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LIF/Mie ratio-metric imaging was used to characterize sprays produced by a simple hollow-cone pressure atomizer, operating under elevated ambient pressures up to 10 atm. A structured laser sheet was used as the source of illumination to suppress the multiple scattered light, generating images that are free of the artefacts typically found in conventional laser sheet images. The resulting LIF/Mie ratio-metric images were calibrated using Phase Doppler anemometry to generate axial planar maps of the spray’s Sauter-mean diameter (SMD). This calibration methodology was applied over a range of ambient pressures and liquid flows to assess the robustness of the structured LIF/Mie ratio-metric imaging as a droplet sizing technique. The test fluids consisted of conventional and alternative jet fuels as well as nozzle calibration fluid. Results presented in the paper indicate both the effectiveness and certain limitations of the technique.

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities., ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Monday 11 June 2018, Oslo, Norway

The splitting of the airflow that passes through the openings in the combustor liner is vital to its performance. Traditionally, numerical simulations of the gas turbine combustor have limited the computational domain to only the flow field inside the liner, while the airflow distribution over the liner is estimated based on semi-empirical correlations. In addition, the airflow rates are assumed to be the same through the identical open passages at each combustor axial cross-section. In the present study, the internal and external flow fields of a practical gas turbine combustor liner are directly coupled, so the air splitting is determined by comprehensive simulations. The predicted results for the air distribution are closely correlated to the dataset estimated from recently improved semi-empirical correlations for passage discharge-coefficients. The simulations also show that the effects of the combustion process on the air splitting can be neglected. Lastly, the results reveal that the airflow through identical passages at the same axial cross-section are not equal, and can vary by up to ±25% of the mean. In summary, the present study suggests that when performing computational models of gas turbine combustor flows, the simulations should couple the liner’s internal and external air splits whenever possible., ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, June 16-20, 2014, Düsseldorf, Germany

In order to assess the remaining life of gas turbine critical components, it is vital to accurately define the aerothermodynamic working environments and service histories. As a part of a major multidisciplinary collaboration program, a benchmark modeling on a practical gas turbine combustor is successfully carried out, and the two-phase, steady, turbulent, compressible, reacting flow fields at both cruise and takeoff are obtained. The results show the complicated flow features inside the combustor. The airflow over each flow element of the combustor can or liner is not evenly distributed, and considerable variations, ±25, around the average values, are observed. It is more important to note that the temperatures at the combustor can and cooling wiggle strips vary significantly, which can significantly affect fatigue life of engine critical components. The present study suggests that to develop an adequate aerothermodynamics tool, it is necessary to carry out a further systematic study, including validation of numerical results, simulations at typical engine operating conditions, and development of simple correlations between engine operating conditions and component working environments. As an ultimate goal, the cost and time of gas turbine engine fleet management must be significantly reduced. © 2012 Leiyong Jiang and Andrew Corber.