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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
ANALYSIS OF ERROR PROPAGATION IN THE MEASUREMENT OF LAMINAR FLAME SPEED USING CONSTANT VOLUME REACTOR
Submission Author:
Jônatas Vicente , SC
Co-Authors:
João Paulo Furlanetto Miranda, Jônatas Vicente, Amir Antonio Martins Oliveira
Presenter: Jônatas Vicente
doi://10.26678/ABCM.ENCIT2020.CIT20-0399
Abstract
The present study aims at estimating the uncertainties in the measurement of laminar flame speed in a constant volume reactor (CVR). In this laboratory equipment, the laminar flame speed of air-fuel mixtures is measured indirectly from the optical observation of the outwardly propagation of a spherical flame. The measurement random errors in the values of laminar flame speed originate from random errors in the mass filing of the reactor with fuel and air, in the initial pressure and temperature of the reacting mixture, in the acquisition and treatment of the high-speed visible images and on the mathematical treatment of the effects of flame stretch. The random errors in these variables propagate in a complex way to compose the final measurement error. In this work, a Monte Carlo technique is used to assess the error propagation. The calculations were performed in Matlab. For the common conditions found in the measurement of laminar flame speed for liquid hydrocarbon fuels, the propagation of random errors resulted in uncertainties that range from +/- 3.5 % at stoichiometric ratios of 0.7 and 1.4, to +/- 0.8 % around the stoichiometric ratio of 1.1, where the effects of random errors reduce to a minimum. The errors in unburned temperature have the greatest importance for fuel lean mixtures and those in unburned pressure and mass of fuel are the most important for fuel rich mixtures. Higher temperatures reduce the effect of temperature in the overall errors.
Keywords
laminar flame speed, Constant Volume Reactor, Error Propagation, Monte Carlo method
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