A method for aerodynamic test based on non-steady flow environment of vehicle wake

Abstract

The present application relates to the field of automotive aerodynamic test technology, and discloses a kind of non-steady flow environment aerodynamic test method based on front vehicle wake, comprising: S1, installs environment measuring device on test vehicle, carries out steady flow test calibration to test vehicle, obtains first environmental physical quantity based on environment measuring device, and establishes the corresponding relationship between first environmental physical quantity and steady flow environmental physical quantity;S2, test vehicle is in non-steady flow environment;S3, in the environment of non-steady flow, second environmental physical quantity is obtained by environment measuring device, and based on the corresponding relationship and second environmental physical quantity, the test environment physical quantity of non-steady flow environment where test vehicle is located is determined;S4, based on test environment physical quantity, carries out aerodynamic test under specific non-steady flow environment.The problem that wind tunnel cannot carry out non-steady flow simulation test and cannot provide important reference for automotive non-steady flow aerodynamic research is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automotive aerodynamics test technology, in particular to a non-steady flow environment aerodynamics test method based on the wake of a preceding vehicle. BACKGROUND

[0002] Automotive aerodynamics is a scientific field that studies the interaction between vehicles and air during motion. With the advancement of technology and the innovation of design, automotive engineers have applied aerodynamic principles to vehicle design. Optimizing aerodynamic design can improve fuel economy, acceleration performance, handling and stability of the vehicle, thereby improving the overall driving experience to achieve better performance, lower energy consumption and higher safety of the vehicle. Therefore, aerodynamic test of the vehicle is a very important part of vehicle research and design.

[0003] Existing automotive aerodynamic tests include wind tunnel tests and road tests. Wind tunnel tests are an important means for current automotive aerodynamic research because they are controllable, not affected by weather and have good repeatability. The purpose of automotive wind tunnel tests is to obtain accurate aerodynamic characteristic data that reflect the driving state of the vehicle, mainly studying the aerodynamic characteristics of the vehicle, the flow field characteristics of each part of the vehicle, the intake and exhaust characteristics of the engine cooling airflow, the ventilation, heating and noise characteristics in the driver's cabin, etc. However, existing automotive aerodynamic wind tunnel tests are mainly carried out under steady flow conditions, which is quite different from the actual situation of the vehicle on the real road. The common state of the vehicle on the road is in a non-steady flow condition, especially when there are wake of preceding vehicle, overtaking, meeting, driving through tunnels and bridges, etc. The non-steady characteristics faced by the vehicle are further enhanced, which leads to a large deviation between the research results of the conventional steady flow in the existing wind tunnel and the actual situation, so that the test data cannot better meet the reference requirements of the aerodynamic test data for the development of existing vehicle design. SUMMARY

[0004] The present application aims to provide a non-steady flow environment aerodynamics test method based on the wake of a preceding vehicle to solve the problem that the existing wind tunnel cannot perform non-steady flow simulation test, thereby failing to provide important reference for automotive non-steady flow aerodynamics research.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solution: a non-steady flow environment aerodynamics test method based on the wake of a preceding vehicle, applied to an automotive environmental wind tunnel simulation system, comprising the following steps:

[0006] S1, installing an environment measuring device on a test vehicle, performing a stable flow test calibration on the test vehicle, obtaining a first environment physical quantity based on the environment measuring device, and establishing a corresponding relationship between the first environment physical quantity and a stable flow environment physical quantity;

[0007] S2, placing the test vehicle in a non-stable flow environment;

[0008] S3, obtaining a second environment physical quantity from the environment measuring device in the non-stable flow environment, determining a test environment physical quantity of the non-stable flow environment in which the test vehicle is located based on the corresponding relationship and the second environment physical quantity;

[0009] S4, performing an aerodynamic test in a specific non-stable flow environment based on the test environment physical quantity.

