A high-precision real-time coupling prediction method and system for icing of rotating components of an engine in an icing wind tunnel test

Abstract

The present application relates to the technical field of rotating component icing test, and discloses a high-precision real-time coupling prediction method and system for engine rotating component icing in ice wind tunnel test, wherein a simulation geometric model is first constructed and a calculation grid is generated according to ice wind tunnel test parameters and component structure, a local water collection coefficient of the rotating component surface is calculated under a set rotating motion condition, a momentum, mass and energy conservation equation containing rotating force, water film mass parameters and heat transfer characteristic parameters is constructed after identifying an icing position, and then the equation is substituted into a fluid volume method to perform real-time coupling solving of a flow field and an icing process, and the model is updated iteratively combined with icing shape change until the icing time is reached to output a final prediction result. The method accurately depicts the influence of the ice-water interface temperature gradient and the rotating effect on icing, has high prediction accuracy, completely covers the whole physical process from water droplet impact to icing heat transfer, and avoids the error of traditional decoupling calculation.

Description

Technical Field

[0001] This invention relates to the field of rotating component icing test technology, and discloses a high-precision real-time coupled prediction method and system for engine rotating component icing in ice wind tunnel tests. Background Technology

[0002] Engine icing is a significant factor affecting flight safety during continuous flight, and accidents caused by icing have resulted in serious consequences and casualties. Engine icing originates from passing through high-moisture clouds with temperatures below freezing, where supercooled water droplets impact engine inlet components, forming ice or a mixture of ice and water.

[0003] Depending on environmental differences, icing mainly occurs in two forms: in drier, colder environments, water droplets freeze immediately upon impact, forming frost ice with a large amount of air and lower density; in humid environments, the latent heat of phase change cannot dissipate quickly, causing some ice to melt and overflow, eventually forming solid, transparent, and dense clear ice; mixed ice is a transitional state between the two. Key meteorological parameters affecting icing include liquid water content, average droplet diameter, and ambient temperature.

[0004] The engine's inlet support plate, fairing hood, and fan blades are prone to icing. Icing alters the aerodynamic shape, reduces intake airflow, causes intake distortion and compressor surge, and increases fan power consumption. For the high-speed rotating fairing and fan blades, centrifugal force can cause water films to be detached and flow into the internal ducts, causing erosion, or cause ice to detach. Detached ice, if sucked into the compressor, can damage the blades, leading to rotational stall, surge, or even engine shutdown, seriously threatening operational safety. The latent heat of phase change released by icing is partially dissipated through convection heat transfer, and some is introduced into components, causing surface temperature rise.

[0005] Ice wind tunnel testing is a core ground-based experimental platform for simulating the aforementioned icing environment, verifying the effectiveness of engine anti-icing systems, and acquiring icing characteristic data. By generating cloud and fog conditions in the wind tunnel that meet airworthiness requirements (controlling liquid water content, droplet diameter, and temperature), icing tests can be conducted on scaled-down or full-size components, allowing for direct observation of ice shape, measurement of icing amount, and its impact on aerodynamic performance. However, purely experimental research has limitations such as long cycles, high costs, limited measurement points, and difficulty in reproducing certain extreme operating conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a high-precision real-time coupled prediction method and system for icing of rotating engine components in ice wind tunnel tests. This method can accurately characterize the influence of the temperature gradient and rotation effect at the ice-water interface on icing, with high prediction accuracy and complete coverage of the entire physical process of heat transfer from water droplet impact to icing, avoiding the errors of traditional decoupling calculations.

[0007] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0008] A high-precision real-time coupled prediction method for icing of rotating engine components during icing wind tunnel testing includes: Step 1: Based on the test section dimensions of the target ice wind tunnel and the structural parameters of the engine rotating components, establish a three-dimensional geometric model for the simulation of the engine rotating components and generate a computational mesh. Step 2: Under the given numerical simulation computational domain, boundary conditions, and rotational motion conditions, based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, analyze and obtain the local water collection coefficient on the surface of the rotating component. Step 3: Based on the temperature distribution on each computational grid of the 3D geometric model, determine the computational grids with temperatures lower than the preset temperature threshold as the freezing locations; Step 4: Using the mass of the liquid water at the freezing point as the mass source term, construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the centrifugal force, Coriolis force, and rotational shear force at the corresponding freezing point as the kinetic source term, construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the latent heat of phase change released during freezing at the corresponding freezing point as the energy source term, construct the energy conservation equation for the corresponding freezing point. Step 5: Within each time step, taking the icing location as the control volume, the fluid volume method is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component, based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, to obtain the new icing amount of the control volume at each time step. Step 6: Determine if the icing time has been reached. If so, output the final icing prediction result for the rotating component surface. Otherwise, based on the shape change caused by icing, rebuild the three-dimensional geometric model for the simulation of the engine rotating component and generate a computational mesh. Update the flow field and temperature field, and use the fluid volume method to perform real-time coupling solution of the flow field and icing process until the final icing prediction result is output.

