Abstract
Experimental studies were conducted to clarify unexpected vibrations which occur in a cylindrical filter made of unwaven cloth. The cloth is made of polypropylene which catches dust from an air conditioner by static electricity. Two types of filters with 1.8m and 3.7m length were used, both of their diameters are 45cm and the thickness is 1.08mm. The filter is hung from the top at intervals of 50cm. The velocity distribution of air flow from a duct and the response frequency and amplitude of the filter were measured. We found that the flow was able to rectifize, when attached honeycomb panel to the duct. By varying the length of the filter and honeycomb panel's cell size, the vibration shape in circumferential direction varies.
