Determination of the Control Points Optimal Number and Their Spatial Location for the Estimation of Flame Front Speed

Abstract

The article describes a study on determination of control point’s optimal number and their location on protected object for electro-optical distributed system of flame front speed estimation. Purpose of the system is to determine (predict) the location of flame front with given error based on the data on flame front speed with the goal of timely activation of the explosion suppression devices. The tasks of determining of the control point’s optimal number and their spatial location are related. Initially, the distance between the control points (flame detectors) is determined to ensure the best parameters of the EOS operation. In turn, the optimal number of control points is determined by ratio of the protected object total length to the optimal distance between the flame detectors. The optimality criteria are formulated for two approaches for predicting of the flame front location: by signals from one flame sensor for speeds no more than 30 m/s; by signals from two flame sensors for speeds above 30 m/s. Appropriate research methods are developed for the proposed options. The studies were carried out on the basis of non-stationary combustion computer simulation for hydrocarbon-air mixtures in conditions typical for coal mines. The optimal distance between photo detectors in the flame detector is 0.05 m. However, the required error values for calculating of the flame front position (no more than 15%) are achieved for flame front speed of no more than 30 m/s using a single flame detector. The optimal distance between the flame detectors is 1.75 m at flame front speed of more than 30 m/s. In this case, the minimum relative error in predicting of the flame front location does not exceed 7.1%.