Hidetomo Mori

Variational Analysis of Screw-Rotor Profiles with the Shortest Seal Line between Rotors.

Screw-rotor profiles with the shortest seal line between male and female rotors of screw compressors were analyzed by calculus of variation. Additionally, a three-dimensional seal line was directly analyzed, and the rotor profiles and the conjugate law were derived by using the seal line coordinates. The calculus of variation was applied to the seal line connecting the top point of the male rotor with the pitch point. Consequently, it was found that (1) the rotor profiles have the shortest seal line when the pressure angle is zero at the pitch point, (2) the curvature radius of each profile has a maximum along the profile, and (3) different seal lines and rotor profiles exist according to the ratio of the pitch-circle diameter to the lead of the rotor.