Hypersonic aircraft dynamic mode conversion window calculation method

Abstract

The invention provides a hypersonic aircraft dynamic mode conversion window calculation method. The hypersonic aircraft dynamic mode conversion window calculation method comprises the following steps that 1, engine data and pneumatic data under different dynamic modes are obtained; 2, calculating a unit residual power two-dimensional interpolation function under different dynamic modes according to engine data and pneumatic data; 3, drawing a unit residual power contour map under different dynamic modes according to the unit residual power two-dimensional interpolation function; and step 4, according to the unit residual power contour map under different dynamic modes, determining whether there is an overlapping area of different dynamic modes, and if yes, determining a mode conversion window according to the overlapping area. According to the method, the power mode conversion window of the combined power hypersonic aircraft can be quickly and accurately determined by utilizing the overlapping area of the unit residual power contour maps under different power modes.

Description

Technical Field

[0001] The present application belongs to the field of combined power hypersonic aircraft design, and in particular relates to a method for calculating a hypersonic aircraft power mode conversion window. Background Art

[0002] Unlike existing hypersonic aircraft (referred to as hypersonic aircraft), combined-power hypersonic aircraft are designed to be able to fly in a wide range of speeds, from autonomous takeoff to cruising and high-altitude flight. In order to meet the power needs for flying in different speed ranges, and considering that different types of engines have different efficiencies at different speeds and altitudes, combined-power hypersonic aircraft are usually designed with multiple power modes. In the mode conversion stage, in order to ensure that the engines in different power modes can work normally and the power can transition smoothly, the concept of the power mode conversion window of the combined-power hypersonic aircraft is proposed. Within the window, the combined-power hypersonic aircraft can smoothly transition between different modes.

[0003] In the overall design stage of a hypersonic aircraft, the performance of the combined power system is crucial. The calculation of the power mode transition window is of great significance at this stage. Through the power mode transition window, it is possible to verify whether the currently selected engine can effectively achieve mode transition. In addition, the window can also be used to calculate a series of overall performance parameters under the mode transition flight state, including but not limited to the maximum climb rate and acceleration and deceleration performance during level flight. These comprehensive performance parameters are crucial to ensure that the aircraft performs well under various flight conditions. Therefore, the accurate calculation of the power mode transition window provides a reliable basis for aircraft design, helps to optimize aircraft performance and ensures that it reaches its best state in actual flight.

[0004] However, for the hypersonic vehicle power mode transition window, the difficulties are mainly reflected in the following aspects: there is currently no clear concept of the mode transition window of hypersonic aircraft, the mode transition window of hypersonic aircraft is not easy to define, and quantitative calculation cannot be achieved.

[0005] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0006] The purpose of the present application is to provide a method for calculating a hypersonic aircraft power mode conversion window to solve at least one problem existing in the prior art.

[0007] The technical solution of this application is:

[0008] A method for calculating a hypersonic aircraft dynamic mode conversion window, comprising:

[0009] Step 1: Obtain engine data and aerodynamic data under different power modes;

[0010] Step 2: Calculate the two-dimensional interpolation function of unit residual power under different power modes according to the engine data and aerodynamic data;

[0011] Step 3: Draw contour diagrams of unit residual power under different dynamic modes according to the two-dimensional interpolation function of unit residual power;

[0012] Step 4: Based on the unit residual power contour diagrams under different dynamic modes, determine whether there is an overlapping area of ​​different dynamic modes. If so, determine the mode conversion window based on the overlapping area.

[0013] In at least one embodiment of the present application, in step 1, obtaining engine data and aerodynamic data under different power modes includes:

[0014] Acquiring turbine engine data and first aerodynamic data in a turbine mode;

[0015] Acquire ramjet engine data and second aerodynamic data in ramjet mode.

[0016] In at least one embodiment of the present application, in step one, a bleed air bypass is provided in a ramjet flow path of the ramjet engine to perform bypass bleed air correction on the engine data and the aerodynamic data.

