Coupling modeling method for high-altitude ventilation and spray combustion in sustainable aviation fuel engines

Abstract

The present invention discloses a method for coupling modeling of high-altitude ventilation and spray combustion of a sustainable aviation fuel engine. The engine is an aviation heavy oil engine, and the coupling modeling method includes the following steps: preliminarily establishing a one-dimensional simulation model and a three-dimensional simulation model; performing a first iteration of the one-dimensional simulation model and the three-dimensional simulation model; conducting a tracer gas ventilation experiment and a constant volume bomb spray combustion experiment on the engine in a ground state, obtaining a first experimental result to calibrate and optimize the model characteristic parameters of the three-dimensional simulation model; performing a second iteration of the one-dimensional simulation model and the three-dimensional simulation model; conducting a high-altitude environment simulation whole machine experiment, a tracer gas ventilation experiment and a constant volume bomb spray combustion experiment on the engine, obtaining a second experimental result to calibrate and optimize the one-dimensional simulation model and the three-dimensional simulation model; performing a third iteration of the one-dimensional simulation model and the three-dimensional simulation model. The present invention can establish a one-dimensional and three-dimensional ventilation and spray combustion coupling simulation model with a high degree of coupling, and the simulation accuracy is high.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation heavy fuel engines, and in particular to a high-altitude ventilation and spray combustion coupling modeling method for a sustainable aviation fuel engine. Background Art

[0002] Aviation heavy fuel oil engines are aviation piston engines that use diesel or aviation kerosene fuels. They are highly safe, readily available, and inexpensive. Against the backdrop of the rapid development of general aviation and drone industries at home and abroad in recent years, aviation heavy fuel oil engines will gradually replace aviation gasoline engines and become one of the mainstream sources of future micro-aviation power. They are also a subject of research that has received significant attention recently.

[0003] However, if aviation heavy oil engines continue to burn traditional diesel and aviation kerosene, relying solely on technologies such as lightweighting and improving combustion efficiency is increasingly unable to meet the requirements of low-carbon sustainable development of aviation. Sustainable aviation fuel (SAF) refers to aviation fuel derived from renewable materials such as biojet fuel. Its carbon emissions over its entire life cycle can be reduced by 85% compared to traditional fuels. The physical and chemical properties of SAF also fall into the category of heavy oil (biodiesel, biojet fuel, etc.). The use of SAF by aviation heavy oil engines has become an important technical path and cutting-edge development trend for "general aviation carbon neutrality."

[0004] Two-stage supercharging or mechanical and turbocharged supercharging can effectively increase the flight ceiling of heavy fuel oil (HFO) engines. However, their high-altitude application is technically complex, particularly in the highly complex and tightly coupled nature of ventilation and spray combustion at altitude. For one thing, ventilation at altitude differs from ground level due to factors such as the altitude environment and the pressurization state. High-altitude ventilation performance determines the initial gas composition involved in combustion, significantly impacting power, fuel economy, and emissions at altitude. Furthermore, the atomization of HFO spray is significantly influenced by the airflow organization during ventilation. For example, in compression-ignition HFO engines, controlling the vortex size during ventilation can effectively aid high-altitude atomization, and ventilation and atomization quality significantly influence combustion performance. Furthermore, the high-altitude combustion and pressurization state jointly influence the ventilation pressure and temperature boundaries. Due to the complex and tightly coupled relationship between ventilation, atomization, and combustion, all three are highly sensitive to changes in HFO engine operating parameters and environmental variations at altitude, making their complex mechanisms difficult to derive using analogy alone.

[0005] If the application of SAF is taken into account, the characteristic characterization and coupling influence of the engine's high-altitude ventilation and spray combustion are even more difficult to determine: at the ventilation level, when SAF is applied, its combustion and boost characteristics are different from those of traditional fuels, and its high-altitude ventilation characteristics will change to a certain extent with the SAF component and altitude; at the spray combustion level, the physical and chemical parameters of SAF such as viscosity, density, cetane number and auto-ignition point are different from those of traditional fuels, and it may be used in a mixture of different components, and its high-altitude spray combustion characteristics will also change to a certain extent with the SAF component and altitude; at the ventilation and spray combustion coupling level, when SAF is applied, the ventilation vortex of different fuel components and different high-altitude working conditions on atomization, the coupling influence of ventilation and atomization performance on combustion, and combustion on ventilation boundary need to be accurately determined.

