An aircraft secondary icing time margin control method, system and computer device

Abstract

The application belongs to the technical field of aircraft deicing parameter control and processing, and discloses a kind of aircraft secondary icing time margin control method, system and computer equipment.The method is by collecting meteorological parameters and aircraft primary deicing parameters, testing aircraft surface roughness related data, computer body surface residual deicing fluid concentration;Calculate the critical radius of ice nucleus and the free energy of ice phase interface in the initial stage of the body surface icing with deicing fluid residue;Calculate the wall ice nucleus nucleation rate and ice nucleus growth rate;Calculate the ice crystal coverage rate in the near-wall space of the body surface and the secondary icing time margin.The control method has the characteristics of low cost, easy implementation, strong anti-interference ability, etc., can predict the secondary icing time margin and icing time point of the whole aircraft, provide scientific and accurate reference for dispatching command department, and effectively improve the flight take-off and landing efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft deicing parameter control and processing, and particularly relates to an aircraft secondary icing time margin control method and system and a computer device. BACKGROUND

[0002] Aircraft icing can greatly damage the aerodynamic performance of the aircraft and seriously affect the efficiency and safety of winter airport operation, so it is necessary to carry out ground deicing / anti-icing before the aircraft takes off to ensure the aerodynamic performance of the aircraft. Aircraft deicing refers to the process of removing ice, snow and frost on the surface of the wings and the fuselage of the aircraft. Since deicing fluid can lower the freezing point of water and thus delay the icing time, heated deicing fluid is usually sprayed onto the surface of the aircraft for ground deicing and anti-icing. The ground icing research is mainly based on temperature, humidity, wind speed and other sensors to obtain the macro icing probability, and there is a deficiency in the prediction of micro icing characteristics and the precision calculation of icing time.

[0003] The aircraft secondary icing time margin refers to the shortest time for which the deicing / anti-icing fluid prevents the icing, frost and snow on the protected surface of the aircraft, and the aircraft must take off within the deicing fluid retention time, otherwise secondary deicing operation must be carried out to prevent the reattachment of ice, snow and frost on the wings and other typical surfaces after the deicing fluid fails.

[0004] The existing aircraft secondary deicing control theory is based on the deicing fluid retention time (HOT), that is, the estimated time for which the deicing fluid can prevent the formation of ice and frost and the accumulation of snow on the protected (treated) surface of the aircraft. The retention time is derived from the Boeing Airbus aircraft manufacturer AMM manual / deicing fluid manufacturer / civil aircraft maintenance industry standard MH3145.49 "Civil aircraft deicing / anti-icing" provisions and recommended data, but since the retention time of the deicing / anti-icing fluid is related to the deicing fluid ratio, flow and on-site meteorological conditions and other parameters, in actual situations, the deicing department often determines the most stringent situation. The difference between the secondary deicing signal time point issued by the deicing department according to the recommended value of the deicing fluid retention time and the secondary deicing signal time point issued according to the actual retention time of the deicing fluid of the aircraft has a great influence on the safety and efficiency of the aircraft deicing process. The secondary operation signal provided based on the method can determine the secondary deicing operation signal time point according to the deicing site environment and operation parameters, thereby facilitating scientific, efficient and safe control of the aircraft deicing process.

[0005] Through the above analysis, the problems and defects of the prior art are: (1) the existing aircraft secondary icing time margin control is not easy to implement, has poor anti-interference ability, and the existing technology mainly relies on manual experience, has poor precision, is time-consuming and laborious in actual operation, and has high cost. (2) The existing technology cannot effectively predict the aircraft whole machine secondary icing time margin and icing time point, and cannot provide scientific and accurate reference for the dispatch command department, so that the flight take-off and landing efficiency is low. (3) In the prior art, the determination of the aircraft secondary icing time depends on the reference value given by the manufacturer and the work experience of the operating personnel, but under the influence of various environmental factors, the value has great volatility and error; the subsequent take-off priority depends on the estimation and judgment of the crew and the air traffic control department, which has great contingency and has problems such as time difference and scheduling conflict, affecting the flight take-off and landing efficiency. SUMMARY

[0006] In order to overcome the problems in the related art, the present application provides a kind of aircraft secondary icing time margin control method, system and computer equipment.

[0007] The technical solution is as follows: the aircraft secondary icing time margin control method comprises the following steps:

[0008] S1, collect aircraft primary deicing process parameters, calculate the concentration of residual deicing fluid on the surface of the aircraft body according to the environmental temperature, humidity, wind speed, surface roughness of the aircraft body and deicing fluid ratio, the process parameters include: flow, pressure, jet temperature;

[0009] S2, establish a contrast database of deicing fluid concentration, freezing point and phase change heat;

[0010] S3, according to the meteorological information released or collected, call the information in the contrast database, calculate the critical nucleation radius of the surface of the aircraft body at different positions and the surface interfacial free energy of the ice nucleus;

[0011] S4, calculate the ice nucleus nucleation rate and ice nucleus growth rate of the surface of the aircraft body at different positions with residual deicing fluid;

[0012] S5, calculate the surface ice crystal coverage rate in the near-wall space of the aircraft body at different positions;

[0013] S6, calculate the ice crystal coverage rate in the initial stage of icing of the aircraft body according to the airworthiness requirements and deicing requirements, and calculate the secondary icing time of the aircraft body at different positions;

[0014] S7, according to the characteristics of different positions and the difference of primary deicing parameters, get the secondary icing time point of different positions, determine the secondary icing time point of the whole machine, and get the aircraft secondary icing time margin.

