Chemical Quick Quench Probe for Engine Emissions Measurements

A need exists to determine the true chemical composition of the exhaust gases from aircraft engines, aircraft combustors and rocket engines. Measurements of these high-speed reacting flows are important for determining the combustion efficiency of these devices and guiding efforts to engineer reduced-emissions engines. Unfortunately, the sampling system used to deliver exhaust gases to the analyzer often introduces a bias because of chemical reactions occurring in the sample line. Because of this bias, emissions measurements made using existing sample probes may not be entirely representative of the true engine exhaust. In response to this challenge, this proposal describes a comprehensive probe effects study which would 1) guide development of novel extractive probes that effectively quench chemical reactions; 2) provide guidelines for the operation of current probes to minimize sampling errors; and 3) provide a tool for estimating corrections that can be applied to measurements taken with current probes. Aerodyne Research, Inc. proposes to develop a computational model of probe flow and chemistry and refine its predictive capability using data collected from previous aircraft measurement campaigns. Subsequently, the model will be used to evaluate the potential of two non-traditional quenching techniques-radical scavenging and dilution with an enhanced third-body collider.