Ratings of cars by aerodynamic properties and modern approaches of 3D modeling of external body shapes

Abstract

The work is devoted to the development of passenger car aerodynamics, which began at the beginning of the 20th century. Radical changes to the shape of the body are not enough, the main attention is focused on the surface elements, their optimization is being carried out while preserving the overall shape determined by the design concept. Much attention has always been paid to the improvement of car aerodynamics, especially to the study of frontal drag - the most important factor affecting the traction and operational qualities of a car. During this time, it was possible to significantly reduce the coefficient of aerodynamic resistance Sh. When developing the external shape of the body, the designers strive to give it such contours that the air flows around it as smoothly as possible, without swirls and disruptions of the flow, i.e., that the surface is visually attractive with the correct shapes and with the most streamlined silhouette.

The relevance of the problem is reduced to the improvement of the external forms of the car, therefore, during development, five components of the overall aerodynamic resistance of the car are taken into account: the resistance of the form; inductive; superficial; interference resistance and resistance of internal flows. The share of each of these components varies depending on the type of car, but, usually, shape resistance accounts for 60...70% of the total aerodynamic resistance, inductive - 7...12% (large values are typical for passenger cars), surface - about 5 ...8%, internal flow resistance - 8...11%.

The purpose of the work is to analyze the influence of the components of the overall aerodynamic resistance C_x on the operational properties of passenger cars (speed, fuel consumption, safety, convenience and comfort during driving) with the formation of a general rating assessment.

In general, it is shown that cars of the last period are characterized mainly by wedge-shaped shapes, to which almost all automobile companies in the world have switched. From the point of view of improved aerodynamic properties, these are cars of small and medium classes (classes B, C and E). On the basis of significant research in this field, the improvement of automotive technologies, aimed primarily at improving fuel economy and dynamic properties, manufacturers managed to achieve relatively low drag. At present, the best representatives of this class have closely approached the value of С_х = 0,29 ... 0,30, which is the limit for the current level of technology. Further efforts of researchers are aimed at reducing the resistance created under the hood, reducing pollution and improving acoustic characteristics.