[0015] In step S1, the parameters of the aircraft primary deicing process are collected, including the deicing fluid flow, the ambient temperature, the humidity, the wind speed, the roughness of the aircraft body, and the residual deicing fluid concentration on the surface of the aircraft body, which is calculated by the following concentration change formula:

[0016] C = a x T + b x W + c x V + d x γ + e x Q + c0

[0017] In the formula, a, b, c, d, and e are the correction coefficients of the environmental factors, T is the ambient temperature, W is the atmospheric humidity, V is the ambient wind speed, γ is the roughness of the surface of the aircraft body, Q is the nozzle deicing fluid flow, c0 is the initial deicing fluid concentration, and C is the residual deicing fluid concentration on the surface of the aircraft body.

[0018] In step S2, the control database of the deicing fluid concentration, the freezing point, and the phase change heat is established, including measuring the freezing phase change heat values of the deicing fluid at different concentrations by using thermocouples and differential scanning calorimetry, establishing the corresponding relationship database of the deicing fluid concentration, the freezing point, and the freezing phase change heat values, and calling the database when controlling the secondary icing time margin;

[0019] In the formula, ΔH is the freezing phase change heat per unit volume,

[0020]

[0021] In the formula, ΔH is the freezing phase change heat per unit volume, is the instrument constant, and A is the area between the peak of the differential scanning calorimetry curve and the interpolated baseline.

[0022] In step S3, the critical nucleation radius of the surface of the aircraft body at different positions and the surface interfacial free energy of the ice nucleus are calculated, including:

[0023] The critical nucleation radius of the ice crystal at the initial stage of the secondary icing at different positions of the aircraft body and the surface free energy of the ice nucleus are calculated according to the phase equilibrium theory and the classical nucleation theory; according to the published or collected meteorological information, the information in the control database is called to calculate the critical nucleation radius of the surface of the aircraft body at different positions and the surface interfacial free energy of the ice nucleus;

[0024] The critical nucleation radius of the ice nucleus The following formula:

[0025]

[0026]

[0027] In the formula, is the critical nucleation radius of the ice nucleus, γ LN is the liquid-nucleus interfacial energy, and ΔG VGibbs free energy per volume; ΔH is the heat of solidification per volume, ΔT is the current environmental supercooling degree, and T0 is the freezing point of the current state;

[0028] The surface interfacial free energy of the ice nucleus is as follows:

[0029]

[0030]

[0031] In the formula, ΔG is the surface interfacial free energy of the ice nucleus, R is the radius of the ice nucleus surface, Δg is the Gibbs energy density difference between ice and liquid water, γ sl is the solid-liquid interfacial tension, f(θ) is a calculation factor, and θ is the apparent contact angle.

[0032] In step S4, the ice nucleus nucleation rate and the ice nucleus growth rate of the surface of the fuselage at different positions with the deicing liquid remaining are calculated. According to the heterogeneous heterogeneous nucleation theory, the ice nucleus nucleation rate and the ice nucleus growth rate of the surface of the fuselage at different positions with the deicing liquid remaining are calculated.

[0033] The nucleation rate I s is calculated by the following formula:

[0034]

[0035] In the formula, I s is the nucleation rate, B s is a constant, ΔG is the surface interfacial free energy of the ice nucleus, ΔG m is the water molecule migration activation energy, R is the radius of the ice nucleus surface, and T is the current environmental temperature.

[0036] The ice nucleus growth rate ΔV is:

[0037]

[0038] In the formula, ΔV is the ice nucleus growth rate, λ is the interface thickness, n is the number of interface molecules, v is the liquid-solid conversion frequency factor, ΔH is the heat of solidification per volume, ΔT is the current environmental supercooling degree, and T0 is the freezing point of the current state.

[0039] In step S5, the surface ice crystal coverage in the near-wall space of the fuselage at different positions is calculated. In the near-wall space of the fuselage at different positions, the coverage area of a single ice crystal in a period of time is calculated by the single ice nucleus growth rate in the initial stage of secondary icing, and the ice crystal coverage is calculated by the nucleation rate per unit area and the cumulative coverage area of all ice crystals. The near-wall space is taken as 1 m 2The fuselage surface is considered as the unit area for detection. Ice nuclei are uniformly distributed within this unit area. The coverage area of ​​a single ice crystal is accumulated, and the ice crystal coverage rate within a time interval t after nucleation is calculated. for:

[0040]

[0041] In the formula, B represents the ice crystal coverage. s Let λ be a constant, n be the number of interfacial molecules, v be the liquid-solid transformation frequency factor, θ be the apparent contact angle, and ΔH be a constant. V To detect the heat of phase transition of the de-icing fluid per unit area, ΔT is the current ambient subcooling, T0 is the current freezing point, R is the radius of the ice nucleus surface, T is the current ambient temperature, and ΔG is the interfacial free energy of the ice nucleus surface. m It is the activation energy for water molecule migration.

