Numerical Simulation Of The Combustion Of Hydrogen In Power MEMS

Power MEMS is micro electromechanical system based power sources, which has extensive prospect in fields of airspace, communication, biomedicine, national defence and so on, and which will bring profound significance to the society. At present, there are many investigates into Power MEMS, but most of which emphasize technique and process. Due to lack of theory and test model, there are few breakthroughs in the field of micro-combustion. Micro -combustion is put forward after Power MEMS. And moreover, researches paid more and more attention into micro-combustion. There are few correlative researches inland.Based on the model of line type micro-scaled combustor and micro-scaled combustor in MIT turbine proposed by Jinsong Hua, This paper investigates into the method of numerical simulation for micro-combustion. Appropriate physical model and numerical methods that include control equation, chemical kinetics, transfer mechanism, the finite-volume method and reasonable boundary condition are employed. FLUENT and its user subprogram, CHEMKIN, are applied to simulate the micro-combustion of the mixture systematically. Besides that, the results of simulation are compared with those Jinsong Hua and Meng Wu obtained.In the first part of this paper, the micro-combustion of H2/air in the line type micro-scaled combustor is simulated and indicates that: with the diameter of combustor increasing, the combustion goes more completely; with the fuel ratio increasing, the exit temperature and the average rate of the chemical reaction rise originally and then fall off; loss of heat through the wall has great influence in the combustor efficiency and the rate of combustion, furthermore, the scale of the combustor is smaller, the influence is more evident; detailed chemical mechanics make the simulation result more quantitative, and the results are similar to what Jinsong Hua and Meng Wu got.Then in the second part, the micro-scaled combustor of the MIT turbine is simulated, and indicates that: with the mass flow of the mixture increasing, the combustor efficiency originally rises and then falls off. If the mass flow is too low, flame will occur in the circulation jacket and ultimately the wall may be damaged. With the fuel ratio increasing, the combustor efficiency increase. Once the ratio gets a certain value, flame will occur in the circulation jacket and then may damage the wall. Therefore, appropriate value of mass flow and the fuel ratio must be selected. Although two-dimensional model and adiabatic wall are applied, the results are reasonable as that Jingsong Hua got.