[0006] Modeling and simulation of the high-altitude ventilation and spray combustion processes of aviation heavy fuel engines primarily involve one-dimensional and three-dimensional simulations. One-dimensional simulation typically calculates the entire engine system cycle, taking into account the coupling of ventilation, spray combustion, and other in-cylinder processes. It offers high computational efficiency and can quickly determine engine ventilation, spray combustion, and power performance. However, due to its one-dimensional nature, it cannot accurately capture the flow field, and improving computational accuracy requires experimental calibration of different modules. Three-dimensional simulation accurately describes the evolution of the in-cylinder flow field during ventilation and spray combustion, capturing details such as heat and mass transfer, air-to-exhaust displacement and mixing, vortex distribution, scavenging blind spots, spray penetration, and flame ignition and diffusion. This provides a more comprehensive and accurate calculation of the ventilation and spray combustion process. However, the computational speed is slow, and accuracy depends on the appropriateness of the selected turbulence model. While one-dimensional and three-dimensional simulations each have their own unique characteristics, coupling them together provides a comprehensive and effective simulation method for optimizing ventilation and spray combustion processes.

[0007] Existing engine simulations typically use separate one-dimensional and three-dimensional simulations, with little or no coupling between the two. This makes them unable to meet the accuracy requirements for the simulation of the ventilation and spray combustion processes. Most existing models are designed for conventional fuels and lack corrections for the physical and chemical properties and related characteristics of SAF, nor are the model characteristic coefficients corrected for high-altitude operating conditions. Uncorrected one- and three-dimensional models cannot accurately simulate the high-altitude ventilation and spray combustion characteristics of SAF. Summary of the Invention

[0008] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, one objective of the present invention is to provide a method for modeling the coupled ventilation and spray combustion of a sustainable aviation fuel engine at high altitude. This method can establish a highly coupled one- and three-dimensional simulation model of ventilation and spray combustion, achieving high simulation accuracy.

[0009] According to an embodiment of the present invention, a method for coupling high-altitude ventilation and spray combustion modeling for a sustainable aviation fuel engine, wherein the engine is an aviation heavy fuel oil engine, comprises the following steps:

[0010] S1: Preliminary establishment of a one-dimensional simulation model and a three-dimensional simulation model, wherein the one-dimensional simulation model is used to simulate the entire thermodynamic cycle and power performance of the engine, and the three-dimensional simulation model is used to simulate the evolution of the flow field in the engine cylinder during the engine ventilation and spray combustion process;

[0011] S2: simulating the one-dimensional simulation model and the three-dimensional simulation model respectively, obtaining simulation results of the one-dimensional simulation model and the three-dimensional simulation model, and performing initial iteration of the one-dimensional simulation model and the three-dimensional simulation model;

[0012] S3: conducting a tracer gas ventilation test and a constant volume bomb spray combustion test on the engine in a ground state to obtain a first experimental result;

[0013] S4: Calibrate and optimize the model characteristic parameters of the three-dimensional simulation model based on the first experimental results: determine whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, modify the model characteristic parameters of the three-dimensional simulation model and repeat step S4. If so, proceed to step S5.

[0014] S5: performing a second round of iteration on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeating step S5; if so, proceeding to step S6. During the second round of iteration, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is always between 5% and 10%.

[0015] S6: conducting a high-altitude environment simulation whole-machine test of the engine, a tracer gas ventilation test in the high-altitude simulation environment, and a constant-volume bomb spray combustion test in the high-altitude simulation environment to obtain a second experimental result;

[0016] S7: Calibrate and optimize the one-dimensional simulation model and the three-dimensional simulation model based on the second experimental result: determine whether the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is less than 5%. If not, modify the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and repeat step S7. If so, proceed to step S8.

[0017] S8: Perform a round of three iterations on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeat step S8. If so, end the process and obtain a three-dimensional ventilation and spray combustion coupled simulation model. During the three iterations, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is ≤5%.

[0018] According to the high-altitude ventilation and spray combustion coupled modeling method of a sustainable aviation fuel engine according to an embodiment of the present invention, by iterating a one-dimensional simulation model and a three-dimensional simulation model in multiple steps, the three-dimensional simulation model and the one-dimensional simulation model are calibrated using first and second experimental results obtained from actual experiments, thereby obtaining a one-dimensional and three-dimensional ventilation and spray combustion coupled simulation model with high coupling degree and high simulation accuracy. The obtained one-dimensional ventilation and spray combustion coupled simulation model can accurately simulate the ventilation and spray combustion characteristics of aviation fuel, so that the one-dimensional ventilation and spray combustion coupled simulation model can be used to comprehensively and effectively optimize the ventilation and spray combustion process, reduce the actual number of experiments, and reduce the research and development costs of aviation heavy fuel engines.