[0042] In step S6, the secondary icing time at different locations on the computer fuselage includes: the critical ice crystal coverage rate for secondary de-icing operations at different locations on the fuselage. Solving the coverage calculation equation yields the following: According to airworthiness requirements, the critical ice crystal coverage for secondary de-icing operations is... The time margin t for secondary icing of the fuselage * for:

[0043]

[0044] In the formula, t * To allow time for secondary icing of the fuselage, B represents the critical ice crystal coverage rate for secondary de-icing operations. s Let ΔG be a constant, and ΔG be the interfacial free energy at the ice core surface. m Let λ be the activation energy for water molecule migration, R be the radius of the ice nucleus surface, T be the current ambient temperature, λ be the interface thickness, n be the number of interface molecules, b be the liquid-solid transformation frequency factor, θ be the apparent contact angle, and ΔH be the interface thickness. V To detect the heat of phase transition of the de-icing fluid in a unit area, ΔT is the current ambient subcooling, and T0 is the current freezing point.

[0045] In step S7, the secondary icing time margin of the aircraft is given by the minimum secondary icing time margin at different critical locations on the fuselage, expressed as:

[0046]

[0047] In the formula, T * To allow for secondary icing time margin for the entire machine, This provides the secondary freezing time margin for each data point.

[0048] Another object of the present application is to provide an out-of-phase nucleation mechanism driven aircraft secondary icing time margin control system, which is implemented by the aircraft secondary icing time margin control method, characterized in that the system comprises:

[0049] A fuselage surface residual deicing fluid concentration calculation module is configured to collect aircraft primary deicing process parameters, and calculate the fuselage surface residual deicing fluid concentration according to the environmental temperature, humidity, wind speed, fuselage surface roughness and deicing fluid ratio;

[0050] A database establishment module is configured to establish a database for comparison between the deicing fluid concentration and the freezing point and the phase change heat;

[0051] A fuselage surface parameter calculation module is configured to calculate the critical nucleation radius and the ice nucleus surface interfacial free energy of the surfaces at different positions of the fuselage according to the published or collected meteorological information and the information in the database;

[0052] A fuselage surface ice nucleus nucleation rate and growth rate calculation module is configured to calculate the ice nucleus nucleation rate and the ice nucleus growth rate of the surfaces at different positions of the fuselage with residual deicing fluid;

[0053] A near-wall space inner surface ice crystal coverage calculation module is configured to calculate the near-wall space inner surface ice crystal coverage of the surfaces at different positions of the fuselage;

[0054] A fuselage surface secondary icing time calculation module is configured to calculate the ice crystal coverage in the initial stage of icing of the fuselage and the secondary icing time of the surfaces at different positions of the fuselage according to the airworthiness requirements and the deicing requirements;

[0055] A whole-machine secondary deicing time point determination module is configured to obtain the secondary deicing time points of the surfaces at different positions, determine the secondary deicing time points of the whole machine and the secondary icing time margin, and issue a secondary deicing operation signal according to the airworthiness requirements, according to the characteristics of the surfaces at different positions and the differences in the primary deicing parameters.

[0056] Another object of the present application is to provide a computer device, which comprises a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the aircraft secondary icing time margin control method.

[0057] In combination with all the above technical solutions, the application has the advantages and positive effects that: in order to solve the problems of the existing secondary icing time detection method, such as relying on manual experience, poor accuracy, time-consuming and laborious in actual operation, etc., a secondary icing time margin control method based on an airplane is proposed in combination with the freezing characteristics of the airplane body surface icing. When the first deicing operation is completed, the deicing liquid remaining on the surface of the airplane body will change in concentration under the influence of operation parameters, environmental parameters and airplane body parameters, and will enter the second icing stage under the influence of factors such as environmental temperature and humidity. Based on this feature, it is possible to predict the icing degree and icing time through the heterogeneous nucleation theory, but there is no related research at present; the application has the characteristics of automation, strong universality and easy implementation, can provide accurate time nodes for the deicing support and flight ground scheduling of the airport, assist the air traffic control department to flexibly control the flight take-off and landing procedure, improve the airspace utilization rate and the airport operation efficiency, and has great significance for the efficient and safe operation of the aviation transportation production. BRIEF DESCRIPTION OF DRAWINGS

[0058] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0059] Figure 1 is a flow chart of the airplane secondary icing time margin control method provided by the embodiment of the application;

[0060] Figure 2 is a principle diagram of the airplane secondary icing time margin control method provided by the embodiment of the application;

[0061] Figure 3 is a schematic diagram of the airplane secondary icing time margin control system driven by the heterogeneous nucleation mechanism provided by the embodiment of the application;

[0062] In the figure: 1, airplane body surface residual deicing liquid concentration calculation module; 2, database establishment module; 3, airplane body surface parameter calculation module at different positions; 4, airplane body surface ice nucleation rate and growth rate calculation module; 5, surface ice crystal coverage rate calculation module in the near-wall space; 6, secondary icing time calculation module at different positions of the airplane body; 7, whole airplane secondary deicing time point determination module. DETAILED DESCRIPTION

[0063] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below in combination with the drawings. In the following description, a lot of specific details are set forth in order to fully understand the application. However, the application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the application, so the application is not limited by the specific implementation disclosed below.

