Numerical Study Of The Vortex Controlled Diffuser

The vortex controlled diffuser (VCD) as a new type of diffuser has been expected tobe widely used in the engine combustion chamber in the future, due to its high pressurerecovery and low pressure loss, but the report about this is much less.In this paper, numerical simulation of the turbulent flow characteristics in2D and3D vortex controlled diffuser has been carried out. The law of the flow field anddiffuser performance influenced by the suction slot has been summed, and the effect oncombustion performance of the sudden expansion chamber for a vortex controlledstructure being introduced has been also studied.When the suction slot is only in the radial direction, with the increase of the slotlength, the average static pressure, the average stagnation pressure and the diffuserefficiency all decreased. When the suction slot is only in the axial direction, with theincrease of the slot length, at the diffuser exit, the average static, stagnation pressure andthe diffuser efficiency also decreased. When the slot length are equal, the average staticpressure, the average stagnation pressure and diffuser efficiency are higher while theslot is only in axial direction than that only in radical direction at the diffuser exit; Thediffuser performance of the optimal length combination of the slot both in radical andaxial directions is better than that only in radical direction, but worse than that only inaxial direction; In addition, the diffuser performance is better when the dump diffuserhas a suction slot, that is to say, suction slot on the wall of the diffuser can improve thediffuser performance, and the suction slot size (x=0.002m, y=0m) is the best to achievethe best diffuser performance.The initial conditions having been changed, with the increase of the velocity, thediffuser efficiency increases, and the total pressure loss decreases, but the difference isnot obvious; With the increase of turbulence, diffuser efficiency decreases, the totalpressure loss increases, and the difference is more obvious; With the increase of bleedfraction, diffuser efficiency increases, total pressure loss decreases, and the effects ofbleed fraction on diffuser performance are most obvious.Finally, the numerical simulation of the sudden expansion chamber with vortexcontrolled structure has been carried out, it is revealed that this structure with suctionslot can benefit combustion, expand the combustion area and make the distribution of the outlet temperature along the radial direction more uniform, which leads to improvecombustion efficiency and reduce pollution environment.