| 摘要 |
PURPOSE:To form an annular gap between the outer periphery of a small diametral column and the internal periphery of a nozzle into a smooth configuration so as not to be conspicious by a method wherein the small diametral column is constituted so as to have a sectional shape except a true circle and the outer periphery of the section thereof is constituted by a closed curve expanding to the direction of the larger diameter thereof. CONSTITUTION:The annular gap 8 is consisting of wide parts 8a and narrow parts 8b by constituting the outer periphery of section of the column with the closed curve except the true circle or the closed curve of an ellipse. According to this method, perfect clogging of the wide parts due to the accumulation of carbon will never be caused when the width W of the wide part 8a is designed so as to be larger than a given value. Further, only the wide parts 8a are designed so as to have large opening widths, therefore, a trouble that the total opening area of the annular gap 8 becomes too large because of the prevention of the perfect clogging due to the carbon, will never be caused. |
