This work presents the latest results of aeromechanical design of two large-scale fan model stages (Dr = 700 mm) for low-noise high-performance single-stage fan prototypes designed for advanced civil aircraft geared and direct-driven turbofans with reduced and ultra-low rotor tip speeds, high specific capacity, and high bypass ratios. They are designed with account of all features of blades made of polymer composite materials (PCM) or titanium alloy. Metal and composite blades have a similar shape in hot state at the design point. The stages are intended for tests in the anechoic chamber of the CIAM’s C-3A special acoustic test facility with the aim of verification new optimal design methods for similar fans to achieve maximum performance.
Performances of the fans and parameters of viscous steady flows are calculated. The calculations show that both fan models can provide a high specific capacity along with a high efficiency and sufficient stall margins. For example, calculated max. efficiency level of the bypass duct in the geared model fan with ultra-low tip speed (Ucor. = 313.4 m/s) is equal to 94%.
Data measured by tests of an ungeared bypass fan model with solid metal rotor blades developed earlier by the authors are used for the mathematical model verification. Tip speed of rotor blades at the design point is Ucor. = 400m/s, bypass ratio — m = 8.4. Four booster stages are installed in the core duct. From first test results it is clear that required values of key parameters are achieved. Comparison of measured and calculated data gives evidence of their good agreement. At present, detailed tests of this fan and a similar fan with 3 booster stages are under way in the anechoic chamber of the CIAM’s C-3A acoustic test facility.
The new direct-driven fan model described in this paper has quite different design values of parameters, geometry of the meridian contours, and shapes of outer and inner ducts. Tip speed of its rotor blades is reduced by 30 m/s, the hub diameter is decreased, and bypass ratio is higher (m = 11).
In the near future, these two new models of non-geared and geared fans can be manufactured and tested.