Search Results

This paper demonstrates the methods used to design an automobile engine cooling system. Basic terminology associated with the cooling system is defined. Topics covered include the radiator, fan, and coolant. The radiator is described in detail. The advantages of aluminum over copper/brass radiators are discussed, as well as the numerous tube, fin, and core designs of automobile radiators. Finally, experimental methods used in radiator and cooling fan selection are discussed. The experimental methods include dynamometer testing and the development of radiator/fan pressure drop vs. volumetric flow rate curves. Experimental data for radiator/fan curves of a typical racing car cooling system are presented. In addition, analytical techniques used to determine the maximum cooling capacity of radiators used for the Comell University Formula SAE Racing Car Team 1996 are described.

The transmission of sound through automotive glazing materials was investigated. The sound transmission loss in one-third octave bands of several different automobile windows was measured at a testing laboratory. The materials tested included monolithic (single-layer) glass, monolithic polycarbonate, and a double glazing with an air gap in between the two panes. The experimental data are given in the paper. Subsequently, a computer spreadsheet program was written and developed to predict the sound transmission loss of single-layer glazing materials, using empirical equations found in the literature. The predicted sound transmission loss values showed good agreement with the experimental values. The sound transmission loss spreadsheet is a useful, easy-to-use tool to predict the acoustic performance of automobile window glazing materials.

The transmission of aerodynamically-generated noise through panels in automobiles has become of more pressing interest in recent years. As automobile engines, transmissions, and tires have become quieter, wind noise has become more noticeable, particularly at higher speeds. Hence, an automobile manufacturer would like to know how to design the automobile to minimize the wind noise levels heard by the passengers. In this investigation, both experimental and analytical methods were applied to the problem. A simplified model of an automobile side window was subjected to wind tunnel tests. The effects of window thickness and edge conditions on the transmitted wind noise level were investigated. An attempt was made to analytically predict the transmitted noise level by using a simple Statistical Energy Analysis (SEA) model, which used an empirical expression for the fluctuating wall pressure on the window of an automobile.

As engine, tire, and other automobile noise is reduced and as driving speeds increase, aerodynamic noise sources on ground vehicles are becoming relatively more important. They often dominate at cruise speeds of 65 mph. Aspiration and leak noise are strong sources but generally can be controlled by known methods. Turbulent pressure fluctuations due to separated and vortical flows are also strong sources. Much interior noise is caused by transmission of these external pressure fluctuations through windows and other surfaces. The paper presents the variety of aeroacoustic sources on automobiles and reviews the state of experimental data, of analysis methods, and noise reduction principles. A new correlation method for predicting external fluctuating pressures in separated regions is presented.