Effects of honeycomb shroud seal dimensions on the aerodynamic performance of the steam turbine stages in the high-pressure cylinder are investigated by using a computational fluid dynamics method. Critical geometrical parameters
including the sealing clearance
hole-depth and hole-diameter
of the honeycomb seal are selected as research objectives to compute the performance of two turbine stages in a range of geometrical dimensions. Numerical results show that as the sealing clearance increases
the secondary loss downstream the rotor blade increases
the total-total isoentropic efficiency of turbine stages decreases and the leakage increases at an approximately linear rate. When the hole-depth increases
the total-total isoentropic efficiency increases at first and then keeps constant
while the leakage rate in the honeycomb seals decreases at first and then keeps constant. The effects of the honeycomb diameter on the leakage rate and stage efficiency are mainly determined by the flow field structure in the honeycomb cells and seal outlet region. As the hole-diameter increases
the total-total isoentropic efficiency increases while the leakage rate decreases. The variation of sealing clearance has a pronounced influence on the main flow field structure
while the change of hole-depth has less effect on the aerodynamic performance of turbine stages than that of sealing clearance. Among the three geometrical parameters
i.e. the sealing clearance
the hole-depth and the hole-diameter
the variation of hole-depth has weakest influence on the main flow field structures in the turbine stages.
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