Abstract
Abstract A simplified empirical-analytic model of flame quenching and subsequent removal of probe boundary-layer gases during in-cylinder sampling was used to study the quench-bias problem. For conditions similar to those of a diesel cylinder the model showed that the flame temperature has the greatest influence on the mass fraction of quench gas in a sample; cylinder pressure, orifice size, and sampling interval have less influence. For flame temperatures greater than 1900°K, the quench-mass fraction was computed to be relatively small—about 4% of the total mass. Even when the hydrodynamic boundary layer is neglected, the quench gas assumed at a uniform temperature equal to the wall temperature and the flame temperature taken at 2222°K, the quench-mass fraction is calculated to be only 9 to 16%. Extension of the model to the case where the bulk gas is flowing did not alter the conclusion that quench bias appears to be relatively unimportant in high temperature regions.
Published Version
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