Method and apparatus for constructing lumped parameter model of self-pressurized tank of high thrust engine

Abstract

This invention discloses a method and apparatus for constructing a lumped parameter model of a self-pressurized propellant tank for a high-thrust engine, relating to the field of high-thrust engine technology, to address the problem of insufficient simulation accuracy in existing traditional propellant tank models. The method includes: based on the basic information of the tank's physical model, calculating the heat transfer rate of the gas-liquid two-phase transition zone using heat transfer formulas, calculating the phase change mass flow rate using mass transfer formulas, and constructing gas conservation equation systems corresponding to the gas region and liquid conservation equation systems corresponding to the liquid region; constructing gas wall heat transfer models and liquid wall heat transfer models respectively; and constructing a lumped parameter model based on the gas conservation equation system, liquid conservation equation system, gas wall heat transfer model, and liquid wall heat transfer model. This invention is used to improve the simulation accuracy of high-thrust engine systems.

Description

Technical Field

[0001] This invention relates to the field of high-thrust engine technology, and in particular to a method and apparatus for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank. Background Technology

[0002] The development of high-thrust engines is a long and complex process, requiring knowledge from multiple disciplines including flow, combustion, heat transfer, structure, strength, and materials. High-thrust engine systems are highly coupled and operate in harsh environments, involving extreme conditions such as high and low temperatures (-180℃ to 3600℃), high and low pressures (0Pa to 70MPa), high speeds (100,000 rpm), and large vibrations (800g impact). During the dynamic processes of starting, shutting down, and adjusting high-thrust engines, various parameters change drastically within a short time (1ms-2ms), making them highly susceptible to failure. Statistics show that over 60% of high-thrust engine failures, both domestically and internationally, are related to dynamic transient processes. Therefore, system dynamic simulation technology is widely used both domestically and internationally to study its dynamic operating mechanisms, supporting product development. Compared to physical experiments, simulation research offers advantages such as shorter cycles, lower costs, higher safety, and more comprehensive observation. It can grasp the overall operating laws of the system and delve into the working mechanisms of individual components, providing far more information than limited experimental measurement points.

[0003] With the development of simulation technology for high-thrust engine systems, relatively complete component models have been built both domestically and internationally. For example, some models (such as cryogenic propellant tank models that consider changes in gas composition) have improved the accuracy of pressurization performance prediction to some extent by refining the component calculation of the gas cushion gas, but they still have significant limitations in dynamic process simulation.

[0004] I. Coarse gas-liquid interaction modeling: The tank is only divided into gas and liquid phase regions, a simplified gas-liquid interface assumption is adopted, only convective heat transfer is considered, no special gas-liquid two-phase transition zone is set, and only convective heat transfer between gas and liquid is considered, resulting in a lack of accurate physical description of the gas-liquid heat transfer process.

[0005] 2. Insufficient equation coupling: The conservation equations for gas and liquid are relatively isolated and do not form a dynamic coupling through the heat transfer rate in the transition zone. The mass transfer process (such as evaporation) and the heat transfer process are loosely related, making it impossible to achieve a closed-loop interaction of gas and liquid energy and mass, and making it difficult to reflect the mutual influence between the two in the dynamic process.

[0006] 3. Simplified wall modeling: Treating the tank wall as a single heat exchange boundary without subdividing it into gas walls and liquid walls makes it impossible to calculate the heat exchange between gas and gas walls, or between liquid and liquid walls. Furthermore, the influence of wall heat capacity on heat transfer dynamics (such as the hysteresis effect of heat storage / release) is ignored, resulting in insufficient simulation accuracy for rapid dynamic processes (such as sudden pressure rise during startup and transient energy changes during shutdown).

[0007] Therefore, although such models have made some improvements in gas composition calculation, they still cannot fully capture the pressure fluctuation mechanism of the self-pressurized tank during dynamic processes (start-up, shutdown, and adjustment). They are difficult to accurately reflect the fine mass and heat transfer in the gas-liquid two-phase transition zone, the coupling characteristics between gas and liquid and the wall, and the impact of transient changes in mass, energy, and momentum in the tank on the outlet pressure and system performance. They cannot meet the high-precision simulation requirements of new reusable high-thrust engines. Summary of the Invention

[0008] The purpose of this invention is to provide a method and apparatus for constructing a lumped parameter model of a self-pressurized tank for a high-thrust engine, so as to improve the simulation accuracy of the high-thrust engine system.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] In a first aspect, the present invention provides a method for constructing a lumped parameter model of a self-pressurized propellant tank for a high-thrust engine, comprising: based on the basic information of the tank's physical model, using a heat transfer formula:

[0011] ;

[0012] Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone. The thermal conductivity is the coefficient of thermal conductivity in the gas-liquid two-phase transition region. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; For liquid temperature;

[0013] Mass transfer formula used:

[0014] ;

[0015] Calculate the phase change mass flow rate; where, The phase change mass flow rate is... The latent heat of vaporization of the liquid;

[0016] Construct heat transfer models for both air walls and liquid walls;

[0017] A gas conservation equation system corresponding to the gas region and a liquid conservation equation system corresponding to the liquid region are constructed respectively. The gas conservation equation system includes at least a gas mass equation and a gas energy equation. The gas mass equation includes at least the phase change mass flow rate, and the gas energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the gas wall heat transfer model. The liquid conservation equation system includes at least a liquid mass equation and a liquid energy equation. The liquid mass equation includes at least the phase change mass flow rate, and the liquid energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model.

[0018] Based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model, and the liquid wall heat transfer model, a lumped parameter model is constructed.

[0019] Optionally, before using the basic information of the tank physical model, the construction method further includes: constructing the basic information of the tank physical model;

[0020] The basic information for constructing the physical model of the storage tank specifically includes:

[0021] The temperature is set to be uniform at any location within the gas region and the liquid region, and the temperature gradient along the flow direction is ignored.

[0022] The gas-liquid two-phase transition zone is set as a homogeneous layer of a preset thickness, which does not store energy. Heat transfer between the gas and liquid is achieved only through thermal conduction, without convective heat transfer caused by tangential flow.

[0023] The inner wall temperature of the tank is set to be the same as the temperature of the fluid in contact, and the heat exchange between the tank wall and the fluid in contact is only through conduction; the fluid in contact is a gas or a liquid.

[0024] Optionally, constructing the air-wall heat transfer model includes:

[0025] Based on the basic information that the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, an air-wall heat transfer model is constructed:

[0026] ;

[0027] in, The heat transfer rate between the gas and the gas wall. The temperature of the inner wall surface. This represents the area of ​​the internal air wall surface; The temperature of the outer wall surface of the storage tank. is the thermal conductivity of the tank wall.

[0028] Optionally, constructing the liquid wall heat transfer model includes:

[0029] Based on the basic information that the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, a liquid wall heat transfer model is constructed:

[0030] ;

[0031] in, The heat transfer rate between the liquid and the liquid wall. The temperature of the inner liquid wall. This represents the area of ​​the inner liquid wall surface.