[0064] Embodiment 1, as shown, is a method for controlling the secondary icing time margin of an aircraft provided by the present application, comprising the following steps: Figure 1

[0065] S1, collect the primary deicing process parameters (flow, pressure, jet temperature) of the aircraft, and calculate the residual deicing fluid concentration on the surface of the aircraft body according to the environmental temperature, humidity, wind speed, surface roughness of the aircraft body, and deicing fluid ratio;

[0066] S2, establish a control database of deicing fluid concentration, freezing point, and phase change heat;

[0067] Use thermocouples and differential scanning calorimetry to measure the freezing phase change heat values of deicing fluid at different concentrations, and establish a corresponding relationship database of deicing fluid concentration, freezing point, and freezing phase change heat values, which is called during secondary icing time margin control;

[0068] S3, according to the released or collected meteorological information, call the information in the database of step S2, calculate the critical nucleation radius and ice nucleus surface interfacial free energy of the surface of the aircraft body at different positions;

[0069] The critical ice crystal nucleation radius and ice nucleus surface interfacial free energy at different positions of the aircraft body at the initial stage of secondary icing are calculated according to the phase equilibrium theory and classical nucleation theory;

[0070] S4, calculate the ice nucleus nucleation rate and ice nucleus growth rate of the surface of the aircraft body at different positions with residual deicing fluid;

[0071] The ice crystal nucleation rate and ice nucleus growth rate at different positions of the surface of the aircraft body at the initial stage of secondary icing are calculated according to the heterogeneous heterogeneous nucleation theory;

[0072] S5, calculate the surface ice crystal coverage in the near-wall space of the aircraft body at different positions;

[0073] In the near-wall space of the aircraft body at different positions, the coverage area of a single ice crystal in a period of time is calculated from the single ice nucleus growth rate at the initial stage of secondary icing, and the ice crystal coverage is calculated by accumulating the nucleation rate per unit area and all ice crystal coverage areas;

[0074] S6, calculate the ice crystal coverage at the initial stage of icing of the aircraft body according to the airworthiness requirements and deicing requirements, and calculate the secondary icing time of the aircraft body at different positions;

[0075] The critical ice crystal coverage of the secondary deicing operation at different positions of the aircraft body is obtained by solving the coverage calculation equation;

[0076] S7, according to the characteristics of different positions and the differences in primary deicing parameters, obtain the secondary deicing time points of different positions, and then determine the secondary icing time margin of the whole aircraft, and issue a secondary deicing operation signal according to the airworthiness requirements;​​

[0077] The secondary icing time margin of the whole aircraft can be given by the minimum value of the secondary icing time margin of different key positions of the fuselage, that is,

[0078]

[0079] In the formula, T * is the secondary icing time margin of the whole aircraft, is the secondary icing time margin of each detection data point.

[0080] In the embodiment of the application, step S1 is to predict the residual deicing liquid concentration at different positions of the fuselage surface, steps S2-S4 are to predict the heterogeneous nucleation non-steady state behavior of the initial stage of the icing of the residual deicing liquid on the fuselage surface, step S5 is a method for calculating the ice crystal coverage rate at the initial stage of the icing of the fuselage surface, and steps S6-S7 finally realize the prediction of the secondary icing time margin of the whole aircraft and the issuance of the deicing warning.

[0081] Further, in step S1, the primary deicing parameters at different positions i of the aircraft are collected, including the deicing liquid flow, the environmental temperature, the humidity, the wind speed, and the roughness of the fuselage, and the residual deicing liquid concentration on the fuselage surface is calculated by the following concentration change formula.

[0082] c=a×T+b×W+c×V+d×γ+e×Q+c0

[0083] In the formula, a, b, c, d, and e are environmental factor correction coefficients, which are calibrated in actual environment. T is the environmental temperature, W is the atmospheric humidity, V is the environmental wind speed, γ is the roughness of the fuselage surface, Q is the nozzle deicing liquid flow, c0 is the initial deicing liquid concentration, and C is the residual deicing liquid concentration on the fuselage surface.

[0084] In the embodiment of the application, the residual deicing liquid concentration on the fuselage surface is calculated by collecting the meteorological parameters, the primary deicing parameters of the aircraft, and combining the related data of the roughness of the aircraft surface, the critical radius of the ice nucleus at the initial stage of the icing of the fuselage surface with residual deicing liquid and the ice phase interface free energy are calculated, the ice nucleus nucleation rate and the ice nucleus growth rate are calculated, the ice crystal coverage rate in the near-wall space of the fuselage surface is calculated, and the secondary icing time margin of the whole aircraft is obtained through comprehensive calculation.

[0085] The embodiment of the application accurately determines the residual deicing fluid concentration affecting the icing process based on the characteristics of the coupling influence of the primary deicing parameters, the operating environment characteristics and the aircraft surface characteristics on the residual deicing fluid concentration; the key control parameters such as the ice nucleus nucleation rate, the ice crystal growth rate and the ice crystal coverage in the near-wall space are calculated by using the aircraft primary deicing parameters, the environmental parameters and the aircraft surface parameters through the classical nucleation theory and the heterogeneous ice nucleation theory, so as to ensure the scientificity and accuracy of the algorithm prediction value; the aircraft secondary icing time point and the whole-machine secondary icing time margin are solved according to the airworthiness requirements and the deicing operation specifications, so as to ensure the professionalism and safety of the margin control mechanism. The application solves the problem that the current secondary icing time mostly depends on artificial experience estimation, has low efficiency and is highly accidental, and is beneficial to the optimization of the take-off sequence and the scheduling process by the scheduling command department, and guarantees the flight operation efficiency.

