. S2. The liquid level difference corresponding to the steady state is converted into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and the pressure difference is set as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level difference exists. It should be noted that converting the liquid level difference into a pressure difference avoids the complexity of directly setting the liquid level, making the simulation model simple and efficient; setting the pressure difference as the simulation boundary condition can accurately simulate the impact of the liquid level difference on the tank pressure, thus improving the accuracy of the simulation. S3. The first net oil flow ratio of the two oil tanks in the initial full state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full are calculated by simulation. When the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. It should be noted that by calculating the net oil flow ratio under the initial full oil condition and the extreme condition, the existence of a steady state is comprehensively determined, avoiding misjudgment; a definite initial interval is provided for the iterative algorithm, ensuring the convergence and effectiveness of the iterative process and improving the search efficiency of the target pressure value; S4. When a stable state is determined to exist, the pressure values corresponding to the initial full oil state and the extreme state are used as an interval. An iterative algorithm is used to find a target pressure value, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. It should be noted that by using an iterative algorithm to find the target pressure value, the algorithm can quickly converge to the target value in a short time, thus improving the iteration efficiency; by continuously adjusting the pressure value, the algorithm can accurately approximate the target pressure value, ensuring the accuracy of the simulation results. S5. Based on the target pressure value found, the corresponding stable liquid level height difference is calculated using the inverse formula of the static pressure formula; It should be noted that by calculating the stable liquid level difference through the inverse formula of the hydrostatic pressure, the remaining oil volume in the large oil tank can be obtained. This provides key data for the design and optimization of the dual oil tank system. By directly calculating the remaining oil volume in the large oil tank, practical applications can be supported.
[0027] This embodiment transforms complex transient simulation into steady-state simulation, quickly determining the difference in fuel level between the two fuel tanks and the remaining fuel volume in the large fuel tank. Compared with traditional methods, it improves simulation efficiency, saves computation time and resources, and enhances prediction accuracy, providing technical support for the design and optimization of dual fuel tank systems in commercial vehicles.
[0028] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another steady-state simulation method for quickly determining the liquid level difference between the two fuel tanks is provided. Taking a commercial vehicle dual-fuel tank fuel supply system, including a large fuel tank and a small fuel tank, as an example, the basic parameter settings of this fuel supply system are shown in Table 1: Table 1
[0029] The following conditions are defined in advance: Volume ratio According to the formula The calculation is used as the target value for the net oil flow rate ratio under steady-state conditions. Net oil flow rate: Defined as the net oil flow rate of the large fuel tank. The net oil flow rate from the small fuel tank is Net oil flow rate = oil flow rate - return oil flow rate; Stable state determination: The liquid levels in the two tanks are at a fixed height difference. Synchronous descent, and satisfying = ; Simulation medium setting: Only liquid fuel oil is used as the computational fluid medium, eliminating the need to set air and oil-gas two-phase parameters, thus simplifying the simulation model; The method includes the following steps: S1. Calculate the volume ratio of the two oil tanks based on their volume parameters, and set the steady-state condition of the dual-tank system as follows: the liquid levels in the large and small oil tanks decrease synchronously with a fixed height difference, and the net oil flow rate ratio between the large and small oil tanks is equal to the volume ratio of the two oil tanks; the specific steps of step S1 are as follows: S11. Obtain the volume of the large fuel tank. and the capacity of the small fuel tank Calculate the volume ratio using the following formula. : ; S12. Define the net oil flow rate of the large