[0032] Optionally, constructing the gas conservation equation system corresponding to the gas region includes:

[0033] Construct the mass equation for the gas:

[0034] ;

[0035] in, For gas mass, For time, The mass flow rate of the gas flowing into the gas region. The mass flow rate of the gas exiting the gas region. Phase change mass flow rate;

[0036] Constructing the gas momentum equation: ;

[0037] In the formula, The inlet pressure is the physical model of the storage tank. The outlet pressure of the storage tank physical model. The loss coefficient, For gas density, The coefficient of dynamic friction loss. It is the acceleration due to gravity. The height of the gas region;

[0038] Construct the gas energy equation:

[0039] ;

[0040] in, The heat transfer rate between the gas and the gas wall. The rate of change of internal energy within a gas region is caused by the change in gas mass due to gas flow. The heat transfer rate of the gas-liquid two-phase transition zone is given. For phase change heat rate, This is the specific heat capacity of a gas at constant pressure.

[0041] Optionally, constructing the liquid conservation equation system corresponding to the liquid region includes:

[0042] Construct the liquid mass equation:

[0043] ;

[0044] In the formula, For liquid mass, The mass flow rate of the liquid flowing into the liquid zone. The mass flow rate of the liquid flowing out of the liquid region;

[0045] Constructing the liquid momentum equation:

[0046] ;

[0047] in, For liquid pressure, For liquid flow capacity;

[0048] Construct the liquid energy equation:

[0049] ;

[0050] in, The heat transfer rate between the liquid and the liquid wall. The rate of change of internal energy within a liquid region is caused by the change in the mass of the liquid due to liquid flow. This is the specific heat capacity of a liquid at constant pressure.

[0051] Optionally, the formula for calculating liquid flow capacity is:

[0052] ;

[0053] in, This is the elastic modulus of the liquid.

[0054] Optionally, when the gas is vapor and non-ideal properties are considered, the lumped parameter model adopts the real gas equation of state:

[0055] ;

[0056] To build;

[0057] in, The average gas pressure Gas volume, , For experimental correction coefficients, The gas constant is This represents the temperature of the real gas.

[0058] Secondly, the present invention also provides a lumped parameter model construction device for a self-pressurized propellant tank of a high-thrust engine, characterized in that it includes:

[0059] Based on the basic information of the tank's physical model, the heat transfer formula is adopted:

[0060] ;

[0061] Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone. The thermal conductivity is the coefficient of thermal conductivity in the gas-liquid two-phase transition region. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; For liquid temperature;

[0062] Mass transfer formula used:

[0063] ;

[0064] Calculate the phase change mass flow rate; where, The phase change mass flow rate is... The latent heat of vaporization of the liquid;

[0065] Construct heat transfer models for both air walls and liquid walls;

[0066] A gas conservation equation system corresponding to the gas region and a liquid conservation equation system corresponding to the liquid region are constructed respectively; the gas energy equation in the gas conservation equation system includes at least the heat transfer rate of the gas-liquid two-phase transition zone, the phase change mass flow rate, and the gas wall heat transfer model; the liquid energy equation in the liquid conservation equation system includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model.

[0067] Based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model, and the liquid wall heat transfer model, a lumped parameter model is constructed.

[0068] Optionally, the apparatus further includes a construction module for constructing the basic information before using the basic information of the tank physical model.

[0069] The beneficial effects of this invention are as follows: Compared with the prior art, the lumped parameter model construction method and device for the self-pressurized tank of a high-thrust engine provided by this invention sets up a gas-liquid two-phase transition zone to accurately describe gas-liquid heat exchange: the heat transfer formula is used to calculate the heat transfer rate of the gas-liquid two-phase transition zone, and by defining the thermal conductivity, thickness, and heat transfer area of ​​the transition zone, the heat transfer process between gas and liquid is accurately described from a physical perspective, making up for the problem of rough gas-liquid interaction modeling and lack of accurate physical description; the mass transfer formula is used to calculate the phase change mass flow rate based on the heat transfer rate of the gas-liquid two-phase transition zone, so that the mass transfer process (phase change) and the heat transfer process (heat transfer in the transition zone) are directly related. The gas and liquid conservation equation systems incorporate heat transfer rates in the transition zone and phase change mass flow rates, respectively. This allows for dynamic coupling of the gas and liquid conservation equations through the heat transfer rate in the transition zone, achieving a closed-loop interaction of energy and mass between the gas and liquid. This addresses the issues of insufficient equation coupling and loose correlation between mass and heat transfer. Separate gas-wall and liquid-wall heat transfer models are constructed, eliminating the assumption that the tank wall is a single heat transfer boundary. Subsequent incorporation of the gas conservation equation system into the gas-wall heat transfer model and the liquid conservation equation system into the liquid-wall heat transfer model allows for targeted calculation of heat exchange between the gas and the gas wall, and between the liquid and the liquid wall, thus compensating for… Simplified wall modeling addresses the issue of inaccurate calculation of heat transfer across different walls, thus improving the accuracy of rapid dynamic process simulations. Based on the gas conservation equation system, liquid conservation equation system, and heat transfer models of gas and liquid walls, a lumped parameter model is constructed. This lumped parameter model integrates the mass and heat transfer characteristics of the gas-liquid transition zone and the coupling between gas, liquid, and the wall, enabling it to capture transient changes in mass and energy during the dynamic process of a self-pressurized tank. This solves the problem of not being able to fully capture the dynamic process mechanism and meet the requirements of high-precision simulation, helping to reflect the impact of transient changes in multiple physical quantities within the tank on system performance and improving the simulation accuracy when the model is applied. Attached Figure Description

[0070] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0071] Figure 1 A flowchart illustrating a method for constructing a lumped parameter model of a high-thrust engine self-pressurized tank, provided as an embodiment of the present invention;

[0072] Figure 2 A schematic diagram of the physical model of the tank corresponding to the lumped parameter model of the self-pressurized tank of a high-thrust engine provided in an embodiment of the present invention;

[0073] Figure 3 A schematic diagram of the workflow of a lumped parameter model of a high-thrust engine self-pressurized tank provided for an embodiment of the present invention;

[0074] Figure 4A schematic diagram of a lumped parameter model construction device for a high-thrust engine self-pressurized tank provided in an embodiment of the present invention;

[0075] Figure 5 A schematic diagram of pressure versus time under different working conditions provided for a simulation embodiment of the present invention;

[0076] Figure 6 A schematic diagram of gas temperature versus time under different operating conditions provided for a simulation embodiment of the present invention;

[0077] Figure 7 A schematic diagram of liquid temperature versus time under different operating conditions provided for a simulation embodiment of the present invention;

[0078] Figure 8 A schematic diagram of the external air wall temperature versus time under different operating conditions provided for a simulation embodiment of the present invention;

[0079] Figure 9 A schematic diagram of the external liquid wall temperature versus time under different operating conditions provided for a simulation embodiment of the present invention;

[0080] Figure 10 This is a schematic diagram of the evaporation mass flow rate versus time under different operating conditions, provided as a simulation embodiment of the present invention. Detailed Implementation

[0081] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0082] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0083] In this invention, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between the associated objects, indicating that three relationships can exist.

