Analysis on tip flow structure in transonic fan rotor

In order to analyze the tip flow structure and explore the intersection of shock and tip clearance vortex, a transonic fan rotor was studied using three dimensional numerical calculation and comparative analysis of flow field with various clearances. Further study of the intersection of tip leakage vortex and shock were obtained by establishing the 3-D flow model of the process, thus enhancing the comprehensive understanding of tip leakage flow. The research indicated that the performance was improved with the decrease of the clearance, including efficiency and pressure ratio. Moreover, with the increase of tip gap, the intensity of tip leakage vortex (TLV) was enhanced and the scope of high-entropy area was expanded along the circumferential direction and spanwise direction. The pressure difference between pressure surface and suction surface provided the impetus for the migration of the leakage flow, and lateral gap offered the migration channel. Under h/c=1.0%, the circumferential movement tended to be more notable and the secondary leakage turned more dramatic with the increase of tip height. Propagating of TLV led to the rapid reduction of the normalized streamwise vorticity, while the constant value of the normalized helicity showed that the concentrated vortex feature was maintained. What's more, the shock was distorted by the tip leakage vortex near suction, weakening the shock wave and pushing the shock upward.