oil tank as... The net oil flow rate of the small oil tank is The condition for setting a steady state is the net oil flow rate ratio. equal to volume ratio ; For example, the capacity of a large fuel tank =800L, the capacity of the small fuel tank =220L, calculated volume ratio =0.275; For example, the volume ratio is calculated by substituting the parameters. =220L / 800L=0.275; The core condition for determining a steady state is the net oil flow rate ratio. = =0.275, at which point the liquid levels in the two tanks maintain a fixed height difference. Synchronous descent; S2. The liquid level difference corresponding to the steady state is converted into a pressure difference between the large and small oil tanks according to the hydrostatic formula, and the pressure difference is set as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state where the liquid level difference exists; the specific steps of step S2 are as follows: S21. Set the liquid level difference corresponding to the steady state as... ; S22. According to the static pressure formula The difference in liquid level Converted into pressure difference ,in, For fuel density, It is the acceleration due to gravity; S23. In the simulation model, the pressure inlet pressure corresponding to the large oil tank is set as the reference value. The pressure inlet pressure corresponding to the small oil tank is and order This will reduce the pressure difference. Set as simulation boundary conditions; For example, setting a reference value ,at this time ; For example, suppose Figure 2 Under the steady-state condition shown, the oil level in the large tank is higher than that in the small tank, and the difference in oil level is... ; According to the static pressure formula This converts the difference in liquid level height into a pressure difference; among which, =833kg / m 3 , =9.8m / s², therefore =833×9.8× =8163.4 (Pa); Set the inlet pressure of the large oil tank as a reference value. =0Pa, the inlet pressure of the small oil tank is 0Pa. ,make (Because the fuel level in the larger tank is higher, the pressure is greater), then The pressure difference is passed through The value of is equivalent to the simulation boundary condition; S3. Calculate the first net oil flow rate ratio of the two oil tanks under the initial full oil condition and the second net oil flow rate ratio of the two oil tanks under the extreme condition of the small oil tank being empty and the large oil tank being full. If the volume ratio of the two oil tanks is between the first and second net oil flow rate ratios, a stable state is determined to exist. The specific steps of step S3 are as follows: S31. In the simulation model, set the pressure boundary condition of the small oil tank as follows: , Simulation Figure 3 The initial full oil condition is shown, and the net oil flow rate of the small oil tank under the initial full oil condition is calculated. Net fuel flow rate from large fuel tank And calculate the first net oil flow rate ratio. ; S32. In the simulation model, set the pressure boundary condition of the small oil tank as follows: Simulating the extreme condition of an empty small fuel tank and a full large fuel tank, the net fuel flow rate of the small fuel tank under extreme conditions was calculated. Net fuel flow rate from large fuel tank And calculate the second net oil flow rate ratio. ;in, This refers to the height of the small fuel tank; for example, the height of the small fuel tank is... ; S33. Determine the volume ratio Does it meet the following conditions: or ; If the conditions are met, a steady state is determined to exist, and the pressure value corresponding to the initial full oil state is recorded. and the pressure value corresponding to extreme conditions Proceed to step S4; If the conditions are not met, it is determined that there is no stable state, and the process ends. For example, setting pressure boundary conditions for the small oil tank. (at this time =0, with the oil levels in both tanks equal (simulating an initial full oil state), the net oil flow rate from the small tank was calculated through steady-state simulation. =0.00473kg / s, net oil flow rate from the large fuel tank =0.00465kg / s; Calculate the first net oil flow rate ratio. =0.00473 / 0.00465≈1.017; Set the pressure boundary conditions for the small oil tank. =-833×9.8×0.66≈-5497.8Pa (simulating the extreme state of the small fuel tank being empty and the large fuel tank being full, where the liquid level in the small fuel tank is 0 and the liquid level in the large fuel tank is H). The net oil flow rate from the small fuel tank is calculated through steady-state simulation. =-0.03025kg / s (a negative value indicates that oil flows from the