[0084] See Figure 1This invention provides a method for constructing a lumped parameter model of a self-pressurized propellant tank for a high-thrust engine, which can be applied to high-thrust engines. The construction method includes the following steps:

[0085] Step 100: Based on the basic information of the tank physical model, the heat transfer formula is used:

[0086] (1)

[0087] Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone represents the heat transferred between the gas and liquid in the two-phase transition zone, and the unit is usually joule (J) or watt. Thermal conductivity is the thermal conductivity of the gas-liquid two-phase transition region (greater than the thermal conductivity of pure gas but less than the thermal conductivity of pure liquid), reflecting the material's ability to conduct heat. Different substances have different thermal conductivity. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; The temperature is the liquid temperature.

[0088] First, a brief introduction to the concepts related to self-pressurized propellant tanks is provided. A self-pressurized propellant tank is a container used in high-thrust engines to store propellant (fuel / oxidizer). Liquid propellant is forced out by an internal gaseous medium (such as high-pressure gas), eliminating the need for an additional pressurization system. Lumped parameter models are a modeling method that simplifies complex systems into lumped parameters (such as mass and energy) for rapid simulation of dynamic processes. Heat transfer refers to the heat exchange between the gas, liquid, and walls within the tank (such as conduction and phase change heat). Mass transfer refers to the mass migration process at the gas-liquid interface caused by the evaporation of liquid into gas, accompanied by a phase change (such as liquid evaporating into gas).

[0089] Secondly, it should be noted that before using the basic information of the tank physical model, the construction method also includes: constructing the basic information of the tank physical model;

[0090] The basic information for constructing the physical model of the storage tank includes:

[0091] Step 1): See Figure 2 The physical model of the self-pressurized tank is divided into a gas region, a liquid region, a gas-liquid two-phase transition zone, and tank walls. The tank walls are further divided into gas walls and liquid walls. The gas-liquid two-phase transition zone connects the gas and liquid regions and has a certain thickness. The gas wall includes an outer gas wall surface and an inner gas wall surface, with the inner gas wall surface in contact with the gas in the gas region. The liquid wall includes an outer liquid wall surface and an inner liquid wall surface, with the inner liquid wall surface in contact with the liquid in the liquid region.

[0092] Unlike traditional tank models, this invention explicitly establishes a separate gas-liquid two-phase transition zone of a certain thickness between the gas and liquid regions. That is, the gas-liquid two-phase transition zone is no longer a thin gas-liquid interface in the traditional tank model, but rather an independent region with a certain thickness, serving as a dedicated area for heat conduction and transfer, as well as phase change and mass transfer between the gas and liquid. For example, high-temperature gas conducts heat to the low-temperature liquid through the gas-liquid two-phase transition zone (heat transfer process), raising the liquid temperature; when the liquid temperature reaches its saturation temperature, it evaporates into gas through the transition zone (mass transfer process). This structure directly addresses the deficiency of traditional models that 'ignore the dynamic exchange at the gas-liquid interface,' providing physical space for simulating phase change processes such as evaporation and condensation.

[0093] Unlike traditional tank models, this invention explicitly divides the tank wall into gas walls and liquid walls, respectively realizing heat conduction and heat exchange between the inner wall surface and the gas / liquid. A gas wall heat transfer model corresponding to the gas wall and a liquid wall heat transfer model corresponding to the liquid wall are constructed. For example, external heat is transferred to the gas through the gas wall or to the liquid through the liquid wall, causing changes in the working fluid temperature. The thermal conductivity rate between the inner wall surface and the working fluid can be adjusted by parameters such as the material's thermal conductivity and wall thickness to simulate the heat conduction process in a real tank. Furthermore, by clearly defining the contact boundaries between the wall surface and different phases (gas / liquid), a foundation is provided for the subsequent construction of wall heat transfer models. Traditional models do not distinguish between gas and liquid walls, making it impossible to accurately calculate the heat transfer process of different phases. The division method in this embodiment allows wall heat transfer to be correlated with the temperature of the gas / liquid separately, improving simulation accuracy.

[0094] The above structural design of the tank physical model provides a spatial carrier for mass transfer (evaporation / condensation), heat transfer (conduction) and phase change processes, breaking the static limitations of traditional models that lack phase separation structure and interface exchange mechanism.

[0095] Step 2): Set the temperature to be uniform at any location within the gas and liquid regions, ignoring the temperature gradient along the flow direction;

[0096] Analysis of the beneficial effects of this step: If the temperature gradient is considered, a complex spatial distribution equation needs to be constructed, which leads to a sharp increase in computational complexity; in this step, the construction of relevant basic information can simplify the problem into solving ordinary differential equations through the lumped parameter method, which is a technical means of utilizing the laws of heat transfer.

[0097] Step 3): Set the gas-liquid two-phase transition zone to a homogeneous layer of a preset thickness. It does not store energy, and heat transfer between the gas and liquid phases is achieved solely through conduction, without convective heat transfer caused by tangential flow. Specifically, the preset thickness is an extremely thin value, for example, the preset thickness can be 1 mm or less. In this case, the gas-liquid two-phase transition zone is a homogeneous layer with a thickness not exceeding 1 mm.

[0098] The basic information description in step 3) is a technical limitation of the heat transfer process. By limiting the physical characteristics of the transition zone (e.g., having a thin thickness and only conducting heat), the complex heat and mass transfer process between gas and liquid can be simplified into a mathematical model based on the law of thermal conductivity.

[0099] In this embodiment of the invention, a gas-liquid two-phase transition zone with a thickness of ≤1mm is set as an independent homogeneous layer. Heat transfer is carried out only through conduction and does not store energy. The heat transfer rate is directly related to the phase change mass flow rate, which is logically simple. Traditional tank models regard gas-liquid interaction as a thicknessless interface and mainly rely on natural convection for heat transfer. The mass transfer model needs to be derived through the interface convection heat transfer difference, which is more complex and implies the indirect influence of interface energy storage.