[0017] In at least one embodiment of the present application, in step 2, calculating the unit residual power two-dimensional interpolation function under different power modes according to the engine data and the aerodynamic data includes:

[0018] S201, constructing a basic dynamic model of a combined power hypersonic aircraft, and simplifying the basic dynamic model to obtain a simplified dynamic model;

[0019] S202. constructing an energy approximation model of a combined power hypersonic aircraft based on the simplified dynamic model;

[0020] S203, determining a unit residual power calculation model according to the energy approximation model;

[0021] S204, calculating unit surplus power data according to the engine data, the aerodynamic data and the unit surplus power calculation model;

[0022] S205. Interpolate the unit surplus power data to obtain a two-dimensional interpolation function of the unit surplus power, wherein the two-dimensional interpolation function of the unit surplus power takes the climb altitude and the Mach number as independent variables and takes the unit surplus power as a dependent variable.

[0023] In at least one embodiment of the present application, in S201, a basic dynamic model of a combined power hypersonic aircraft is constructed, and the basic dynamic model is simplified to obtain a simplified dynamic model, including:

[0024] In the track coordinate system, the force analysis of the aircraft is carried out to obtain the basic dynamic model of the climb phase:

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] Where V is the ground speed of the aircraft, m is the mass of the aircraft, T is the engine thrust, α is the angle of attack, is the engine installation angle, D is the aircraft drag, μ is the earth's gravitational constant, γ is the climb angle, R e is the radius of the earth, h is the climbing altitude, L is the lift of the aircraft, SFC is the fuel consumption rate, and x is the flight range;

[0031] When the throttle is fixed, the engine thrust T and fuel consumption rate SFC are functions of altitude and speed, and the aircraft lift L and drag D are functions of altitude, speed and angle of attack:

[0032] The basic dynamic model is further expressed as:

[0033]

[0034]

[0035]

[0036]

[0037] in, is the throttle coefficient, throttle coefficient is the ratio of the actual thrust to the maximum thrust in the current state, is the relationship function between actual fuel consumption rate and maximum fuel consumption rate, SFC max is the maximum fuel consumption rate, ρ is the atmospheric density, C L is the lift coefficient, C D is the drag coefficient;

[0038] Assuming that the aircraft is climbing at a small angle during the climb, we have:

[0039]

[0040]

[0041] cosγ≈1

[0042] When the climbing height h is relative to the earth radius R e For small amount:

[0043]

[0044] Simplify the basic dynamic model to obtain a simplified dynamic model:

[0045]

[0046]

[0047]

[0048] In at least one embodiment of the present application, in S202, constructing an energy approximation model of a combined power hypersonic aircraft according to the simplified dynamic model includes:

[0049] The total energy of the aircraft is defined as:

[0050]

[0051] The energy per unit weight is defined as energy height:

[0052]

[0053] The total energy change rate is:

[0054]

[0055] According to the energy approximation, the normal acceleration is neglected. The simplified dynamic model is further simplified as:

[0056]

[0057] L=mg

[0058]

[0059] In the above formula Substituting into the total energy change rate formula, the energy approximation model is obtained as follows:

[0060]

[0061] In at least one embodiment of the present application, in S203, determining a unit residual power calculation model according to the energy approximation model includes:

[0062] According to the energy approximation model, the unit residual power calculation model is obtained as follows:

[0063]

[0064] In at least one embodiment of the present application, in S204, calculating the unit residual power data according to the engine data, the aerodynamic data and the unit residual power calculation model includes:

[0065] According to the lift equation of an aircraft:

[0066] L(α,h,Ma)=mg

[0067] Substitute the engine data and aerodynamic data to calculate the angle of attack α;

[0068] According to the drag equation of an aircraft:

[0069] D=1 / 2ρV 2 SC D =L / K(α,Ma)

[0070] Where, S is the wing area;

[0071] Substitute the engine data and aerodynamic data to calculate the aircraft's drag D;

[0072] According to the engine thrust equation:

[0073] T=T(h,Ma)

[0074] Substitute the engine data and aerodynamic data to calculate the engine thrust T;

[0075] According to the unit residual power calculation model, the unit residual power data at different climbing altitudes and Mach numbers are calculated.

