A simulation method for aerodynamic control of lateral pulse jet based on CFD and RBD coupling

Abstract

The present invention discloses a transverse pulse jet aerodynamic control simulation method based on CFD and RBD coupling, which relates to the technical field of aircraft transverse jet aerodynamic control, and includes: calculating the initial flow field before any nozzle is opened; simulating the jet opening process; simulating the jet working state; simulating the jet closing state. The present invention can realize the transverse pulse jet aerodynamic control simulation of any number and any working sequence based on the CFD and RBD coupling calculation method, and obtain the motion trajectory of the aircraft under the transverse pulse jet control and the attitude, aerodynamic force and flow field data at any time.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft lateral jet aerodynamic control, and in particular to a lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling. Background Art

[0002] Lateral jet control is an effective and relatively mature technology for aircraft attitude and trajectory control. The use of multiple pulse jets at different positions can achieve fine control of the aircraft. There are three major means to study aircraft lateral jet control, including flight tests, ground wind tunnel tests and numerical simulations. Since the preparation period for flight tests and ground wind tunnel tests is long and expensive, numerical simulation is the main method for rapid iteration of design schemes in the early stages of aircraft design. Existing aircraft lateral jet simulation methods are usually based on CFD (Computational Fluid Dynamic) methods to simulate the point state of fixed flight attitude or based on CFD and RBD (Rigid Body Dynamics) coupling methods to simulate the attitude and trajectory changes of aircraft under fixed jet conditions. For the simulation of aircraft lateral pulse jet aerodynamic control, it is necessary to consider the boundary condition changes of different nozzle jet opening and closing and the change of jet conditions over time when the jet is open on the basis of the traditional numerical method based on CFD and RBD coupling. Summary of the invention

[0003] In view of this, the present invention provides a lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling, which is suitable for the flight attitude and trajectory simulation of an aircraft under the control of any number of lateral pulse jets and any working sequence. For any single nozzle, the simulation method can be divided into four typical stages, stage one is the initial flow field simulation before the jet opens, stage two is the simulation of the jet opening process, stage three is the aerodynamic control simulation under non-time-varying (i.e., long-term steady state or square wave pulse platform) or time-varying jet conditions, and stage four is the simulation of the jet closing process. The flow field at the moment before each nozzle opens is defined as the initial flow field before the nozzle opens. When multiple jet pulses from the same nozzle are involved, this can be achieved by cycling stages two to four.

[0004] The present invention discloses a transverse pulse jet pneumatic control simulation method based on CFD and RBD coupling, which comprises:

[0005] Step 1: Calculate the initial flow field before any nozzle is opened;

[0006] Step 2: Simulate the jet opening process;

[0007] Step 3: Simulate the working state of the jet;

[0008] Step 4: Simulate the jet closed state.

[0009] Furthermore, if the numerical simulation involves the working condition of multiple pulse jets from the same nozzle, steps 2 to 4 can be repeated at corresponding times.

[0010] Furthermore, the step 1 comprises:

[0011] The wall boundary condition is set at the nozzle boundary. If the nozzle is the first jet opened in the case, the initial flow field before the jet is opened is obtained only through CFD calculation according to the incoming flow conditions and flight attitude of the aircraft.

[0012] Furthermore, the step 1 further comprises:

[0013] The nozzle boundary is set as the wall boundary condition. If the nozzle is not the first jet opened in the example, the aircraft attitude and initial flow field before the jet is opened are calculated by coupling CFD and RBD.

[0014] Furthermore, the step 2 comprises:

[0015] Agreed time is the time before the first jet opens, and for the No. The jet is opened at the moment of , switch the nozzle boundary from the wall boundary condition to the jet boundary condition, and give the initial velocity vector at the nozzle ,pressure ,temperature , the initial density of the jet gas is obtained by the ideal gas state equation ; Based on the initial flow field and attitude of the nozzle, the flow field around the aircraft, the attitude and trajectory of the aircraft during the jet opening process are obtained by coupling CFD and RBD; Among them, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis.

[0016] Furthermore, the step 3 comprises:

[0017] Definition No. The duration of the jet pulse is , the current physical time is , the jet condition at the current moment for:

[0018] (1)

[0019] in, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For time Time No. The pressure of the secondary jet, For time Time No. The temperature of the secondary jet.

[0020] Furthermore, when the jet is time-invariant, the current jet condition for:

[0021] (2).

