Design and Analysis of Cavity-Based Flameholder Using in Supersonic Combustion Flow PDF Download
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Languages : en
Pages : 0
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Author:
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Languages : en
Pages : 0
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Author: Independently Published
Publisher:
ISBN: 9781723862571
Category :
Languages : en
Pages : 68
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The current work has focused on finding the optimum cavity properties to enhance themixing phenomenon and combustion processes in supersonic flow using ComputationalFluid Dynamics (CFD) ANSYS Fluent. Various models has been modeled with differentvalues of offset ratios (OR) and aft ramp angles (ϴ) while keeping the length-to-depth ratioconstant. All cavity flows have taken open type i.e. length-to-depth ratio
Author: K.-Y. Hsü
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 14
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An experimental investigation of cavity-based flameholders with strut injectors in a supersonic flow is reported. In this ongoing research program, emphases are placed on understanding cavity-based flameholders and providing alternative methods for improving overall combustor performance in scramjet engines. Three different struts with fuel injectors are mounted near the cavity leading edge to study flame propagation and ignition of fuel in the core flow region. OH-PLIF (planar laser induced fluorescence) is used to identify the flame zone around the cavity and strut-wake regions over a range of conditions. Shadowgraphy is used to capture the flow features around the strut and cavity. In-stream probing is conducted to characterize the flow features associated with the different strut configurations. Stagnationtemperature profiles are obtained for all struts operating over the same conditions in the combusting-flow study. Two cavity fueling schemes are used to compare flameholder performance. Direct cavity air injection is found to improve combustion significantly. For each strut, upstream and downstream fueling schemes are compared over a range of conditions.--P. i.
Author: Stephen Alexander Schumaker
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Author:
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ISBN:
Category :
Languages : en
Pages : 14
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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.
Author: Douglas L. Davis
Publisher:
ISBN: 9781423575771
Category : Airplanes
Languages : en
Pages : 239
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This study investigated the flame holding properties of recessed cavities in supersonic flow using numerical analysis techniques. A simplified analytical model indicated that an important property for flame holding was the lower residence time. Several chemical kinetic rate models for hydrogen and hydrocarbon combustion were compared. The perfectly stirred reactor model also indicated that trace species diffusion should increase flame spreading rate, and that heat loss reduces flame holding limits. After nonreacting calibration, two- dimensional simulations confirmed the perfectly stirred reactor results for blowout limits. Also, the effect of trace species diffusion on flame spreading was shown to be negligible, and the reduced flammability with heat loss was confirmed. Lowering the temperature of the inflow boundary layer was shown to reduce the flammability limits. Three-dimensional cavities were shown to generate axial vorticity and slightly enhance flame spreading. The methodology developed in this research provides a design guide for the size of cavity required to provide flame holding for a scramjet combustor. Also, reduction of heat losses was shown to be a method to improve flame holding performance without increasing the cavity size.
Author: William H. Allen (Jr.)
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 178
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Author:
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ISBN:
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.
Author: Corin Segal
Publisher: Cambridge University Press
ISBN: 0521838150
Category : Technology & Engineering
Languages : en
Pages : 271
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Book Description
Demand for high-speed propulsion has renewed development of the supersonic combustion ramjet engine (Scramjet engine) for hypersonic flight applications.
Author: Scott G. Edens
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 186
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