Combustion in micro-cylindrical combustors with and without a backward facing step

Micro-combustors are critical components for micro-power systems using hydrogen and hydrocarbon fuels as an energy source. The micro-thermophotovoltaic (TPV) power system requires an output of high and uniform temperature from the wall of the combustor. This paper presents the experimental results of three types of stainless cylindrical micro-combustor with or without a backward facing step. Hydrogen was used as the fuel. The temperatures at exit and along the wall of the combustors were measured. The results show that the backward facing step provides a simple yet effective solution to enhance the mixing of fuel mixture and prolong the residence time. In addition, the step is very useful in controlling the position of flame and widening the operational range of the flow rate and H2/air ratio. A high and uniform temperature distribution has been achieved for micro-combustors with a backward facing step. This result is relevant to the application of micro-TPV power systems we are currently pursuing.