[0086] In the implementation process, the embodiment of the application realizes the prediction and control of the secondary icing time margin by collecting the primary deicing parameters, the environmental characteristic parameters and the fuselage surface parameter data set; the application is suitable for different meteorological conditions and deicing fluid types, and has wide universality; the required primary deicing parameters, temperature, humidity, wind speed and other information can be provided by the deicing equipment or the airport meteorological department, so that only the fuselage surface roughness related parameters need to be collected by the detection equipment, and the implementation is easy; the secondary icing time margin calculation is completely completed by the computer system without human intervention, does not affect the subsequent take-off process of the aircraft, and the secondary icing time margin can be real-time summarized to the airport operation command department and the air traffic control department, so as to provide a reference for take-off scheduling or secondary deicing, and has good application prospect.

[0087] In summary, the control method described in the embodiment of the application has the characteristics of low cost, easy implementation, professional and accurate data, and can realize the prediction of the whole-machine secondary icing time point and time margin of the aircraft, so as to provide scientific and accurate reference for the scheduling command department, and can effectively improve the take-off and landing efficiency of the flight.

[0088] As advantages of the application, the following aspects are also embodied: (1) the secondary icing time margin of the aircraft predicted by the application is used as the decision reference of the scheduling command department, greatly shortens the waiting time in the airport caused by deicing, further reduces the fuel consumption in this process, reduces the secondary deicing artificial, deicing fluid and time cost caused by estimation accidents, reduces the airspace and runway idle time, releases the additional airspace resources, increases the capacity of the route, is beneficial to the improvement of the transportation capacity, reduces the operation cost of the civil aviation department, and improves the travel experience of passengers. (2) The technical scheme of the application creatively uses the heterogeneous nucleation mechanism to develop the prediction of the secondary icing time margin of the aircraft, breaks the shackles of the empiricism in the current deicing operation process of the aircraft, overcomes the technical bias, and opens up a new world for deicing engineering application with a scientific and professional method.

[0089] Embodiment 2, as another implementation of the embodiment of the present application, as shown in Figure 2 The method for controlling the time margin of secondary icing of an airplane provided by the embodiment of the present application specifically comprises the following steps:

[0090] Step 1: calculating the residual deicing liquid concentration on the surface of the airplane body specifically comprises:

[0091] According to the requirements of airworthiness and deicing, the key positions for deicing of the airplane include: the upper surface and leading edge of the wing; the upper surface and leading edge of the horizontal stabilizer; the upper surface of the elevator; the vertical stabilizer and rudder; the trim tab and flap mechanism. The primary deicing is to rapidly spray the heated deicing liquid onto the surface of the airplane body to form a liquid film attached to the surface of the airplane body, and rely on the heat emitted by the liquid film to melt the ice / snow / frost covering the airplane body. At the same time, the melted ice / snow / frost and the excess deicing liquid flow along the surface of the airplane body to the ground of the airport.

[0092] A data point i of primary deicing and environmental parameter collection is established for each square meter of the above-mentioned key deicing positions, and the collection data set is D i The collection data includes: the initial deicing liquid concentration c0, the environmental temperature T, the atmospheric humidity W, the environmental wind speed V, the surface roughness γ of the airplane body, and the nozzle deicing liquid flow Q. The deicing liquid concentration calculation formula after the environmental factor correction is as follows:

[0093] C=a×T+b×W+c×V+d×γ+e×Q+c0

[0094] Wherein, a, b, c, d, and e are environmental factor correction coefficients, which are sampled and calibrated in the actual operating environment, T is the environmental temperature, W is the atmospheric humidity, V is the environmental wind speed, γ is the surface roughness of the airplane body, Q is the nozzle deicing liquid flow, c0 is the initial deicing liquid concentration, and C is the residual deicing liquid concentration on the surface of the airplane body.

[0095] Step 2: establishing a control database of deicing liquid concentration, freezing point, and phase change heat:

[0096] A control database of deicing liquid concentration, freezing point, and phase change heat is established based on the liquid freezing theory. Since the freezing point and the phase change heat of deicing liquid of different concentrations are constant under standard atmospheric pressure, the freezing point and the phase change heat data are calibrated through experiments. The measurement method is as follows: deicing liquid samples with concentration varying from 0% to 75% are prepared, the concentration variation step is 1%, and the freezing point of the deicing liquid sample at each concentration is measured by using a thermocouple; the freezing and freezing process of the sample is measured by differential scanning calorimetry (DSC), and the area A between the peak of the DSC curve and the interpolated baseline is proportional to the enthalpy of the sample, i.e. the phase change heat value:

[0097]

[0098] In the formula, ΔH is the phase change heat per unit volume, A is the area between the peak and the interpolated baseline of the differential scanning calorimetry curve.

[0099] Based on the experimental measurement data at different concentrations, a database of the corresponding relationship between the concentration of the deicing liquid and the freezing point and the solidification phase change heat value is established, which is called in the control of the secondary icing time margin.

[0100] Step 3: According to the published or collected weather information, the information in the reference database is called, and the critical nucleation radius of the surface of the fuselage at different positions and the surface interfacial free energy of the ice nucleus are calculated.

[0101] According to the classical nucleation theory, the critical nucleation radius of the ice nucleus is The following formula:

[0102]

[0103]

[0104] In the formula, The critical nucleation radius of the ice nucleus is γ LN The liquid-nucleus interfacial energy is ΔG V The volume Gibbs free energy is ΔH, the unit volume solidification phase change heat is ΔT, the current environmental supercooling degree is ΔT=T-T0, and T0 is the current state freezing point.