[0019] According to some embodiments of the present invention, step S3 includes, in a ground state, conducting a tracer gas ventilation experiment and a constant volume bomb spray combustion experiment on the engine with different SAF compositions, and comparing the experimental results with the same experiments with traditional fuels, analyzing the changes in ventilation and spray combustion characteristics brought about by the change of SAF composition, and obtaining a first experimental result;

[0020] Correspondingly, step S4 includes simulating a three-dimensional simulation model of SAF with different components, calibrating and optimizing the model characteristic parameters of the three-dimensional simulation model of SAF with different components based on the first experimental results, and then inputting the simulation results obtained from the simulation of the three-dimensional simulation model of SAF with different components into a one-dimensional simulation model, simulating the one-dimensional simulation model of SAF with different components, obtaining the model characteristic parameters of the one-dimensional simulation model of SAF with different components, and establishing a correspondence between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the changes in the SAF components.

[0021] According to some embodiments of the present invention, step S6 includes conducting a high-altitude environment simulation whole-machine experiment of the engine at different altitudes, a tracer gas ventilation experiment in a high-altitude simulation environment, and a constant-volume bomb spray combustion experiment in a high-altitude simulation environment to obtain a second experimental result; step S7 includes performing a one-dimensional simulation model simulation of a high-altitude environment at different altitudes and a three-dimensional simulation model simulation of a high-altitude environment at different altitudes, and according to the second experimental result, calibrating and optimizing the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and establishing a correspondence between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the change in altitude.

[0022] According to some embodiments of the present invention, the three-dimensional simulation model includes a ventilation sub-model and a spray combustion sub-model.

[0023] According to some embodiments of the present invention, the ventilation sub-model includes a turbulence model, a near-wall function, and a scavenging sub-model, and the spray combustion sub-model includes a WAVE spray sub-model and a Weber combustion sub-model.

[0024] According to some embodiments of the present invention, the one-dimensional simulation model includes an intake and boost sub-model, a cylinder sub-model, a crank-connecting rod sub-model and an exhaust sub-model; the intake and boost sub-model and the exhaust sub-model include an environmental module, and the environmental module is used for simulating environments at different altitudes.

[0025] According to some embodiments of the present invention, a round of the first iteration, a round of the second iteration and a round of the third iteration all include performing a one-dimensional simulation model simulation to obtain simulation results, and the simulation results of the one-dimensional simulation model provide and input the initial state parameters in the cylinder, the boundary condition parameters of the intake and exhaust ducts, the dynamic boundary parameters of the piston connecting rod, and the temperature parameters of each wall surface of the engine to the three-dimensional simulation model; then the three-dimensional simulation model is simulated to obtain simulation results, and the simulation results of the three-dimensional simulation model provide and input the valve flow coefficient, swirl coefficient, ventilation model curve, spray model coefficient and combustion model coefficient to the one-dimensional simulation model.

[0026] According to some embodiments of the present invention, the initial state parameters in the cylinder include the initial temperature in the cylinder, the initial pressure in the cylinder and the initial composition in the cylinder, and the intake and exhaust duct boundary condition parameters include the change curves of the intake and exhaust temperature, pressure and flow during the entire ventilation process.

[0027] According to some embodiments of the present invention, in the simulation of a three-dimensional simulation model, the computational fluid domain of the three-dimensional simulation model includes an intake duct, an exhaust duct, a cylinder block and a combustion chamber. The fluid domain is meshed during calculation, and the meshes at the intake valve, the exhaust valve and the cylinder block involve dynamic mesh reconstruction, and mesh reconstruction is set to be performed every 1° to 2° crankshaft angle.

[0028] According to some embodiments of the present invention, after meshing the fluid domain, the three-dimensional simulation model calibrates and verifies whether its own meshing is reasonable through a mesh scale-independent solution and a time step-independent solution.

[0029] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0031] Figure 1 This is a flowchart of a method for coupling high-altitude ventilation and spray combustion modeling for a sustainable aviation fuel engine according to an embodiment of the present invention.

[0032] Figure 2 Schematic diagram of the iterative process between the one-dimensional simulation model and the three-dimensional simulation model and the experimental calibration and optimization of the one-dimensional simulation model and the three-dimensional simulation model in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0034] The following combination Figure 1 and Figure 2 This paper describes the coupled modeling method of high-altitude ventilation and spray combustion of a sustainable aviation fuel engine of the present invention.

[0035] like Figure 1 and Figure 2 As shown, the high-altitude ventilation and spray combustion coupling modeling method of a sustainable aviation fuel engine according to an embodiment of the present invention includes the following steps:

[0036] S1: Preliminary establishment of one-dimensional and three-dimensional simulation models. The one-dimensional simulation model is used to simulate the entire thermodynamic cycle and power performance of the engine, and the three-dimensional simulation model is used to simulate the evolution of the flow field in the engine cylinder during the engine ventilation and spray combustion process.