[0009] Furthermore, in the given numerical simulation computational domain range, boundary conditions, and rotational motion conditions, the computational domain range includes: the geometry of the computational domain, the inlet boundary dimensions, and the outlet boundary dimensions; the boundary conditions include: the incoming flow velocity, the incoming flow temperature, the liquid water content, and the average droplet diameter; and the rotational motion conditions include: the rotational speed of the rotating components.

[0010] Furthermore, the local water collection coefficient on the surface of the rotating component ,in The mass of liquid water per unit volume of incoming flow. The velocity of the incoming flow from the ice tunnel. This represents the volume fraction of the water droplet component in the incoming stream. Let be the impact velocity of the water droplet. is the unit normal vector of the surface at the impact location.

[0011] Furthermore, the mass conservation equation for the icing process following the impact of water droplets at the corresponding icing location with the surface of the rotating component is as follows: ,in For the mass of liquid water, The mass of the water film flowing into and out of the control volume within the current time step. ,in The density of the water droplet, Let be the impact velocity of the water droplet. The differential symbol, The area of ​​the icing site; For impact mass, ,in The liquid water content in the incoming flow; The mass of liquid water evaporated. ,in The mass transfer coefficient is . The density of saturated vapor in air at the surface temperature of the rotating component. The density of saturated vapor in air at air temperature; Add ice volume to the control body at the current time step. This refers to the quantities that are solved in real-time using coupled solutions.

[0012] Furthermore, the momentum conservation equation for the icing process after the water droplet at the current icing location collides with the surface of the rotating component is as follows: ;in Represents partial derivatives, For time, The density of the water droplet, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. The viscosity of air. It is the acceleration due to gravity. For centrifugal force, Coriolis force, It is a rotational shear force; The momentum source terms within the corresponding time step are as follows: Centrifugal force ; Coriolis force ; Rotational shear force ; in To control the quality of the body water film, The rotational speed of the rotating component. The radius of rotation of the icing location. Indicates the time step. The flow velocity of the liquid water film. The dynamic viscosity of water, This represents the area of ​​the icing location.

[0013] Furthermore, the energy conservation equation for the icing process after the water droplet at the current icing location collides with the surface of the rotating component is as follows: ,in The latent heat of vaporization released by the evaporation of the water film. The negative sign indicates that the evaporation process absorbs heat from the system. The mass of liquid water evaporated. This represents the latent heat of vaporization of liquid water; The latent heat of phase change released during freezing. , This represents the increase in icing volume of the control body at the current time step. This represents the latent heat of phase transition during freezing; To control the heat conduction between the water inside the body and the surface of the rotating component structure, , The thermal conductivity of the rotating component structure, This represents the surface temperature of the solid structure of the rotating component at the current time step. In order to control the temperature of the body's water film in the next moment, Indicates the thickness of the solid structure along the direction of thermal conduction. For heat exchange between the water film and the airflow, , The heat transfer coefficient between the water film and the airflow is convective. To restore the temperature of the water film and airflow boundary layer, This is the change in the internal energy of water, calculated based on the changes in the internal energy of the water within the body at the previous and next moments. This is the change in the internal energy of the ice, calculated based on the changes in the internal energy of the ice within the body at the previous and next moments.

[0014] Furthermore, in the real-time coupled solution of the flow field and icing process using the fluid volume method, the coupled solution equation is:

[0015] in, Represents partial derivatives, For time, For the density of water droplets, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. air viscosity, It is the acceleration due to gravity. This represents the volume fraction of the water droplet component in the incoming stream. For the mass of liquid water, The momentum source term of centrifugal force. The momentum source term of the Coriolis force. The momentum source term for the shear force of the rotating airflow. To control the total energy in the body, For effective thermal conductivity, For the effective viscous stress tensor, The latent heat of phase change released during freezing.

[0016] Furthermore, the preset temperature threshold is 273.15K.