[0010] The beneficial effects of the present scheme are: 1. A controllable non-stable flow environment aerodynamic test environment based on the wake of a preceding vehicle is created for the test vehicle to be tested, which makes up for the defects of aerodynamic research in non-stable flow test data in whole vehicle testing, provides an important reference for non-stable flow aerodynamic research in the automotive industry, and effectively improves the consistency of the automotive aerodynamic development environment and the actual driving environment, providing technical support and reference for engineering practice.

[0011] 2. In the non-stable flow simulation environment, the test environment physical quantity becomes an unknown quantity, but the second environment physical quantity can be accurately measured by the environment measuring device. The position of the environment measuring device and the test vehicle remain unchanged. Based on the corresponding relationship between the stable flow environment physical quantity and the first environment physical quantity obtained in S1, the non-stable flow aerodynamic environment physical quantity of the test vehicle in the current test condition can be calculated, i.e. the test environment physical quantity is obtained. Then, the test results of the test vehicle in the non-stable flow environment are recorded based on the test environment physical quantity, and the aerodynamic test data under the non-stable flow condition is obtained.

[0012] Preferably, in S2, the test vehicle is placed in a non-stable flow environment by placing a simulation vehicle in front of the test vehicle, and the test environment physical quantity of the non-stable flow environment in which the test vehicle is located is adjusted by changing the type of the simulation vehicle and adjusting the placement state of the simulation vehicle.

[0013] Preferably, in S2, the different placement states of the simulation vehicle are achieved by changing the placement angle and distance of the simulation vehicle relative to the test vehicle, and the types of the simulation vehicle include a sedan, an SUV, an MPV, a pickup truck, and a medium truck.

[0014] Preferably, in S3, the correspondence between the test environment physical quantity in the non-steady airflow test environment, the simulation vehicle placement state and the simulation vehicle model is established based on the test environment physical quantity, which further facilitates the simulation of a specific non-steady airflow test environment.

[0015] Preferably, in S1, the first environment physical quantity obtained by the installation environment measuring device includes airflow speed, airflow direction, turbulence intensity, environment temperature, environment humidity and atmospheric pressure.

[0016] Preferably, in S1, the environment measuring device includes a plurality of sensors, and the installation positions of the plurality of sensors include any one or more of the front of the vehicle, above the vehicle hood and above the roof.

[0017] Preferably, the correspondence between the first environment physical quantity and the steady airflow environment physical quantity includes airflow speed, airflow direction, turbulence intensity, environment temperature, environment humidity and atmospheric pressure.

[0018] Preferably, in S1, the steady airflow test calibration test environment includes a plurality of wind speeds, a plurality of angles and a plurality of combination test environments of the two.

[0019] Preferably, in S4, before the aerodynamic test under a specific non-steady airflow test environment is performed, it is verified whether the airflow environment measured by the test vehicle is consistent with the required non-steady airflow test environment, and if so, the test is started.

[0020] Preferably, the placement angle of the simulation vehicle relative to the test vehicle ranges from -30° to 30°, and the distance between the simulation vehicle and the test vehicle is set to any one of 3m, 4m, 5m and 6m. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the test method in the embodiment of the present application is shown;

[0022] Figure 2 The relationship diagram between the steady airflow and the test vehicle in the embodiment of the present application is shown;

[0023] Figure 3 The airflow speed correspondence diagram established in the steady airflow calibration test in the embodiment of the present application is shown;

[0024] Figure 4 The airflow angle correspondence diagram established in the steady airflow calibration test in the embodiment of the present application is shown;

[0025] Figure 5 The schematic diagram of the placement angle of the simulation vehicle in the embodiment of the present application is shown;

[0026] Figure 6This is a schematic diagram illustrating the simulated vehicle placement distance in an embodiment of the present invention;

[0027] Figure 7 This is a diagram showing the relationship between the placement angle and turbulence intensity in an embodiment of the present invention;

[0028] Figure 8 This is a graph showing the relationship between placement distance and turbulence intensity in an embodiment of the present invention. Detailed Implementation

[0029] The following detailed description illustrates the specific implementation method:

[0030] The reference numerals in the accompanying drawings include: test vehicle 1, simulated vehicle 2.

