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Evaluation of Nonlinear Rotor Wake/Stator Interaction by using Time Domain Chorochronic Solver

Martin Olausson (Institutionen för tillämpad mekanik, Strömningslära) ; Lars-Erik Eriksson (Institutionen för tillämpad mekanik, Strömningslära) ; Stephane Baralon
Proceedings of the 8th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows (ISAIF), Lyon, July 2007 64, (2007)
[Konferensbidrag, övrigt]

Rotor wake interactions with stators is an important aspect in turbomachinery noise generation. This paper deals with the time lagged periodic boundary condition (chorochronic periodicity) used in time domain Navier-Stokes equations solvers and its advantages/drawbacks over frequency domain linearized N-S equations solvers. The time lag periodic b.c. is used to solve the nonlinear three dimensional N-S equations using realizable k-epsilon turbulence model and time dependent wake defined at the inlet, with only a limited number of blade passages discretized. The time lag periodic b.c. has been validated through a number of 3D test cases. The acoustic response from a stator vane with wakes defined at the inlet is calculated using both a frequency domain linearized N-S equations solver and unsteady RANS equations solver with chorochronic periodicity, and the results are compared. Convergence time for the unsteady nonlinear calculation expressed in number of periods needed to reach a periodic solution depend on time lag size. This motivates a possible use of a few blades in the computational domain to minimize time lag/period ratio. Making the time lag periodic b.c. absorbing was shown to be a robust solution to handle instabilities that appeared in some of the test cases.

Nyckelord: Fan noise, Computational aeroacoustics, Nonlinear rotor-stator interaction noise, Chorochronic periodicity



Denna post skapades 2008-01-02. Senast ändrad 2010-12-16.
CPL Pubid: 64083