[0017] To achieve the above-mentioned technical effects, the present invention also provides a high-precision real-time coupled prediction system for icing of engine rotating components in icy wind tunnel tests, used to implement the aforementioned high-precision real-time coupled prediction method for icing of engine rotating components in icy wind tunnel tests, comprising: The simulation model building module is used to build a three-dimensional geometric model for simulating the rotating engine components and generate a computational mesh based on the test section dimensions of the target ice wind tunnel and the structural parameters of the rotating engine components. The impact model analysis module is used to analyze and obtain the local water collection coefficient of the rotating component surface based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, within a given numerical simulation calculation domain, boundary conditions, and rotational motion conditions. The icing location analysis module is used to identify icing locations in computational grids where the temperature is below a preset temperature threshold based on the temperature distribution on each computational grid of the 3D geometric model. The conservation model construction module is used to construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the mass of the liquid water at the freezing location as the mass source term; to construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the centrifugal force, Coriolis force, and rotational shear force at the freezing location as the kinetic source term; and to construct the energy conservation equation for the freezing location, using the latent heat of phase change released during freezing at the freezing location as the energy source term. The icing amount analysis module is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component in each time step, taking the icing location as the control volume. Based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, the fluid volume method is used to obtain the new icing amount of the control volume in each time step. The discrimination output module is used to determine whether the icing time has been reached. If so, it outputs the final icing prediction result of the rotating component surface; otherwise, it re-establishes the three-dimensional geometric model for the simulation of the engine rotating component based on the shape change caused by icing and generates a computational mesh. It updates the flow field and temperature field and uses the fluid volume method to perform real-time coupling solution of the flow field and icing process until the final icing prediction result is output.

[0018] Compared with the prior art, the beneficial effects of this invention are: 1. High accuracy: The temperature gradient is finely characterized by the phase interface data exchange model, and the rotation effect is accurately described by the rotation momentum source term model, which comprehensively improves the accuracy of rotating components in predicting complex icing conditions (especially open ice).

[0019] 2. Complete physical process: For the first time, it integrates the entire process of water droplet impact, water film flow, and icing heat transfer within the same framework with high fidelity simulation. It realizes real-time coupled calculation of flow field and icing physical field, overcomes the error caused by decoupling in traditional multi-step method, and can reflect the feedback of icing shape change on flow field.

[0020] 3. High practicality: The developed model is ultimately integrated into an operable software module, which can be directly applied to the icing safety design and evaluation of rotating components such as engine intake cones and fan blades, and has significant engineering application value. Attached Figure Description

[0021] Figure 1 Flowchart of a high-precision real-time coupled prediction method for icing of rotating engine components during ice wind tunnel testing; Figure 2 This is a schematic diagram of the interface data exchange model in Example 2; Figure 3 This is a schematic diagram comparing the engine icing test results and the predicted results in Example 2. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Example 1 like Figure 1 A high-precision real-time coupled prediction method for icing of engine rotating components during icing wind tunnel testing includes: Step 1: Based on the test section dimensions of the target ice wind tunnel and the structural parameters of the engine rotating components, establish a three-dimensional geometric model for the simulation of the engine rotating components and generate a computational mesh. Step 2: Under the given numerical simulation computational domain, boundary conditions, and rotational motion conditions, based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, analyze and obtain the local water collection coefficient on the surface of the rotating component. Step 3: Based on the temperature distribution on each computational grid of the 3D geometric model, determine the computational grids with temperatures lower than the preset temperature threshold as the freezing locations; Step 4: Using the mass of the liquid water at the freezing point as the mass source term, construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the centrifugal force, Coriolis force, and rotational shear force at the corresponding freezing point as the kinetic source term, construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the latent heat of phase change released during freezing at the corresponding freezing point as the energy source term, construct the energy conservation equation for the corresponding freezing point. Step 5: Within each time step, taking the icing location as the control volume, the fluid volume method is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component, based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, to obtain the new icing amount of the control volume at each time step. Step 6: Determine if the icing time has been reached. If so, output the final icing prediction result for the rotating component surface. Otherwise, based on the shape change caused by icing, rebuild the three-dimensional geometric model for the simulation of the engine rotating component and generate a computational mesh. Update the flow field and temperature field, and use the fluid volume method to perform real-time coupling solution of the flow field and icing process until the final icing prediction result is output.

