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Show Inconel Insert P o rous Cylinder Entrainment Chamber --------4:~ Baffle Water - Cooled Injector Refracto ry Mixin& Cham ber No te : Drawing not to scale Optically - Accessible Entrainment Chamber Win dow ! Burner Fig. 2. Schematic diagram of the bench-scale apparatus. (-1366 K) oxidant (7-27% 02). Note that natural gas was used throughout the research program as the fuel, while either air or pure oxygen was used as the oxidant. The natural gas was analyzed using a UTI 100C mass spectrometer and was nearly pure methane (95% vol.). The bench-scale apparatus consisted of a coaxial-tube burner, a gas mixing chamber equipped with ten water-cooled heat sinks, an entrainment chamber and a water-cooled injector element, as shown in Fig. 2. A coaxial-tube burner was used to generate a high-temperature oxidant in the mixing chamber (inner diameter = 305 mm, inner length=775 mm) by burning natural gas and oxygen at a given equivalence ratio. Hence, the major species in the mixing chamber were CO2, H20 and 02. Retractable heat sinks were used to tailor the gas temperature. The hot gas traveled to the cylindrical-shaped entrainment chamber via two pipes. The entrainment chamber mimics, to a large extent, the experimental apparatus of Ricou and Spalding [2]. It consisted of a top and bottom steel endcap and a (or several) steel midsection(s). Different midsections were used to vary the chamber height. Note that two entrainment chambers were used, one without windows (used for mass entrainment measurements) and the other with windows (used for flame lift -off height measurements). The high-temperature oxidant from the mixing chamber subsequently passed through a porous cylinder (or a porous disk depending on which entrairunent chamber was being used) and interacted with the natural gas emanating from the water-cooled injector. The injector diameters available were 0.794, 1.59,3.18 and 4.72 mm. All of the gases subsequently exited the entrainment chamber through the circular opening in the Inconel insert. The size of this opening was chosen based on the criteria delineated by Ricou and Spalding [2]. Thus, the angle from the jet centerline to the edge of the circular opening, with the injector exit as the vertex, was 15°. Thermocouples in both the mixing and the entrainment chambers were used to monit temperatures. The thermocouple in the entrainment chamber was embedded in the porous or material in order to acquire a close approximation to the gas temperature. The temperature acquired from this thermocouple was taken as the gas temperature with no corrections performed. 5 |