[0022] Furthermore, when the jet is time-varying, the jet condition of each jet at any time is given As input:

[0023] (3)

[0024] in, For any time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For any time No. The pressure of the secondary jet, For any time No. The temperature of the secondary jet;

[0025] When the physical time of the numerical simulation is inconsistent with the moment of any given jet condition, the jet condition corresponding to the two adjacent moments of the given jet state is interpolated to give the jet condition at the current moment.

[0026] Furthermore, the jet condition interpolation corresponding to the moments of two adjacent given jet states is used to give the jet condition at the current moment, including:

[0027] Set any current physical time The two adjacent moments are recorded as and , then the jet condition at any time is:

[0028] (4)

[0029] in, For the moment The jet conditions, For the moment jet conditions.

[0030] Furthermore, the step 4 comprises:

[0031] Switch the boundary condition to the wall boundary, and continue calculating until the next jet opening moment or the required physical time based on the flow field and attitude at the last moment in step 3.

[0032] Due to the adoption of the above technical scheme, the present invention has the following advantages: the present invention can realize the aerodynamic control simulation of lateral pulse jets of any number and any working sequence based on the CFD and RBD coupling calculation method, and obtain the motion trajectory of the aircraft under the lateral pulse jet control and the attitude, aerodynamic force and flow field data at any time. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0034] Figure 1A schematic flow chart of a transverse pulse jet aerodynamic control simulation method based on CFD and RBD coupling according to an embodiment of the present invention;

[0035] FIG. 2( a ) is a side view of an aircraft according to an embodiment of the present invention;

[0036] FIG2( b ) is a front view of an aircraft according to an embodiment of the present invention;

[0037] FIG3( a ) is a graph showing the change of the angle of attack of an aircraft over time according to an embodiment of the present invention;

[0038] FIG3( b ) is a graph showing the change of the axial displacement of the aircraft over time according to an embodiment of the present invention;

[0039] FIG. 3( c ) is a graph showing the change of the normal displacement of the aircraft over time according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present invention.

[0041] See also Figure 1 The present invention provides an embodiment of a transverse pulse jet aerodynamic control simulation method based on CFD and RBD coupling, which comprises the following steps:

[0042] Step 1: Calculate the initial flow field before any nozzle is opened. Set the nozzle boundary as the wall boundary condition. If the nozzle is the first jet opened in the example, the initial flow field before the jet is opened is obtained only through CFD calculation according to the incoming flow conditions and flight attitude of the aircraft; if the nozzle is not the first jet opened in the example, the aircraft attitude and initial flow field before the jet is opened are calculated by coupling CFD and RBD.

[0043] Step 2: Simulation of the jet opening process. is the time before the first jet opens. No. The jet is opened at the moment of , switch the nozzle boundary from the wall boundary condition to the jet (velocity inflow) boundary condition, and give the initial velocity vector at the nozzle ,pressure( ),temperature( ) parameters, the initial density of the jet gas ( ) is calculated by the ideal gas state equation. Based on the initial flow field and attitude of the nozzle, the CFD and RBD coupling method is used to calculate the flow field around the aircraft, the attitude and trajectory of the aircraft during the jet opening process. Among them, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis.

[0044] Step 3: Simulation of the jet working state. Define No. The duration of the jet pulse is , the current physical time is , the jet condition at the current moment for:

[0045] (1)

[0046] in, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For time Time No. The pressure of the secondary jet, For time Time No. The temperature of the secondary jet.

[0047] When the jet is time-invariant, the current jet condition is:

[0048] (2)

[0049] When the jet is time-varying, the jet condition of each jet at any time can be given As input:

[0050] (3)

[0051] in, For any time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For any time No. The pressure of the secondary jet, For any time No. The temperature of the secondary jet;

[0052] When the physical time of the numerical simulation is inconsistent with the time of any given jet condition, the jet condition at the current moment is given by interpolating the jet conditions corresponding to the two adjacent given jet states. The two adjacent moments are recorded as and , then the jet condition at any time is:

[0053] (4)

[0054] in, For the moment The jet conditions, For the moment jet conditions.

[0055] Step 4: Simulation of the jet closed state. Switch the boundary condition to the wall boundary, and based on the flow field and attitude at the last moment of the previous step, continue to calculate until the next jet opening moment or the required physical time.

[0056] If the numerical simulation involves the working condition of multiple pulse jets from the same nozzle, steps 2 to 4 can be repeated at the corresponding time.

[0057] For ease of understanding, the present invention provides a more specific embodiment:

[0058] like Figure 1 As shown, it is implemented by the following steps:

[0059] Step 1: Select typical flight conditions (Table 1) and obtain the initial flow field before the jet opens through CFD calculation.

