Choice of optimum parameters in stabilizing combustion in a flow with a forechamber jet of H2 combustion products

Abstract

In this paper, the authors examine the effects of the basic parameters in a jet of combustion products from hydrogen-air mixtures as regards the concentration limits for the stabilization of the flame from previously mixed propane-air mixtures in a turbulent flow. Also determined were the simulation criteria for the stabilization with the use of forechamber devices. The results show that the stabilization effect is greatest when the excess air coefficient in the forechamber approx. = 0.7. Results indicate that chemical and aerodynamic factors have important effects in the forechamber method of stabilizing combustion in a flow. Theoretical analysis of the stabilization conditions is based on an ignition model for a turbulent flow containing a hot gas jet. In the simulation, it is assumed that ignition by the forechamber method is due to the temperature rise in the flow of the main mixture because the hot combustion products from the forechamber mix in with it. Calculations of the concentrations show that there is a logarithmic relationship for the effect of the initial activecenter concentration on the ignition for isothermal conditions. The active-center concentration is not quantitatively increased by enriching the mixture with fuel, nor is the chemical activity in the flamemore » raised. One can explain results in which there was some improvement in the performance of a forechamber device when the forechamber mixture was rich by saying that there was an increased concentration of molecular hydrogen in the forechamber flame.« less