[0031] Example

[0032] The basic implementation examples are as follows: Figures 1-8 As shown, Figure 1 This paper presents an aerodynamic testing method for unsteady incoming flow environments based on the wake of a preceding vehicle. It utilizes existing automotive wind tunnel simulation systems to simulate the incoming flow environment of vehicles under road driving conditions, further improving the testing environment and method. Based on testing requirements, it creates a controllable aerodynamic testing environment for the test vehicle based on the wake of a preceding vehicle, compensating for the deficiencies in unsteady incoming flow test data in whole-vehicle testing aerodynamics research. This provides an important reference for unsteady incoming flow aerodynamic research in the automotive industry, effectively improving the consistency between the automotive aerodynamic development environment and the actual driving environment, and providing technical support and reference for practical engineering applications.

[0033] This experimental method specifically includes the following steps:

[0034] S1. An environmental measurement device is installed on the test vehicle to perform a stable incoming flow test calibration on the test vehicle. The first environmental physical quantity is obtained based on the environmental measurement device, and the correspondence between the first environmental physical quantity and the stable incoming flow environmental physical quantity is established.

[0035] The test vehicle is the vehicle to be tested. Aerodynamic testing of the test vehicle focuses on the impact of air resistance on the vehicle during driving. This leads to improvements in the vehicle's exterior design, external components that cause air resistance (such as rearview mirrors, door handles, and lights), surface friction, and internal air resistance (i.e., resistance caused by airflow passing through the radiator and engine in the front of the vehicle). The goal is to enhance the driving experience and passenger safety. Therefore, environmental measurement devices need to be installed on the test vehicle to obtain data on various environmental physical quantities in the actual environment in which the test vehicle operates.

[0036] The environment physical quantity obtained by the environment measuring device installed at the installation position of the environment measuring device during the stable incoming flow calibration test is a first environment physical quantity; and the stable incoming flow environment physical quantity is the environment physical quantity of the airflow output by the automobile environment wind tunnel simulation system according to the system setting, which can be consistent with the system setting data according to the existing function of the wind tunnel. The first environment physical quantity and the stable incoming flow environment physical quantity both include airflow speed, airflow direction, turbulence intensity, environment temperature, environment humidity and atmospheric pressure.

[0037] The environment measuring device includes a plurality of different sensors, and in this embodiment, the data of airflow speed and airflow direction are measured by a five-hole probe, the turbulence intensity of the airflow is measured by a cobra probe, the airflow environment temperature and environment humidity are measured by a temperature and humidity sensor, and the atmospheric pressure of the airflow is measured by a barometer. All the above sensors are installed on the test vehicle, and the installation positions include the front of the test vehicle, the top of the test vehicle roof and the top of the test vehicle hood, and the specific installation position can be set according to the actual situation of the test vehicle.

[0038] When the wind tunnel starts to perform the stable incoming flow test, the main fan in the wind tunnel blows the airflow to the test vehicle through the air duct, thereby realizing the simulation of the road driving state of the test vehicle in the wind tunnel. The existing automobile environment wind tunnel simulation system can accurately control the wind direction, speed, humidity, temperature and atmospheric pressure of the air flow through the air duct, but there is a certain distance between the outlet of the air duct and the position where the test vehicle is placed. After the airflow flows through this distance, there will be a certain gap between the stable incoming flow environment physical quantity originally controlled by the wind tunnel and the first environment physical quantity obtained by the sensors of the test vehicle, and the first environment physical quantity measured by different types of test vehicles will be different. Then, after the test vehicle is determined, the test vehicle needs to be calibrated for stable incoming flow test. At the same time, in order to avoid the situation that the environment physical quantity required for subsequent test exceeds the calibration range due to too small test calibration range, the set stable incoming flow should include multiple wind speeds, multiple angles and various combinations of the two during the stable incoming flow test calibration, specifically including 136 combined conditions of the two two-by-two combinations of the stable incoming flow wind speed set as 60 km / h, 70 km / h, 80 km / h, 90 km / h, 100 km / h, 110 km / h, 120 km / h, 130 km / h and the yaw angle of the stable incoming flow relative to the test vehicle as -15°, -12°, -9°, -7°, -5°, -3°, -2°, -1°, -0°, 1°, 2°, 3°, 5°, 7°, 9°, 12°, 15°.

