A columnar lump body includes a first lump body end face that forms an air inflow end, a second lump body end face that forms an air outflow end, and a lump body side face that continues into an outer periphery of the first lump body end face and an outer periphery of the second lump body end face. The columnar lump body is disposed in such a way as to block an inside space of the cylindrical body side wall by the lump body side face contacting any portion of an inner surface of the cylindrical body side wall. A first space is provided at least either between the first cylindrical body end face and the first lump body end face or between the second cylindrical body end face and the second lump body end face.