The velocity vector diagram of seal system with different depth–width ratios of rotor chamber: (a) the depth–width ratio of rotor chamber is 1.0; (b) the depth–width ratio of rotor chamber is 0.8; (c) the depth–width ratio of rotor chamber is 0.6; (d) the depth–width ratio of rotor chamber is 0.4; (e) the depth–width ratio of rotor chamber is 0.2.