Numerical Investigation of Rotor-Stator Interaction in a High-Bypass Ratio Fan Stage

Both steady and time-accurate simulations of the flow through a high-bypass ratio fan stage consisting of transonic fan rotor blade (FAN), outlet guide vane (OGV) of bypass duct, and inlet guide vane (IGV) of low-pressure compressor (LPC) are performed at design operating point to address the fundamental questions regarding the impacts of unsteady rotor-stator interactions. The original ratios of fan blade number to OGV and IGV vane numbers are scaled to avoid the full wheel computation, thus reducing the amount of time-accurate computation effort. The comparison between time-averaged unsteady results and steady results shows minor differences in the performance of bypass and core ducts. The transient flow field investigation shows that the unsteady interaction between FAN and IGV is much stronger than that in the bypass duct. Considering aerodynamic response and excitation mechanism due to rotor-stator interaction, the unsteady pressure distributions are examined. The time traces and frequency contents of the unsteady pressure show complex rotor-stator interaction arising from the incoming wakes and potential effects of downstream blade rows.