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[YesAuto basic knowledge] How can I experience the changes from minus 40℃ to minus 60℃ and various climatic conditions? I think most readers think that the most effective way is to fly directly from the North and South Pole to the hot Sahara Desert; for developers who do road tests all the year round, this may be between Mohe in the winter and the Tarim Desert in the following summer. Distance; for the Roewe RX5, this is just all it has experienced during its stay in the thermal wind tunnel for a week.

So what method does the thermal wind tunnel use to achieve the wind and rain, and the alternating cold and heat? What made SAIC determined to spend 150 million yuan to build such a laboratory? In addition, what are the connections between the thermal wind tunnel and the Roewe RX5 that will be launched this year? With these questions, I came to SAIC's R&D center in Anting Town, Shanghai to find out.

● What is a thermal wind tunnel? A wind tunnel that simulates various extreme weather conditions .

When it comes to wind tunnels, the first thing you think of should be the mechanical wind tunnel used to test the aerodynamic design of the car body. However, the thermal wind tunnel system built by SAIC is not for this purpose. Thermal wind tunnels are also called thermodynamic wind tunnels. Its role is more to simulate most extreme weather conditions in the natural environment, and to place vehicles in such environments for corresponding tests. According to SAIC staff, during the entire new product development process, the ratio of thermal wind tunnel test to road test has reached 10:1 , which shows that this equipment is very important to SAIC.

● How is the wind tunnel test different from the actual road test? The test conditions are more controllable .

Since the thermal wind tunnel is to simulate various climatic conditions in the natural environment, shouldn’t it be enough to just throw the vehicle to a place with harsh environment? However, the reality is not entirely true. After all, God’s temper is unclear . It is possible for the test team to wait a week in the field without waiting for a suitable test environment. This makes the results of the road test uncontrollable. The purpose of SAIC's establishment of a thermal wind tunnel is to test vehicles under the premise of a controllable climate, which is helpful for improving the reference and objectivity of the data.

Of course, having a thermal wind tunnel does not mean that road test engineers will lose their jobs. Most of the initial design and calibration work of product development replaced by wind tunnel tests. After the vehicle is basically ready, the prototype car still has to go All parts of the country verify the previous design and modification to confirm whether the previous work is effective and whether the vehicle can actually be mass-produced.

● Wind tunnel construction process: The total investment is 150 million yuan and it took more than 4 years to complete .

SAIC Thermal Energy’s wind tunnel project started in May 2011, with a total investment of about 150 million yuan, which is considered to be comparable to the larger-scale wind tunnel of Tongji University (that is, the Shanghai Ground Transportation Wind Tunnel Center), which cost 500 million yuan. It's relatively “cheaper”. Construction officially started in June 2013, and was completed and put into use on September 18, 2015. After being put into use, the first vehicle to be tested by it is the SUV that will be launched this year-Roewe RX5. From the outside, the wind tunnel test room is just a small white building, which looks very inconspicuous.

Previously, General Motors Shanghai Pan Asia Automotive Technology Center also established a thermal wind tunnel laboratory. Its building scale and experimental purpose are basically the same as SAIC’s laboratory. It uses a vertical air duct and has many functions such as rainfall, snowfall, and sunshine. . As for the wind tunnel center of Tongji University…it uses a horizontal air duct, and the parking room is more spacious. It can not only test ordinary passenger cars, but also heavy trucks and buses.

● What are the main functions of the thermal wind tunnel? At present, there are more than ten kinds of test projects .

Thermal wind tunnels can simulate various extreme weather conditions encountered or impossible in reality, and test various performances of vehicles in this environment. In addition to the basic winter cold start, air-conditioning and refrigeration performance, window defrosting/defogging performance, for new energy vehicles, cruising range tests can also be carried out in the wind tunnel.

● Roewe RX5 field experience project:

Due to the limited time to visit, we only saw part of the test items of Roewe RX5 in the wind tunnel. Before the start of the test, the test vehicle will first enter the immersion room (a small room where the test vehicle is preheated/cooled to the test temperature and the condition of the vehicle is checked at the same time) for initial inspection. The adjustable range of the temperature in the immersion compartment is -40~60℃ as in the parking compartment, so that the vehicle can be prepared for preheating/cooling before entering the parking compartment for testing, especially when there are many test vehicles and heavy tasks Can improve work efficiency.

The adjustable temperature range of the thermal wind tunnel is -40~60℃, and can simulate weather conditions such as sunrise and sunset, cloudy, sunny, rainy and snowy. With the wind tunnel, the test during the entire R&D process will not be affected by the actual external weather conditions, thus shortening the test time of the new car, which is also beneficial to shorten the R&D cycle.

It’s not enough to just be a solarium SPA. Next, I’ll take a good shower. The humidity adjustment range in the thermal wind tunnel is 5%~95%, and with direct lighting, it can jump from the dry desert climate to the sweltering rainy weather in one day. The wind tunnel can also turn rain into snow, and reduce the indoor temperature to a temperature lower than that of the freezer compartment of a household refrigerator. Vehicles in an extremely cold environment need to test the starting system, battery life, and anti-icing and snow immersion capabilities. Confirm that the vehicle is reliable in various environments. However, due to the extremely high energy consumption of the ice and snow test, it takes about two days of preparation time, so we did not experience it on site.

● Article summary:

Although thermal wind tunnels are not very advanced equipment in the automotive industry, the high initial investment and high operating costs are not affordable for all car companies. According to reports, the hourly use cost of SAIC's wind tunnel laboratory is 13,500 yuan , and the cost per minute is 225 yuan , which is much cheaper than the price of 400 yuan per minute in the Tongji University wind tunnel. In addition, after the completion of the wind tunnel, a lot of the cost and labor cost of the preliminary road test are saved. As long as the Roewe and MG brands continue to introduce new ones, building a thermal wind tunnel is relatively cost-effective.

From the product level, after having a wind tunnel, the product can be tested more carefully and rigorously. After simulating various extreme conditions, possible hidden dangers and problems will be exposed as soon as possible for subsequent modifications and adjustments. It is also very beneficial for the development of new products, and it is also helpful to improve the reliability of the products. It is reported that in the future, all traditional power passenger cars and new energy vehicles of SAIC Motor will experience heat and wind power. The Roewe RX5 is expected to announce the price on June 16, which makes us very looking forward to it. As for more new models in the future, we will wait and see.