[0100] Analysis of the beneficial effects of this step: Balancing modeling accuracy and simplification. Traditional tank models simplify gas-liquid interaction to a thicknessless interface and rely on convective heat transfer, making it difficult to accurately capture the microscopic heat transfer mechanism during phase change. This embodiment sets a gas-liquid two-phase transition zone with a certain thickness and limits heat conduction to dominate, thus preserving the physical space carrier of gas-liquid heat transfer (avoiding the idealization error of zero interface thickness) and simplifying the mathematical model through the "heat conduction only" assumption, allowing the heat transfer to be directly and quantitatively calculated through parameters such as temperature difference and thermal conductivity. 2) This embodiment has strong coupling between heat transfer and mass transfer: The mass transfer model in traditional tank models needs to be derived from the interfacial convective heat transfer difference, while in this embodiment, the heat conduction rate of the gas-liquid two-phase transition zone is directly used as the input of the mass transfer formula, forming heat transfer → phase change mass flow rate. The direct correlation between the two is clearer, and the empirical parameter errors in the calculation of the convective heat transfer coefficient are avoided, thus improving the robustness of the model. 3) During the dynamic processes such as start-up and shutdown of the high-thrust engine tank, the parameters change drastically (on the order of milliseconds). Since the transition zone model of this invention does not assume energy storage, it does not need to consider the thermal inertia of the transition zone itself, and can respond quickly to changes in gas-liquid temperature, making it more suitable for simulating transient heat and mass transfer; while the convective heat transfer model in the traditional tank model involves more dynamic changes in physical properties (such as viscosity and thermal diffusivity), resulting in higher computational complexity and slower response speed.

[0101] Step 4): Set the temperature of the inner wall of the tank to be the same as the temperature of the fluid in contact, and set the heat exchange method between the tank wall and the fluid to be only conduction; the fluid in contact is gas or liquid.

[0102] Step 200: Apply the mass transfer formula:

[0103] (2)

[0104] Calculate the phase change mass flow rate; where, For phase change mass flow rate, It is the latent heat of vaporization of the liquid.

[0105] For example, when the liquid temperature is greater than or equal to the saturation temperature, the phase change mass flow rate calculated using the mass transfer formula is the mass flow rate of the liquid evaporating into the gas region.

[0106] For example, phase change mass flow rate also includes the mass flow rate of gas condensation entering the liquid region.

[0107] Compared to traditional tank models, the mass transfer formula in this embodiment relates the heat transfer rate in the gas-liquid two-phase transition zone to the phase change mass flow rate. Its physical logic is simple and direct, with all heat transfer utilized for phase change (evaporation / condensation), requiring no additional energy allocation assumptions. Traditional tank models, on the other hand, require consideration of the sharp difference in interfacial convection heat transfer, making their logic complex.

[0108] Compared with the traditional tank model, the mass transfer formula in this embodiment explicitly covers bidirectional phase transitions: it includes both liquid evaporation into gas (positive phase transition) and gas condensation into liquid (negative phase transition).

[0109] Therefore, the advantages of this embodiment are: 1) Mass transfer and heat transfer are directly related through heat exchange → latent heat of phase change, skipping the complex calculation of convective heat transfer coefficient, allowing engineers / simulation personnel to more intuitively understand how heat drives mass phase change, especially suitable for the simplified model requirements of fast dynamic processes (such as start-up and shutdown) like high-thrust engine tanks. 2) It has stronger engineering practicality. The formula only requires heat exchange in the gas-liquid transition zone and latent heat of vaporization r to calculate the phase change mass flow rate. It has fewer input parameters and faster calculation, perfectly adapting to engineering scenarios where lumped parameter models need to balance accuracy and efficiency (the calculation of convective heat transfer coefficient in traditional tank models relies on a large number of empirical parameters, which is prone to introducing errors). 3) It explicitly supports bidirectional phase change of evaporation and condensation, which is more in line with actual working conditions (such as when the tank temperature fluctuates, there may be local evaporation and condensation at the same time). The unidirectional evaporation model in traditional tank models is prone to distortion under complex working conditions.

[0110] Setting the basic information also includes setting the structural and physical property parameters required for the lumped parameter model calculation. Structural parameters include, but are not limited to, the height of the gas region, the volume of the gas region, the volume of the liquid region, the thickness and area of ​​the gas-liquid two-phase transition zone, the inner gas wall surface area of ​​the gas wall and the inner liquid wall surface area of ​​the liquid wall, the tank wall thickness, etc. Physical property parameters include, but are not limited to, the thermal conductivity of the gas-liquid two-phase transition zone, the specific heat capacity of the gas at constant pressure, the specific heat capacity of the liquid at constant pressure, the latent heat of vaporization of the liquid, the gas constant, the elastic modulus of the liquid, the surface thermal conductivity of the tank wall, the loss coefficient, the dynamic friction loss coefficient, etc.

[0111] Based on the basic information that 'the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact, and the heat exchange method between the tank wall and the fluid in contact is only conduction', step 300 is performed: construct the gas wall heat exchange model and the liquid wall heat exchange model respectively.

[0112] For example, constructing an air-wall heat transfer model includes:

[0113] Based on the basic information that the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, the gas wall heat transfer model is constructed as follows:

[0114] (3)

[0115] in, The heat transfer rate between the gas and the gas wall. The temperature of the inner wall surface. This represents the area of ​​the internal air wall surface; The temperature of the outer wall surface of the storage tank. The thermal conductivity of the tank wall; The thickness of the tank wall (the thickness of both the gas wall and the liquid wall is the same).

[0116] Constructing a liquid-wall heat transfer model includes:

[0117] Based on the basic information that the inner wall temperature of the tank is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, the liquid wall heat transfer model is constructed as follows:

[0118] (4)

[0119] Construct a liquid wall heat transfer model; where, The heat transfer rate between the liquid and the liquid wall. The temperature of the inner liquid wall. This represents the area of ​​the inner liquid wall surface.

[0120] Analysis of the beneficial effects of this embodiment: From the perspective of temperature setting, this embodiment explicitly sets the temperature of the inner wall surface of the tank to be the same as the temperature of the fluid (whether gas or liquid) in contact with it. That is, there is no temperature difference between the inner wall surface and the fluid. Traditional tank models do not make such an assumption of the same temperature and calculate the heat transfer based on the existing temperature difference. This embodiment avoids the complex calculation of the convective heat transfer coefficient in traditional tank models (which requires fitting with empirical parameters such as Rayleigh number and characteristic length), greatly reducing the model complexity and making it more suitable for the rapid dynamic simulation requirements of lumped parameter models. It is especially suitable for the efficient simulation of transient processes (such as start-up and shutdown) of high-thrust engines.

[0121] From the perspective of heat transfer method, this embodiment limits the heat transfer between the tank wall and the contact fluid to only conduction. A heat transfer model can be constructed using Fourier's law. The amount of conduction heat transfer (e.g., the heat transfer rate in the gas-liquid two-phase transition zone) can be directly used as input to the gas energy equation. Furthermore, the mass transfer rate is correlated through a logical chain of heat transfer → temperature change → phase change mass transfer, avoiding the interference of convective heat transfer coefficient fluctuations on mass transfer calculations in traditional tank models and improving the model's stability in dynamic processes. In addition, the core parameters of the heat conduction model ( , The convective heat transfer coefficient in traditional tank models can be obtained directly from material properties and design drawings without relying on empirical formulas for fitting; while the convective heat transfer coefficient in traditional tank models needs to be calculated indirectly through Rayleigh numbers, which is easily affected by changes in operating conditions and has a large error.

