CN112131667A - Physical simulation method for thermal deformation of wind tunnel scaling model - Google Patents

Abstract

The invention provides a physical simulation method for thermal deformation of a wind tunnel scale model, and belongs to the technical field of design and manufacture of aircraft wind tunnel models. The method comprises a scaling model for a wind tunnel test and piezoelectric fiber composite actuators, wherein the scaling model for the wind tunnel test is made of fiber reinforced resin matrix composite materials, a plurality of piezoelectric fiber composite actuators are distributed on the inner surface of a scaling structure according to a certain layout, and the piezoelectric fiber composite actuators are driven by an external independent power supply to generate deformation so as to simulate structural thermal deformation. The invention can simulate a wide temperature range and can be widely used for wind tunnel test scale models with different proportions.

Description

A Physical Simulation Method for Thermal Deformation of Wind Tunnel Scale Models

technical field

The invention belongs to the technical field of aircraft physical similarity models, and relates to a method for simulating thermal deformation of an aircraft model in a real flight environment. It is a new, low-cost and high-fidelity simulation method.

Background technique

With the rapid development of technology in the aerospace field, hypersonic aircraft is very important for the future confrontation of aerospace forces. With the increase of the flying speed of the aircraft, the temperature of the environment in which the aircraft is located will rise sharply, and the impact of temperature on the structural deformation of the aircraft will become more and more. Serious, mainly reflected in: first, the mechanical properties such as material modulus and damping change with the increase of temperature; second, aerodynamic heating causes additional thermal deformation of the structure, thereby changing the aerodynamic shape of the wing and affecting the structural function of the aircraft . These new features bring a series of new aeroelasticity problems, so it is of great practical and strategic significance to consider the theoretical basis and experimental system of thermo-aeroelasticity in the actual flight environment, especially in the high temperature environment.

Aiming at the aeroelastic problem caused by aerodynamic heating of aircraft, relevant theoretical analysis, numerical simulation, wind tunnel test and flight test have been carried out. The main method of the phenomenon. Therefore, the most direct method to study the influence of temperature on the aerodynamic performance of the aircraft is to manufacture a scale model with similar structure and conduct wind tunnel tests. However, it is quite difficult to realize the high-speed blowing test in the actual hypersonic flight thermal environment based on the existing wind tunnel conditions, which is embodied in: In order to study the aerothermal effect of the aircraft in the hypersonic flight state, it is necessary to use an external heating method to To construct a temperature field in a hypersonic flight state, the test device is extremely complex and the test period is short. The single cost of such a hypersonic wind tunnel test is very high, and multiple tests often cause the test to consume a lot of energy and capital. Therefore, in terms of the current infrastructure, technical level and the speed index of hypersonic vehicles, it is difficult to conduct effective thermo-aeroelasticity tests in wind tunnels for a long period of time.

SUMMARY OF THE INVENTION

In order to solve the problem that it is difficult to construct an ambient temperature field under hypersonic flight conditions under the current wind tunnel test conditions, so that the influence of aerodynamic thermal effects on the aerodynamic performance of the aircraft cannot be obtained, a wind tunnel scale model based on smart materials is invented. Thermal effect physical simulation method. The purpose is to solve the problem that the thermo-aeroelasticity wind tunnel test cost of the existing aircraft is extremely high, and the construction progress of the test facility cannot keep up with the actual test requirements. The inner surface and the inverse piezoelectric effect are used to generate a driving force to drive the scaled model to deform, to replace the thermal deformation of the hypersonic vehicle due to aerodynamic heat under actual flight conditions, and to adjust the driving voltage and piezoelectric fiber composite materials. The actuator layout simulates thermal deformation caused by different temperature fields, so that thermo-aeroelasticity tests can be performed in conventional wind tunnels, breaking through the limitations of existing wind tunnel technical conditions and significantly reducing wind tunnel test costs.

The technical scheme adopted in the present invention:

A physical simulation method for thermal deformation of a wind tunnel scaled model, the steps are as follows:

The piezoelectric fiber composite material is used as the actuator to be bonded to the inner surface of the scale model 1 in the wind tunnel test. Using its inverse piezoelectric effect, a suitable voltage is applied to the piezoelectric fiber composite material actuator 2 to make the wind tunnel test. The scaled model 1 produces corresponding deformation, thereby simulating the thermal deformation caused by the test model caused by aerodynamic heat under actual flight conditions;

(1) Calculate the thermal load and the corresponding thermal deformation of the wind tunnel test scaled model 1 under the specified flight environment conditions;