[0024] In this embodiment, a simulated three-dimensional geometric model is constructed and a computational mesh is generated. The temperature distribution of the three-dimensional geometric model is obtained through simulation. Mesh grids with temperatures below a preset threshold are identified as icing locations. Momentum, mass, and energy conservation equations for the icing process at the icing locations are constructed based on mass, power, and energy source terms, respectively. Subsequently, at each time step, the flow field and the icing process at the icing location on the surface of the rotating component are coupled and solved in real time using the fluid volume method according to the mass, momentum, and energy conservation equations for the corresponding icing location. The newly added icing amount of the control volume at each time step is obtained. The coupling solution is then continuously iterated until the icing time is reached, at which point the final icing prediction result is output. This method can precisely characterize the temperature gradient in the ice-water coexistence zone, accurately reproduce the influence of rotational effects on water film flow and icing, significantly improve the icing prediction accuracy under complex conditions such as open ice and mixed ice, and fully cover the entire physical process from water droplet impact to icing heat transfer. It achieves real-time bidirectional coupling between the flow field and the icing physical field, overcomes the errors caused by traditional decoupling calculations, and can be directly applied to the icing safety design and evaluation of rotating components such as engine intake cones and fan blades, providing high-confidence numerical support for anti-icing design verification and airworthiness certification.

[0025] Based on the same inventive concept, this embodiment also provides a high-precision real-time coupled prediction system for icing of engine rotating components in icy wind tunnel tests, used to implement the aforementioned high-precision real-time coupled prediction method for icing of engine rotating components in icy wind tunnel tests, including: The simulation model building module is used to build a three-dimensional geometric model for simulating the rotating engine components and generate a computational mesh based on the test section dimensions of the target ice wind tunnel and the structural parameters of the rotating engine components. The impact model analysis module is used to analyze and obtain the local water collection coefficient of the rotating component surface based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, within a given numerical simulation calculation domain, boundary conditions, and rotational motion conditions. The icing location analysis module is used to identify icing locations in computational grids where the temperature is below a preset temperature threshold based on the temperature distribution on each computational grid of the 3D geometric model. The conservation model construction module is used to construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the mass of the liquid water at the freezing location as the mass source term; to construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the centrifugal force, Coriolis force, and rotational shear force at the freezing location as the kinetic source term; and to construct the energy conservation equation for the freezing location, using the latent heat of phase change released during freezing at the freezing location as the energy source term. The icing amount analysis module is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component in each time step, taking the icing location as the control volume. Based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, the fluid volume method is used to obtain the new icing amount of the control volume in each time step. The discrimination output module is used to determine whether the icing time has been reached. If so, it outputs the final icing prediction result of the rotating component surface; otherwise, it re-establishes the three-dimensional geometric model for the simulation of the engine rotating component based on the shape change caused by icing and generates a computational mesh. It updates the flow field and temperature field and uses the fluid volume method to perform real-time coupling solution of the flow field and icing process until the final icing prediction result is output.

[0026] Example 2 See Figures 1 to 3 A high-precision real-time coupled prediction method for icing of engine rotating components during icing wind tunnel testing includes: Step 1: Based on the test section dimensions of the target ice wind tunnel and the structural parameters of the engine rotating components, establish a three-dimensional geometric model for the simulation of the engine rotating components and generate a computational mesh. In this embodiment, a simplified rotating cap geometry model is established using 3D modeling software (such as SpaceClaim), and a high-quality structured mesh is generated using mesh generation software (such as ICEM).

[0027] Step 2: Under the given numerical simulation computational domain, boundary conditions, and rotational motion conditions, based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, analyze and obtain the local water collection coefficient on the surface of the rotating component. In this embodiment, the computational domain and boundary conditions (velocity inlet, pressure outlet, no-slip wall, incoming flow velocity, incoming flow temperature, liquid water content, average droplet diameter, and rotational speed of the rotating component) are set in the CFD software. A suitable turbulence model (such as the SA model) is selected to first calculate the clean air flow field. Then, the Eulerian multiphase flow model is enabled in the CFD software, and a user-defined function (UDF) is loaded to solve the droplet motion control equations that incorporate a rotational force source term, thereby solving for the droplet impact velocity. and the volume fraction of water droplet components in the incoming flow. ; and combined with the incoming flow velocity of the ice wind tunnel Mass of liquid water per unit volume of incoming flow Obtain the local water collection coefficient on the surface of the rotating component. Distribution cloud map; where the local water collection coefficient of the rotating component surface is shown. , Let be the unit normal vector of the impact point surface. The local water collection coefficient formula is originally defined as the ratio of the liquid water mass flux normal to the impact surface to the incoming reference liquid water mass flux; expanding the two mass fluxes and canceling out the common liquid water density, yields the formula. The calculation formula. When When inputting liquid water mass concentration, first divide by the liquid water density to convert to volume fraction.