[0122] Step 400: Construct the gas conservation equation system corresponding to the gas region and the liquid conservation equation system corresponding to the liquid region respectively; the gas conservation equation system includes at least the gas mass equation and the gas energy equation, the gas mass equation includes at least the phase change mass flow rate, and the gas energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the gas wall heat transfer model; the liquid conservation equation system includes at least the liquid mass equation and the liquid energy equation, the liquid mass equation includes at least the phase change mass flow rate, and the liquid energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model;

[0123] Step 500: Based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model, and the liquid wall heat transfer model, a lumped parameter model is constructed.

[0124] Specifically, step 500 refers to combining all the constructed equation systems and individual models to obtain the lumped parameter model.

[0125] Analysis of the beneficial effects of the embodiments of the present invention: The lumped parameter model construction method and device for the self-pressurized tank of the high thrust engine provided by the present invention sets up a gas-liquid two-phase transition zone to accurately describe gas-liquid heat exchange: the heat transfer formula is used to calculate the heat transfer rate of the gas-liquid two-phase transition zone, and by defining the thermal conductivity, thickness and heat transfer area of ​​the transition zone, the heat transfer process between gas and liquid is accurately described from a physical perspective, making up for the problem of rough gas-liquid interaction modeling and lack of accurate physical description; using the mass transfer formula, the phase change mass flow rate is calculated based on the heat transfer rate of the gas-liquid two-phase transition zone, so that the mass transfer process (phase change) and the heat transfer process (heat exchange in the transition zone) are directly related. The gas and liquid conservation equation systems incorporate heat transfer rates in the transition zone and phase change mass flow rates, respectively. This allows for dynamic coupling of the gas and liquid conservation equations through the heat transfer rate in the transition zone, achieving a closed-loop interaction between gas and liquid energy and mass. This addresses the issues of insufficient equation coupling and loose correlation between mass and heat transfer. Separate gas-wall and liquid-wall heat transfer models are constructed, eliminating the assumption that the tank wall is a single heat transfer boundary. Subsequent incorporation of the gas conservation equation system into the gas-wall heat transfer model and the liquid conservation equation system into the liquid-wall heat transfer model allows for targeted calculations of heat transfer between gas and the gas wall, and between the liquid and the liquid wall. This approach addresses the issue of simplified wall modeling, which hinders accurate calculation of heat transfer across different walls, thus improving the accuracy of rapid dynamic process simulations. Based on the gas conservation equation system, the liquid conservation equation system, and heat transfer models of the gas and liquid walls, a lumped parameter model is constructed. This model integrates the mass and heat transfer characteristics of the gas-liquid transition zone and the coupling between the gas, liquid, and the wall, enabling it to capture transient changes in mass and energy during the dynamic process of a self-pressurized tank. This solves the problem of not being able to fully capture the dynamic process mechanism and meet the requirements of high-precision simulation, helping to reflect the impact of transient changes in multiple physical quantities within the tank on system performance.

[0126] Next, the construction process of the two conservation equation systems will be described in detail, including:

[0127] Step 1: Construct the gas mass equation:

[0128] (5)

[0129] in, The mass of the gas (i.e., the mass of the gas); For time, For mass flow rate; This refers to the mass flow rate of the gas flowing into the gas region. The gas mass flow rate in the outflowing gas region (understandably, in actual implementation, considering the unknown time it will take for the liquid to be completely drained, the gas mass flow rate in the outflowing gas region is considered here to ensure the stability of the model). Phase change mass flow rate; This represents the change in gas mass with respect to time.

[0130] The specific process of constructing the gas mass equation is as follows:

[0131] Step 1: Obtain the relationship formula between the system's rate of change in mass and mass flow rate, which is:

[0132] (6)

[0133] in, The rate of change of system mass. This is the system's net mass flow rate;

[0134] Step 2: Refine the formula based on the gas region scenario.

[0135] In this model (gas region), the system is equivalent to a gas region, and its mass change is affected by three types of mass flow rates: the inflow gas mass flow rate... Outflow gas mass flow rate and internal conversion quality traffic .

[0136] According to the principle of conservation of mass: Substitute The gas mass equation can be obtained. .

[0137] Step 2: Constructing the gas momentum equation:

[0138] (7)

[0139] The ideal gas equation is: ; The temperature of an ideal gas (i.e., the temperature of the following gas) ), For the pressure of an ideal gas, For the density of an ideal gas, Let be the gas constant for an ideal gas; The inlet pressure of the gas region. The outlet pressure of the gas region. This represents the pressure difference between the inlet and outlet of a gas region, which is one of the driving forces for gas flow. The unit is Pa (Pascal). This item reflects the effect of gas outflow rate changes over time on the pressure difference. Overall, this item reflects the additional pressure changes caused by dynamic changes in flow rate, and the unit is Pa. This refers to the outflow mass flow rate of the gas. This represents the rate of change of the outflow mass flow rate of gas with respect to time. For example, if the outflow mass flow rate of gas changes rapidly in a short period of time, an additional pressure change will be generated to balance this dynamic effect. This is the loss coefficient.

[0140] The specific process of constructing the gas momentum equation is as follows:

[0141] Step 1: Obtain the Bernoulli equation.

[0142] The Bernoulli equation describing energy conservation during fluid flow is obtained, with the following forms for fluid inflow and outflow states:

[0143] Inflow end: (8)

[0144] Outflow end: (9)

[0145] in, These are Bernoulli constants. The height of the inflow end relative to the reference plane. The height of the outflow end relative to the reference plane. This is the gas mass flow rate. The pressure at the inflow end (i.e., the inlet of the gas region) is... The pressure at the outlet (i.e., the outlet of the gas region) The outflow mass flow rate of the fluid. This refers to the mass flow rate of the fluid entering the vessel.

[0146] Step 2: Derive the basic correlation of pressure difference (eliminate the constant Bernoulli equation constant).

[0147] In the gas region, subtracting the Bernoulli equations at the inflow and outflow ends eliminates the Bernoulli equation constant. We can obtain:

[0148] (10)

[0149] in, .

[0150] In actual flow, if the gas mass flow rate is stable and the inflow and outflow mass flow rates are equal, then formula (10) can be simplified to: .

[0151] Step 3: Introduce local flow resistance loss to improve the gas momentum equation.

[0152] To account for local flow resistance losses during the flow process (such as energy dissipation caused by sudden changes in pipe flow or valves), a flow resistance loss term needs to be added. Through theoretical derivation and experimental fitting, the flow resistance loss can be expressed as a dynamic term related to the rate of change of mass flow rate. .

[0153] Finally, by combining energy conservation and local flow resistance losses, the complete gas momentum equation is constructed:

[0154] .

