Labyrinth seal for fan assembly

A transport refrigeration unit for use with a transport trailer comprising:

• a structural framework mountable to a wall of the transport trailer;
• a condenser heat exchanger unit mounted to the structural framework;
• an evaporator housing separated from the condenser heat exchanger by a distance;
• and
• at least one condenser fan assembly positioned aft of the condenser heat exchanger unit and forward of the evaporator housing, the at least one condenser fan assembly including:
• a fan casing having a plurality of guide vanes connected thereto, the fan casing having a trench formed therein, a first and second end surface of the trench being beveled;
• a fan rotor arranged upstream from the plurality of guide vanes relative to a flow through the condenser fan assembly, the fan rotor being rotatable relative to the fan casing about an axis, the fan rotor having:
• a plurality of fan blades;
• and
• a shroud coupled to a radially outer end of the plurality of fan blades, the shroud including an axially oriented protrusion extending from a distal end of the shroud towards the fan casing, wherein the protrusion is aligned with a central portion of the trench and includes a first beveled edge and a second beveled edge, the first beveled edge being positioned adjacent to the first beveled surface and the second beveled edge being located adjacent to the second beveled surface;
• and
• a clearance formed between the protrusion and the casing defining a convoluted flow path that wraps around both the first beveled edge and the second beveled edge of the protrusion.