Flowfield in a dual-inlet side-dump combustor

Abstract

The cold flowfield of a side-dump combustor, which consisted of a plexiglass, circular duct with two 60-deg curved inlets located radially at an angle of 180 deg, is measured quantitatively using laser-Doppler velocimetry. Air was used as a flow medium. The Reynolds number, based on the combustor diameter and bulk velocity, was 2.6 x 10 4 . Detailed profiles of mean velocities and turbulence intensities are reported. The impinging stagnation point of the inlet jets, the lengths needed to reach both one-way flow and fully developed mean-velocity profile, and the primary combustor flow regions are determined. In addition, the homogeneity and isotropy of the turbulence are documented. Furthermore, the results also identify the part of fluid dynamic characteristics unable to be predicted by two-dimensional models. This information will be useful to test and develop combustor modeling in this area.Nomenclature combustor diameter, mm dome height, mm combustor radial coordinate, mm normalized combustor radial coordinate, =2R C /D C combustor Reynolds number, =pU Tef D c /iJL combustor bulk velocity, m/s radial mean velocity, m/s radial turbulence intensity, m/s axial mean velocity, m/s axial turbulence intensity, m/s = tangential mean velocity, m/s = tangential turbulence intensity, m/s = combustor longitudinal coordinate, mm = normalized combustor longitudinal coordinate definitions: X* C >0:X* C =X C /D C ; --inlet-duct axial coordinate, deg = combustor tangential coordinate, deg = air dynamic viscosity, kg/m-s = air density, kg/m 3

Approximate velocity scale for primary and secondary dual-inlet side-dump flows

“…To mimic physical inflow condition, an inlet duct is extended to upstream of the reference point ( * (1) and (2) are only applied to the quarterly segmented grid system. As noted in the previous studies [5][6][7], the ram flow exhibits unique and complex flow characteristics. Paralleled with the use of a robust high-resolution numerical method, the physical domain must be finely segmented so that the small-scale fluid motions can be resolved.…”

“…2. For the convenience of the code validation, the geometry of the combustor repeats previous experimental study [5]. The dome height ( D L ) and the combustor diameter ( c D ) are 50mm and 100mm, respectively.…”

“…The flow distribution above the dump plate is neither the uniform nor the seventh power law. It is characterized by the six-vortex structure in the transverse direction and flow reversal in the streamwise direction, and resulting helical flow is dumped into the combustion chamber [5]. To mimic physical inflow condition, an inlet duct is extended to upstream of the reference point ( * (1) and (2) are only applied to the quarterly segmented grid system.…”

“…The combustor flows are distinguished by two flow regimes bifurcated at the jet-impingement stagnation point. The low speed fluids in the head dome, especially those adjacent to the head plate, play the role of a nearly stagnant wall to the upstream bifurcating flow [5]. If the dome height is equal to or greater than the radius of the cylinder, the flow field downstream of the jet-impingement stagnation point is no longer altered by the dome height [6].…”

“…Particularly, many experimental and analytical efforts have centered on determining an optimal dome height for the best blow-off performance [3,[5][6][7][8][9]. The combustor flows are distinguished by two flow regimes bifurcated at the jet-impingement stagnation point.…”