large oil tank into the small oil tank), net oil flow rate from the large oil tank. =0.03963kg / s; Calculate the second net oil flow rate ratio. =-0.03025 / 0.03963≈-0.763; Determine the volume ratio Is 0.275 within the range? =1.017 and = between -0.763, that is The conditions are met, therefore a stable state is determined to exist; record the pressure value corresponding to the initial full oil state. Pressure value corresponding to extreme conditions =-5497.8Pa, proceed to step S4; S4. When a steady state is determined to exist, the pressure values corresponding to the initial full oil state and the extreme state are used as an interval. An iterative algorithm is used to find a target pressure value such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. The iterative algorithm in step S4 adopts the bisection method. The specific steps of step S4 are as follows: S41. Set the lower bound of the iterative search interval and upper limit Initial command , ,in and These are the pressure values corresponding to the initial full oil state and the pressure values corresponding to the extreme state, as recorded in step S3. S42. Calculate the pressure at the midpoint of the interval. : ; S43. In the simulation model, the pressure boundary condition of the small oil tank is set as the pressure at the midpoint of the interval. The net oil flow rate of the small oil tank under the pressure boundary conditions was calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S44. Compare the current net oil flow rate ratio with volume ratio : like Then let ; like Then let ; If the current net oil output flow rate is... equal Or approximate within the preset tolerance range Then the current midpoint pressure will be... As the target pressure value And end the iteration; S45. Repeat steps S42 to S44 until the target pressure value is found. For example, the target pressure value obtained through bisection iterative calculation. ; For example, the lower bound of the initial iterative search interval = =-5497.8Pa, upper limit = ; Midpoint pressure in the first iteration =-2748.9Pa; set up = =-2748.9Pa, simulation results =0.0012kg / s, =0.0085kg / s, current flow rate ratio =0.0012 / 0.0085≈0.141, which is less than =0.275; because < This indicates the current pressure difference. =2748.9Pa is too high (the pressure in the small oil tank is too low), the pressure difference needs to be reduced. = =-2748.9Pa; Second iteration: =(-2748.9+0) / 2=-1374.45Pa, obtained from simulation. ≈0.213<0.275, let =-1374.45Pa; Third iteration: =(-1374.45+0) / 2=-687.225Pa, obtained from simulation. ≈0.251<0.275, let =-687.225Pa; Fourth iteration: =(-687.225+0) / 2=-343.61Pa, obtained from simulation. ≈0.283>0.275, let =-343.61Pa; When it was continuously iterated to the 8th time, =-378Pa, simulation results =0.00202kg / s, =0.00735kg / s, current flow rate ratio =0.00202 / 0.00735≈0.275, within the preset tolerance range, stop the iteration and determine the target pressure value. =-378Pa; S5. Based on the target pressure value found, calculate the corresponding stable liquid level height difference using the inverse formula of the static pressure formula; the specific steps of step S5 are as follows: S51. Obtain the target pressure value Based on the model boundary conditions established in step S2, the target pressure value is... Substituting into the pressure difference calculation formula, we obtain the actual pressure difference under steady-state conditions. : ; S52. In extreme conditions, the fuel level in the small fuel tank is depleted, causing... ,but ; S53. Calculate the actual pressure difference. Substituting into the inverse formula of the hydrostatic pressure equation, the stable liquid level difference can be calculated. :
[0030] S54. Based on the calculated stable liquid level difference The remaining fuel in the large fuel tank when the small fuel tank is depleted is calculated using the following formula. :
[0031] in, This refers to the height of the small fuel tank. For the volume of the large fuel tank; For example, the calculated stable liquid level difference =45.38mm, corresponding to the remaining fuel level in the large fuel tank. =54.55L; For example, set according to boundary conditions =0-(-378)=378Pa; Substituting into the inverse formula of static pressure ,have to =378 / (833×9.8)≈0.04538m=45.38mm; When the fuel in the small tank is depleted, the remaining fuel level in the large tank is equal to the difference in stable fuel level. (Because the fuel level in the small tank is 0, the height difference remains constant under stable conditions); based on the linear relationship between the fuel tank volume and the fuel level, the remaining fuel volume... =(45.38mm / 660mm)×800L≈54.55L.