[0105] The surface interfacial free energy of the ice nucleus is as follows:

[0106]

[0107]

[0108] In the formula, ΔG is the surface interfacial free energy of the ice nucleus, R is the radius of the ice nucleus surface, Δg is the Gibbs energy density difference between ice and liquid water, γ sl The solid-liquid interfacial tension is f(θ), the calculation factor is θ, and the apparent contact angle is θ.

[0109] Step 4: According to the heterogeneous heterogeneous nucleation theory, the ice nucleus nucleation rate and the ice nucleus growth rate of the surface of the fuselage at different positions with residual deicing liquid are calculated.

[0110] The nucleation rate I s Is calculated by the following formula:

[0111]

[0112] In the formula, I s The nucleation rate is B s The constant is calibrated by the working environment; ΔG is the surface interfacial free energy of the ice nucleus, and ΔG mwhere ΔH is the heat of fusion of the deicing fluid per unit area, and ΔT is the current environmental supercooling degree.

[0113] The ice nucleus growth rate ΔV is:

[0114]

[0115] where ΔV is the ice nucleus growth rate, λ is the interface thickness, n is the number of interface molecules, v is the liquid-solid conversion frequency factor, ΔH is the heat of fusion per unit volume, ΔT is the current environmental supercooling degree, and T0 is the current state freezing point.

[0116] Step 5: Calculate the surface ice crystal coverage in the initial stage in the near-wall space at different positions of the fuselage;

[0117] Take 1 m 2 The fuselage surface is a detection unit area, and it is assumed that the formed ice nuclei are uniformly distributed in the detection unit area. The ice crystal coverage in the time interval t after nucleation is accumulated by accumulating the coverage area of a single ice crystal. is:

[0118]

[0119] where ΔH V is the heat of fusion of the deicing fluid per unit area.

[0120] Step 6: Calculate the secondary icing time at different positions of the fuselage according to airworthiness requirements and deicing requirements;

[0121] According to airworthiness requirements, the critical ice crystal coverage for secondary deicing operation is The secondary icing time margin t * of the fuselage is:

[0122]

[0123] where t * is the secondary icing time margin of the fuselage, is the critical ice crystal coverage for secondary deicing operation, B s is a constant, ΔG is the interface free energy of the ice nucleus surface, ΔG m is the migration activation energy of water molecules, R is the radius of the ice nucleus surface, T is the current environmental temperature, λ is the interface thickness, n is the number of interface molecules, v is the liquid-solid conversion frequency factor, θ is the apparent contact angle, ΔH V is the heat of fusion of the deicing fluid per unit area, ΔT is the current environmental supercooling degree, and T0 is the current state freezing point.

[0124] Step 7: Calculate the secondary icing time margin at different positions to obtain the secondary icing time margin of the entire aircraft;

[0125] According to the established each key position once deicing and environmental parameter collection data set D i , the single point secondary icing time margin is calculated as The aircraft whole machine secondary icing time margin is:

[0126]

[0127] In the formula, T * is the whole machine secondary icing time margin, is the secondary icing time margin of each detection data point.

[0128] The whole machine secondary icing time margin is determined by the whole machine secondary icing time point, and the icing warning and secondary deicing operation signal are issued according to the airworthiness requirements.

[0129] Embodiment 3, as shown in Figure 3 The out-of-phase nucleation mechanism driven aircraft secondary icing time margin control system provided by the embodiment of the application comprises:

[0130] A fuselage surface residual deicing liquid concentration calculation module 1 is configured to collect aircraft primary deicing process parameters (flow, pressure, jet temperature), calculate the fuselage surface residual deicing liquid concentration according to the environmental temperature, humidity, wind speed, fuselage surface roughness and deicing liquid ratio, and calculate the fuselage surface residual deicing liquid concentration according to the environmental temperature, humidity, wind speed, fuselage surface roughness and deicing liquid ratio;

[0131] A database establishment module 2 is configured to establish a deicing liquid concentration and freezing point, phase change heat comparison database;

[0132] A fuselage different position surface parameter calculation module 3 is configured to calculate the critical nucleation radius and ice nucleus surface interfacial free energy of the fuselage different position surface according to the published or collected meteorological information and the information in the database;

[0133] A fuselage surface ice nucleus nucleation rate and growth rate calculation module 4 is configured to calculate the ice nucleus nucleation rate and growth rate of the fuselage different position surface with residual deicing liquid;

[0134] A near-wall space inner surface ice crystal coverage calculation module 5 is configured to calculate the near-wall space inner surface ice crystal coverage of the fuselage different position surface;

[0135] A fuselage different position secondary icing time calculation module 6 is configured to calculate the ice crystal coverage of the fuselage initial icing stage and the secondary icing time of the fuselage different position according to the airworthiness requirements and deicing requirements;

[0136] A whole machine secondary deicing time point determination module 7 is configured to obtain the secondary deicing time points of different positions according to the characteristics of different positions and the differences of primary deicing parameters, and further determine the whole machine secondary deicing time margin, and issue the secondary deicing operation signal according to the airworthiness requirements.

