Automobile positive projection area measuring method

Abstract

The invention provides an automobile positive projection area measuring method, which comprises the following steps of 1, putting a sample automobile to be tested onto a flat and straight road; 2, putting a reference plate with the known area at the tail end of a sample automobile and tightly attaching the reference plate to the sample automobile; putting the upper edge of the reference plate in a position aligned with the height of the sample automobile; enabling the reference plate to be vertical to the flat and straight road, and the transverse length of the reference plate to be greater than the width of the sample vehicle; 3, installing a background plate behind the reference plate; 4, installing a camera right in front of the sample automobile; right aligning a lens of the camera with the front side of the sample automobile; enabling the height of the lens of the camera to be positioned between the upper edge of the sample automobile windshield and the upper end of an engine cover; 5, after the setting completion, shooting sample photos; importing the sample photos into a computer; selecting optimum sampling photos to be imported into CAD (computer-aided design) processing software; 6, after the sample automobile outline area and the reference plate outline area in the sample photos are respectively calculated, calculating the positive projection area of the sample automobile according to a formula; taking an average value which is the positive projection area of the sample automobile. The method has the advantages that the requirements on the equipment are low; the cost is low; the measurement speed is high.

Description

technical field [0001] The invention relates to the measurement of the aerodynamic parameters of the whole vehicle, in particular to a method for measuring the front projection area of ​​the vehicle. Background technique [0002] The air resistance of a car is one of the four major resistances to its driving. It is the main factor affecting fuel consumption, acceleration, and handling, and affects the power and fuel economy of the car. The air resistance of a car refers to the sum of the resistance from the two sources of pressure and friction caused by the interaction between the surrounding air and the car body, chassis and convex parts when the car is running. The international general formula for calculating the air resistance of automobiles is as follows: Fw=0.5×V^2×ρ×Cd×A; where V is the relative speed between the car and the air in the direction of the car’s driving, and generally defaults to the speed of the car itself or the speed in the wind tunnel test. ρ is the ...

AI Technical Summary

Problems solved by technology

[0005] This method has high test accuracy, but the disadvantage is: high-intensity parallel laser emission device is required, the equipment itself is expensive, and the high-precision one may cost more than 800,000; the subsequent 1:1 projection contour drawing and area test are also required. It is time-consuming and labor-intensive

Therefore, the economic, human and time costs are high

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