(2) In the simulation process, the scaled model 1 of the wind tunnel test is divided into mesh areas, and piezoelectric fiber composite actuators 2 with fixed size are added to each grid on the inner surface of the scaled model 1 of the wind tunnel test. The deformation state of the wind tunnel test scaled model 1 driven by the piezoelectric fiber composite actuator 2, extract a number of target design points on the wind tunnel test scale model 1, and use the target design points under the flight environment conditions in step 1. Deformation and the absolute error sum of squares of the driving deformation of the piezoelectric fiber composite actuator 2 are the optimization goals, and the driving voltage and the fiber angle of the piezoelectric fiber composite material actuator 2 are used as the optimization design variables, so as to ensure the piezoelectric fiber composite material. The deformation driven by the actuator 2 is consistent with the thermal deformation in the actual environment; the equivalent calculation method is:

Find:X _i (U _i ,θ _i )i=1,2,…,n

Min:

Subject to:-500≤U _i ≤1500 i=1,2,…,n

0≤θ _i ≤πi=1,2,…,n

where U _i represents the driving voltage of each piezoelectric fiber composite actuator 2 , θ _i represents the fiber angle of each piezoelectric fiber composite actuator 2 , and i represents the pasted piezoelectric fiber composite actuator 2 area number, j represents the target design point number for evaluating the thermal deformation physical simulation effect of the model, v _j represents the displacement of the selected evaluation point of the wind tunnel test scale model 1 in the flight environment, v _j ^* represents the wind tunnel test scale model 1 Displacement of the selected evaluation point driven by the piezoelectric fiber composite actuator 2;

(3) According to the optimization results in step 2, the piezoelectric fiber composite material actuator 2 is evenly pasted on each grid on the inner surface of the wind tunnel test scaled model 1, and each piece of piezoelectric fiber composite material actuator 2 has The voltage and angle are determined according to the theoretical analysis results of the wind tunnel test, and must meet the needs of the thermal deformation of the model in the test.

The wind tunnel test scale model 1 is manufactured by contact molding, and the wind tunnel test scale model 1 is a fiber-reinforced resin matrix composite material; the adhesive used for the piezoelectric fiber composite material actuator 2 to be pasted on the wind tunnel test scale model 1 is: Epoxy resin glue; each piezoelectric fiber composite material actuator 2 is driven by an external -500~+1500V independent power supply 3 to generate deformation.

The beneficial effects of the present invention are: (1) the piezoelectric fiber composite material actuator adopted has good flexibility and machining performance, and strong driving ability; (2) the design is strong, and can be designed according to the different heating conditions of the structure. , design the fiber angle and control voltage of each piezoelectric fiber composite actuator; (3) Compared with the traditional wind tunnel test, this method can save the test cost, and can quickly realize the thermal deformation of the model under actual flight conditions. simulations to conduct thermo-aeroelasticity experimental studies in conventional wind tunnels.

Description of drawings

FIG. 1 is a schematic structural diagram of the wing model of the simulation method adopted in the present invention.

FIG. 2 is a schematic diagram of thermal deformation of the model according to the present invention.

In the figure: 1 wind tunnel test scale model, 2 piezoelectric fiber composite material actuator, 3 driving power supply.

Detailed ways

The specific embodiments are described in detail below according to the technical solutions of the present invention and the accompanying drawings:

(1) A method for simulating thermal deformation in the actual flight situation of an aircraft involved in the present invention includes a wind tunnel test scale model 1 of the aircraft and a piezoelectric fiber composite material actuator 2 . Among them, the piezoelectric fiber composite material actuator 2 is pasted on the inner surface of the wind tunnel test scale model 1. The voltage and angle of each actuator are determined according to the theoretical analysis results of the wind tunnel test, and must be able to meet the requirements of the test. thermal deformation of the model required.

(2) Calculate the thermal load and the corresponding thermal deformation of the wind tunnel test model under the specified flight environment conditions using computational fluid dynamics and finite element simulation software.

(3) Considering the manufacturability of the wind tunnel test model, the inner surface of the model is divided into several piezoelectric fiber composite actuators with a fixed size, and the finite element analysis software is used to simulate and calculate the wind tunnel test driven by the piezoelectric fiber composite actuator. Model deformation state, extract several target design points on the model, take the thermal deformation of these points under the flight environment conditions in step (2) and the absolute sum of square errors of the piezoelectric fiber composite actuator driving deformation as the optimization target, and take the pressure The driving voltage and fiber angle of the electric fiber composite actuator are optimized design variables to ensure that the deformation driven by the piezoelectric fiber composite is consistent with the thermal deformation in the actual environment. Its equivalent calculation method is:

Find:X _i (U _i ,θ _i )i=1,2,…,n

Min:

Subject to:-500≤U _i ≤1500 i=1,2,…,n

0≤θ _i ≤π i=1,2,…,n

where U _i represents the driving voltage of each piezoelectric fiber composite actuator, θ _i represents the fiber angle of each piezoelectric fiber composite actuator, and i represents the area number where the piezoelectric fiber composite actuator is attached , j represents the target design point number for evaluating the physical simulation effect of thermal deformation of the model, v _k represents the displacement of the selected evaluation point of the wind tunnel test model in the flight environment, v _k ^* represents the wind tunnel test model in the piezoelectric fiber composite material actuation The displacement of the selected evaluation point under drive.