[0039] As Figure 2As shown, the embodiment takes airflow speed and airflow direction as examples to illustrate: the wind tunnel continuously outputs stable airflow with speed V1 and angle θ1 to the test vehicle, and the environmental measurement device installed on the test vehicle measures the speed V2 and angle θ2 of the stable airflow, V1 and θ1 are the stable airflow environmental physical quantities, V2 and θ2 are the first environmental physical quantities actually measured, and the corresponding relationship between the airflow speed and airflow direction can be established based on the measurement under multiple working conditions.

[0040] Part of the data of the two environmental physical quantities is shown in the following table:

[0041] [V1 (given)] [V2 (measured)] [theta1 (given)] [theta2 (measured)] 60 km / h 67 km / h 0° 0° 70 km / h 78.3 km / h 1° 1.05° 80 km / h 89.6 km / h 2° 2.25° 90 km / h 101 km / h 3° 3.25° 100 km / h 112.3 km / h 5° 5.55° 110 km / h 123.6 km / h 7° 7.65° 120 km / h 135 km / h 9° 9.95° 130 km / h 146.3 km / h 12° 13.15°

[0042] First, in combination with Figure 3 As shown, based on multiple V1 and V2 data, the corresponding coordinate system under stable airflow conditions is established, so that the functional relationship between V1 and V2 is obtained according to the coordinate system, and the corresponding relationship between the airflow speed in the stable airflow environment and the airflow speed at the installation position of the environmental measurement device is obtained, and the specific relationship is V1 = 0.8904*V2, and then the airflow speed value measured by the environmental measurement device can be combined with the relationship to calculate the airflow speed.

[0043] Similarly, as Figure 4 As shown, based on multiple θ1 and θ2 data, the coordinate system between them under stable airflow conditions is established, so that the functional relationship between θ1 and θ2 is obtained according to the coordinate system, and the corresponding relationship between the airflow angle (i.e. airflow direction data) in the stable airflow environment and the airflow angle at the installation position of the environmental measurement device is obtained, and the specific relationship is θ1 = 0.9084*θ2, that is, the airflow angle value measured by the environmental measurement device can be combined with the relationship to calculate the airflow angle data. Other environmental physical quantities can be determined by the same method.

[0044] S2, the test vehicle is in a non-stable airflow environment.

[0045] In this embodiment, a method for setting the test vehicle in a non-stable airflow environment of the front vehicle wake in the wind tunnel environment is given, that is, a simulation vehicle for changing the test environment is placed in front of the test vehicle, and the airflow is disturbed by the blocking action of the front simulation vehicle, and the stable airflow is changed into a non-stable airflow, and a more realistic non-stable airflow road driving state simulation working condition is realized.

[0046] Meanwhile, when the test environment in which the test vehicle is placed in front of the simulation vehicle to generate the unsteady flow is set, by changing the type of the simulation vehicle and adjusting the placement state of the simulation vehicle, the numerical value of the test environment physical quantity of the unsteady flow in which the test vehicle is placed can also be adjusted, and then various test working conditions of the test vehicle in the unsteady flow can be created. The type of the simulation vehicle includes a car, an SUV, an MPV, a pickup truck and a medium truck, and the simulation vehicle selected in the embodiment is an SUV. Meanwhile, as shown in FIGS. 1 and 2, the adjustment of the placement state of the simulation vehicle is achieved by changing the placement angle and the placement distance of the simulation vehicle relative to the test vehicle. The placement angle of the simulation vehicle relative to the test vehicle ranges from -30° to 30°, and the distance between the simulation vehicle and the test vehicle is set to be any one of 3 m, 4 m, 5 m and 6 m. The actual situation of the too large placement angle and the too far or too close placement distance is less, and thus the remaining working conditions are not tested in the embodiment. Figure 5 and Figure 6

