Parallel Computation of Turbine Blade Clocking
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This paper presents a numerical study of airfoil clocking of a six-row test turbine configuration with equal pitches. Since the rotor-stator interaction flow is highly unsteady, the numerical simulation of airfoil clocking requires the use of time marching methods, which can be computationally expensive. The large turnaround time and the associated cost for such simulations makes it unacceptable for the turbomachinery design process. To reduce the turnaround time and cost/MFLOP, a parallel code based on Message-Passing Interface libraries was developed. The relative circumferential positions of the three stator and three rotor rows in an industrial steam turbine were varied to increase turbine efficiency. A grid density study was performed to verify the grid independence of the computed solutions. The clocking of the second-stage airfoils gave approximately a 50% greater efficiency variation than the clocking of the third-stage airfoils. This was true for clocking both rotor and stator airfoils. Rotor clocking produces an efficiency variation which is approximately twice the efficiency variation produced by stator clocking. For both stator and rotor clocking, the maximum efficiency is obtained when the wake impinges on the leading edge of the clocked airfoil.
