On loading corrections and loss distributions in low-speed forward swept axial compressor rotors

Loading of a swept aerofoil blade is typically reduced as its lifting line is inclined (at the sweep angle) with the radial direction. Various estimations are available in the literature about the correction to be made on the loading of a wing when the same is swept. However, it is difficult to obtain an accurate and a more general estimation of correction for a range of sweep angles and for a range of mass flowrates. This article presents two aspects of the flow field in forward swept compressor blade passages: (a) Loading of swept rotors from the present computational study (on a baseline unswept rotor and forward swept rotors of 20°, 30°, and 40° sweep angles; for different tip clearance and stagger configurations) is compared with a number of load correction estimations reported in the literature. Loading of the swept rotors obtained through numerical simulations is compared with the existing estimations obtained from the loading of unswept rotor. A correction factor blend is evaluated, which is found to provide good estimations of loading characteristics for various sweep configurations. (b) Spanwise and streamwise resolved loss coefficient distributions are studied, which showed that the high endwall losses observed in the unswept rotor were significantly reduced with blade sweeping. However, tip clearance is found to result in increased overall loss in the swept rotors.