Host Institution: Technische Universität Darmstadt (Germany)
Reactive Flows and Diagnostics, Technische Universität Darmstadt
Phone: +49 6151 16-28919
Fax: +49 6151 16-28900
At the TU-Darmstadt I will focus my attention on turbulence-chemistry interactions in turbulent flame, and one of the main goal is to provide reliable data for developing and validating of models for the numerical simulation of stratified, premixed and partially-premixed flames.
Experiments will be conducted on a stratified burner fueled with a mixture of CH4 and H2 at different compositions and air/fuel ratios, using a multiscalar measurement technique for a detailed understanding of the interaction. In particular will be used the Raman/Rayleigh spectroscopy, a diagnostic tool that can provide temperature measurements simultaneously with compositions for the main species. In addiction a cross-sheet laser will be used for evaluating the flame-front position. This experimental work will be intersected with data evaluations and post-processing.
Project title: Experimental investigations using complex geometry of injectors and different fuels by means of advanced measurement techniques
Objectives. Piloted flames are regularly used for stabilization of overall lean combustion. Piloted flames are typically fuel-rich such that an overall lean flame is anchored by a flame burning in a fuel stratified or non-premixed mode. The underlying turbulence-chemistry interactions with their impact on flame stabilization or pollutant formation is not well understood. Present combustion models need to be benchmarked against well-suited experiments. At TUDA an enclosed combustion system has been developed that mimics most important properties of gas turbine combustion. The fuel nozzle provides a swirled annular flow of premixed fuel and air. As a special feature the geometrical swirl number can be changed during operation. This allows operation at different stabilization points. In case of lean combustion an additional pilot flame is needed. The pilot flame is formed by a central jet issuing from a central bluff body that is surrounded by the annular swirled flow. The mass flow ratio between pilot and main flow can be changed from 0 to 1 providing a second measure for flame stabilization. The combustor is throttled to ensure no backflow from the exhaust pipe system. Optical access allows for the application of common laser diagnostics. Due to the optical access operational pressures are limited to below 10 bar.
Expected results. In this project a series of practically relevant piloted lean flames at elevated pressures is selected. Flow fields and flame brushs are measured by means of particle image velocimetry and laser-induced fluorescence of OH radicals that are formed in the reaction zones. Based on this data the location of flame stabilization is investigated. The data are explored in cooperation with the project partners for validation of combustion models in this close-to-reality combustor.
Planned secondment. FR-CS (8-10 months). Data post processing and involvement to validation of numerical simulations.