[0076] In at least one embodiment of the present application, in S205, thin plate spline interpolation is performed on the unit residual power data at different climbing altitudes and Mach numbers to obtain a two-dimensional interpolation function Ps(h, Ma) of the unit residual power.

[0077] In at least one embodiment of the present application, in step 4, the climbing altitude range and Mach number range corresponding to the overlapped area are used as the mode conversion window of the aircraft.

[0078] The invention has at least the following beneficial technical effects:

[0079] The method for calculating the power mode conversion window of a hypersonic aircraft of the present application can quickly and accurately determine the power mode conversion window of a combined power hypersonic aircraft by using the overlapping area of ​​the unit residual power contour diagrams under different power modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 is a flow chart of a method for calculating a hypersonic aircraft power mode conversion window according to one embodiment of the present application;

[0081] Figure 2 It is a schematic diagram of a flow supply of a super aircraft with a bleed air bypass according to an embodiment of the present application;

[0082] Figure 3 It is a schematic diagram of a contour diagram of unit residual power when the bleed air bypass is not opened according to an embodiment of the present application;

[0083] Figure 4 It is a flow chart of a method for calculating a hypersonic aircraft power mode conversion window considering bypass bleed air according to an embodiment of the present application;

[0084] Figure 5 It is a schematic diagram of the force condition of an aircraft in a track coordinate system according to an embodiment of the present application;

[0085] Figure 6 It is a schematic diagram of unit residual power data of an implementation mode of the present application;

[0086] Figure 7 is a unit residual power contour map of one embodiment of the present application;

[0087] Figure 8 It is a contour map of unit residual power under two power modes in one embodiment of the present application;

[0088] Fig. 9 It is a schematic diagram of the overlapping area of ​​one embodiment of the present application. DETAILED DESCRIPTION

[0089] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0090] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0091] The following is combined with Figures 1 to 9 This application is described in further detail.

[0092] The present application provides a method for calculating a hypersonic aircraft dynamic mode conversion window, comprising the following steps:

[0093] Step 1: Obtain engine data and aerodynamic data under different power modes;

[0094] Step 2: Calculate the two-dimensional interpolation function of unit residual power under different power modes according to the engine data and aerodynamic data;

[0095] Step 3: Draw contour diagrams of unit residual power under different dynamic modes according to the two-dimensional interpolation function of unit residual power;

[0096] Step 4: Based on the unit residual power contour diagrams under different dynamic modes, determine whether there is an overlapping area of ​​different dynamic modes. If so, determine the mode conversion window based on the overlapping area.

[0097] The method for calculating the power mode conversion window of a hypersonic aircraft of the present application mainly considers the two power modes of a combined power hypersonic aircraft. When acquiring data, it includes acquiring turbine engine data and first aerodynamic data under turbine mode, and acquiring ramjet engine data and second aerodynamic data under ramjet mode. The unit residual power contour is calculated based on the engine data and aerodynamic data under these two power modes, thereby realizing the calculation of the mode conversion window.

[0098] From the analysis of the characteristics of the combined power hypersonic aircraft engine, it can be known that the turbine engine has a larger specific impulse at low and medium Mach numbers, while the ramjet engine has a larger specific impulse at medium and high Mach numbers. Therefore, for the internal parallel combined power hypersonic aircraft engine, it is necessary to give full play to the performance advantages of the turbine engine and the ramjet engine at each stage. When the flight speed is low, the turbine engine works and the ramjet channel is closed. When the flight speed is high, the channel of the turbine engine is closed, the turbine engine gradually stops working, and the ramjet engine works alone. In the transition stage of the two engines, the splitter reduces the airflow to the turbine engine by adjusting the airflow to the two flow channels, and at the same time reduces the oil supply to the turbine engine to reduce the rotor speed. The turbine engine slowly enters the slow-speed state and finally gradually closes. At this time, the airflow to the ramjet engine increases, so that the thrust generated by the ramjet engine gradually increases, so that the total thrust of the engine remains basically unchanged until the mode conversion ends.