[0032] In some embodiments, unlike the embodiments described above, the iterative algorithm in step S4 uses the difference method; The specific steps of step S4 are as follows: S41A. Set the first test pressure value And set the initial value of the first test pressure value to the pressure value corresponding to the initial full oil state. Pressure values corresponding to extreme conditions Selected within the defined range; for example, the first test pressure value. The initial value was chosen to be -2000 Pa; S42A. In the simulation model, the pressure boundary condition of the small oil tank is set to the current first test pressure value, and the net oil flow rate of the small oil tank under the pressure boundary condition is calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S43A. Compare the current net oil flow rate ratio with volume ratio : like If the current pressure difference setting is determined to be too small, a new test pressure value that is reduced according to preset rules will be generated. To increase the current pressure difference; like If the current pressure difference setting is determined to be too large, a new test pressure value that is increased according to preset rules will be generated. To reduce the current pressure difference; In step S43A, a new test pressure value is generated. The rule is: based on the current net oil output ratio with volume ratio The magnitude and direction of the deviation are calculated according to a preset step size sequence or interpolation method; For example, when the first test pressure value = At 2000Pa, the current net oil flow rate ratio = 0.495 is less than the volume ratio (0.275) will generate a new test pressure value that increases according to preset rules. (e.g., -300Pa); S44A. New test pressure value Assign the value to the first test stress value And repeat steps S42A to S43A; S45A. Repeat the iterative process until the current net oil flow rate ratio is reached. Equal to or approaching the volume ratio within a preset tolerance range Then the first test pressure value at this time As the target pressure value And end the iteration; For example, in the interval [ , The initial test pressure is selected within the range of [-5497.8Pa, 0Pa]. =-2000Pa; set up =-2000Pa, obtained from simulation =-0.00919kg / s, =0.01856kg / s, current flow rate ratio =-0.00919 / 0.01856≈-0.495; because =-0.495< =0.275, indicating that the current pressure difference is too large. (Too small), needs to be enlarged (Reduce pressure difference), adjust by preset step size + 1700Pa, new test pressure. =-2000+1700=-300Pa; set up =-300Pa, simulation results =0.00258kg / s, =0.00608kg / s, current flow rate ratio =0.00258 / 0.00608≈0.379>0.275, indicating the pressure difference is too small. Adjust according to a step size of 22Pa and test the new pressure. =-300+22=-278Pa; The rule iterates continuously by adjusting the step size according to the direction of deviation, when At -378 Pa, =0.275, meets the requirements, determine the target pressure value. =-378Pa.
[0033] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
[0034] like Figure 4 As shown, the following is an embodiment of the steady-state simulation system for rapidly determining the liquid level difference between two oil tanks provided by this disclosure. This system and the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the steady-state simulation system for rapidly determining the liquid level difference between two oil tanks, please refer to the embodiments of the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks described above.
[0035] The system includes: The parameter acquisition and criterion definition module is used to calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and to set the stable state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the ratio of the net oil flow rate of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. The boundary condition conversion module is used to convert the liquid level height difference corresponding to the steady state into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and set the pressure difference as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level height difference exists. The state existence judgment module is used to calculate the first net oil flow ratio of the two oil tanks in the initial full oil state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full through simulation. When the value of the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. The pressure iteration solution module is used to find a target pressure value by using the pressure values corresponding to the initial full oil state and the extreme state as an interval when a steady state is determined to exist, through an iterative algorithm, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. The height difference calculation module is used to calculate the corresponding stable liquid level height difference based on the target pressure value found, using the inverse formula of the static pressure formula.
[0036] This embodiment achieves rapid determination of the liquid level difference between the two fuel tanks through the interactive collaboration of the parameter acquisition and criterion definition module, boundary condition transformation module, state existence judgment module, pressure iterative solution module, and height difference calculation module. This improves simulation efficiency, saves computation time and resources, and provides a basis for the design and optimization of dual fuel tank systems for commercial vehicles.
[0037] The storage medium provided in this application stores a program product that enables a steady-state simulation method for rapidly determining the liquid level difference between two oil tanks.
[0038] A rapid steady-state simulation method for determining the liquid level difference between two oil tanks includes: calculating the volume ratio of the two tanks based on their volume parameters, and setting the steady-state conditions of the dual-tank system as follows: the liquid levels in the large and small tanks decrease synchronously with a fixed liquid level difference, and the ratio of the net oil flow rate of the large and small tanks is equal to the volume ratio of the two tanks; converting the liquid level difference corresponding to the steady state into a pressure difference between the large and small tanks according to the static pressure formula, and setting the pressure difference as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state where the liquid level difference exists; and calculating the first... The first net oil flow rate ratio and the second net oil flow rate ratio of the two oil tanks under the extreme condition of the small oil tank being empty and the large oil tank being full are used to determine the existence of a stable state when the volume ratio of the two oil tanks is between the first net oil flow rate ratio and the second net oil flow rate ratio. When the stable state is determined to exist, a target pressure value is found through an iterative algorithm, using the pressure values corresponding to the initial full state and the extreme state as the interval. This target pressure value is used as the boundary condition in the simulation calculation, and the net oil flow rate ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. Based on the found target pressure value, the corresponding stable liquid level height difference is calculated through the inverse formula of the hydrostatic pressure formula.