[0155] Step 3: Constructing the gas energy equation:

[0156] (11)

[0157] in, For gas temperature, It represents the rate of change of gas temperature over time, reflecting how fast the gas temperature changes at each instant, and is a key term in the model used to track the dynamic evolution of gas temperature. The heat transfer rate between the gas and the gas wall; The rate of change of internal energy within a gas region is caused by the change in gas mass due to gas flow. The heat transfer rate in the gas-liquid two-phase transition zone; This refers to the phase change heat transfer rate (i.e., the heat transfer rate generated by the phase change of gas and liquid). For gas mass; This refers to the specific heat capacity of a gas at constant pressure. Overall, it represents the amount of heat required to raise the temperature of a unit mass of gas by a unit, that is, the effect of the heat obtained on the temperature increase; This reflects the effect of changes in gas mass on temperature. When the gas mass changes (such as an increase or decrease in gas mass due to mass transfer), it will have a corresponding effect on temperature. This item quantifies this relationship.

[0158] The functions of the gas energy equation are as follows: 1) To perform dynamic temperature simulation: When the lumped parameter model is running, this formula (3) is used to calculate the change in gas temperature in real time. As time progresses, the model will adjust according to the various input heat values. and changes in gas mass The change in gas temperature within each time step can be calculated using this formula. This updates the gas temperature. 2) Energy coupling calculation: It is coupled with the gas mass equation, gas momentum equation, and liquid-related equations. For example, changes in gas temperature affect gas pressure (e.g., through the ideal gas law), and also affect heat and mass transfer between gas and liquid. Through this coupling relationship, a comprehensive dynamic simulation of energy, mass, and momentum transfer in the gas-liquid two-phase system within the tank can be achieved, thus accurately reflecting the complex physical processes of the self-pressurized tank of a high-thrust engine in actual operation.

[0159] The specific process of constructing the gas energy equation includes:

[0160] Step 1: Formula for obtaining heat: (12)

[0161] in, Heat of the fluid;

[0162] Step 2: During the gas flow process, the gas temperature and gas mass change. We need to consider the differential relationship of energy with respect to time. The differential variable with respect to time on both sides is: (13)

[0163] Step 3: The law of conservation of energy is expressed as: the rate of change of energy equals the rate of change of heat. By rearranging and transforming terms, we can... Placing it alone on one side of the equation, we get:

[0164] (14)

[0165] in, This is the change in energy over time, i.e., the total heat transfer rate;

[0166] Step 4: In the gas region, Let be the change in gas energy with respect to time, which is the sum of all heat transfer rates of the gas. Considering the influence of heat transfer between the gas and the gas wall, heat transfer during gas flow, phase change heat transfer, and heat transfer in the gas-liquid transition zone, all of these factors are substituted into the equation. The gas energy equation can be obtained as follows:

[0167] .

[0168] Step 4: Construct the liquid mass equation:

[0169] (15)

[0170] in, This item indicates the liquid quality. Over time The rate of change; For liquid mass, The mass flow rate of the liquid flowing into the liquid zone. This refers to the mass flow rate of the liquid flowing out of the liquid region.

[0171] The formula for calculating the fluid capacity is: , This is the elastic modulus of the liquid.

[0172] The process of constructing the liquid mass equation specifically includes:

[0173] Step 1: Obtain the formula: ;

[0174] Step 2: In the liquid region, calculate all factors that cause changes in liquid mass flow rate, including:

[0175] ;

[0176] Step 5: Construct the liquid momentum equation (also known as the liquid state equation):

[0177] (16)

[0178] in, For liquid pressure, This represents the change in liquid pressure over time.

[0179] The process of constructing the liquid momentum equation specifically includes: the change in momentum of the liquid, i.e., the change in pressure, is related to the compressibility of the liquid, that is:

[0180] ;

[0181] Let be the liquid flow volume; the formula for calculating liquid flow volume is:

[0182] (17)

[0183] This is the elastic modulus of the liquid.

[0184] Step 6: Constructing the liquid energy equation:

[0185] (18)

[0186] in, For liquid temperature, This represents the change in liquid temperature with respect to time. The heat transfer rate between the liquid and the liquid wall; The rate of change of internal energy within a liquid region is caused by the change in the mass of the liquid due to the flow of the liquid. The specific heat capacity of a liquid at constant pressure; This indicates the heat that a liquid gains from different sources; It represents the amount of heat required to raise the temperature of a unit mass of liquid by a unit, that is, the effect of heat input through different pathways on the increase of liquid temperature; This reflects the effect of changes in liquid mass on temperature. When the liquid mass changes due to mass transfer (such as evaporation), medium inflow or outflow, etc. It will take into account the current liquid temperature It affects the temperature of the liquid.

[0187] The role of the liquid energy equation in the lumped parameter model: 1) Temperature dynamic simulation: During the operation of the lumped parameter model, this formula is used to calculate the change in liquid temperature in real time. As time progresses, the model calculates the change in liquid temperature within each time step based on various input heat values ​​and changes in liquid mass, and then updates the liquid temperature. 2) Multi-equation coupling: The liquid energy equation is coupled with the liquid mass equation, the liquid momentum equation, and gas-related equations. For example, changes in liquid temperature affect the liquid's physical properties (such as density and viscosity), thus affecting the pressure calculation in the momentum equation; changes in liquid temperature also affect the heat and mass transfer between gas and liquid, relating to the gas energy equation. Through this coupling, a comprehensive dynamic simulation of the complex physical processes of the gas-liquid two-phase system within the tank is achieved.

[0188] The form of the liquid energy equation is the same as that of the gas energy equation. The difference lies in the different heat exchange rates between the gas and the liquid. For the liquid, we have the following liquid energy equation:

[0189] .

[0190] refer to Figure 3 As can be seen, the lumped parameter model of the high-thrust engine self-pressurizing tank in this embodiment of the invention considers the heat and mass transfer process between gas and liquid propellants during pressurization, and simplifies this process to a certain extent. When constructing the model, the three fundamental equations of mass, momentum, and energy of the gas and liquid are the main focus, and the influence of heat and mass transfer during pressurization is incorporated into these three fundamental equations. According to the basic laws of fluid mechanics, the three fundamental equations can determine the physical state of the gas and liquid. After determining the basic states of the gas and liquid, the changes in gas / liquid physical properties such as density, viscosity, and bulk modulus can be further obtained. Furthermore, based on the gas-liquid state, the heat transfer rate with the wall can be calculated, which further affects the momentum and energy equations of the gas-liquid medium.

[0191] For example, in practical implementation, the formula for calculating gas density is:

[0192] (19)

[0193] in, For gas density, For gas mass; This represents the volume of the gas.

[0194] The formula for calculating liquid density is:

[0195] (20)

[0196] in, For the density of the liquid, For liquid mass; Let the volume be the liquid volume. The gas viscosity and thermal conductivity are calculated from the gas temperature derived from the gas energy equation by referring to tables or fitting formulas. Similarly, the liquid viscosity and thermal conductivity are calculated from the liquid temperature derived from the liquid energy equation by referring to tables or fitting formulas. For gases, the bulk modulus is obtained from the gas pressure derived from the gas momentum equation and the gas temperature derived from the gas energy equation.