[0099] However, for ramjet engines, the maximum unit thrust that the engine can provide is mainly limited by the maximum temperature of the engine combustion chamber, and this limit is determined by the engine material. Therefore, it is not easy to directly increase the unit thrust of the engine. Figure 2 As shown, the method of introducing a bleed air bypass to supply additional flow to the ramjet engine is easier to implement in design and is used to achieve a smooth transition of thrust during the conversion of the combined power hypersonic aircraft engine from the turbine mode to the ramjet mode.

[0100] In order to prevent the aircraft from being unable to perform power mode conversion, the method for calculating the power mode conversion window of the hypersonic aircraft of the present application, in step 1, by setting a bleed air bypass in the ramjet flow path of the ramjet engine, the engine data and the aerodynamic data are corrected by bypass bleed air, which can significantly increase the power mode conversion window of the hypersonic aircraft. When the unit residual power method is used to calculate the power mode conversion window, the bleed air bypass can be approximated as increasing the engine cross-sectional area of ​​the ramjet engine, which is equivalent to increasing the air flow rate. Figure 3 As shown in the calculation results without opening the bypass bleed air, it can be seen that due to the limitation of the engine intake volume, the aircraft does not have a power mode conversion window and cannot achieve power mode conversion. The flow chart of the calculation method of the power mode conversion window of the hypersonic aircraft considering the bypass bleed air is shown in Figure 4 shown.

[0101] The method for calculating the power mode conversion window of a hypersonic aircraft of the present application, in step 2, calculates the two-dimensional interpolation function of unit residual power under different power modes according to engine data and aerodynamic data, including:

[0102] S201, constructing a basic dynamic model of a combined power hypersonic aircraft, and simplifying the basic dynamic model to obtain a simplified dynamic model;

[0103] S202. constructing an energy approximation model of a combined power hypersonic aircraft based on the simplified dynamic model;

[0104] S203, determining a unit residual power calculation model according to the energy approximation model;

[0105] S204, calculating unit surplus power data according to the engine data, the aerodynamic data and the unit surplus power calculation model;

[0106] S205. Interpolate the unit surplus power data to obtain a two-dimensional interpolation function of the unit surplus power, wherein the two-dimensional interpolation function of the unit surplus power takes the climb altitude and the Mach number as independent variables and takes the unit surplus power as a dependent variable.

[0107] Specifically, in S201, a basic dynamic model of the combined power hypersonic aircraft is constructed, and the basic dynamic model is simplified to obtain a simplified dynamic model, including the following processes:

[0108] The climbing process of the combined-power hypersonic aircraft is regarded as the symmetrical motion of a particle in a vertical plane, and the influence of mass change on the force on the aircraft during the climbing process is ignored; since the aircraft's climbing altitude spans a large range, the curvature of the earth is taken into consideration, and it is regarded as a perfect sphere and the rotation of the earth is ignored; the influence of wind speed is not considered, and the aircraft's ground speed is equal to the airspeed.