[0037] S2: simulating the one-dimensional simulation model and the three-dimensional simulation model respectively, obtaining simulation results of the one-dimensional simulation model and the three-dimensional simulation model, and performing initial iteration of the one-dimensional simulation model and the three-dimensional simulation model;

[0038] S3: Conduct a tracer gas ventilation test and a constant volume bomb spray combustion test on the engine in a ground state, and obtain the first experimental results;

[0039] S4: Calibrate and optimize the model characteristic parameters of the three-dimensional simulation model based on the first experimental results: determine whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, modify the model characteristic parameters of the three-dimensional simulation model and repeat step S4. If so, proceed to step S5.

[0040] S5: performing a second iteration on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeating step S5; if so, proceeding to step S6. During the second iteration, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is always between 5% and 10%.

[0041] S6: Conduct a full-machine test of the engine in a high-altitude environment simulation, a tracer gas ventilation test in a high-altitude simulation environment, and a constant-volume bomb spray combustion test in a high-altitude simulation environment, and obtain the second experimental results;

[0042] S7: Calibrate and optimize the one-dimensional simulation model and the three-dimensional simulation model based on the second experimental result: determine whether the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is less than 5%. If not, modify the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and repeat step S7. If so, proceed to step S8.

[0043] S8: Perform a round of three iterations on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeat step S8. If so, end the process and obtain a three-dimensional ventilation and spray combustion coupled simulation model. During the three iterations, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is ≤5%.

[0044] Specifically, S1: Initially establish one-dimensional and three-dimensional simulation models. The one-dimensional simulation model is used to simulate the entire engine's thermodynamic cycle and power performance. This includes simulations of the ventilation and spray combustion processes. The one-dimensional simulation model can be established using commercial simulation platforms such as GT-Power and AVL-Boost, or through custom programming using platforms such as Matlab Simulink. The structural parameters of the initial one-dimensional simulation model are determined by referring to the specific engine design drawings or taking equivalent values.

[0045] 3D simulation models are used to simulate the evolution of the flow field within the engine cylinder during engine ventilation and spray combustion, including details such as heat and mass transfer, air-exhaust replacement and mixing, vortex flow distribution, scavenging blind spots, spray penetration, and flame ignition and spread. Specifically, 3D simulation models can be established using simulation platforms such as Converge, Ansys Fluent, and AVL-Fire. Uncertain model parameters in the initially established 1D and 3D simulation models can be input based on empirical values or recommended values from other similar studies.

[0046] S2: Simulate the one-dimensional simulation model and the three-dimensional simulation model respectively, obtain simulation results of the one-dimensional simulation model and the three-dimensional simulation model, and perform an initial iteration on the one-dimensional simulation model and the three-dimensional simulation model to achieve preliminary coupling between the one-dimensional simulation model and the three-dimensional simulation model. This initial iteration can be 1 to 2 times.

[0047] S3: Conduct a tracer gas ventilation experiment and a constant volume bomb spray combustion experiment on the engine in a ground state to obtain the first experimental results; the tracer gas ventilation experiment is used to verify the three-dimensional ventilation modeling, and the constant volume bomb spray combustion experiment includes a schlieren spray experiment and a two-color combustion experiment. The thermodynamic state in the cylinder at different operating altitudes is used as the initial condition, and the filling density in the constant volume bomb is changed to simulate different cylinder atmospheres. The schlieren spray experiment is used for three-dimensional spray modeling verification, and the two-color combustion experiment is used for three-dimensional combustion modeling verification. S4: Based on the first experimental results, calibrate and optimize the model characteristic parameters of the three-dimensional simulation model: Determine whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, modify the model characteristic parameters of the three-dimensional simulation model and repeat step S4. If so, proceed to step S5. It is understood that calibrating and optimizing the model characteristic parameters of the three-dimensional simulation model based on the first experimental results refers to determining whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, the model characteristic parameters of the three-dimensional simulation model are modified and step S4 is repeated. If so, step S5 is performed. In step S4, the three-dimensional simulation model that undergoes the first calculation process is the three-dimensional simulation model after the first iteration. The present invention calibrates and optimizes the model characteristic parameters of the three-dimensional simulation model using the first experimental results, thereby achieving the first calibration of the three-dimensional simulation model in the ground state. The ventilation and spray combustion results include ventilation parameter indicators such as charging efficiency, air supply ratio, and capture rate, and spray combustion parameter indicators such as spray cone angle, spray penetration distance, oil droplet breakup and Sauter mean diameter, gas-liquid phase velocity, flame ignition morphology, brightness characteristics, and flame temperature distribution.

[0048] S5: Perform a round of secondary iteration on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeat step S5. If so, proceed to step S6. During the secondary iteration process, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is always between 5% and 10%. It is understandable that the three-dimensional simulation model of the first round of secondary iteration is a three-dimensional simulation model that has been calibrated for ground conditions. By performing multiple rounds of secondary iterations between the calibrated three-dimensional simulation model and the one-dimensional simulation model, on the one hand, the coupling between the one-dimensional simulation model and the three-dimensional simulation model can be increased, and on the other hand, the simulation accuracy of the one-dimensional simulation model can be improved.

