Abstract
Keywords: Weather strip, Rubber, Wind noise, Vortex, Fluid Dynamics, Sound pressure level, Wave equation, Aero-acoustics
Automobile weather-strip is a rubber or plastic product attached to door frame and used to help keep sound and vibration as well as water, snow, ice and dust out of vehicles. It has various forms such as fixed glass run, body-side, door-side and trunk lid. In the past, original function and strong endurance were requirements for automotive parts. Meanwhile, with the automotive industries developed, the high technologies have been required. Weather-strip is one of the important polymeric parts to meet the requirement above. Weather strip itself, however, sometimes causes wind noise due to the protuberance on a weather-strip. Sophisticated and various sectional shapes are prerequisites for the reduction of wind noise. This study was focused on calculating wind noise caused by protrusion part in the car exterior. Aero-acoustic noise isn´t issued under usual driving condition and speed but it makes topic in high speed region.
In this research, sound pressures level with and without weather-strip in tunnel test were compared. To measure wind noise of a weather-strip, wind tunnel test should be necessary because it is so difficult to distinguish wind noise with other noises generated from engine, gears and tires etc. It is not easy to calculate the sound pressure difference directly in fluid dynamics because acoustic pressure is smaller than energy difference by air flow. The vehicle door is the region where turbulent flow occurs due to a rear mirror. Prior to 3-dimensional analysis, 2-dimentional analysis was first performed and the noise-generated regions and tendencies were also checked followed by 3-dimensional analysis. Detailed flow phenomenon on weather-strip generating small turbulent flow was also simulated.