[0137] In another embodiment of the present application, the computer program product of the present application is used to control the operation of the control computer to execute the steps of the above-mentioned method embodiments for an aircraft that has completed a primary deicing and entered a takeoff waiting procedure, and the specific flow is as follows:

[0138] (1) The program is started and executed, and the meteorological environment parameters, primary deicing parameters, and the like from external inputs or sensors are collected, and the residual deicing fluid concentration calculation process is executed.

[0139] (2) The freezing point and phase change heat parameters in the database are called, and the critical nucleation radius and ice nucleus surface interfacial free energy calculation process of the surfaces at different positions of the fuselage is executed.

[0140] (3) The surface heterogeneous nucleation rate, growth rate, and near-wall space surface ice crystal coverage calculation process is executed.

[0141] (4) The near-wall space surface ice crystal coverage at different positions of the fuselage and the initial stage ice crystal coverage of the fuselage are integrated, and the secondary icing time calculation process at different positions of the fuselage is executed.

[0142] (5) The secondary icing time margin selection procedure and the final result output are executed according to the fuselage position and airworthiness requirements.

[0143] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0144] The information interaction, execution process, and the like between the above-mentioned devices / units, since based on the same concept as the method embodiments of the present application, the specific functions and the technical effects brought about can be referred to the method embodiment part, and will not be repeated here.

[0145] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of software functional unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the unit and module in the system can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

[0146] The integrated unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the present application realizes all or part of the processes in the foregoing embodiment methods, which can be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when the processor executes the computer program, the steps of each method embodiment can be realized. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium at least includes any entity or device that can carry the computer program code to the photographing device / terminal equipment, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc.

[0147] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any modification, equivalent replacement and improvement made by those skilled in the art within the technical range disclosed by the present application, as long as it is within the spirit and principle of the present application, should be covered within the protection scope of the present application.

Claims

1. A method for controlling the time margin of secondary icing in aircraft, characterized in that, The method includes the following steps: S1, collect the aircraft's primary de-icing process parameters, and calculate the concentration of residual de-icing fluid on the fuselage surface based on ambient temperature, humidity, wind speed, fuselage surface roughness, and de-icing fluid ratio; the process parameters include: flow rate, pressure, and jet temperature. S2, establish a comparative database of de-icing fluid concentration, freezing point, and phase change heat; S3, based on the published or collected meteorological information, calls information from the comparison database to calculate the critical nucleation radius and ice nucleus surface interface free energy at different locations on the computer body; S4, calculate the ice nucleation rate and ice nucleus growth rate on the surface of different locations on the fuselage where de-icing fluid remains; S5, ice crystal coverage rate of the near-wall space inner surface of the computer body at different locations; S6, based on airworthiness requirements and de-icing requirements, calculate the ice crystal coverage rate of the computer fuselage in the initial stage of icing, and the secondary icing time at different locations of the computer fuselage; S7. Based on the characteristics of different locations and the differences in primary de-icing parameters, the secondary icing time points at different locations are obtained, the secondary icing time point of the entire aircraft is determined, and the secondary icing time margin of the aircraft is obtained. In step S1, collecting the aircraft's primary de-icing process parameters includes: collecting primary de-icing parameters at different locations i on the aircraft, including de-icing fluid flow rate, ambient temperature, humidity, wind speed, and fuselage roughness, and calculating the residual de-icing fluid concentration on the fuselage surface using the following concentration change formula; C=a×T+b×W+c×V+d×γ+e×Q+C0 In the formula, C is the concentration of residual de-icing fluid on the fuselage surface, a, b, c, d, and e are environmental factor correction coefficients, T is the ambient temperature, W is the atmospheric humidity, V is the ambient wind speed, γ is the surface roughness of the fuselage, Q is the flow rate of de-icing fluid at the nozzle, and c0 is the initial de-icing fluid concentration.

2. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S2, establishing a database of references between de-icing fluid concentration, freezing point, and heat of phase change includes: measuring the heat of phase change of de-icing fluid at different concentrations using thermocouples and differential scanning calorimetry, establishing a database of the correspondence between de-icing fluid concentration, freezing point, and heat of phase change, and calling it when controlling the secondary freezing time margin. In this method, the area A between the peak of the differential scanning calorimetry curve and the interpolation baseline is proportional to the enthalpy change of the sample, i.e., the solidification phase transition heat value is: In the formula, ΔH is the heat of solidification phase transition per unit volume. is the instrument constant, and A is the area between the peak of the differential scanning calorimetry curve and the interpolation baseline.

3. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S3, the critical nucleation radius and the free energy of the ice nucleus surface interface at different locations on the computer body include: The critical nucleation radius and surface free energy of ice crystals at different locations on the fuselage during the initial stage of secondary icing were calculated based on phase equilibrium theory and classical nucleation theory. The critical nucleation radius and surface free energy of ice crystals at different locations on the fuselage were calculated based on published or collected meteorological information and referenced information from the database. Critical nucleation radius of ice nuclei The following formula: In the formula, γ is the critical nucleation radius of ice nuclei. LN For the liquid-nuclear interface energy, ΔG V ΔH is the volumetric Gibbs free energy; ΔH is the solidification phase transition heat per unit volume; ΔT is the current ambient supercooling; T0 is the current freezing point. The interfacial free energy of the ice core surface is as follows: In the formula, ΔG is the interfacial free energy at the ice core surface, R is the radius of the ice core surface, Δg is the Gibbs energy density difference between the ice and liquid water, and γ is the free energy at the ice core surface. sl Let f(θ) be the solid-liquid interfacial tension, f(θ) be the calculation factor, and θ be the apparent contact angle.

4. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S4, the ice nucleation rate and ice nucleus growth rate of the fuselage surface at different locations with residual de-icing fluid are calculated based on the ice crystal nucleation rate and ice nucleus growth rate at the initial stage of secondary icing at different locations on the fuselage surface. According to the heterogeneous phase nucleation theory, the ice nucleation rate and ice nucleus growth rate of the fuselage surface at different locations with residual de-icing fluid are calculated. Nucleation rate I s It can be calculated using the following formula: In the formula, I s For nucleation rate, B s Let ΔG be a constant, and ΔG be the interfacial free energy at the ice core surface. m R is the activation energy for water molecule migration, R is the radius of the ice core surface, and T is the current ambient temperature. The ice nucleus growth rate ΔV is: In the formula, ΔV is the ice nucleus growth rate, λ is the interface thickness, n is the number of interface molecules, v is the liquid-solid transformation frequency factor, ΔH is the heat of phase transition per unit volume, ΔT is the current ambient supercooling, and T0 is the current freezing point.

5. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S5, the surface ice crystal coverage rate near the wall space at different locations on the computer fuselage includes: in the initial stage of secondary icing near the wall space at different locations on the fuselage, the coverage area of ​​a single ice crystal over a period of time is calculated from the growth rate of a single ice nucleus; the ice crystal coverage rate is calculated by accumulating the nucleation rate per unit area and the coverage area of ​​all ice crystals; taking 1m 2 The fuselage surface is considered as the unit area for detection. Ice nuclei are uniformly distributed within this unit area. The coverage area of ​​a single ice crystal is accumulated, and the ice crystal coverage rate within a time interval t after nucleation is calculated. for: In the formula, B represents the ice crystal coverage. s Let λ be a constant, n be the number of interfacial molecules, v be the liquid-solid transformation frequency factor, θ be the apparent contact angle, and ΔH be a constant. V To detect the heat of phase transition of the de-icing fluid per unit area, ΔT is the current ambient subcooling, T0 is the current freezing point, R is the radius of the ice nucleus surface, T is the current ambient temperature, and ΔG is the interfacial free energy of the ice nucleus surface. m It is the activation energy for water molecule migration.

6. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S6, the secondary icing time at different locations on the computer fuselage includes: the critical ice crystal coverage rate for secondary de-icing operations at different locations on the fuselage. Solving the coverage calculation equation yields the following: According to airworthiness requirements, the critical ice crystal coverage for secondary de-icing operations is... The time margin t for secondary icing of the fuselage * for: In the formula, t * To allow time for secondary icing of the fuselage, B represents the critical ice crystal coverage rate for secondary de-icing operations. s Let ΔG be a constant, and ΔG be the interfacial free energy at the ice core surface. m Let R be the activation energy for water molecule migration, T be the radius of the ice nucleus surface, λ be the current ambient temperature, n be the interface thickness, v be the number of interfacial molecules, θ be the liquid-solid transition frequency factor, and ΔH be the apparent contact angle. V To detect the heat of phase transition of the de-icing fluid in a unit area, ΔT is the current ambient subcooling, and T0 is the current freezing point.

7. The aircraft secondary icing time margin control method according to claim 1, characterized in that, In step S7, the secondary icing time margin of the aircraft is given by the minimum secondary icing time margin at different critical locations on the fuselage, expressed as: In the formula, T* represents the time margin for secondary icing of the entire machine. This provides the secondary freezing time margin for each data point.

8. An aircraft secondary icing time margin control system, wherein the system is implemented by the aircraft secondary icing time margin control method according to any one of claims 1-7, characterized in that, The system includes: The module for calculating the concentration of residual de-icing fluid on the fuselage surface (1) is used to collect the parameters of the aircraft's primary de-icing process and calculate the concentration of residual de-icing fluid on the fuselage surface based on ambient temperature, humidity, wind speed, fuselage surface roughness, and de-icing fluid ratio. Database creation module (2) is used to create a comparison database of de-icing fluid concentration, freezing point, and phase change heat; The surface parameter calculation module (3) at different locations of the fuselage is used to calculate the critical nucleation radius and the free energy of the ice nucleus surface interface at different locations of the fuselage based on the meteorological information released or collected and the information in the database. The module (4) for calculating the nucleation rate and growth rate of ice nuclei on the fuselage surface is used to calculate the nucleation rate and growth rate of ice nuclei on different locations of the fuselage surface with residual de-icing fluid. The near-wall space inner surface ice crystal coverage calculation module (5) is used to calculate the near-wall space inner surface ice crystal coverage of different positions on the body. The secondary icing time calculation module (6) for different positions of the fuselage is used to calculate the ice crystal coverage rate in the initial stage of fuselage icing and the secondary icing time at different positions of the fuselage according to airworthiness requirements and de-icing requirements. The whole machine secondary de-icing time point determination module (7) is used to obtain the secondary de-icing time point at different locations based on the characteristics of different locations and the differences in primary de-icing parameters, and to determine the whole machine secondary de-icing time point and secondary icing time margin, and to issue a secondary de-icing operation signal according to airworthiness requirements.

9. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the aircraft secondary icing time margin control method according to any one of claims 1-7.

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