[0039] In some possible implementations, the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks disclosed herein can be implemented as a program product comprising program code that, when run on a terminal device, causes the terminal device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this disclosure.
[0040] The storage medium disclosed herein may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.
[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A steady-state simulation method for rapidly determining the liquid level difference between two oil tanks, characterized in that, Includes the following steps: S1. Calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and set the steady state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the net oil flow ratio of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. S2. The liquid level difference corresponding to the steady state is converted into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and the pressure difference is set as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level difference exists. S3. The first net oil flow ratio of the two oil tanks in the initial full state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full are calculated by simulation. When the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. S4. When a stable state is determined to exist, the pressure values corresponding to the initial full oil state and the extreme state are used as an interval. An iterative algorithm is used to find a target pressure value, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. S5. Based on the target pressure value found, the corresponding stable liquid level height difference is calculated using the inverse formula of the static pressure formula.
2. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 1, characterized in that, The specific steps of step S1 are as follows: S11. Obtain the volume of the large fuel tank. and the capacity of the small fuel tank Calculate the volume ratio using the following formula. : ； S12. Define the net oil flow rate of the large oil tank as... The net oil flow rate of the small oil tank is The condition for setting a steady state is the net oil flow rate ratio. equal to volume ratio .
3. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 2, characterized in that, The specific steps of step S2 are as follows: S21. Set the liquid level difference corresponding to the steady state as... ; S22. According to the static pressure formula The difference in liquid level Converted into pressure difference ,in, For fuel density, It is the acceleration due to gravity; S23. In the simulation model, the pressure inlet pressure corresponding to the large oil tank is set as the reference value. The pressure inlet pressure corresponding to the small oil tank is and order This will reduce the pressure difference. Set as simulation boundary conditions.
4. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 3, characterized in that, The specific steps of step S3 are as follows: S31. In the simulation model, set the pressure boundary condition of the small oil tank as follows: , Simulating an initial full oil condition, the net oil flow rate of the small oil tank under the initial full oil condition was calculated. Net fuel flow rate from large fuel tank And calculate the first net oil flow rate ratio. ; S32. In the simulation model, set the pressure boundary condition of the small oil tank as follows: Simulating the extreme condition of an empty small fuel tank and a full large fuel tank, the net fuel flow rate of the small fuel tank under extreme conditions was calculated. Net fuel flow rate from large fuel tank And calculate the second net oil flow rate ratio. ;in, This refers to the height of the small fuel tank. S33. Determine the volume ratio Does it meet the following conditions: or ; If the conditions are met, a steady state is determined to exist, and the pressure value corresponding to the initial full oil state is recorded. and the pressure value corresponding to extreme conditions Proceed to step S4; If the conditions are not met, it is determined that there is no stable state, and the process ends.
5. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 4, characterized in that, The iterative algorithm in step S4 uses the bisection method; The specific steps of step S4 are as follows: S41. Set the lower bound of the iterative search interval and upper limit Initial command , ,in and These are the pressure values corresponding to the initial full oil state and the pressure values corresponding to the extreme state, as recorded in step S3. S42. Calculate the pressure at the midpoint of the interval. : ; S43. In the simulation model, the pressure boundary condition of the small oil tank is set as the pressure at the midpoint of the interval. The net oil flow rate of the small oil tank under the pressure boundary conditions was calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S44. Compare the current net oil flow rate ratio with volume ratio : like Then let ; like Then let ; If the current net oil output flow rate is... equal Or approximate within the preset tolerance range Then the current midpoint pressure will be... As the target pressure value And end the iteration; S45. Repeat steps S42 to S44 until the target pressure value is found. .
6. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 4, characterized in that, The iterative algorithm in step S4 uses the finite difference method; The specific steps of step S4 are as follows: S41A. Set the first test pressure value And set the initial value of the first test pressure value to the pressure value corresponding to the initial full oil state. Pressure values corresponding to extreme conditions Select from the defined interval; S42A. In the simulation model, the pressure boundary condition of the small oil tank is set to the current first test pressure value, and the net oil flow rate of the small oil tank under the pressure boundary condition is calculated. Net fuel flow rate from large fuel tank And calculate the current net oil flow ratio. ; S43A. Compare the current net oil flow rate ratio with volume ratio : like If the current pressure difference setting is determined to be too small, a new test pressure value that is reduced according to preset rules will be generated. To increase the current pressure difference; like If the current pressure difference setting is determined to be too large, a new test pressure value that is increased according to preset rules will be generated. To reduce the current pressure difference; S44A. New test pressure value Assign the value to the first test stress value And repeat steps S42A to S43A; S45A. Repeat the iterative process until the current net oil flow rate ratio is reached. Equal to or approaching the volume ratio within a preset tolerance range Then the first test pressure value at this time As the target pressure value Then, the iteration ends.
7. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 5, characterized in that, In step S43A, a new test pressure value is generated. The rule is: based on the current net oil output ratio with volume ratio The magnitude and direction of the deviation are calculated according to a preset step sequence or interpolation method.
8. The steady-state simulation method for rapidly determining the liquid level difference between two oil tanks according to claim 5, characterized in that, The specific steps of step S5 are as follows: S51. Obtain the target pressure value Based on the model boundary conditions established in step S2, the target pressure value is... Substituting into the pressure difference calculation formula, we obtain the actual pressure difference under steady-state conditions. : ； S52. In extreme conditions, the fuel level in the small fuel tank is depleted, causing... ,but ; S53. Calculate the actual pressure difference. Substituting into the inverse formula of the hydrostatic pressure equation, the stable liquid level difference can be calculated. : S54. Based on the calculated stable liquid level difference The remaining fuel in the large fuel tank when the small fuel tank is depleted is calculated using the following formula. : in, This refers to the height of the small fuel tank. This refers to the volume of the large fuel tank.
9. A steady-state simulation system for rapidly determining the liquid level difference between two oil tanks, characterized in that, include: The parameter acquisition and criterion definition module is used to calculate the volume ratio of the two oil tanks based on the volume parameters of the large oil tank and the small oil tank, and to set the stable state condition of the dual oil tank system as follows: the liquid levels of the large oil tank and the small oil tank drop synchronously with a fixed liquid level height difference, and the ratio of the net oil flow rate of the large oil tank and the small oil tank is equal to the volume ratio of the two oil tanks. The boundary condition conversion module is used to convert the liquid level height difference corresponding to the steady state into the pressure difference between the large oil tank and the small oil tank according to the static pressure formula, and set the pressure difference as the boundary condition of the corresponding pressure inlet in the simulation model to equivalently simulate the physical state in which the liquid level height difference exists. The state existence judgment module is used to calculate the first net oil flow ratio of the two oil tanks in the initial full oil state and the second net oil flow ratio of the two oil tanks in the extreme state of the small oil tank being empty and the large oil tank being full through simulation. When the value of the volume ratio of the two oil tanks is between the first net oil flow ratio and the second net oil flow ratio, it is determined that a stable state exists. The pressure iteration solution module is used to find a target pressure value by using the pressure values corresponding to the initial full oil state and the extreme state as an interval when a steady state is determined to exist, through an iterative algorithm, such that in the simulation calculation with the target pressure value as the boundary condition, the net oil flow ratio of the two oil tanks is equal to the volume ratio of the two oil tanks. The height difference calculation module is used to calculate the corresponding stable liquid level height difference based on the target pressure value found, using the inverse formula of the static pressure formula.
10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the steady-state simulation method for rapidly determining the liquid level difference between two oil tanks as described in any one of claims 1 to 8.