What is a Wind Tunnel? 100, What is a wind tunnel?

Wind tunnel is a kind of pipe-like experimental equipment that can artificially generate and control air flow to simulate the flow of gas around aircraft or objects, and can measure the effect of air flow on objects and observe physical phenomena, and it is the most commonly used and effective tool for aerodynamic experiments.

Wind tunnel experiments are an indispensable part of aircraft development. It not only plays an important role in the research and development of aviation and aerospace engineering, but also is indispensable in the fields of transportation, housing construction, and wind energy utilization with the development of industrial aerodynamics. In this way, the flow conditions are easy to control, but the important basis is the principle of relativity of motion.

During the experiment, the model or physical object is often fixed in the wind Forte and the experimental data is obtained economically. In order for the experimental results to be accurate, the flow during the experiment must be similar to the actual flow state, that is, the requirements of the similarity law must be satisfied. However, due to the size and dynamics of the wind tunnel, it is difficult to simulate all similar parameters in a wind tunnel at the same time, and it is usually necessary to select the most influential parameters for simulation according to the topic to be studied.

In addition, the quality of the flow field in the wind tunnel experimental section, such as the uniformity of the airflow velocity distribution, the deviation of the average airflow direction from the axis of the wind tunnel, the pressure gradient along the axis of the wind tunnel, the uniformity of the cross-section temperature distribution, the turbulence and noise level of the airflow, etc., must meet certain standards and be checked and measured regularly.

Wind tunnel is a kind of pipe-like experimental equipment that can artificially generate and control air flow to simulate the flow of gas around aircraft or objects, and can measure the effect of air flow on objects and observe physical phenomena.

Wind tunnel is an indispensable part of aircraft development.

Poem Title: Wind TunnelDynasty: MingFull Text:

The cliff is a thousand jade and exquisite, and the dust is collected and the smile is cold.

The solution to the leakage refers to the song of Yu Dize, and the control of the border is long to remember the great Wang Xiong.

The sunny screen is seen layer by layer, and the road into the gate of heaven is faintly passed.

The origin of Xun's life is gradually Haiyu, and the sunset grass is in autumn.

When developing a car, the world's leading automotive companies first make a 1:2 or 1:1 clay model of the car, and then conduct experiments in the wind tunnel to test the performance of the car model in the moving air, and then continuously modify and improve.

An automobile wind tunnel is a large-scale experimental facility used to study the aerodynamics of automobiles, and is a pipe used to generate artificial air flow (artificial wind). There are two wind tunnels in BMW's new aerodynamic test center: a wind tunnel called aerolab, which can test 1:2 models of automotive clay; The other, called the "Main Wind Tunnel", can test 1:

1 model of car clay. According to the experimental situation, the details of each part of the body are modified to make the drag coefficient meet the design requirements, and then the three-dimensional coordinate measuring instrument is used to measure the shape of the body, draw the body drawings, and carry out the design and production of the body heavy pressure mold. In fact, the wind tunnel is not a hole, but a large tunnel or pipe, which is more in line with the original meaning of his English name wind tuennl, which I don't know who translated it as a wind tunnel.

Inside there is a giant fan blade that creates a strong air current. The airflow passes through some style grilles to reduce the generation of vortex before entering the laboratory. The biggest function of the wind tunnel is to measure the wind resistance of the car, the size of the wind resistance is expressed by the wind resistance coefficient CD, the smaller the wind resistance coefficient, the less it is affected by the air resistance.

Of course, in addition to measuring wind resistance, wind tunnels can also be used to study the effects of air currents around the body, such as lift, downforce, and to simulate different climatic conditions, such as hot and cold, rain or snow. In this way, engineers can know how the car works in different environments, especially the cooling water tank heat dissipation, brake heat dissipation and other issues. In the styling design stage of a new car, the car must be made into a wind tunnel test model for wind tunnel testing, so as to improve the shape of the car and improve the aerodynamic performance.

According to the size of the size, the wind tunnel can be divided into a wind tunnel for a reduced scale model test and a large wind tunnel for vehicle testing, and according to the form of air flow, the wind tunnel can be divided into two types: DC type and return flow type. With the method of road test, it is impossible to measure the six components of the air force at the same time, so the wind tunnel test has become the most effective means to study the aerodynamic performance of automobiles, and the wind tunnel is the first application in the aircraft manufacturing industry. There are model wind tunnels, real car wind tunnels and climate wind tunnels.

At present, there are not many real car wind tunnels in the world, mainly concentrated in Japan, the United States, Germany, France, Italy and other large automobile companies. At present, the largest wind tunnel in China is the wind tunnel laboratory of China Aviation Power Research Institute. He is mainly responsible for wind tunnel experiments in China's aerospace and aviation machinery, and can also be used as wind tunnel experiments for automobiles, buildings and sports equipment.

With the increasing scale of the aircraft, the lack of Reynolds number simulation ability in wind tunnel testing has become more prominent. There are many ways to improve the Reynolds number in the wind tunnel, among which reducing the total temperature of the test airflow has the advantages of low cost and operating cost, and the same model can be used to carry out the variable Reynolds number test under the same total pressure condition, which can avoid the additional error caused by the change of shape caused by different models and the change of load, and make the Reynolds number effect test results more reliable. Under the same conditions of model size and total airflow pressure, the total temperature of the test airflow is reduced from the original 322K to 100K, the Reynolds number can be increased by 5 times, and the driving power can be reduced by 45.

To put it simply, cryogenic wind tunnels are used for the design of aircraft. Because the temperature is low, the test is easier to do, so a low-temperature wind tunnel is used.