[0049] S6: Conduct a high-altitude environment simulation whole-machine test of the engine, a tracer gas ventilation test in a high-altitude simulation environment, and a constant-volume bomb spray combustion test in a high-altitude simulation environment to obtain the second experimental result. The high-altitude environment simulation whole-machine test of the engine refers to creating an environment similar to high-altitude conditions in ground test equipment, making the engine operate in this environment, and conducting various tests such as performance, reliability, and service life, including measuring the engine speed, torque, power, fuel consumption rate, etc. in the high-altitude test state. The tracer gas ventilation test in a high-altitude simulation environment and the constant-volume bomb spray combustion test in a high-altitude simulation environment refer to the tracer gas ventilation test and the constant-volume bomb spray combustion test here being conducted in an environment similar to high-altitude conditions. The tracer gas ventilation test can be coupled with the high-altitude environment simulation whole-machine test. S7: Calibrate and optimize the one-dimensional simulation model and the three-dimensional simulation model based on the second experimental results: Determine whether the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental results is less than 5%. If not, modify the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and repeat step S7. If so, proceed to step S8. It can be understood that calibrating and optimizing the one-dimensional simulation model and the three-dimensional simulation model based on the second experimental results means determining whether the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental results is less than 5%. If not, modify the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and repeat step S7. If so, proceed to step S8. The high-altitude environment simulation full-machine experiment of the engine is mainly used to calibrate the first simulation model, that is, to verify the one-dimensional full-machine model to improve the simulation accuracy of the one-dimensional simulation model.

[0050] S8: Perform a three-round iteration of the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeat step S8. If so, end the process and obtain a three-dimensional ventilation and spray combustion coupled simulation model, wherein, during the three-round iteration process, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is ≤5%. The present invention further improves the coupling degree between the one-dimensional simulation model and the three-dimensional simulation model by performing multiple three-round iterations of the one-dimensional simulation model and the three-dimensional simulation model, and further improves the simulation accuracy of the one-dimensional simulation model and the three-dimensional simulation model.

[0051] In summary, the one-dimensional simulation model and the three-dimensional simulation model iterate with each other in multiple steps to achieve close coupling simulation results, that is, a high degree of coupling is achieved; the three-dimensional simulation model and the one-dimensional simulation model are calibrated by using the first experimental results and the second experimental results obtained in actual experiments, thereby improving the simulation accuracy of the one-dimensional simulation model and the three-dimensional simulation model, and thus the obtained one-dimensional and three-dimensional ventilation and spray combustion coupled simulation model can accurately simulate the ventilation and spray combustion characteristics of aviation fuel.

[0052] According to the high-altitude ventilation and spray combustion coupled modeling method of a sustainable aviation fuel engine according to an embodiment of the present invention, by iterating a one-dimensional simulation model and a three-dimensional simulation model in multiple steps, the three-dimensional simulation model and the one-dimensional simulation model are calibrated using first and second experimental results obtained from actual experiments, thereby obtaining a one-dimensional and three-dimensional ventilation and spray combustion coupled simulation model with high coupling degree and high simulation accuracy. The obtained one-dimensional ventilation and spray combustion coupled simulation model can accurately simulate the ventilation and spray combustion characteristics of aviation fuel, so that the one-dimensional ventilation and spray combustion coupled simulation model can be used to comprehensively and effectively optimize the ventilation and spray combustion process, reduce the actual number of experiments, and reduce the research and development costs of aviation heavy fuel engines.

[0053] According to some embodiments of the present invention, step S3 includes, in a ground state, conducting a tracer gas ventilation experiment and a constant volume bomb spray combustion experiment on the engine with different SAF compositions, and comparing the experimental results with the same experiments using conventional fuels, analyzing the changes in ventilation and spray combustion characteristics caused by the change in SAF composition, and obtaining a first experimental result;