[0047] The simulation vehicle with different types and different placement states can simulate different unsteady flow test environments. As shown in FIGS. 1 and 2, the relationship diagram between the placement angle of the simulation vehicle and the turbulence intensity and the speed of the airflow, and as shown in FIGS. 3 and 4, the relationship diagram between the placement distance of the simulation vehicle and the turbulence intensity and the speed of the airflow, further indicate that various unsteady flow test environments can be simulated by adjusting the placement state of the simulation vehicle. Figure 7 Figure 8

[0048] S3, in the unsteady flow environment, the second environment physical quantity is obtained by the environment measuring device, and based on the corresponding relationship and the second environment physical quantity, the test environment physical quantity of the unsteady flow environment in which the test vehicle is placed is determined.

[0049] In the unsteady flow calibration test, the environment measuring device on the test vehicle obtains the second environment physical quantity at the installation position. In the unsteady flow simulation environment, the test environment physical quantity of the airflow after being blocked by the simulation vehicle becomes an unknown quantity, but the second environment physical quantity can be accurately measured by the environment measuring device. The position of the environment measuring device is unchanged, and the test vehicle is unchanged. Based on the corresponding relationship between the stable flow environment physical quantity and the first environment physical quantity obtained in S1, the environment physical quantity of the unsteady flow airflow in which the test vehicle is placed under the current test working condition can be inversely calculated, that is, the test environment physical quantity is obtained. Then, the manifestation of the test result of the test vehicle in the unsteady flow environment is recorded according to the test environment physical quantity, and the aerodynamic test data under the unsteady flow working condition is obtained.

[0050] ​​​The two environmental physical quantities of airflow speed and airflow direction are further illustrated in this embodiment. It is assumed that in the non-steady airflow condition, the airflow speed of the non-steady airflow is V3, and the airflow angle is θ3; the airflow speed measured by the environmental measurement device in the non-steady airflow condition is V4, and the airflow angle is θ4; according to the corresponding relationship between the environmental physical quantities obtained in S1, the following is derived:

[0051] V4=0.8904*V3

[0052] θ4=0.9084*θ3

[0053] Thus, the data of the airflow speed V3 and the airflow angle θ3 of the non-steady airflow can be calculated according to the measured V4 and θ4. In addition, other environmental physical quantity data in the non-steady airflow condition can be calculated by the same method.

[0054] In order to further improve the test efficiency, in this embodiment, based on the test environmental physical quantity, a corresponding relationship between the test environmental physical quantity in the non-steady airflow test environment and the placement state of the simulation vehicle and the simulation vehicle model is further established, so that in the test process, based on the test requirements, the placement state of the simulation vehicle can be directly set to more conveniently realize the specific non-steady airflow test environment simulation operation. When establishing the corresponding relationship between the non-steady airflow test environment and the placement state of the simulation vehicle and the simulation vehicle model, the environmental physical quantities involved also include airflow speed, airflow direction, turbulence intensity, environmental temperature, environmental humidity, and atmospheric pressure.

[0055] S4, based on the test environmental physical quantity, perform aerodynamic test in specific non-steady airflow environment.

[0056] Through the above steps, the relationship between the placement state of the simulation vehicle and the non-steady airflow environmental physical quantity can be determined, so that in actual test, according to different test requirements (test needs, i.e. test vehicle needs to be tested in specific non-steady airflow environment), the model and placement state of the simulation vehicle can be directly determined, and it is further verified whether the airflow environment measured by the test vehicle is consistent with the required non-steady airflow test environment. If consistent, the aerodynamic force test can be started to ensure that the test data is referable.