(4) The wind tunnel test model is manufactured by contact molding, and the model material is fiber-reinforced resin matrix composite material.

(5) Before the final assembly of the model is completed, each piezoelectric fiber composite material actuator 2 is bonded to the inner surface of the test model according to the specified position and angle, and the bonding agent is epoxy resin glue. After the adhesive is cured, the assembly of the wind tunnel test model is completed.

(6) By applying a corresponding voltage to the piezoelectric fiber composite material actuator 2, the piezoelectric fiber composite material actuator 2 can generate an appropriate stretching force or contraction force to drive the wind tunnel test model to deform, so that the model can be deformed in the piezoelectric fiber composite material. The deformation effect driven by the fiber composite actuator is equivalent to the thermal deformation of the model in the thermal environment.

On the basis of the wind tunnel test system based on the scaled model of the aircraft, the invention adopts the piezoelectric fiber composite material as the actuator, and the model is deformed by applying a voltage to simulate the thermal deformation of the model in the actual flight environment, and solves the problem of high The cost of thermal environment construction for wind tunnel test under supersonic flight conditions provides a solution for studying the thermo-aeroelasticity of hypersonic vehicles.

Claims (2)

1. A physical simulation method for thermal deformation of a wind tunnel scale model is characterized by comprising the following steps:

the physical simulation method realizes thermal deformation simulation through a wind tunnel test scaling model (1) and a piezoelectric fiber composite material actuator (2);

1) calculating the heat load and the corresponding heat deformation of the wind tunnel test scaling model (1) under the specified flight environment condition;

2) in the simulation process, the wind tunnel test scaling model (1) is divided into grid areas, a piezoelectric fiber composite actuator (2) with fixed size is added on each grid on the inner surface of the wind tunnel test scaling model (1), the deformation state of the wind tunnel test scaling model (1) driven by the piezoelectric fiber composite actuator (2) is calculated, a plurality of target design points on the wind tunnel test scaling model (1) are extracted, taking the sum of the squares of the absolute errors of the thermal deformation of the target design point under the flying environment condition in the step 1) and the driving deformation of the piezoelectric fiber composite material actuator (2) as an optimization target, the driving voltage and the fiber angle of the piezoelectric fiber composite material actuator (2) are taken as optimization design variables, thereby ensuring that the deformation under the driving of the piezoelectric fiber composite material actuator (2) has consistency with the thermal deformation under the actual environment; the equivalent calculation method comprises the following steps:

Find:X_i(U_i,θ_i)i＝1,2,…,n

Min:

Subject to:-500≤U_i≤1500 i＝1,2,…,n

0≤θ_i≤πi＝1,2,…,n

wherein, U_iRepresents a driving voltage, theta, of each piezoelectric fiber composite actuator (2)_iDenotes a fiber angle of each piezoelectric fiber composite actuator (2), i denotes a number of a region to which the piezoelectric fiber composite actuator (2) is attached, j denotes a number of a target design point for evaluating a physical simulation effect of a model for thermal deformation, v_jRepresenting the displacement, v, of a selected evaluation point of a wind tunnel test scaling model (1) in a flight environment_j ^*Representing the displacement of the selected evaluation point of the wind tunnel test scaling model (1) under the drive of the piezoelectric fiber composite actuator (2);

3) according to the optimization result in the step 2), uniformly sticking the piezoelectric fiber composite actuators (2) on each grid on the inner side surface of the wind tunnel test scaling model (1), wherein the voltage and the angle of each piezoelectric fiber composite actuator (2) are determined according to the theoretical analysis result of the wind tunnel test, and the requirement of model thermal deformation in the test needs to be met.

2. The physical simulation method of thermal deformation of a wind tunnel scaling model according to claim 1,

manufacturing a wind tunnel test scaling model (1) by adopting contact molding, wherein the wind tunnel test scaling model (1) is a fiber reinforced resin matrix composite material; the piezoelectric fiber composite material actuator (2) is stuck on the wind tunnel test scaling model (1) by using epoxy resin glue as a sticking agent; each piezoelectric fiber composite material actuator (2) is driven by an external-500- +1500V independent power supply (3) to generate deformation.

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