CFD Analysis of Contrarotating Open Rotor Aerodynamic Interactions

Abstract

High efficiency and low fuel consumption make the contrarotating open rotor (CROR) system a viable economic and environmentally friendly powerplant for future aircraft. While the potential benefits are well accepted, concerns still exist with respect to the vibrations and noise caused by the aerodynamic interactions of CROR systems. In this paper, emphasis is placed on the detailed analysis of the aerodynamic interactions between the front and aft propellers of a puller CROR configuration. For the first step, unsteady Reynolds-averaged Navier-Stokes (URANS) simulations coupled with dynamic patched grid technology are implemented on the isolated single-rotating propeller (SRP) configuration in various operating conditions in order to test the accuracy and feasibility of the numerical approach. The numerical results are verified by a wind tunnel test, showing good agreements with the experimental data. Subsequently, the URANS approach is applied to the CROR configuration. The numerical results obtained through the URANS approach help to improve the understanding of the complex flow field generated by the CROR configuration, and the comparison of SRP flow field and CROR flow field allows for a detailed analysis of the aerodynamic interactions of the front propeller blade wakes and tip vortices with the aft propeller. The main reason of the aerodynamic interactions is the mutual effects of the blade tip vortices, and the aft propeller reduces the strength of the blade tip vortices of the front propeller. Aerodynamic interactions will lead to the periodic oscillations of the aerodynamic forces, and the frequency of the oscillations is linked to the blade numbers. In addition, a CROR has a larger thrust and power coefficient than that of the SRP configuration in the same operating conditions. The URANS approach coupled with a dynamic patched grid method is tested to be an efficient and accurate tool in the analysis of propeller aerodynamic interactions.

Preliminary Design Framework for the Power Gearbox in a Contra-Rotating Open Rotor

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The numerical CFD investigation of hub losses of pushing air propellers with tandem joined blades of small sized unmanned aerial vehicles

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Effects of Stage Spacing on Contra-Rotating Propeller Aerodynamic Interactions

“…Reference [7] reported that the front blades exhibited larger deformation than the rear ones, but the latter saw a significantly greater change in performance than the former. Reference [8] studied the aerodynamic interactions of a CRP through unsteady Reynolds-averaged Navier-Stokes (URANS) simulations and found that aerodynamic interactions were the result of the mutual effects of the blade tip vortices, and the aft propeller absorbed the energy of the front propeller and thus reduced the strength of its blade tip vortices. Reference [9] numerically calculated the unsteady flow field of contra-rotating open rotors using the URANS method, compared the calculation results under different incoming flow conditions, and analyzed the complex aerodynamic interactions between propellers, finding that axial flow contributed to the improvement of propfans' aerodynamic performance.…”