Combustion Characteristics by Plate Shape of Turbulence Generator in Low Swirl Combustor : Part I Non-reactive Isothermal Flow

This paper investigates the concept of fractal grid as turbulence generator which has constant reduce rate of grid thickness in low swirl combustor. Turbulence performance comparison of with and without swirler in a non-reactive isothermal flow of model nozzle was investigated using a fractal grid with various RRBT ratios and a general grid with conventional perforated hole configuration. As comparison barometers of turbulence performance, turbulence mean velocity((U) over bar), turbulence fluctuation(u') and turbulence intensity (u'/(U) over bar) were investigated. For all the case, the turbulence intensity of fractal grid was higher than the general grid based on perforated holes. A maximum u' showed to locate at a minimum position of (U) over bar, which is consistent with wake interaction theory. Also, the turbulence intensity increased with smaller value of RRBT in fractal grid. With a constant bulk velocity of 6 m/s, the inner recirculation zone was not detected by using a PIV system and a hot-wire anemometry analysis with radial direction, which is a very important phenomenon to meet the low swirl combustion.