Influence of blade untwist on transonic high bypass ratio fan performance

Influence of blade untwist on transonic high bypass ratio fan performance were studied using the software based on the fluid-solid coupling algorithm, considering the nonlinear effects of unsteady aerodynamic force on the blade deformation. Firstly, the deformation induced by centrifugal force was calculated starting from the cold blade shape, and then the deformation induced by unsteady aerodynamic force was obtained using the fluid-solid coupling software. The effect of the dynamic blade deformation on aerodynamic performance of the high bypass ratio fan was investigated at three rotation speeds. Results show that changes of the shock position on the blade surface have significant influence on the blade untwist angle under the transonic conditions. In the rotation speed range concerned, the calculated mass flow rate by the designed blade shape is greater than that by the dynamic one up to 7%, which causes the engine takeoff thrust less than the predicted value. The results also indicate that the accurate blade shape is important for predicting aerodynamic performance during the design stage.