[0197] In an alternative implementation, when the gas is vapor and non-ideal properties are considered, the lumped parameter model uses the real gas equation of state:

[0198] (twenty one)

[0199] To build;

[0200] in, The average gas pressure Gas volume, , For experimental correction coefficients, The gas constant is... This represents the temperature of the real gas.

[0201] Understandably, when applying the lumped parameter model of a high-thrust engine's self-pressurized propellant tank constructed using the aforementioned method, the following application steps can be referenced:

[0202] First, input the initial parameters: initial gas pressure and temperature in the storage tank, liquid mass and temperature, thermal conductivity of the wall material, etc.

[0203] Second, simulate the dynamic process of the startup phase:

[0204] Conservation of mass: When liquid is pumped into the combustion chamber, the mass of the liquid decreases ( (increases), while the liquid evaporates into gas ( (Increase), and the gas mass increases accordingly.

[0205] Conservation of momentum: Gas pressure maintains a dynamic equilibrium due to the increase in mass and changes in temperature and volume, driving the continuous outflow of liquid. The fluctuation of outlet pressure can be calculated using the liquid momentum equation. (It is understandable that the gas temperature may also decrease, and there is heat exchange between the gas and the gas wall. The final increase or decrease depends on the heat exchange rate. As the liquid is gradually discharged, the gas volume also changes.)

[0206] Energy conservation: Gas-liquid heat transfer: The high-temperature gaseous working fluid conducts heat to the liquid through the transition zone. If the liquid temperature reaches the saturation temperature, evaporation (mass transfer) is triggered, absorbing heat and causing mass transfer (it should be noted that after reaching saturation, it remains saturated, and the temperature basically does not change). Wall heat transfer: The external environment heats / cools the gaseous / liquid working fluid through the wall, affecting the temperature field distribution. For example, when low-temperature liquid oxygen comes into contact with a high-temperature wall, it absorbs heat and accelerates evaporation.

[0207] Third, output key parameters: monitor parameters such as gas pressure, liquid temperature, and outlet flow rate in real time, analyze whether the pressure fluctuation during the start-up process is within the safe range, and determine whether the start-up failure is caused by abnormal heat and mass transfer (such as insufficient liquid supply due to slow evaporation).

[0208] Fourth, optimize the design: adjust the tank structure (such as adding a heat insulation layer on the wall to reduce heat loss) or the working fluid filling ratio based on simulation results to ensure stable start-up and improve the reliability of high-thrust engines.

[0209] In a specific simulation embodiment, the lumped parameter model constructed using the aforementioned method for constructing a lumped parameter model of a high-thrust engine's self-pressurizing tank is applied in simulation. Based on the Modelica language and the domestic MWorks platform, a self-pressurizing simulation model of the tank is built. The parameters and variables of the tank model are defined according to the specific structure, inputs, and outputs of the tank, and the source code is written. The written tank model is then simulated and verified, assuming a constant gas pressure source continuously supplies gas to the tank for pressurization, and liquid is continuously discharged downstream. Simulations are performed for four operating conditions: pressurized gas at 500K, 1000K, heat exchange between the tank's outer wall and air, and tank adiabatic conditions. Details are as follows: Figures 5-10 As shown. The specific analysis is as follows:

[0210] The pressure in the tank is as follows Figure 5 As shown, the pressurization effect is best when the inlet boundary condition is an inlet temperature of 500K and the tank is adiabatic. The reasons are as follows: When the tank is adiabatic, there is no heat exchange between the wall and the external environment, reducing gas temperature loss. According to the ideal gas law, the tank pressure is related to the gas temperature; therefore, the smaller the gas temperature loss, the better the pressurization effect. When the tank inlet temperature is 1000K, due to the large temperature difference between the inlet temperature and the wall and liquid, the heat exchange rate is faster, and the heat loss is larger compared to the inlet temperature of 500K, resulting in a poorer pressurization effect. In the curve of an inlet temperature of 1000K and an adiabatic tank, the pressure rebounds after about 60 seconds. This is because as the liquid in the tank is discharged, the gas temperature loss gradually decreases, while the inlet continuously provides 1000K pressurized gas. The energy gained is greater than the energy lost, leading to an increase in temperature and consequently, an increase in pressure.

[0211] Gas temperature change such as Figure 6As shown in the figure, the temperature loss is smaller and the pressurization effect is better when the tank is insulated. At the same time, the temperature difference between the inlet pressurized gas and the tank wall and liquid should not be too large, otherwise the pressurization effect inside the tank will be affected.

[0212] Liquid temperature change Figure 7 As shown, under non-insulated conditions in the storage tank, the liquid temperature decreases because the heat transferred from the gas to the liquid is less than the heat transferred from the liquid to the wall, thus causing the liquid temperature to drop. Under insulated conditions in the storage tank, when the inlet temperature is 1000K, the liquid reaches its saturation temperature in about 63 seconds, and the temperature no longer rises. At this point, the liquid absorbs heat and generates gas, initiating the mass transfer process.

[0213] External air wall temperature, such as Figure 8 As shown, the temperature of the outer gas wall (i.e., the outer surface of the gas wall) is generally affected by the gas temperature, and the trend is consistent with the gas temperature, which will not be elaborated further here. The temperature of the outer liquid wall is as follows: Figure 9 As shown, the temperature of the external liquid wall is generally affected by the liquid temperature, and the trend is consistent with that of the liquid temperature, which will not be elaborated further here. The mass flow rate of liquid evaporation is as follows: Figure 10 As shown, under the boundary conditions of an inlet temperature of 1000K and an adiabatic tank, the liquid temperature reaches the saturation temperature in about 63s and begins to produce steam. Under the other three boundary conditions, the liquid temperature does not reach saturation and no steam is produced.

[0214] In summary, the temperature of the pressurized gas is a key factor in ensuring the pressurization effect of the storage tank. Temperature loss should be minimized during the pressurization process. This can be achieved by adding an insulation layer to the outer wall of the storage tank for heat insulation and reducing the inlet gas temperature.

[0215] The following describes the lumped parameter model construction device for the self-pressurized tank of a high-thrust engine provided by the present invention. The lumped parameter model construction device for the self-pressurized tank of a high-thrust engine described below can be referred to in correspondence with the lumped parameter model construction method for the self-pressurized tank of a high-thrust engine described above.

[0216] like Figure 4 As shown, this embodiment of the invention also provides a lumped parameter model construction device for a high-thrust engine self-pressurized tank, used to implement the lumped parameter model construction method for a high-thrust engine self-pressurized tank in any of the above embodiments. This lumped parameter model construction device for a high-thrust engine self-pressurized tank may include: a first calculation module 410, used to calculate the lumped parameter model based on the basic information of the tank's physical model, using the heat transfer formula:

[0217] ;

[0218] Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone. The thermal conductivity is the coefficient of thermal conductivity in the gas-liquid two-phase transition region. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; For liquid temperature;

[0219] The second calculation module 420 is used to apply the mass transfer formula:

[0220] ;

[0221] Calculate the phase change mass flow rate; where, For phase change mass flow rate, The latent heat of vaporization of the liquid is used; the first construction module 430 is used to construct the gas wall heat transfer model and the liquid wall heat transfer model respectively; the second construction module 440 is used to construct the gas conservation equation system corresponding to the gas region and the liquid conservation equation system corresponding to the liquid region respectively; the gas energy equation in the gas conservation equation system includes at least the heat transfer rate of the gas-liquid two-phase transition zone, the phase change mass flow rate and the gas wall heat transfer model; the liquid energy equation in the liquid conservation equation system includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model; the third construction module 450 is used to construct a lumped parameter model based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model and the liquid wall heat transfer model.

