ID#: 139
Abstract Title: Heat Loss Rates from Hydrogen-Air Turbulent Flames in Tubes
Session Title: Premixed Turbulent Flames I
Session Date: 7/30/01
Session Start Time: 8:55 AM
Contributing Author: Dorofeev, S.B.
Organization: RRC - Kurchatov Institute
Country: Russia
Authors: M. Kuznetsov, I. Matsukov, S. Dorofeev
Short Abstract: Experimental study of heat losses from turbulent combustion processes in obstructed tubes is presented. Tests are made with hydrogen-air mixtures in tubes with internal diameter of 174 mm and 520 mm. Direct measurements of heat flux to tube walls versus time during flame propagation are conducted. It is shown that total energy absorbed by tube walls is equivalent to the mixture chemical energy for all the mixtures tested. The rate of energy losses from combustion processes depends significantly on the speed of the flame propagation. The average heat flux, q(0.5), at the time of half-energy release is used to characterize the intensity of heat losses. The value of q(0.5) increases from 10 to about 80 W/sq.cm with increase of turbulent flame speed from 10 to 800 m/s. It is shown that tube diameter does not influence significantly the characteristic values of heat fluxes, while the characteristic duration of energy losses as well as total energy absorbed differ greatly in two tubes. This observation indicates that the main mechanism for heat losses under the conditions of present tests is convective heat transfer. This conclusion is supported by comparison of overall rate of heat losses with the measurements of its radiant component. The results suggest that qualitative and quantitative account for heat losses from combustion products is necessary to be included in turbulent combustion models to increase reliability of their predictions.