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Kuang-Yu Hsu

Bio: Kuang-Yu Hsu is an academic researcher from Air Force Research Laboratory. The author has contributed to research in topics: Combustor & Scramjet. The author has an hindex of 17, co-authored 43 publications receiving 1096 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, an experimental investigation of the mixing and combustion processes that occur in and around a cavity-based flameholder in a supersonic flow is reported, which is part of an ongoing research program aimed at providing information to help fill these voids and improve the overall understanding of cavities for use as scramjet flameholders.
Abstract: An experimental investigation of the mixing and combustion processes that occur in and around a cavity-based flameholder in a supersonic flow is reported. Cavity-based flameholders are commonly found in hydrocarbon-fueledscramjet combustors; however, detailed information concerning the behavior of these devices, their optimal shape and fueling strategies, combustion stability, and interactions with disturbances in the main airflow (i.e., shock trains or shock-boundary layer interactions) is largely unavailable in the existing literature. This work is part of an ongoing research program aimed at providing information to help fill these voids and improve the overall understanding of cavities for use as scramjet flameholders.

332 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental investigation of cavity-based flameholders with strut injectors in a supersonic flow is reported, where 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.
Abstract: An experimental investigation of cavity-based flameholders with strut injectors in a supersonic flow is reported. In this ongoing research program, emphasis is 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. Planar laser-induced fluorescence of the OH radical is used to identify the flame zone around the cavity and strut-wake regions over a range of conditions. Shadowgraphy is employed 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. Stagnation-temperature profiles are obtained for all struts operating under the same condition 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. Overall, successful combustion is observed in the strut-wake region using upstream strut-fueling schemes for the three struts employed in this study.

110 citations

01 Jul 2007
TL;DR: In this paper, an experimental investigation of cavity-based flameholders with strut injectors in a supersonic flow is reported, where 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.
Abstract: : 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 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. Stagnation-temperature 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.

102 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present results from both computational fluid dynamic and wind-tunnel experiments of in-stream fueling pylons injecting air, ethylene, and methane gas into Mach number 2.0 cold airflow.
Abstract: This paper presents results from both computational fluid dynamic and wind-tunnel experiments of in-stream fueling pylons injecting air, ethylene, and methane gas into Mach number 2.0 cold airflow. Three fuel-injection pylons studied include a basic pylon, a ramp pylon, and an alternating-wedge pylon. The latter two pylons introduce streamwise vorticity into the flow to increase mixing action. The computational fluid dynamic solution was accomplished using the commercial code FLUENT®. Three wind-tunnel experimental techniques were used: aerothermal probing, Raman spectroscopy, and nitric-oxide planar laser-induced fluorescence. Four measures reported include streamwise vorticity, total-pressure-loss, mixing efficiency, and flammable plume extent. The ramp and alternating-wedge pylons show decisive increases in mixing capability compared with the basic pylon for a finite distance downstream of the injector. The alternating-wedge pylon exhibits a measurable increase in total pressure loss compared with the basic pylon, and the ramp pylon exhibits a negligible increase in total pressure loss compared with the basic pylon. For comparison, the downstream mixing effectiveness of the three pylons is compared with the downstream mixing effectiveness of a transverse circular wall injector studied in past research. In addition, a qualitative comparison between the computational fluid dynamic and wind-tunnel experimental results is made.

74 citations

Journal ArticleDOI
01 Jan 2015
TL;DR: In this paper, the authors used two energy deposition techniques: a spark discharge and a pulse detonator (PD) to achieve successful combustion of an ethylene-fused cavity in a supersonic flow.
Abstract: Ignition of an ethylene fueled cavity in a supersonic flow was achieved through the application of two energy deposition techniques: a spark discharge and pulse detonator ( PD ). High-frequency shadowgraph and chemiluminescence imaging showed that the spark discharge ignition was passive with the ignition kernel and ensuing flame propagation following the cavity flowfield. The PD produced a high-pressure and temperature exhaust that allowed for ignition at lower tunnel temperatures and pressures than the spark discharge, but also caused significant disruption to the cavity flowfield dynamics. Under certain cavity fueling conditions a multiple regime ignition process occurred with the PD that led to decreased cavity burning and at times cavity extinction. Simulations were performed of the PD ignition process, capturing the decreased cavity burning observed in the experiments. The PD exhaust initially ignited and burned the fuel within the cavity rapidly. Simultaneously, the momentary elevated pressure from the detonation caused a blockage of the cavity fuel, starving the cavity until the PD completely exhausted and the flowfield could recover. With sufficiently high cavity fueling, the decrease in burning during the PD ignition process could be mitigated. Cavity fuel injection and entrainment of fuel through the shear layer from upstream injection allowed for the spark discharge ignition process to exhibit similar behavior with peaks and valleys of heat release (but to a lesser extent). The results of using the two energy deposition techniques emphasized the importance of cavity fueling and flowfield dynamics for successful ignition.