[0060] Table 1 Flight condition parameters

[0061]

[0062] Step 2: Given the mass, inertia and center of mass of the aircraft (Table 2), and the data on the change of flow parameters of the jet over time (Table 3), the wall conditions at the boundary of nozzle 1 are switched to the jet boundary conditions, and the calculation is continued to 5ms by coupling CFD and RBD.

[0063] Table 2 Aircraft mass attributes

[0064]

[0065] Table 3 Jet flow parameters

[0066]

[0067] Step 3: Switch the jet boundary condition of nozzle 1 to the wall boundary condition, and continue the calculation to 7ms by coupling CFD and RBD.

[0068] Step 4: Switch the wall boundary condition at the boundary of nozzle 3 to the jet boundary condition, and continue the calculation to 12ms by coupling CFD and RBD.

[0069] Step 5: Switch the jet boundary condition of nozzle 3 to the wall boundary condition, and continue the calculation to 30ms by coupling CFD and RBD, and then the calculation ends.

[0070] In FIG. 2( a ), D represents the diameter of the aircraft in this embodiment, and CG represents the position of the center of mass of the aircraft in this embodiment; in FIG. 2( b ), The direction of the axis of the nozzle 1 is defined as the 0° circumferential angle of the aircraft in this embodiment.

[0071] Figure 3(a) is a graph showing the change of the angle of attack of the aircraft according to an embodiment of the present invention over time; Figure 3(b) is a graph showing the change of the axial displacement of the aircraft according to an embodiment of the present invention over time; and Figure 3(c) is a graph showing the change of the normal displacement of the aircraft according to an embodiment of the present invention over time.

[0072] The contents not described in detail in the present invention are well known to those skilled in the art.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A transverse pulse jet aerodynamic control simulation method based on CFD and RBD coupling, characterized in that: include: Step 1: Calculate the initial flow field before any nozzle is opened; Step 2: Simulate the jet opening process; Step 3: Simulate the working state of the jet; Step 4: Simulate the jet closed state; The step 1 comprises: The nozzle boundary is set as the wall boundary condition. If the nozzle is not the first jet opened in the example, the aircraft attitude and initial flow field before the jet is opened are calculated by coupling CFD and RBD. The step 2 comprises: Agreed time is the time before the first jet opens, and for the No. The jet is opened at the moment of , switch the nozzle boundary from the wall boundary condition to the jet boundary condition, and give the initial velocity vector at the nozzle ,pressure ,temperature , the initial density of the jet gas is obtained by the ideal gas state equation ; Based on the initial flow field and attitude of the nozzle, the flow field around the aircraft, the attitude and trajectory of the aircraft during the jet opening process are obtained by coupling CFD and RBD; Among them, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis; The step 3 comprises: Definition No. The duration of a jet pulse is , the current physical time is , the jet condition at the current moment for: (1) in, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For time Time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For time Time No. The pressure of the secondary jet, For time Time No. The temperature of the secondary jet; When the jet is time-varying, the jet condition of each jet at any time is given by As input: (3) in, For any time No. The velocity component of the initial velocity vector of the secondary jet on the X-axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Y axis, For any time No. The velocity component of the initial velocity vector of the secondary jet on the Z axis, For any time No. The pressure of the secondary jet, For any time No. The temperature of the secondary jet; When the physical time of the numerical simulation is inconsistent with the time of any given jet condition, the jet condition corresponding to the two adjacent given jet states is interpolated to give the jet condition at the current time. The step 4 comprises: Switch the boundary condition to the wall boundary, and based on the flow field and attitude at the last moment in step 3, continue calculating until the next jet opening moment or the required physical time.

2. The lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling according to claim 1 is characterized in that: If the numerical simulation involves the working condition of multiple pulse jets from the same nozzle, steps 2 to 4 can be repeated at the corresponding time.

3. The lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling according to claim 1 is characterized in that: The step 1 also includes: The wall boundary condition is set at the nozzle boundary. If the nozzle is the first jet opened in the case, the initial flow field before the jet is opened is obtained only through CFD calculation according to the incoming flow conditions and flight attitude of the aircraft.

4. The lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling according to claim 1 is characterized in that: When the jet is time-invariant, the current jet condition for: (2)。 5. The lateral pulse jet aerodynamic control simulation method based on CFD and RBD coupling according to claim 1 is characterized in that: The jet condition interpolation corresponding to the moments of two adjacent given jet states is used to give the jet condition at the current moment, including: Set any current physical time The two adjacent moments are recorded as and , then the jet condition at any time is: (4) in, For the moment The jet conditions, For the moment jet conditions.

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