z. xia

Experiments on a two-phase rotating detonation combustor operating with gasoline and high total temperature air were conducted to investigate the initiation characteristics, operation mode, and propagation characteristics of a two-phase rotating detonation wave (RDW). The outer diameter, inner diameter, and length of the annular combustor were 204 mm, 166 mm, and 155 mm, respectively. The initiation characteristics, operation mode, and propagation characteristics of the two-phase RDW were studied by varying the total air temperature. The experimental results show that the initiation time of the RDW first decreases and then increases with an increase in the total air temperature and reaches an extreme value at a total air temperature of 713 K. Four operation modes (failure, intermittent detonation, single wave, coexistence of double wave collision, and single wave) of the detonation combustor were found for different total air temperatures. The effect of the total air temperature on the peak pressure stability and propagation frequency of the RDW was studied in detail. From the results, the effect of the equivalence ratio on the working characteristics of a rotating detonation engine (RDE) was investigated at a total air temperature of 713 K. Four detonation propagation modes (sporadic detonation, intermittent detonation, single-wave mode, coexistence of double-wave collision and single wave) were obtained in the combustor. When the equivalence ratio was 0.52, the detonation initiation failed. The pressure characteristics in the combustor and propagation frequency of the RDW were studied with different equivalence ratios. In addition, a long-duration test was performed for 3 s to verify the continuous working feasibility of the two-phase RDE.

Swirling flow has been widely used in gas turbine and aero-engine combustor to stabilize the flame. However, accurate numerical prediction of the swirling turbulent flow is difficult due to complex vortex movement in the flow, and turbulence modeling is a key factor. To assess the turbulence modeling in predicting the swirling flow, numerical studies are conducted for a well-documented swirling flow case. Three turbulence models are applied in the framework of scale resolved models, i.e. a newly developed VLES (Very-large eddy simulation) model, two LES (Large eddy simulation) models including the WALE (Walladapting local eddy viscosity model) and CSM (Coherent Structure Method). Numerical results are compared with the experimental results including the mean and RMS velocities. It is found that VLES model performs best among the three models and the other two LES models give comparable predictions. The complex vortex structures are explored based on the unsteady simulation results. The study demonstrates the high potential of VLES modeling for accurate prediction of complex swirling flow.