Development of Low-noise Air Conditioning Ducts

Air conditioners need to be installed under the car floor in order to reduce wayside noise when increasing Shinkansen speed. Currently, rolling stock used for through service between conventional and Shinkansen lines have cabin units on their roofs for air conditioners due to limitations of underfloor space, so those cabin units will have to be relocated under the floor along with existing underfloor units for rolling stock that will be manufactured in the future. From the viewpoint of effectiveness in space conservation, an all-in-one underfloor air conditioner is desirable in that location. Conversely, such an air conditioning system has a disadvantage in terms of cabin noise because the two separate air conditioners and one ventilator have to be combined into one unit that generates more noise. Thus, the authors worked on reduction of cabin noise by the FASTECH360Z air conditioning system. During development, the authors produced a mockup model of air conditioning ducts for actual cars and used that model to evaluate the air conditioning system generated noise and to improve the ducts. The authors have successfully reduced the cabin noise by the air conditioning system of the FASTECH360Z by 3.4 dB as a result.