umerical simulations employing RNG κ-ε turbulent model and κ-ε turbulent model respectively were made to investigate the effect of swirling chamber structure on the forward flow and reverse flowNumerical results were in good agreement with experimental dataBased on the numerical simulation，computations with different structures and geometrical parameters were performed for both flow directionsThe optimal structure was obtainedThe results showed that the converging chamber had the largest resistance for the reverse flow，the thin cylindrical chamber had the smallest resistance for the forward flowAs to the overall performance，the converging one is the best，with an increase of 30%The height of the chamber center should be designed following the equivalent velocity principle，and the best value was slightly less than 1/4 of the diameter of the axial pipe.