57 citations


Cited by
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Journal ArticleDOI
TL;DR: It appears that the group of schizophrenics had difficulties in social adjustment which were even greater than those of work adjustment, and the men concerned had greater difficulty in living outside hospital, than in working outside hospital.
Abstract: a time as one year after leaving the Rehabilitation Unit, and about one quarter were not in competitive jobs but were in sheltered employment. Only just over one quarter were still working in ordinary jobs. Their average wage was £8 I is. 6d. Furthermore if one compares the type of work these patients were able to perform there was a definite decline from their premorbid position. The social class grouping before and after rehabilitation was Class II, i-i, Class III, 9-3, Class IV, 4-6, and Class V, IO-I4. Indeed the authors report that 'even the least handicapped of these patients presented continuous problems . . .' and it is noted that such a programme requires special personnel and a great deal of work. Comparing these results with the extra cost in personnel, time, and effort (which could be directed elsewhere) a Doctor Beeching of the psychiatric services would probably scrap such a rehabilitation service before it even started. But is this the right way of looking at it? The authors point out that such a programme, if applied throughout the country, would affect about 6,ooo patients. If the failure rate were the same as in this experiment, about I,500 would be rescued from a disabled life in a mental hospital and once more returned to an at least partially useful and, one assumes, more satisfying life. Obviously more is involved here than mere economics. We were interested to read that as regards behaviour at the Rehabilitation Centre and during the follow-up year 'There were no outstanding differences' between the schizophrenic and the non-schizophrenic rehabilitees. It appears that the group of schizophrenics had difficulties in social adjustment which were even greater than those of work adjustment. '. . . the men concerned had greater difficulty in living outside hospital, than in working outside hospital. If, however, adequate arrangements are made to cater for these various needs, there seems to be every reason to expect that a small selected group of long stay schizophrenic patients can be successfully resettled in work.' The experiment and the report show the high standards we have come so confidently to expect from Dr. Wing and his colleagues, and the publication will be read with interest, not only by psychiatrists, but by all those concemed with rehabilitation problems of chronically disabled patients. J. HOENIG

665 citations

Book
26 Apr 2002
TL;DR: In this paper, the authors assembled a world-class group of contributors who address the questions the combustion diagnostic community faces, including chemists who identify the species to be measured and the interfering substances that may be present; physicists who push the limits of laser spectroscopy and laser devices and who conceive suitable measuremen.
Abstract: The editors have assembled a world-class group of contributors who address the questions the combustion diagnostic community faces. They are chemists who identify the species to be measured and the interfering substances that may be present; physicists, who push the limits of laser spectroscopy and laser devices and who conceive suitable measuremen

492 citations

Journal ArticleDOI
TL;DR: In this paper, a review of recent advances in boundary layer interaction research is presented, including low frequency unsteadiness, heat transfer prediction capability, complex (multi-shock boundary layer) interactions and flow control techniques.

435 citations

Journal ArticleDOI
TL;DR: In this article, an experimental investigation of the mixing and combustion processes that occur in and around a cavity-based flameholder in a supersonic flow is reported, which is part of an ongoing research program aimed at providing information to help fill these voids and improve the overall understanding of cavities for use as scramjet flameholders.
Abstract: An experimental investigation of the mixing and combustion processes that occur in and around a cavity-based flameholder in a supersonic flow is reported. Cavity-based flameholders are commonly found in hydrocarbon-fueledscramjet combustors; however, detailed information concerning the behavior of these devices, their optimal shape and fueling strategies, combustion stability, and interactions with disturbances in the main airflow (i.e., shock trains or shock-boundary layer interactions) is largely unavailable in the existing literature. This work is part of an ongoing research program aimed at providing information to help fill these voids and improve the overall understanding of cavities for use as scramjet flameholders.

332 citations

Journal ArticleDOI
TL;DR: The transverse jet has been studied extensively because of its relevance to a wide variety of flows in technological systems, including fuel or dilution air injection in gas turbine engines, thrust vector control for high speed airbreathing and rocket vehicles, and exhaust plumes from power plants as discussed by the authors.

329 citations