An assembled annular stepwise diverging tube for the measurement of laminar burning velocity and quenching distance

Abstract

Laminar burning velocities of premixed flames provide essential data in combustion studies. To facilitate an in situ monitoring in the field, a method using the annular diverging tube (ADT) and its improved version of the annular stepwise diverging tube (ASDT) were introduced in previous studies. Although the reliability and applicability of these methods has been verified, additional improvements are necessary for the field application. In this study, an assembled annular stepwise diverging tube (A-ASDT) was introduced. Each step-unit was fabricated separately to have higher dimensional precision and to selectively assemble suitable step-units. Thus, the burner configuration could be easily adjusted, and the experimental resolution could be controlled. Heat transfer through the burner was suppressed to extend the duration of the experiment. The characteristics of the critical flame-propagation-velocity (FPV) that are less affected by the channel gap scale were investigated in more detail. The critical FPVs were comparable to the laminar burning velocities for methane, propane, and DME. The quenching distances could be measured easily, and the quenching Peclet number was directly evaluated. In conclusion, in our knowledge, this A-ASDT may be one of the fastest, easiest, and approvable methods for the prediction of the laminar burning velocity and the quenching distance. Therefore, it can be adopted in the fuel-consuming field to monitor the characteristics of flammable mixtures.