Abstract

This paper presents a preliminary, numerical what-if analysis of selected geometrical parameters of the tip seal of the last stage of an aircraft engine turbine and the impact of the parameters on the leakage mass flow. The analysis is a part of the task of improving the rotor tip seal configuration in aircraft turbines. Calculations were carried out using the commercial computational fluid dynamics code. A straight-through seal with two leaning fins and a honeycomb land was analysed. The computational model was prepared based on some simplifications introduced to improve the eficiency of the calculations. The rotor entire blade-to-blade channel was analysed, while the seal pitch was reduced to the dimensions of two honeycomb cells. The geometry of the fins themselves was simplified too. In the original variant, the fin tips had caps to protect them from wear (shape deformation) due to rubbing. In the simplified model, the caps were omitted. The simplifications did not change the leakage mass flow significantly. Several variants of changes in the basic geometrical parameters of the seal were analysed to assess their effect on the leakage mass flow for altered flow conditions. Parameters such as the fin thickness, the fin inclination angle and the position of the fins and of the entire labyrinth were analysed. The best seal variant was selected, the flow phenomena were commented on and some points in the design of this type of the labyrinth seal were discussed.