Abstract
An air conditioning equipment is usually set in a rail vehicle in order to keep comfortable However the noise is offensive to the ear especially when the rail vehicle is under suspension. Then the noise reduction is very important from the point of view of keeping the car room comfortable and one of the distinguished techniques. This paper describes acoustic and flow noise characteristics of the bending duct The experiments were carried out in various parameters such as the absorbing ability, bending numbers and flow velocities by use of the bending duct As a result it was clarified that the noise reduction effect due to the bending is proportional to the number of times of bending. Moreover the reduction of pressure fosses by use of the guide and the airfoil is very effective to the noise reduction.v
