CIRCUMFERENTIALLY SMEARED COMPUTED EFFECTS OF RIM SEAL CLEARANCE ON WHEELSPACE THERMAL DISTRIBUTIONS

An advanced finite volume computer code, recently benchmarked against rotor-stator cavity measurements (Ko and Rhode, 1992), was used to obt ain an enhanced partial understanding of hot gas ingress heating of a generic turbine wheelspace cavity, This problem is extremely complicat ed, with a three-dimensional, probably circumferentially periodic ingr ess/egress flow through the rim seal due to mainstream pressure asymme tries resulting from the presence of blades, etc. The present study do es not assume that the complete problem can be modeled as steady and t wo-dimensional axisymmetric. Rather, the objective of this study is to obtain a partial understanding of the complete problem from investiga ting the circumferentially smeared, steady, two-dimensional axisymmetr ic subproblem. It was found that, contrary to the case of the nominal rim seal axial clearance, for a clearance of one-fourth of the nominal value, the temperature of the ''hot spot'' on the rotor is sharply re duced with increasing purge-coolant flow because the rim seal gap reci rculation zone does not form. Also, it was found that smaller rim seal axial clearances give less rotational drag as well as less heat trans port from the mainstream into the wheelspace.