[0109] like Figure 5 As shown in the figure, in the track coordinate system, the force analysis of the aircraft is carried out. According to Newton's second law of constant mass objects, the particle dynamics equation of the aircraft in the climbing phase is obtained, which is the basic dynamic model:

[0110]

[0111]

[0112]

[0113]

[0114]

[0115] The points on each state quantity in the formula represent the first-order derivative of the state quantity, that is, the rate of change of the state quantity;

[0116] Where V is the ground speed of the aircraft, m is the mass of the aircraft, T is the engine thrust, α is the angle of attack, is the engine installation angle, D is the aircraft drag, μ is the earth's gravitational constant, γ is the climb angle, R e is the radius of the earth, h is the climbing altitude, L is the lift of the aircraft, SFC is the fuel consumption rate, and x is the flight range;

[0117] According to the basic knowledge of aircraft engines and aerodynamics, when the throttle is fixed, the engine thrust T and fuel consumption rate SFC are functions of altitude and speed, and the aircraft lift L and drag D are functions of altitude, speed and angle of attack:

[0118] The basic dynamic model is further expressed as:

[0119]

[0120]

[0121]

[0122]

[0123] in, is the throttle coefficient, throttle coefficient is the ratio of the actual thrust to the maximum thrust in the current state, is the relationship function between actual fuel consumption rate and maximum fuel consumption rate, SFC max is the maximum fuel consumption rate, ρ is the atmospheric density, C L is the lift coefficient, C D is the drag coefficient;

[0124] The dynamic in the basic dynamic model refers to the mathematical model used, which is a set of ordinary differential equations, taking into account the real-time changes of various state quantities during the climb process; the basic in the basic dynamic model refers to the generality and breadth of the model's applicability. The basic model will be further simplified below based on the principles of flight mechanics and the actual situation of the climb phase.

[0125] During the climb, it is assumed that the aircraft is climbing at a small angle, that is, the angle of attack α and the engine installation angle All are small angles, then:

[0126]

[0127]

[0128] cosγ≈1

[0129] When the climbing height h is relative to the earth radius R e For small amount:

[0130]

[0131] In addition, it can be seen from the basic dynamic model that the flight range x and the mass m of the aircraft can be solved independently and decoupled from the equations of the original model.

[0132] Under the above new assumptions, the basic dynamic model of the climbing phase can be further simplified into a simplified dynamic model:

[0133]

[0134]

[0135]

[0136] In the quasi-static approximation method, the center-of-mass acceleration of the aircraft is ignored, and the aircraft at each moment is considered to be in an instantaneous force equilibrium state, and we have:

[0137]

[0138]

[0139] According to the simplified dynamic model, the quasi-static approximate model is obtained as follows:

[0140] TD-mgsinγ=0

[0141] L=mg

[0142] The climbing altitude change rate is expressed as:

[0143]

[0144] The climbing angle is:

[0145]

[0146] Among them, W is the weight of the aircraft mg, and K is the lift-to-drag ratio.

[0147] The above formula fully reflects that the size of the climb angle is closely related to the dynamic characteristics, structural characteristics, and aerodynamic characteristics.

[0148] For supersonic aircraft and even hypersonic aircraft, the influence of acceleration is difficult to ignore, so an improved method of the quasi-static approximation is introduced, namely the energy approximation.

[0149] In S202, an energy approximation model of a combined power hypersonic aircraft is constructed based on the simplified dynamic model, including:

[0150] The total energy of the aircraft is defined as:

[0151]

[0152] The energy per unit weight is defined as energy height:

[0153]

[0154] The total energy change rate is:

[0155]

[0156] It can be seen from the above formula that the energy approximation method takes into account the rate of change of the velocity at each moment, that is, the tangential acceleration of the aircraft cannot be ignored, while the normal acceleration can be ignored here.

[0157] According to the energy approximation, the normal acceleration is neglected. The simplified dynamic model is further simplified as:

[0158]

[0159] L=mg

[0160]

[0161] In the above formula Substituting into the total energy change rate formula, the energy approximation model is obtained as follows:

[0162]

[0163] The energy approximation model starts from the perspective of energy, focusing on the input and conversion of energy, and explains that when the thrust is greater than the drag, the residual thrust (TD) will lead to an increase in the total energy of the aircraft, and the increase in total energy corresponds to an increase in kinetic energy or potential energy, that is, an increase in speed or an increase in altitude. The quasi-static approximation model ignores the instantaneous change in speed, and all the residual thrust is used for the increase in altitude. This is the difference between the two models.