[0054] Correspondingly, step S4 includes performing a three-dimensional simulation model simulation of SAF with different components, that is, changing the SAF components and performing multiple three-dimensional simulation model simulations. Based on the first experimental results (it can be understood that the first experimental results here include experimental results corresponding to different SAF components), calibrating and optimizing the model characteristic parameters of the three-dimensional simulation model of SAF with different components. Here, calibrating and optimizing the model characteristic parameters of the three-dimensional simulation model of SAF with different components includes, for each different SAF component, determining whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, modifying the model characteristic parameters of the three-dimensional simulation model and repeating step S4. If so, performing step S5. Then, inputting the simulation results obtained from the three-dimensional simulation model of SAF with different components into the one-dimensional simulation model to calibrate the one-dimensional simulation model. Then, performing the one-dimensional simulation model simulation of SAF with different components to obtain the model characteristic parameters of the one-dimensional simulation model of SAF with different components, and establishing a corresponding relationship between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the change in SAF components. The correspondence between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the changes in the SAF components can be numerically adjusted or expressed as a function of the SAF components or other physicochemical property parameters, wherein the numerical adjustment means that if the numerical change range is very small or the change is very simple, the numerical value of the model characteristic parameter can be directly changed only according to the change in the SAF component. In summary, the present invention facilitates the high-precision simulation of the SAF ventilation and spray combustion process by the three-dimensional simulation model and the one-dimensional simulation model through the adaptive correction and calibration of the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model with respect to the SAF components.

[0055] According to some embodiments of the present invention, step S6 includes conducting a high-altitude environment simulation whole-machine experiment at different altitudes of the engine, a tracer gas ventilation experiment in the high-altitude simulation environment, and a constant-volume bomb spray combustion experiment in the high-altitude simulation environment to obtain a second experimental result; step S7 includes conducting a one-dimensional simulation model simulation of the high-altitude environment at different altitudes and a three-dimensional simulation model simulation of the high-altitude environment at different altitudes, and according to the second experimental result, calibrating and optimizing the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, so that in the high-altitude environment at different altitudes, the one-dimensional simulation model and the three-dimensional simulation model both have corresponding calibrated and optimized model characteristic coefficients, so that the corresponding relationship between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the altitude change can be established. It can be understood that the present invention is conducive to achieving a high-precision simulation of the SAF high-altitude ventilation and spray combustion process by a one-dimensional ventilation and spray combustion coupled simulation model through adaptive correction and calibration of the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model in terms of SAF components and high-altitude environment.

[0056] It can be understood that, correspondingly, at each different altitude, the one-dimensional simulation model and the three-dimensional simulation model will perform multiple simulations and multiple three-dimensional iterations to ensure that the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%, so as to establish a correspondence between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the changes in altitude, so that the present invention can achieve high-precision simulation of high-altitude ventilation and spray combustion processes.

[0057] According to some embodiments of the present invention, a three-dimensional simulation model includes a ventilation sub-model and a spray combustion sub-model. The ventilation sub-model includes a turbulence model, a near-wall function, and a scavenging sub-model. Specifically, for example, the turbulence model can adopt the RNG k-ε turbulence model, and the near-wall function can adopt the standard wall function. The spray combustion sub-model includes a WAVE spray sub-model and a Weber combustion sub-model. The spray combustion sub-model uses the WAVE spray sub-model and the Weber combustion sub-model to ensure the accuracy of the spray combustion sub-model in simulating power performance, ventilation initialization, and boost boundary conditions.

[0058] According to some embodiments of the present invention, a one-dimensional simulation model includes an intake and boost sub-model, a cylinder sub-model, a crankshaft and connecting rod sub-model, and an exhaust sub-model. The intake and boost sub-model and the exhaust sub-model include an environmental module, which is used to simulate environments at different altitudes. When simulating environments at different altitudes, parameters such as pressure, temperature, and humidity at different altitudes can be input into the environmental module to meet the environmental simulation requirements for engine operating conditions at different altitudes. The structural parameters of the intake and boost sub-model, cylinder sub-model, crankshaft and connecting rod sub-model, and exhaust sub-model are initially established by referring to the specific engine design drawings or taking equivalent values. For example, the actual cross-section of the intake and exhaust ducts is not circular, so the diameter of the model component takes the value corresponding to the equivalent cross-section; in the cylinder sub-model, the number and diameter of the nozzle holes of the injector module are determined according to the actual customized injector; the cyclic injection volume is determined according to the engine load; the injection advance angle takes the optimized value obtained from simulation and testing; the temperature values of each cylinder wall, including the cylinder liner, piston top and cylinder head, are measured according to the test; because the heat transfer calculated by the Woschni model is in good agreement with the measured values, the Woschni model can be used to calculate the heat transfer of high-temperature gas and ventilation flow to the cylinder wall and piston; in the modeling of the crank-connecting rod sub-model, the weight and size data of components such as the crankshaft, connecting rod, and piston are derived from the measurement of real components, and the piston movement law, effective compression ratio, etc. are also verified through engine tests.

