Mixing Effects of Pylon-aided Fuel Injection Located Upstream of a Flameholding Cavity in Supersonic Flow PDF Download
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Author: Daniel R. Montes
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 428
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Author: Daniel R. Montes
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 428
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Author: Lane C. Haubelt
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 306
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Author:
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Category :
Languages : en
Pages : 13
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An investigation of the nonreacting flow associated with pylon-aided gaseous fuel injection into a Mach 2 crossflow is described. In this study, a small pylon was positioned just upstream of a circular flush-wall fuel injector. Three pylon geometries were studied, along with a no-pylon reference case. In all cases, a typical cavity-based flameholder was positioned downstream of the fuel injector. The injectant plume characteristics were interrogated using a variety of laser-based and probe-based measurement techniques. Planar laser-induced fluorescence of nitric oxide was used to study the instantaneous plume structure. Spontaneous vibrational Raman scattering provided time-averaged plume characteristics and mixing information. Probe-based instrumentation was used in conjunction with the mixing data to estimate the total pressure losses associated with each configuration. Each pylon had a unique influence on the fuel-injection plume. In all cases, the presence of the pylon resulted in improved fuel penetration into the supersonic crossflow without significantly changing the total pressure-loss characteristics. Mixing efficiencies of the pylon-aided injection cases were not substantially different from the reference case.
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 544
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Author: Steven J. Etheridge
Publisher:
ISBN:
Category :
Languages : en
Pages : 55
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Typical studies of scramjet combustion employ as uniform a flowpath as possible. These studies are important to isolate the effects of a given combustor configuration. However, such studies tend to ignore the effects of a shock train created by the vehicle installation and that this shock train changes over the flight envelope. Consequently, the performance of a given configuration is measured without considering the considerable effects of this shock train or how it changes with different flight conditions. This thesis includes experimental and computational studies of the effects of an incident shockwave on the flowfield, fuel distribution and combustion within a cavity flameholder with upstream fuel injection. The effect of the shockwave location (on the upstream fuel jet or over the cavity) and shock angle are controlled by adjusting a shock generator mounted in the tunnel test section. The effect of fuel injection momentum ratio is also examined. Shadowgraphy is used to characterize the flowfield while planar laser induced fluorescence of the NO and OH molecules are used to measure the fuel mixing and combustion, respectively. These experimental data are compared with CFD solutions of the Reynolds Averaged Navier-Stokes equations provided in previous CFD work. The effect of the shock on the cavity shear layer is found to control the fuel distribution within the cavity. The shock on jet impingement forces the shear layer deep within the cavity and results in higher concentrations near the cavity centerline, but low mixing uniformity. The shock on cavity case causes the shear layer to separate upstream of the cavity, mixing uniformity is enhanced by the increased breakup of the fuel plume. Combustion is stronger and more uniform in the shock on cavity case, while it is limited to the edges of the cavity with shock impingement on the jet. The greater mixing afforded in the shock on cavity case reduces the fuel concentration near the centerline and permits stronger burning in the center of the cavity. Small changes in the fuel injection momentum ratio (doubling) do not strongly affect the pattern of fuel distribution in any case. Combustion in the shock on cavity case is reduced by increasing fuel injection momentum because the fuel concentration at the centerline is too high. Small increases in the shock angle did not strongly affect the results.
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 666
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Author: Mitchell R. Pohlman
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 246
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Author: Qiuya Tu
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ISBN:
Category :
Languages : en
Pages : 124
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Simulation for shock wave/ boundary-layer interaction was conducted in Fluent for case of M=1.9 at 60% blockage by using k- RNG model with two different near wall treatments. In both cases, the shock ran out of isolator before the computation converged, this is different from experimental results. Proper actual wall friction force may have a very important effect on the computation, which needs to be evaluated.
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Category :
Languages : en
Pages : 14
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Book Description
The effect of direct fuel and air injection was experimentally studied in a cavity-based flameholder in a supersonic flow. Cavity- based fuel injection and flameholding offer an obstruction-free flow path in hydrocarbon-fueled supersonic combustion ramjet (scram jet) engines. Additionally, this study included characterization of the operational limits (i.e., sustained combustion limits) over a variety of fuel and air flow rates. The cavity rearward ramp includes 10 spanwise injection ports at each of 3 axial stations configured to inject air, fuel, and air, respectively. Planar laser-induced fluorescence (PLIF) techniques were utilized to collect planar distributions of the OH radical at various axial locations within the cavity under different flow conditions. A high-speed emissions camera was used to evaluate the combustion across the cavity. Direct injection of both fuel and air provided additional capability to tune the cavity such that a more stable decentralized flame results. The addition of air injection provided the most improvement over the baseline case (fuel only) near the upstream portion of the cavity close to the cavity step.
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Category :
Languages : en
Pages : 0
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This report describes the results of a recent series of experiments designed to examine the fundamental behavior of several cavity-based flameholder candidates in a non-reacting supersonic flow. Seven geometries were tested in conjunction with a new facility nozzle. Results indicate that the cavity aft ramp plays a strong role in determining the character of the shear layer which spans the length of the cavity. For rectangular cavities, a compression wave forms as the flow separates from the upstream corner of the cavity. Thus, the pressure on the upstream face increases above the freestream value. In these cases, the recompression which occurs at the aft wall is very sharp with strong pressure gradients at the axial location corresponding to the aft wall. These cases are also visibly unsteady. Reductions in the ramp angle yield more stable, two-dimensional flowfields. However, the character of the separation wave changes gradually from compressive to expansive as the ramp angle is reduced. As such, the shear layer tends to dip into the cavity and the recompression occurs more gradually as the shear layer reattaches to the aft wall. Changes in cavity offset ratio result in more dramatic changes in the cavity flowfield. The separation wave becomes strongly expansive leading to severe shear layer intrusion into the cavity. Aft wall changes do not strongly impact the character of the shear layer, although stability is enhanced and recompression is more gradual for shallower ramp angles.