[0164] The energy approximation method is based on the total energy of the aircraft. By calculating the ratio of the total energy change rate of the aircraft to the aircraft's gravity, the unit residual power of the aircraft is obtained. The unit residual power can more intuitively represent the performance of the aircraft's propulsion system or energy system, thereby evaluating the dynamic mode conversion window of the hypersonic aircraft.

[0165] The unit residual power of an aircraft is an important performance parameter in aeronautical engineering and flight mechanics. It represents the additional power that an aircraft can use to overcome gravity and other resistance at a certain moment. The unit residual power of an aircraft can be used to measure the vertical speed capability of the aircraft, that is, the speed at which the aircraft can climb or descend in the vertical direction. The greater the unit residual power of an aircraft, the better the performance of the aircraft, and the faster it can rise, avoid threats, or perform vertical maneuvers. The study of the unit residual power of an aircraft is of great significance to aircraft design, performance evaluation, flight planning, and mission execution.

[0166] In the preferred embodiment of the present application, the combined power hypersonic aircraft adopts a turbojet-ramjet dual-power mode TBCC engine. During the conversion of different power modes, the key issue is to ensure a smooth transition of thrust. In the engine mode conversion stage, the unit residual power of the aircraft can be used to determine whether the current engine thrust can meet the TBCC engine's smooth conversion from the turbojet mode to the ramjet mode.

[0167] In this embodiment, in S203, determining a unit residual power calculation model according to an energy approximation model includes:

[0168] According to the energy approximation model, the unit residual power calculation model is obtained as follows:

[0169]

[0170] In S204, the unit surplus power data is calculated according to the engine data, the aerodynamic data and the unit surplus power calculation model, including:

[0171] According to the lift equation of an aircraft:

[0172] L(α,h,Ma)=mg

[0173] Substitute the engine data and aerodynamic data to calculate the angle of attack α;

[0174] According to the drag equation of an aircraft:

[0175] D=1 / 2ρV 2 SC D =L / K(α,Ma)

[0176] Where, S is the wing area;

[0177] Substitute the engine data and aerodynamic data to calculate the aircraft's drag D;

[0178] According to the engine thrust equation:

[0179] T=T(h,Ma)

[0180] Substitute the engine data and aerodynamic data to calculate the engine thrust T;

[0181] According to the unit residual power calculation model, the unit residual power at different climbing altitudes and Mach numbers is calculated, and the two-dimensional interpolation function of unit residual power Ps(h,Ma) is obtained.

[0182] It can be understood that by calculating the unit surplus power at different climb altitudes and Mach numbers, a basic data table is obtained, and a two-dimensional interpolation function Ps(h,Ma) of the unit surplus power is established based on the data table.

[0183] After obtaining the two-dimensional interpolation function Ps(h,Ma) of unit surplus power, various methods for solving extreme values ​​with equality constraints can be used to obtain the maximum value of unit surplus power at different energy altitudes and the corresponding climb altitude and Mach number.

[0184] In the engine mode conversion stage, the power switching between the two engines is involved. First, based on the turbine engine data and aerodynamic data of the combined power hypersonic aircraft, the unit residual power data of the aircraft within the working range of the turbine engine is obtained, and a two-dimensional interpolation function of the unit residual power is established. Secondly, based on the ramjet engine data and aerodynamic data of the combined power aircraft, the unit residual power data of the aircraft within the working range of the ramjet engine is obtained, and a two-dimensional interpolation function of the unit residual power is established. The unit residual power data obtained is as follows: Figure 6 As shown in the scattered points.

[0185] In S205, thin plate spline interpolation is performed on the unit surplus power data at different climbing altitudes and Mach numbers to obtain a two-dimensional interpolation function Ps(h, Ma) of the unit surplus power.