[0059] According to some embodiments of the present invention, a first iteration, a second iteration, and a third iteration all include performing a one-dimensional simulation model to obtain simulation results, wherein the simulation results of the one-dimensional simulation model provide and input the initial state parameters in the cylinder, the boundary condition parameters of the intake and exhaust ports, the dynamic boundary parameters of the piston and connecting rod, and the temperature parameters of each engine wall surface to the three-dimensional simulation model; then the three-dimensional simulation model is simulated to obtain simulation results, wherein the simulation results of the three-dimensional simulation model provide and input the valve flow coefficient, swirl coefficient, ventilation model curve, spray model coefficient, and combustion model coefficient to the one-dimensional simulation model. The spray model coefficient and combustion model coefficient include the oil droplet atomization breakup coefficient, the combustion heat release law curve, the premixed combustion factor, the diffusion combustion factor, etc. It can be understood that the one-dimensional simulation model provides sufficient boundary conditions for the three-dimensional simulation model (initial state parameters in the cylinder, intake and exhaust port boundary condition parameters, piston connecting rod dynamic boundary parameters, and engine wall temperature parameters), and the three-dimensional simulation model provides the one-dimensional simulation model with key coefficients related to the detailed flow field of ventilation and spray combustion (valve flow coefficient, swirl coefficient, ventilation model curve, spray model coefficient and combustion model coefficient). The one-dimensional simulation model and the three-dimensional simulation model iterate with each other by inputting simulation results to each other to achieve closeness and accuracy of the coupled simulation results, that is, to achieve a higher degree and more comprehensive coupling.

[0060] The combustion heat release curve includes parameters such as ignition point, ignition delay, and combustion duration. The results from the one-dimensional simulation model provide the piston and connecting rod dynamic boundary parameters, which are then fed into the three-dimensional simulation model. This allows the model's in-cylinder volume change pattern to more closely resemble reality. This is because changes in speed and altitude can affect piston and connecting rod dynamics, which the one-dimensional simulation model can simulate. The results from the one-dimensional simulation model provide the engine wall temperature parameters, which are then fed into the three-dimensional simulation model, allowing it to account for convective heat transfer between the in-cylinder gas and the cylinder liner, cylinder head, and piston crown.

[0061] According to some embodiments of the present invention, the initial state parameters in the cylinder include the initial temperature in the cylinder, the initial pressure in the cylinder and the initial composition in the cylinder, and the boundary condition parameters of the intake and exhaust ducts include the change curves of the temperature, pressure and flow of the intake and exhaust during the entire ventilation process.

[0062] According to some embodiments of the present invention, in a three-dimensional simulation model, the computational fluid domain of the three-dimensional simulation model includes an intake duct, an exhaust duct, a cylinder block, and a combustion chamber. During the calculation, the fluid domain is meshed. The flow state near the intake valve and the exhaust valve is relatively complex. In order to obtain accurate calculation results, the meshes near the intake valve and the exhaust valve can be refined. In the simulation of the ventilation and spray combustion process, the meshes at the intake valve, the exhaust valve, and the cylinder block involve dynamic mesh reconstruction. Considering the deformation of the corresponding scale mesh, an excessively large aspect ratio will cause the calculation to be unable to continue. Therefore, a mesh reconstruction is set every 1° to 2° crankshaft angle. Specifically, for example, a mesh reconstruction can be set every 1°, 1.2°, 1.4°, 1.6°, 1.8°, and 2° crankshaft angles.

[0063] According to some embodiments of the present invention, after the fluid domain is meshed, the three-dimensional simulation model calibrates and verifies whether its own meshing is reasonable through a mesh scale-independent solution and a time step-independent solution, thereby improving the computational accuracy of the three-dimensional simulation model.

[0064] Throughout this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" indicate that the specific features, structures, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0065] While 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 invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine, characterized in that: The engine is an aviation heavy fuel oil engine, comprising the following steps: S1: Preliminary establishment of a one-dimensional simulation model and a three-dimensional simulation model, wherein the one-dimensional simulation model is used to simulate the entire thermodynamic cycle and power performance of the engine, and the three-dimensional simulation model is used to simulate the evolution of the flow field in the engine cylinder during the engine ventilation and spray combustion process; S2: simulating the one-dimensional simulation model and the three-dimensional simulation model respectively, obtaining simulation results of the one-dimensional simulation model and the three-dimensional simulation model, and performing initial iteration of the one-dimensional simulation model and the three-dimensional simulation model; S3: conducting a tracer gas ventilation test and a constant volume bomb spray combustion test on the engine in a ground state to obtain a first experimental result; S4: Calibrate and optimize the model characteristic parameters of the three-dimensional simulation model based on the first experimental results: determine whether the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is between 5% and 10%. If not, modify the model characteristic parameters of the three-dimensional simulation model and repeat step S4. If so, proceed to step S5. S5: performing a second round of iteration on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeating step S5; if so, proceeding to step S6. During the second round of iteration, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the three-dimensional simulation model and the first experimental results is always between 5% and 10%. S6: conducting a high-altitude environment simulation whole-machine test of the engine, a tracer gas ventilation test in the high-altitude simulation environment, and a constant-volume bomb spray combustion test in the high-altitude simulation environment to obtain a second experimental result; S7: Calibrate and optimize the one-dimensional simulation model and the three-dimensional simulation model based on the second experimental result: determine whether the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is less than 5%. If not, modify the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and repeat step S7. If so, proceed to step S8. S8: Perform a round of three iterations on the one-dimensional simulation model and the three-dimensional simulation model to determine whether the deviation between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model is ≤3%. If not, repeat step S8. If so, end the process and obtain a three-dimensional ventilation and spray combustion coupled simulation model. During the three iterations, it is necessary to ensure that the error between the ventilation and spray combustion results calculated by the one-dimensional simulation model and the ventilation and spray combustion results calculated by the three-dimensional simulation model and the second experimental result is ≤5%.

2. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 1, characterized in that: Step S3 includes conducting a tracer gas ventilation test and a constant volume bomb spray combustion test on the engine with different SAF compositions on the ground, comparing the test results with the same test results using conventional fuels, analyzing changes in ventilation and spray combustion characteristics caused by changes in SAF compositions, and obtaining a first experimental result. Correspondingly, step S4 includes simulating a three-dimensional simulation model of SAF with different components, calibrating and optimizing the model characteristic parameters of the three-dimensional simulation model of SAF with different components based on the first experimental results, and then inputting the simulation results obtained from the simulation of the three-dimensional simulation model of SAF with different components into a one-dimensional simulation model, and then simulating the one-dimensional simulation model of SAF with different components to obtain the model characteristic parameters of the one-dimensional simulation model of SAF with different components, and establishing a correspondence between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the changes in the SAF components.

3. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 2, characterized in that: The step S6 includes conducting a high-altitude environment simulation whole-machine experiment of the engine at different altitudes, a tracer gas ventilation experiment in the high-altitude simulation environment, and a constant-volume bomb spray combustion experiment in the high-altitude simulation environment to obtain a second experimental result; the step S7 includes conducting a one-dimensional simulation model simulation of the high-altitude environment at different altitudes and a three-dimensional simulation model simulation of the high-altitude environment at different altitudes, and according to the second experimental result, calibrating and optimizing the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model, and establishing a corresponding relationship between the model characteristic parameters of the one-dimensional simulation model and the model characteristic parameters of the three-dimensional simulation model and the change in altitude.

4. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to any one of claims 1 to 3, characterized in that: The three-dimensional simulation model includes a ventilation sub-model and a spray combustion sub-model.

5. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 4, characterized in that: The ventilation sub-model includes a turbulence model, a near-wall function and a scavenging sub-model, and the spray combustion sub-model includes a WAVE spray sub-model and a Weber combustion sub-model.

6. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to any one of claims 1 to 3, characterized in that: The one-dimensional simulation model includes an intake and boost sub-model, a cylinder sub-model, a crank-connecting rod sub-model and an exhaust sub-model; the intake and boost sub-model and the exhaust sub-model include an environment module, and the environment module is used for simulating environments at different altitudes.

7. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 3, characterized in that: A round of the first iteration, a round of the second iteration and a round of the third iteration all include performing a one-dimensional simulation model simulation to obtain simulation results. The simulation results of the one-dimensional simulation model provide and input the initial state parameters in the cylinder, the boundary condition parameters of the intake and exhaust ducts, the dynamic boundary parameters of the piston and connecting rod, and the temperature parameters of each wall of the engine to the three-dimensional simulation model; then the three-dimensional simulation model is simulated to obtain simulation results. The simulation results of the three-dimensional simulation model provide and input the valve flow coefficient, swirl coefficient, ventilation model curve, spray model coefficient and combustion model coefficient to the one-dimensional simulation model.

8. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 7, characterized in that: The initial state parameters in the cylinder include the initial temperature, initial pressure and initial composition in the cylinder, and the boundary condition parameters of the intake and exhaust ducts include the change curves of the temperature, pressure and flow of the intake and exhaust during the entire ventilation process.

9. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 7, characterized in that: In the three-dimensional simulation model simulation, the computational fluid domain of the three-dimensional simulation model includes the intake duct, exhaust duct, cylinder block and combustion chamber. The fluid domain is meshed during calculation. The meshes at the intake valve, exhaust valve and cylinder block involve dynamic mesh reconstruction, and mesh reconstruction is set to be performed every 1° to 2° crankshaft angle.

10. The method for coupling high-altitude ventilation and spray combustion modeling of a sustainable aviation fuel engine according to claim 9, characterized in that: After the fluid domain is meshed, the three-dimensional simulation model is calibrated and verified to determine whether its own meshing is reasonable through a mesh scale-independent solution and a time step-independent solution.

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