[0028] Step 3: Based on the temperature distribution on each computational grid of the 3D geometric model, determine the computational grids with temperatures lower than the preset temperature threshold as the freezing locations; In this embodiment, the preset temperature threshold is 273.15K.

[0029] Step 4: Using the mass of the liquid water at the freezing point as the mass source term, construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the centrifugal force, Coriolis force, and rotational shear force at the corresponding freezing point as the kinetic source term, construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the latent heat of phase change released during freezing at the corresponding freezing point as the energy source term, construct the energy conservation equation for the corresponding freezing point. In this embodiment, the mass conservation equation for the icing process after the water droplet at the corresponding icing position collides with the surface of the rotating component is as follows: ,in For the mass of liquid water, The mass of the water film flowing into and out of the control volume within the current time step. ,in The density of the water droplet, Let be the impact velocity of the water droplet. The differential symbol, The area of ​​the icing site; For impact mass, ,in The liquid water content in the incoming flow; The mass of liquid water evaporated. ,in The mass transfer coefficient is . ,in Where is the convective heat transfer coefficient between the water film and the airflow, and Cp is the specific heat capacity ratio of air. The density of saturated vapor in air at the surface temperature of the rotating component. The density of saturated vapor in air at air temperature; This represents the increase in icing volume of the control body at the current time step. The quantities are to be solved in real-time coupling. The above mass conservation equation is based on the law of conservation of mass of the control volume (Reynolds' transport theorem) in continuum mechanics: the change in mass of liquid water within the control volume is equal to the sum of the net inflow at the boundary and the impact input of water droplets, minus the evaporation loss and freezing consumption; integrating this conservation relationship over a single time step and rearranging it according to the aforementioned sign convention yields the mass conservation equation. It is obtained by integrating the mass flux over the boundary area of ​​the control volume; Mass flux of liquid water from the source Multiply by the local collection factor and the area of ​​ice formation get; It is obtained from the basic convective mass transfer relationship: "evaporation rate equals the product of mass transfer coefficient, the density difference between the interface and the incoming saturated vapor, and the mass transfer area." Wherein, the mass transfer coefficient... The relationship is based on the Chilton-Colburn heat and mass transfer analogy, and incorporates the Lewis number L. e Take 0.845 and press =(h / C p )L e The expression is obtained by converting ^(-2 / 3).

[0030] In the momentum equation describing water film flow, centrifugal force, Coriolis force, and rotational shear force generated by rotation are explicitly added as momentum source terms to accurately simulate the influence of rotation on the water film flow path, thickness, and water-throwing effect. Therefore, the momentum conservation equation for the icing process after the water droplet at the current icing position collides with the surface of the rotating component is constructed as follows: ;in Represents partial derivatives, For time, The density of the water droplet, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. The viscosity of air. It is the acceleration due to gravity. For centrifugal force, Coriolis force, It is a rotational shear force; The momentum source terms within the corresponding time step are as follows: Centrifugal force ; Coriolis force ; Rotational shear force ; in To control the quality of the body water film, The rotational speed of the rotating component. The radius of rotation of the icing location. Indicates the time step. The flow velocity of the liquid water film. The dynamic viscosity of water, Let be the area of ​​the icing location. The above momentum conservation equation is based on the Navier-Stokes momentum equation in a rotating reference frame; the momentum equation in an inertial coordinate system is transformed to a coordinate system with an angular velocity of . After rotating the coordinate system, the eccentric and Coriolis terms are obtained. Discretized within one time step according to the notation of the source term in this paper, the following results are obtained: and The rotational shear force is obtained from Newton's law of viscosity, characterized by the near-wall velocity gradient as the rotational angular velocity, and integrated over the area A at the icing location.

[0031] The energy conservation equation for the icing process after the water droplet at the current icing location collides with the surface of the rotating component is as follows: ,in The latent heat of vaporization released by the evaporation of the water film. The negative sign indicates that the evaporation process absorbs heat from the system. The mass of liquid water evaporated. This represents the latent heat of vaporization of liquid water; The latent heat of phase change released during freezing. , This represents the increase in icing volume of the control body at the current time step. This represents the latent heat of phase transition during freezing; To control the heat conduction between the water inside the body and the surface of the rotating component structure, , The thermal conductivity of the rotating component structure, This represents the surface temperature of the solid structure of the rotating component at the current time step. In order to control the temperature of the body's water film in the next moment, Indicates the thickness of the solid structure along the direction of thermal conduction. For heat exchange between the water film and the airflow, , The heat transfer coefficient between the water film and the airflow is convective. To restore the temperature of the water film and airflow boundary layer, ,in For incoming flow temperature data, For incoming flow velocity data values, The specific heat ratio of air. This is the change in the internal energy of water, calculated based on the changes in the internal energy of the water within the body at the previous and next moments. This represents the change in the internal energy of ice, calculated based on the changes in the internal energy of the ice within the body at the previous and next moments. The above energy equation is based on the first law of thermodynamics; the latent heat terms for evaporation and freezing are derived from Q=m L The thermal conductivity term is derived from Fourier's law, and the convection term from Newton's law of cooling. The recovery temperature formula originates from the recovery temperature relationship of a compressible adiabatic boundary layer. Take the recovery factor =0.9, which gives us the expression used in this paper.