[0186] In the method for calculating the power mode conversion window of the hypersonic aircraft of the present application, in step 3, the unit residual power contour map under different power modes is drawn according to the unit residual power two-dimensional interpolation function. In this embodiment, the unit residual power contour line and energy height contour line of the combined power hypersonic aircraft are drawn according to the obtained unit residual power two-dimensional interpolation function. Figure 7 As shown in the figure. The energy height contour is represented by a dotted line in km, and the value of the unit residual power contour is marked in the figure in m / s. The two peaks shown in the unit residual power contour are consistent with the previous analysis, reflecting the typical energy characteristics of supersonic aircraft.

[0187] The hypersonic aircraft power mode conversion window calculation method of the present application obtains the unit residual power contour map under the two power modes, such as Figure 8 In step 4, according to the unit residual power contour diagrams under the two power modes, it is determined whether there is an overlap area of ​​different power modes. If so, the climbing altitude range and Mach number range corresponding to the overlap area are used as the aircraft's mode conversion window.

[0188] In a preferred embodiment of the present application, through the unit residual power contour map of the combined power hypersonic aircraft under two power modes, different sizes of mode conversion windows can be determined according to different overlap areas. Fig. 9As shown, in this embodiment, it can be clearly determined that in the area within the circle, there is an overlapping area where the unit residual power is zero under the two power modes. In this area, the combined power hypersonic aircraft can achieve constant speed level flight under both power modes. Without considering the thrust change during the mode conversion process, the altitude range and Mach number range corresponding to this area can be regarded as the maximum conversion window of the power mode of the combined power hypersonic aircraft. Under this window, the hypersonic aircraft power mode conversion can only be achieved under constant speed level flight, but it has a relatively large altitude and Mach number range, and the conditions for power mode conversion are relatively loose. Similarly, the minimum area where the unit residual power contour lines overlap is the minimum conversion window. The altitude and Mach number range under this window are relatively small, and the conditions for mode conversion are relatively harsh, but under this window, the hypersonic aircraft can achieve mode conversion under a certain climb rate or acceleration. The mode conversion window can also obtain the maximum climb rate and acceleration and deceleration performance during level flight that can be achieved under the conditions of achieving mode conversion.

[0189] The hypersonic aircraft dynamic mode conversion window calculation method of the present application can quickly and accurately determine the dynamic mode conversion window of the combined power hypersonic aircraft by using the overlapping area of ​​the unit residual power contour map under the two dynamic modes. At the same time, the influence of the bypass bleed air technology on the modal conversion window calculation is considered. A quantifiable method for calculating the dynamic mode conversion window of the combined power hypersonic aircraft is proposed, and whether the behavior such as climbing or acceleration can be performed during the mode conversion process can be determined by the numerical value of the contour line.

[0190] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for calculating a hypersonic aircraft dynamic mode conversion window, characterized in that: include: Step 1: Obtain engine data and aerodynamic data under different power modes; Step 2: Calculate the two-dimensional interpolation function of unit residual power under different power modes according to the engine data and aerodynamic data; Step 3: Draw contour diagrams of unit residual power under different dynamic modes according to the two-dimensional interpolation function of unit residual power; Step 4: Based on the unit residual power contour diagrams under different dynamic modes, determine whether there is an overlapping area of ​​different dynamic modes. If so, determine the mode conversion window based on the overlapping area.

2. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 1, characterized in that: In step 1, engine data and aerodynamic data under different power modes are obtained, including: Acquiring turbine engine data and first aerodynamic data in a turbine mode; Acquire ramjet engine data and second aerodynamic data in ramjet mode.

3. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 2, characterized in that: In step 1, a bleed air bypass is provided in a ramjet flow path of the ramjet engine to perform bypass bleed air correction on the engine data and the aerodynamic data.

4. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 1, characterized in that: In step 2, based on the engine data and aerodynamic data, the two-dimensional interpolation function of unit residual power under different power modes is calculated, including: S201, constructing a basic dynamic model of a combined power hypersonic aircraft, and simplifying the basic dynamic model to obtain a simplified dynamic model; S202. constructing an energy approximation model of a combined power hypersonic aircraft based on the simplified dynamic model; S203, determining a unit residual power calculation model according to the energy approximation model; S204, calculating unit surplus power data according to the engine data, the aerodynamic data and the unit surplus power calculation model; S205. Interpolate the unit surplus power data to obtain a two-dimensional interpolation function of the unit surplus power, wherein the two-dimensional interpolation function of the unit surplus power takes the climb altitude and the Mach number as independent variables and takes the unit surplus power as a dependent variable.

5. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 4, characterized in that: In S201, a basic dynamic model of a combined power hypersonic aircraft is constructed, and the basic dynamic model is simplified to obtain a simplified dynamic model, including: In the track coordinate system, the force analysis of the aircraft is carried out to obtain the basic dynamic model of the climb phase: Where V is the ground speed of the aircraft, m is the mass of the aircraft, T is the engine thrust, α is the angle of attack, is the engine installation angle, D is the aircraft's drag, μ is the earth's gravitational constant, γ is the climb angle, R e is the radius of the earth, h is the climbing height, L is the lift of the aircraft, SFC is the fuel consumption rate, and x is the flight range; When the throttle is fixed, the engine thrust T and fuel consumption rate SFC are functions of altitude and speed, and the aircraft lift L and drag D are functions of altitude, speed and angle of attack: The basic dynamic model is further expressed as: in, is the throttle coefficient, throttle coefficient is the ratio of the actual thrust to the maximum thrust in the current state, is the relationship function between actual fuel consumption rate and maximum fuel consumption rate, SFC max is the maximum fuel consumption rate, ρ is the atmospheric density, C L is the lift coefficient, C D is the drag coefficient; Assuming that the aircraft is climbing at a small angle during the climb, we have: cosγ≈1 When the climbing height h is relative to the earth radius R e For small amount: Simplify the basic dynamic model to obtain a simplified dynamic model:

6. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 5, characterized in that: In S202, an energy approximation model of a combined power hypersonic aircraft is constructed based on the simplified dynamic model, including: The total energy of the aircraft is defined as: The energy per unit weight is defined as energy height: The total energy change rate is: According to the energy approximation, the normal acceleration is neglected. The simplified dynamic model is further simplified as: L=mg In the above formula Substituting into the total energy change rate formula, the energy approximation model is obtained as follows:

7. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 6, characterized in that: In S203, a unit residual power calculation model is determined according to the energy approximation model, including: According to the energy approximation model, the unit residual power calculation model is obtained as follows:

8. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 7, characterized in that: In S204, the unit surplus power data is calculated according to the engine data, the aerodynamic data and the unit surplus power calculation model, including: According to the lift equation of an aircraft: L(α,h,Ma)=mg Substitute the engine data and aerodynamic data to calculate the angle of attack α; According to the aircraft drag equation: D=1 / 2ρV 2 SC D =L / K(α,Ma) Where, S is the wing area; Substitute the engine data and aerodynamic data to calculate the aircraft's drag D; According to the engine thrust equation: T=T(h,Ma) Substitute the engine data and aerodynamic data to calculate the engine thrust T; According to the unit residual power calculation model, the unit residual power data at different climbing altitudes and Mach numbers are calculated.

9. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 8, characterized in that: In S205, thin plate spline interpolation is performed on the unit surplus power data at different climbing altitudes and Mach numbers to obtain a two-dimensional interpolation function Ps(h, Ma) of the unit surplus power.

10. The method for calculating the dynamic mode conversion window of a hypersonic aircraft according to claim 9, characterized in that: In step 4, the climbing altitude range and Mach number range corresponding to the overlapped area are used as the aircraft's mode conversion window.

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