http://www.seipub.org/VE/paperInfo.aspx?ID=6995
An air conditioning equipment is usually set to keep a rail vehicle comfortable. However its noise is annoying especially when the vehicle is stationary. The noise reduction is very important from the point of view of keeping the car interior space comfortable and is one of the differentiating techniques for the manufactures. This paper describes characteristics of flow noise generated from the duct with some holes. Both the acoustic experiment and the flow experiment were carried out in various parameters such as the flow velocity, the absorbing ability and the hole area size by use of the straight duct. As a result, it was clarified that the noise reduction effect of the absorbing treatment could be neglected when the noise source was made only by the flow and is much when the fan noise is greater than the flow noise.