[0032] Step 5: Within each time step, use the icing location as the control volume (e.g., ...). Figure 2 The dashed box in the figure represents the control body in this embodiment. Based on the mass conservation equation, momentum conservation equation, and energy conservation equation of the corresponding icing position, the fluid volume method is used to perform real-time coupling solution of the flow field and the icing process at the icing position on the surface of the rotating component, so as to obtain the new icing amount of the control body at each time step. In this embodiment, during the real-time coupled solution of the flow field and icing process using the fluid volume method, the coupled solution equation is:

[0033] in, Represents partial derivatives, For time, For the density of water droplets, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. air viscosity, It is the acceleration due to gravity. This represents the volume fraction of the water droplet component in the incoming stream. For the mass of liquid water, The momentum source term of centrifugal force. The momentum source term of the Coriolis force. The momentum source term for the shear force of the rotating airflow. To control the total energy in the body, For effective thermal conductivity, For the effective viscous stress tensor, This refers to the latent heat of phase change released during freezing. It should be noted that, similar to... , , These quantities are intermediate quantities in the VOF model's own calculation process and do not need to be specified manually. The above set of equations is obtained by finite volume integration and time discretization of the phase volume fraction transport equation and the mass, momentum, and energy conservation equations of the fluid volume method. The aforementioned mass source term, rotational momentum source term, and phase change heat source term are added to the corresponding equations to achieve coupled solution within the same time step.

[0034] Step 6: Determine if the icing time has been reached. If so, output the final icing prediction result for the rotating component surface. Otherwise, based on the shape change caused by icing, rebuild the three-dimensional geometric model for the simulation of the engine rotating component and generate a computational mesh. Update the flow field and temperature field, and use the fluid volume method to perform real-time coupling solution of the flow field and icing process until the final icing prediction result is output.

[0035] In this embodiment, when performing coupled calculations of the icing process, the VOF (Volume of Fluid) model and transient calculations can be activated in the CFD software. A user-defined function (UDF) program integrating all models from steps two through six is ​​compiled and loaded. The program executes the following loop within each time step: 1) Locate the corresponding computational domain, input and calculate the physical property parameters required for icing; 2) Determine if the current temperature within the control chamber is greater than 273.15K; if yes, proceed to step 7); otherwise, proceed to step 3). 3) Solve the energy balance equation under the open ice condition to obtain the preliminary temperature distribution and water film flow within the control body; 4) Solve the interfacial heat conduction equilibrium equation to obtain the precise temperature distribution and water film flow within the control volume; such as Figure 2 The diagram shown is a schematic of the phase interface data exchange model, and the corresponding phase interface heat conduction balance equation is: ,in This represents the thermal conductivity of ice. This indicates the density of ice. This represents the thermal conductivity of water. The density of the water droplet, This indicates the control of the total amount of ice in the body at the next moment. This indicates the control of the total amount of water film in the body at the next moment. Indicates the temperature of ice. This indicates the temperature of the water film within the body at the next moment. The phase interface heat conduction balance equation is based on Fourier's law of heat conduction and the condition of continuous heat flow on both sides of the phase interface: write out the one-dimensional heat conduction on the ice side and the water side respectively, replace the thickness of the ice layer and water film with the mass and density of each phase, and then make the heat conduction on both sides of the interface equal and cancel the common area term to obtain the expression.

[0036] 5) Solve for the water film mass source term, momentum source term, energy source term, and the newly added ice amount; 6) Solving VOF equations based on the PISO scheme; 7) Determine if the freezing time has been reached; if yes, proceed to 8); otherwise, proceed to 1). 8) Once the final icing calculation result is obtained, the program will end.