[0057] Through the test method, the non-steady flow environment is established and the whole vehicle aerodynamic test is completed. Through the calibration of the steady flow test, the corresponding relationship between the physical quantity obtained by the environmental measurement device installed on the test vehicle and the flow is determined. Then, by changing the test environment, the test vehicle is placed in the non-steady flow environment. The data of the physical quantity of the test environment in the non-steady flow environment is calculated through the corresponding relationship. Then, the test vehicle is tested in the known non-steady flow environment, so as to ensure the referenceability of the obtained test data. At the same time, the consistency of the development environment and the actual driving environment of the automobile aerodynamics can be effectively improved, and technical support and reference for engineering practical application can be provided. In addition, after the test method completes the setting of the non-steady flow test condition, in addition to the aerodynamic test, the noise test test can also be carried out.

[0058] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the present application. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A method for aerodynamic testing in unsteady flow environments based on the wake of a preceding vehicle, characterized by: Be applied to automobile environment wind tunnel simulation system, It includes the following steps: S1, install the environment measuring device on the test vehicle, and calibrate the stable flow test of the test vehicle, wherein the test environment of the stable flow test includes multiple wind speeds, multiple angles, and multiple combination test environments of the two, obtain the first environment physical quantity based on the environment measuring device, and establish the corresponding relationship between the first environment physical quantity and the stable flow environment physical quantity; S2, the test vehicle is in a non-stable flow environment; S3, in the non-stable flow environment, the second environment physical quantity is obtained by the environment measuring device, the test environment physical quantity of the non-stable flow environment where the test vehicle is located is determined based on the corresponding relationship and the second environment physical quantity; S4, based on the test environment physical quantity, the aerodynamic test under the specific non-stable flow environment is carried out.

2. The method according to claim 1, wherein the method is characterized by: In S2, the test vehicle is placed in a non-stable flow environment by placing a simulation vehicle in front of the test vehicle, and the test environment physical quantity of the non-stable flow environment where the test vehicle is located is adjusted by changing the type of the simulation vehicle and adjusting the placement state of the simulation vehicle.

3. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 2, characterized in that: In S2, different placement states of the simulation vehicle are realized by changing the placement angle and distance of the simulation vehicle relative to the test vehicle, and the type of the simulation vehicle includes sedan, SUV, MPV, pickup truck and medium truck.

4. The method according to claim 3, wherein the method is characterized by: In S3, based on the test environment physical quantity, the corresponding relationship between the test environment physical quantity in the non-stable flow test environment and the placement state of the simulation vehicle and the type of the simulation vehicle is established, which further facilitates the realization of specific non-stable flow test environment simulation.

5. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 4, characterized in that: In S1, the first environment physical quantity obtained by installing the environment measuring device includes airflow speed, airflow direction, turbulence intensity, environment temperature, environment humidity and atmospheric pressure.

6. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 5, characterized in that: In S1, the environment measuring device includes a plurality of sensors, and the installation position of the plurality of sensors includes any one or more of the front of the vehicle, the top of the vehicle hood and the top of the vehicle roof.

7. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 6, characterised in that: The corresponding relationship between the first environment physical quantity and the stable flow environment physical quantity includes airflow speed, airflow direction, turbulence intensity, environment temperature, environment humidity and atmospheric pressure.

8. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 7, characterized in that: In S4, before the aerodynamic test under the specific non-stable flow test environment is carried out, it is verified whether the flow environment measured by the test vehicle is consistent with the required non-stable flow test environment, and if so, the test is started.

9. A method of unsteady flow environment aerodynamic testing based on the wake of a preceding vehicle as claimed in claim 8, characterised in that: The placement angle of the simulation vehicle relative to the test vehicle ranges from -30° to 30°, and the distance between the simulation vehicle and the test vehicle is set to any one of 3m, 4m, 5m and 6m.

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