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摘要
This article presents the detailed study of rotor tip leakage related phenomena in a low speed axial compressor rotor passages for three sweep configurations [Unswept (UNS), Tip Chordline Swept (TCS) and Axially Swept (AXS)]. Fifteen domains are numerically studied with 5 sweep configurations (0～, 20～ TCS, 30～ TCS, 20～ AXS, and 30～ AXS) and for 3 tip clearances (0.0%, 0.7% and 2.7% of the blade chord). Results were well validated with experimental data. Observations near the tip reveal that UNS rotor shows high sensitivity than the swept rotors in the blade pressure distribution with change in tip clearance. AXS rotor has high loading capability and less tip clearance effect on blade loading at the near stall mass flow. Downstream shift of the vortex rollup along the chord is observed with increased flow coefficient and increment in the tip gap height. In particular, the effect of flow coefficient is more predominant on this effect. Tip vortex-related flow blockage is less with the swept rotors. Among the rotors, the AXS rotor is found to incur low total pressure losses attributable to tip leakage. Effect of incidence is observed on the flow leakage direction. 1. Introduction This paper presents the results of a detailed study conducted to investigate various parameters affecting tip leakage phenomena, including the effect when the rotor is given two varieties of forward sweep. In the first part (Ramakrishna and Govardhan [1]) some fundamental differences a forward sweep brings to the compressor flow pattern (on incidence, deflection, and streamline curvature; and to some extent, effect on the succeeding radial stator) were described. A little on some global performance parameters was also discussed (total pressure rise and stagnation loss coefficient). In this paper, more insight on the internal flow physics, especially tip leakage phenomena with the three sweep configurations (UNS, TCS, and AXS), is presented. Background to this work, computational formulation, validation and so forth, have been presented in Part 1 and so will not be repeated here. The effects of sweep and tip clearance on the overall performance of the stage from the present study are presented in detail in Ramakrishna and Govardhan [2]. Literature available on the effect of tip clearance in swept rotors to assess the same for various sweep configurations is not substantial. Notable works on this subject are of: Gallimore et al. [3], in which they studied both sweep and dihedral effects through low-speed multistage models for a given constant tip gap. The application of forward sweep
