Premixing quality and flame stability: A theoretical and experimental study

Models for predicting flame ignition and blowout in a combustor primary zone are presented. A correlation for the blowoff velocity of premixed turbulent flames is developed using the basic quantities of turbulent flow, and the laminar flame speed. A statistical model employing a Monte Carlo calculation procedure is developed to account for nonuniformities in a combustor primary zone. An overall kinetic rate equation is used to describe the fuel oxidation process. The model is used to predict the lean ignition and blow out limits of premixed turbulent flames; the effects of mixture nonuniformity on the lean ignition limit are explored using an assumed distribution of fuel-air ratios. Data on the effects of variations in inlet temperature, reference velocity and mixture uniformity on the lean ignition and blowout limits of gaseous propane-air flames are presented

1988,"The Effect of Inlet Velocity Distribution and Magnitude on In-Cylinder Turbulence Intensity and Burn Rate - Model vs. Experiment

Steady flow measurements of velocity and mass flux distributions around the intake valve were used as input to a General Engine Simulation Model (GESIM) to assess the assumptions of uniform velocity and mass flux distributions and their effects on in-cylinder Introduction In the past, thermodynamic, quasi-dimensional engine simulation models have not been able to predict the burn rate and ISFC for different engine combustion chamber/intake port configurations. Measurements of burn rate and average fuel consumption at a minimum of one engine operating condition for each engine configuration were required for model calibration. With this limitation, models of this type may only be used to evaluate combustion chamber geometry effects on burn rate and ISFC while keeping the intake port flow generating characteristics the same The approach taken in this work is to use steady flow bench measurements as input to the engine simulation model in order to characterize the turbulence and swirl generation capabilities for a given intake port. One characteristic of an intake port is the unique velocity distributions produced near the valve/head interface as the flow enters the cylinder. The goal of this wor