[0037] In this embodiment, following the above-described steps, a rotating cap icing experiment was conducted in an ice wind tunnel. Based on the icing calculation model developed in this embodiment, icing simulation calculations were performed, yielding the following results: Figure 3 The calculation results shown in (a), (b), (c), and (d) are compared with the experimental results. Figure 3 As shown, Figure 3 In the model, X represents the axial coordinate of different positions on the cap surface, Y represents the radial height, L represents the cap length, and R represents the cap bottom radius (a spatial rectangular coordinate system established with the cap's front edge as the origin and the cap's axis as the x-axis). The error between the maximum icing thickness at the front edge (25.91 cm) and the experimental result (24.50 cm) is 5.76%. The error in the maximum icing thickness is controlled within 10%, indicating that the icing calculation model developed in this study has good accuracy.

[0038] This is a mixed-ice icing condition under engine idle conditions. Its icing shape exhibits characteristics of both clear ice and frost ice, representing a transitional ice form. In the initial icing state, due to the lower temperature (compared to clear ice), liquid water droplets immediately freeze upon impact with the wall surface, releasing latent heat of freezing. As the amount of impacting water increases, the latent heat of freezing heat heats the wall surface, gradually increasing its temperature and creating an overflow water film on the cap surface. The leading edge water film flows towards the trailing edge under the influence of airflow, and experiences a greater rotational force as the cap's rotation radius increases. Under the influence of this rotational force, the water film tends to detach from the surface, and the rotation enhances the convective heat transfer process. Therefore, in... Figure 3 Ice corners were generated in (d). Since the cap is a symmetrical rotating body, the flow direction of the water film on the cap surface is random. Even slight disturbances are amplified under high-speed rotation, so the appearance of ice corners is highly random.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision real-time coupled prediction method for icing of rotating engine components during icing wind tunnel testing, characterized in that, include: Step 1: Based on the test section dimensions of the target ice wind tunnel and the structural parameters of the engine rotating components, establish a three-dimensional geometric model for the simulation of the engine rotating components and generate a computational mesh. Step 2: Under the given numerical simulation computational domain, boundary conditions, and rotational motion conditions, based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, analyze and obtain the local water collection coefficient on the surface of the rotating component. Step 3: Based on the temperature distribution on each computational grid of the 3D geometric model, determine the computational grids with temperatures lower than the preset temperature threshold as the freezing locations; Step 4: Using the mass of the liquid water at the freezing point as the mass source term, construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the centrifugal force, Coriolis force, and rotational shear force at the corresponding freezing point as the kinetic source term, construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the corresponding freezing point. Using the latent heat of phase change released during freezing at the corresponding freezing point as the energy source term, construct the energy conservation equation for the corresponding freezing point. Step 5: Within each time step, taking the icing location as the control volume, the fluid volume method is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component, based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, to obtain the new icing amount of the control volume at each time step. Step 6: Determine if the icing time has been reached. If so, output the final icing prediction result for the surface of the rotating component. Otherwise, based on the shape changes caused by icing, a new three-dimensional geometric model for simulating the rotating components of the engine is rebuilt and a computational mesh is generated. The flow field is updated and coupled with the temperature field using the fluid volume method to solve the flow field and icing process in real time until the final icing prediction result is output.

2. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, The given numerical simulation computational domain, boundary conditions, and rotational motion conditions include: the computational domain's geometry, inlet boundary dimensions, and outlet boundary dimensions; the boundary conditions include: inflow velocity, inflow temperature, liquid water content, and average droplet diameter; and the rotational motion conditions include: the rotational speed of the rotating components.

3. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, Local water collection coefficient on the surface of rotating components ,in The mass of liquid water per unit volume of incoming flow. The velocity of the incoming flow from the ice tunnel. This represents the volume fraction of the water droplet component in the incoming stream. Let be the impact velocity of the water droplet. is the unit normal vector of the surface at the impact location.

4. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 3, characterized in that, The mass conservation equation for the icing process after the water droplet at the corresponding icing location collides with the surface of the rotating component is as follows: ,in For the mass of liquid water, The mass of the water film flowing into and out of the control volume within the current time step. ,in The density of the water droplet, Let be the impact velocity of the water droplet. The differential symbol, The area of ​​the icing site; For impact mass, ,in The liquid water content in the incoming flow; The mass of liquid water evaporated. ,in The mass transfer coefficient is . The density of saturated vapor in air at the surface temperature of the rotating component. The density of saturated vapor in air at air temperature; Add ice volume to the control body at the current time step. This refers to the quantities that are solved in real-time using coupled solutions.

5. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, The momentum conservation equation for the icing process after the water droplet at the current icing location collides with the surface of the rotating component is as follows: ;in Represents partial derivatives, For time, The density of the water droplet, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. The viscosity of air. It is the acceleration due to gravity. For centrifugal force, Coriolis force, It is a rotational shear force; The momentum source terms within the corresponding time step are as follows: Centrifugal force ; Coriolis force ; Rotational shear force ; in To control the quality of the body water film, The rotational speed of the rotating component. The radius of rotation of the icing location. Indicates the time step. The flow velocity of the liquid water film. The dynamic viscosity of water, This represents the area of ​​the icing location.

6. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, The energy conservation equation for the icing process after the water droplet at the current icing location collides with the surface of the rotating component is as follows: ,in The latent heat of vaporization released by the evaporation of the water film. The negative sign indicates that the evaporation process is an endothermic process. The mass of liquid water evaporated. This represents the latent heat of vaporization of liquid water; The latent heat of phase change released during freezing. , This represents the increase in icing volume of the control body at the current time step. This represents the latent heat of phase transition during freezing; To control the heat conduction between the water inside the body and the surface of the rotating component structure, , The thermal conductivity of the rotating component structure, This represents the surface temperature of the solid structure of the rotating component at the current time step. To control the temperature of the body's water film in the next moment, Indicates the thickness of the solid structure along the direction of thermal conduction. For heat exchange between the water film and the airflow, , The heat transfer coefficient between the water film and the airflow is the convective heat transfer coefficient. To restore the temperature of the water film and airflow boundary layer, This is the change in the internal energy of water, calculated based on the changes in the internal energy of the water within the body at the previous and next moments. This is the change in the internal energy of the ice, calculated based on the changes in the internal energy of the ice within the body at the previous and next moments.

7. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, In the real-time coupled solution of the flow field and icing process using the fluid volume method, the coupled solution equation is: in, Represents partial derivatives, For time, For the density of water droplets, Represents the Hamiltonian operator. The flow velocity of the liquid water film. The fluid pressure at the freezing point. This is the transpose of the flow velocity of the liquid water film. air viscosity, It is the acceleration due to gravity. This represents the volume fraction of the water droplet component in the incoming stream. For the mass of liquid water, The momentum source term of centrifugal force. The momentum source term of the Coriolis force. The momentum source term for the shear force of the rotating airflow. To control the total energy in the body, For effective thermal conductivity, For the effective viscous stress tensor, The latent heat of phase change released during freezing.

8. The high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test according to claim 1, characterized in that, The preset temperature threshold is 273.15K.

9. A high-precision real-time coupled prediction system for icing of engine rotating components in an ice wind tunnel test, used to implement the high-precision real-time coupled prediction method for icing of engine rotating components in an ice wind tunnel test as described in any one of claims 1 to 8, characterized in that, include: The simulation model building module is used to build a three-dimensional geometric model for simulating the rotating engine components and generate a computational mesh based on the test section dimensions of the target ice wind tunnel and the structural parameters of the rotating engine components. The impact model analysis module is used to analyze and obtain the local water collection coefficient of the rotating component surface based on the impact model when water droplets in the incoming flow collide with the surface of the rotating component, within a given numerical simulation calculation domain, boundary conditions, and rotational motion conditions. The icing location analysis module is used to identify icing locations in computational grids where the temperature is below a preset temperature threshold based on the temperature distribution on each computational grid of the 3D geometric model. The conservation model construction module is used to construct the mass conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the mass of the liquid water at the freezing location as the mass source term; to construct the momentum conservation equation for the freezing process after the water droplet collides with the surface of the rotating component at the freezing location, using the centrifugal force, Coriolis force, and rotational shear force at the freezing location as the kinetic source term; and to construct the energy conservation equation for the freezing location, using the latent heat of phase change released during freezing at the freezing location as the energy source term. The icing amount analysis module is used to perform real-time coupling solution of the flow field and the icing process at the icing location on the surface of the rotating component in each time step, taking the icing location as the control volume. Based on the mass conservation equation, momentum conservation equation and energy conservation equation of the corresponding icing location, the fluid volume method is used to obtain the new icing amount of the control volume in each time step. The output module is used to determine whether the icing time has been reached. If so, it outputs the final icing prediction result of the rotating part surface. Otherwise, based on the shape changes caused by icing, a new three-dimensional geometric model for simulating the rotating components of the engine is rebuilt and a computational mesh is generated. The flow field is updated and coupled with the temperature field using the fluid volume method to solve the flow field and icing process in real time until the final icing prediction result is output.

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