| Trapped vortex combustor(TVC)becomes a popular research direction of the combustion chamber because of its simple structure, combustion stability, low emissions, excellent performance in altitude relight and low lean blowout and a wide operating range of high combustion efficiency. In this paper,we designed a DC trapped vortex combustor with experimental and numerical technologies based on a Turboshaft engine DC combustor parameters. Numerical simulation results show that the trapped vortex combustor combustion has high combustion efficiency and the outlet temperature distribution is reasonable.Firstly, we determined the overall program in the vortex chamber reference based on literature and design requirements, use the split diffuser to reduce the separation and get the right flow distribution for the large radial height difference between the combustor inlet and outlet. A dome with evaporation tube were designed,and it integrated oil and gas mixing, uniform hydrocarbon, the united flame and the control of blockage ratio. The dome fits steady flame effect with the cavity and simplified the flame cylindar head configuration. The height of the cavity is 1.1 times the length and the total length of the flame cylindar is 5 times the cavity length. By numerical simulation, it finds that the closer of the position of the front wall jet hole to the bottom surface of the cavity, the greater of the main eddy.Secondly, using the PIV measurements of complicated flow fields in the cavity, we do further research of cavity wall based on the numerical results. Keeping the the same area of cavity holes, we changed the ratio of the hole area of front wall and rear wall to research the eddy distribution in the cavities. While the area ratio of the front and rear jet holes is 1.7:1, and the distance from jet holes in posterior wall to the underside of reentrant cavity is 43.6 percent of cavity height, the main eddy was greater and the main vortex had a larger mainstream transition area, which is favorable for combustion stability of the cavity.Thirdly, composite wall cooling experiments were carried out for the high temperature of the cavity wall in numerical simulation. In this paper,we study two composite wall cooling solutions. The one scenario is the direction of efffusion hole consistent with the eddy flow and the other one is effusion hole has the opposite direction to the eddy flow. It demonstrates that the cooling effect of the holes in the opposite direction with flow is more effective in small blowing ratio to the bottom surface and the cooling effect of the holes in the same direction with flow is more effective in large blowing ratio to the bottom surface. Also, the cooling effect of the holes in the same direction with flow is more effective in same blowing ratio to the front surface. Besides, improving the blowing ratio from 0.5 to 1, the cooling effect of the holes in the same direction with flow gets more evident.Finally, we improved the combustion chamber according to the above study and obtain a chamber program with the combustion efficiency of the vortex combustor 99.52%, outlet temperature distribution coefficient 0.30 and the temperature of flame tube wall under 1200 K. |