[0222] Optionally, the lumped parameter model building device for the self-pressurized tank of a high-thrust engine may further include: a building module for building basic information of the tank physical model before using the basic information of the tank physical model.

[0223] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results. Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Obviously, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank, characterized in that, include: Based on the basic information of the tank's physical model, the heat transfer formula is adopted: ； Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone. The thermal conductivity is the coefficient of thermal conductivity in the gas-liquid two-phase transition region. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; For liquid temperature; Mass transfer formula used: ； Calculate the phase change mass flow rate; where, The phase change mass flow rate is... The latent heat of vaporization of the liquid; Construct heat transfer models for both air walls and liquid walls; A gas conservation equation system corresponding to the gas region and a liquid conservation equation system corresponding to the liquid region are constructed respectively. The gas conservation equation system includes at least a gas mass equation and a gas energy equation. The gas mass equation includes at least the phase change mass flow rate, and the gas energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the gas wall heat transfer model. The liquid conservation equation system includes at least a liquid mass equation and a liquid energy equation. The liquid mass equation includes at least the phase change mass flow rate, and the liquid energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model. Based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model, and the liquid wall heat transfer model, a lumped parameter model is constructed.

2. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 1, characterized in that, Before using the basic information of the tank physical model, the construction method further includes: constructing the basic information of the tank physical model; The basic information for constructing the physical model of the storage tank specifically includes: The temperature is set to be uniform at any location within the gas region and the liquid region, and the temperature gradient along the flow direction is ignored. The gas-liquid two-phase transition zone is set as a homogeneous layer of a preset thickness, which does not store energy. Heat transfer between the gas and liquid is achieved only through thermal conduction, without convective heat transfer caused by tangential flow. The inner wall temperature of the tank is set to be the same as the temperature of the fluid in contact, and the heat exchange between the tank wall and the fluid in contact is only through conduction; the fluid in contact is a gas or a liquid.

3. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 2, characterized in that, The construction of the air-wall heat transfer model includes: Based on the basic information that the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, an air-wall heat transfer model is constructed: ； in, The heat transfer rate between the gas and the gas wall. The temperature of the inner wall surface. This represents the area of ​​the internal air wall surface; The temperature of the outer wall surface of the storage tank. is the thermal conductivity of the tank wall.

4. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 3, characterized in that, The construction of the liquid wall heat transfer model includes: Based on the basic information that the inner wall temperature of the tank wall is the same as the temperature of the fluid in contact with it, and that the heat exchange between the tank wall and the fluid in contact with it is only conduction, a liquid wall heat transfer model is constructed: ； in, The heat transfer rate between the liquid and the liquid wall. The temperature of the inner liquid wall. This represents the area of ​​the inner liquid wall surface.

5. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 4, characterized in that, The construction of the gas conservation equation system corresponding to the gas region includes: Construct the mass equation for the gas: ； in, For gas mass, For time, The mass flow rate of the gas flowing into the gas region. This refers to the mass flow rate of the gas exiting the gas region. Constructing the gas momentum equation: ; In the formula, The inlet pressure is the physical model of the storage tank. The outlet pressure of the storage tank physical model. The loss coefficient, For gas density, The coefficient of dynamic friction loss. It is the acceleration due to gravity. The height of the gas region; Construct the gas energy equation: ； in, The rate of change of internal energy within a gas region is caused by the change in gas mass due to gas flow. The heat transfer rate of the gas-liquid two-phase transition zone is given. For phase change heat rate, This is the specific heat capacity of a gas at constant pressure.

6. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 5, characterized in that, The construction of the liquid conservation equation system corresponding to the liquid region includes: Construct the liquid mass equation: ； In the formula, For liquid mass, The mass flow rate of the liquid flowing into the liquid zone. The mass flow rate of the liquid flowing out of the liquid region; Constructing the liquid momentum equation: ； in, For liquid pressure, For liquid flow capacity; Construct the liquid energy equation: ； in, The heat transfer rate between the liquid and the liquid wall. The rate of change of internal energy within a liquid region is caused by the change in the mass of the liquid due to liquid flow. This is the specific heat capacity of a liquid at constant pressure.

7. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 6, characterized in that, The formula for calculating the fluid capacity is: ； in, This is the elastic modulus of the liquid.

8. The method for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank according to claim 1, characterized in that, When the gas is vapor and non-ideal properties are considered, the lumped parameter model adopts the real gas equation of state: ； To build; in, The average gas pressure Gas volume, , For experimental correction coefficients, The gas constant is... This represents the temperature of the real gas.

9. A device for constructing a lumped parameter model of a high-thrust engine's self-pressurized propellant tank, characterized in that, include: The first calculation module is used to calculate heat transfer formulas based on the basic information of the tank's physical model: ； Calculate the heat transfer rate in the gas-liquid two-phase transition zone; where, The heat transfer rate in the gas-liquid two-phase transition zone. The thermal conductivity is the coefficient of thermal conductivity in the gas-liquid two-phase transition region. The thickness of the gas-liquid two-phase transition zone; This represents the heat transfer area of ​​the gas-liquid two-phase transition zone. The gas temperature; For liquid temperature; The second calculation module is used to apply the mass transfer formula: ； Calculate the phase change mass flow rate; where, The phase change mass flow rate is... The latent heat of vaporization of the liquid; The first construction module is used to construct the gas wall heat transfer model and the liquid wall heat transfer model respectively; The second construction module is used to construct a gas conservation equation system corresponding to the gas region and a liquid conservation equation system corresponding to the liquid region, respectively. The gas conservation equation system includes at least a gas mass equation and a gas energy equation. The gas mass equation includes at least the phase change mass flow rate, and the gas energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the gas wall heat transfer model. The liquid conservation equation system includes at least a liquid mass equation and a liquid energy equation. The liquid mass equation includes at least the phase change mass flow rate, and the liquid energy equation includes at least the heat transfer rate of the gas-liquid two-phase transition zone and the liquid wall heat transfer model. The third construction module is used to construct a lumped parameter model based on the gas conservation equation system, the liquid conservation equation system, the gas wall heat transfer model, and the liquid wall heat transfer model.

10. The lumped parameter model construction device for the self-pressurized tank of a high-thrust engine according to claim 9, characterized in that, Also includes: A building module is used to build the basic information before using the basic information of the tank physical model.

Images