Gas sampling method for determining pollutant concentrations in the flame zone of two swirl-can combustor modules

A gas sampling probe and traversing mechanism were developed to obtain detailed measurements of gaseous pollutant concentrations in the primary and mixing regions of combustors in order to better understand how pollutants are formed. The gas sampling probe was actuated by a three-degree-of-freedom traversing mechanism and the samples obtained were analyzed by an on-line gas analysis system. The pollutants in the flame zone of two different swirl-can combustor modules were measured at an inlet-air temperature of 590 K, pressure of 6 atmospheres, and reference velocities of 23 and 30 meters per second at a fuel-air ratio of 0.02. Typical results show large spatial gradients in the gaseous pollutant concentration close to the swirl-can module. Average concentrations of unburned hydrocarbons and carbon monoxide decrease rapidly in the downstream wake regions of each module. By careful and detailed probing, the effect of various module design features on pollutant formation can be assessed. The techniques presently developed seem adequate to obtain the desired information

Advanced technology for controlling pollutant emissions from supersonic cruise aircraft

Gas turbine engine combustor technology for the reduction of pollutant emissions is summarized. Variations of conventional combustion systems and advanced combustor concepts are discussed. Projected results from far term technology efforts aimed at applying the premixed prevaporized and catalytic combustion techniques to aircraft combustion systems indicate a potential for significant reductions in pollutant emission levels

Quantum Dynamics with Bohmian Trajectories

We describe the advantages and disadvantages of numerical methods when Bohmian trajectory-grids are used for numerical simulations of quantum dynamics. We focus on the crucial non crossing property of Bohmian trajectories, which numerically must be paid careful attention to. Failure to do so causes instabilities or leads to false simulations.Comment: 17 pages, 18 figures; some typos corrected, 4 figures added, some paragraphs extended, source code extende

Effect of flameholder pressure drop on emissions and performance of premixed-prevaporized combustors

Parametric tests were conducted to determine the effects of flameholder pressure drop on the emissions and performance of lean premixed-prevaporized combustors. A conical flameholder mounted in a diverging duct was tested with two values of flameholder blockage. Emissions of nitrogen oxides, carbon monoxide, carbon dioxide, and unburned hydrocarbons were measured for combustor entrance conditions of 600 to 800 K air temperature, 0.3 MPa to 0.5 MPa pressure, and 20 m/sec to 35 m/sec reference velocity. Jet A fuel was injected at flow rates corresponding to an equivalence ratio range from 0.8 down to the lean stability limit. Emission results for the high-blockage flameholder were a substantial improvement over the low-blockage emission results. A correlation of combustion efficiency with flameholder pressure drop was developed for pressure drops less than 9 percent