BUSINESS IN A PIPE
At the beginning of the century, a car, like a sculpture, was sculpted. Without rushing, on a hunch, by trial and error. Today, the approach is different and the results are visible even to the naked eye.
A modern car, among other advantages, should have, as far as possible, low aerodynamic drag.
The first object of aerodynamic research at the VAZ was the G8. Before her, this process was very much like shooting a gangster action movie. Two cars raced side by side along the road. One, the subject, was glued with ribbons indicating the direction of the air currents, and the other, where the crew was, hung with movie cameras, fixed everything on tape. Many important parameters remained “behind the scenes” (it is not known how the wind walks under the hood, bottom, etc.). They tried to use the wind tunnels of aviation institutes, but the equipment, designed for other objects and speeds (the car is still not an airplane), did not answer many questions of motorists. The only suitable pipe was the Dmitrov Central Test Site TsNIIAT. However, each new plasticine model from Tolyatti to Moscow is not lucky - too far and troublesome. In the summer, delicate “sculptures” melted from the heat, and in winter they cracked from the frost.
Recently, the Special Testing Department of the General Development Department of the VAZ has been engaged in all this at the plant. In 1997, in Togliatti, its own full-blown wind tunnel appeared, designed by DSMA INTERNATIONALINC. In her womb, you can blow any cars with a cross-sectional area of up to four square meters or models of buses and trucks on a scale of 1: 2 and 1: 2.5.
The air flow creates the main fan - a cyclopean structure with a blade diameter of 7.4 meters, a maximum speed of 300 rpm and a flow speed of up to 60 m / s (216 km / h). At first, fearing to overload the power substation and leave the whole plant without light, they decided to start up the system (operating power - 2300 kW) only at night.
One of the main elements of the installation is the aerodynamic balance of Carl SCHENCK AG. They show the efforts with which the hurricane attacks the car. The buildup of the car under the pressure of the wind is recorded by a television camera - the amplitude is determined by the vibrations of the target fixed on its bottom. All information is received and processed by the electronic computer complex IBM.
Too bulky test objects are sent to the pipe in the form of reduced copies. They are made mainly of plasticine, so that the weight of the layout reaches 2-3 tons. It is not so easy to roll this ingot into the pipe, therefore, a special turntable is provided at the entrance.
They create models, however, not only because of the "oversize". In the process of fine-tuning, the shape of the car has to be changed more than once, and sometimes thoroughly. To build each life-size is long and expensive, especially since you can get by with models on a scale of 1: 5 or 1:10. To work with them in 1995, a four-fold copy of a full-blown pipe with all its main systems was involved. The requirements for purged layouts are high - the accuracy of surface reproduction, including the engine compartment and underbody, is 0.5 mm.
Research conducted on such equipment have considerable scientific value. But their main goal is a perfect car. And this is very difficult. For example, already at the finished G8, they found that the angle of inclination of the fifth door was incorrectly selected. She was in an aerodynamic shadow - and dirt was sticking to the glass from the road. They did not begin to change the geometry of the body (actually completely redoing it) - too expensive. Limited to installing a wiper. "Hump" on the roof of "Samara" also did not appear immediately. His task is to press the car harder to the road at high speed.
"Ten" was built differently. Working with mock-ups, and then with kind (then still in other people's pipes) helped to eliminate miscalculations at the design stage. The bottom was first streamlined. But they soon found out that at the same time the engine compartment and exhaust system are poorly cooled. The surface was "ruffled" by putting special aerodynamic shields (which some people mistakenly take for protection of the engine crankcase) as a compromise. Then they discovered that at speeds of more than 120 km / h, the wipers were torn off the glass, leaving a water film on it. And the machine got up on the conveyor with modified levers. There are many similar examples. But the most important thing, and this was already determined in his pipe, the drag coefficient (Cx) of the “tens” turned out to be lower than that of the “Ford Focus” (car of the year, 1999), “Alpha-156” (car of the year, 1998 ) and the new "Opel Astra."
Most cars work all year round, so VAZ has acquired its own aeroclimatic complex, in the laboratories of which they lay down the necessary “all-weather” qualities of the car. The basis of the complex is an aeroclimatic pipe, where you can recreate literally any road and climatic conditions. This happens approximately like this. The test object enters the running drums. Independent drives allow them to rotate at different frequencies, simulating descents, ascents and turns. You can even turn around on the spot! The total power of the "underground" mechanism is 400 kW. The oncoming air flow is created by a fan unit, thanks to which you can "race" at a speed of up to 250 km / h. Instead of the sun - a special radiator under the ceiling. The plastic floor covering is easily likened to hot sand or asphalt - a special system heats it to 75 ° C. Do not forget about rainfall. The operator has at his disposal a fine autumn rain, and tropical rain, and hail, and snowfalls of any intensity. The frost here can be serious - up to minus 45 ° С, and then the cameras tightened with hoarfrost and frozen grates for draining the melt water have to be heated.
Of course, the weather control center itself is reliably isolated from cataclysms inside the pipe, where there is only a car with a driver. For him, a monitor is installed in the camera in a special box, through which the driver is set all the parameters of the "movement" corresponding to the given test program.
In addition to the air pipe itself, the complex has several smaller test chambers. Baroclimatic, for example, allows you to "rise" to a height of up to 2700 meters above sea level.
Although we check our JI at every opportunity, this is not the only threat to the environment for transport. The current car is a collection of all kinds of artificial materials, which, when heated, emit not harmless substances. To assess the threat, conduct special tests. The car is allowed to "ride" on roller skates, heating it outside with artificial sun, and then driven into a sealed room, where the volume of fumes and their composition are measured. All these parameters are strictly normalized. So, when buying some exotic braid on the steering wheel, look for the Rosstandart sign on the label so that when it warms up in the sun, it does not turn the interior into a gas chamber.
By the way, the magazine plans to soon conduct a series of studies on this complex related to the daily operation of the car, which our readers will learn from the next issues.
As you can see, a car is a very delicate matter. And to bring a beginner “into the people” today is only possible for specialists with the most advanced testing equipment.