Numerical And Experimental Investigation On Premixed Hydrogen/Air Combustion In Amicro-combustor With A Bluff-body

With the developing of micro-mechanical, the study of micro-combustor is becoming more and more important. Attribute to microscale-effect, the combustion efficiency of the micro-combustor is low, and the flame is instable. Thus stabilizing the flame becomes an important issue of combustion in microscale.In this paper, author trys to introduce the bluff-body combustion stabilization technology from conventional scale combustor for micro-combustor, by using laminar flow model and turbulence model of the commercial software FLUENT, and detailed chemical reaction mechanism of hydrogen/air mixture, author simulates the velocity field, the temperature field and the flame structure in the combustion chamber. Then, verificate the effect of the equivalence ratio on blow out limit with experimental result. By comparing the simulation and experimental results, we draw the following conclusions:(1)As the velocity of inlet increases, the flame-front gradually moves from the front of the bluff-body to the rear of the bluff-body, the distribution of the combustion chamber wall temperature becomes more smooth, indicating that the installation of a bluff-body significantly improve the life of the combustor;(2)Increasing of the bow area in front of the bluff-body reduces the oscillating frequency of the vortex behind the bluff-body. To replace the triangular bluff-body in the micro-combustor with semi-circular bluff-body has some effects on stabilizing the velocity field;(3)As the frontal area of the bluff-body increases, replacing the triangular bluff-body in the micro-combustor with semi-circularbluff body has a good effect on stabilizing flame in the low-speed state, the combustion efficiency also increases. In the high-speed state, the semi-circularbluff body has the same effect as the triangular bluff body;(4)The flame structure and the temperature distribution is not sensitive to the thickness of the micro-combustor’s wall;(5)Replace the material of micro-combustor with a higher thermal conductivity one, the development of flame accelerates as the speed of inlet increase. The combustion efficiency improves under the low speed state, but decreases under the high speed state;(6)Through the comparison of calculation results on the blow out limit, the calculation of the laminar flow model and low Reynolds number turbulence models are close to the experimental result in low-speedstate; but only the result of low Reynolds number turbulence model’s calculation is close to the experimental results in high speed state.