Upper Bounds on the Flight Speed of Hydrocarbon-Fueled Scramjet-Powered Vehicles

Waltrup, P. J.

doi:10.2514/2.5895

Cited by 41 publications

(25 citation statements)

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“…Hydrocarbons are the fuel of choice for low-Mach hypersonic scramjet operations, such as the Air Force HyTech program [13]. Waltrup [14] has shown that a reasonable upper bound on flight Mach number for a hydrocarbon-fueled scramjet is between Mach 9 and 10, which is well within the flight speed range to be examined for practical applications in the near future. Lewis [12] has demonstrated that for a cruiser operating in the Mach 8-10 corridor, in which it is desired to maximize cruise range for a given total takeoff weight, the aerodynamic and volumetric advantages of storable hydrocarbons are about equivalent or superior to the specific impulse advantages of hydrogen in determining cruiser range.…”

Section: Fuelsmentioning

confidence: 98%

Plasma Torch Atomizer-Igniter for Supersonic Combustion of Liquid Hydrocarbon Fuels

Billingsley¹,

O’Brien²,

Schetz³

2006

14th AIAA/AHI Space Planes and Hypersonic Systems and Technologies Conference

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To realize supersonic combustion of hydrocarbons, an effective atomizer-igniter combination with the capabilities of fuel preheating, atomization, penetration, mixing, ignition and flameholding is desired. An original design concept incorporating these capabilities was built and tested at Virginia Tech, and was found to provide good penetration, effective atomization, and robust ignition and flameholding. Quiescent testing with kerosene and JP-7 provided initial performance data. The atomizer-injector design was then modified for insertion In the quiescent environment, the regeneratively cooled plasma torch igniter was found to significantly increase electrode life while heating, atomizing, and igniting the liquid fuel. Jet breakup length was measured and characterized, and mean droplet size was estimated using an existing correlation. Several qualitative observations regarding quiescent combustion were made, including torch power effects and the process of flame formation. In the supersonic environment, the effect of fuel injection direction was analyzed. Best results were obtained when fuel was injected with a velocity component opposite to the direction of main tunnel flow. Repeatable ignition occurred in the supersonic boundary layer at the fuel stagnation location near the plasma torch plume. Direct, filtered, shadowgraph, and schlieren photographs, temperature ii measurements, and visible emission spectroscopy provided evidence of combustion and the details of the flame structure.The new atomizer-igniter design provided robust and reliable ignition and flameholding of liquid hydrocarbon fuels in an unheated supersonic flow at M=2.4, with no ramp, step, or other physical penetration into the flowpath.iii Acknowledgements Dr. O'Brien, I enjoyed the relaxed lab atmosphere, and am grateful for your unique ability to promote progress without being overbearing. Thank you for recognizing my circumstances, and being flexible as I managed my young family. Thank you for the enthusiasm you show for your research; it was a privilege and a joy working with you.

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Section: Fuelsmentioning

confidence: 98%

Plasma Torch Atomizer-Igniter for Supersonic Combustion of Liquid Hydrocarbon Fuels

Billingsley¹,

O’Brien²,

Schetz³

2006

14th AIAA/AHI Space Planes and Hypersonic Systems and Technologies Conference

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“…However, hydrogen has three to four times a lower energy density than typical storable hydrocarbons, and it is difficult to store and handle on a routine basis. In contrast to hydrogen, hydrocarbon fuels package better, exhibiting a greater energy per unit volume, so that they require less room onboard than hydrogen fuel for an equivalent amount of energy [7]. And now, to model the performance of a dual-mode scramjet engine, the heat release distribution must be accurately predicted, because the heat release distribution have an influence on the thermal choking point, the profiles of pressure and Mach number et al Tomioka et al carried out dual-mode combustion tests with hydrogen fuel injection in diverging section and a one-dimensional calculation to estimate combustion efficiency [8].…”

Section: Introductionmentioning

confidence: 98%

Investigation of Ethylene Fuel Combustion in a Dual-Mode Combustor

Nojima¹,

Suzuki²,

Tomioka³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Experiments and a quasi-one-dimensional equilibrium calculation were conduced to estimate performances of a dual-mode combustor with ethylene fuel injection in a directconnect wind-tunnel facility in JAXA Kakuda Space Center (JAXA-KSPC). In the facility, a gaseous H 2 fueled lean combustion heater was used to make high enthalpy flow. The high enthalpy flow was then accelerated with a Mach 2.5 supersonic nozzle. The experiments were executed with a rectangular dual-mode combustor with constant area section and following diverging section at various fuel equivalence ratios. Fuel injectors upstream of cavity flameholders were installed in the constant area section and the diverging section on opposite walls. Heat flux distributions in the streamwise were measured using heat flux transducers mounted flush with the combustor inner wall. The compositions of gas at the exit cross-section of the combustor were sampled using a water-cooled reaction-quench sampling probe. The compositions of sample gas were eccentrically located on the fuel injection side under both of scramjet and dual-mode operation. Therefore, there is a need to consideration of the non-uniformity to estimate state quantities like combustion efficiency and heat flux by quasi-one-dimensional calculation. Heat flux distributions calculated using the "two-flow tubes model" indicated good agreement to measured heat flux. The combustion efficiency defined as the fraction of the oxygen rate that reacted over the total oxygen flow rate was closer to the experimental value than that defined as the fraction of the reacted fuel rate. NomenclatureA = cross-sectional area H = lower heating value M = Mach number P = pressure T = Temperature Y i = mass fraction of chemical species i x = streamwise location from onset of duct divergence y = spanwise location from center of the duct z = height from center of the duct η c = local combustion efficiency Φ = bulk fuel-equivalence ratio = local fuel-equivalence ratio * Graduate Student, Department of Aerospace Engineering. Student Member AIAA. † Graduate Student, Department of Aerospace Engineering.

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“…In this case, the upper speed limit lies in the range of Mach numbers 1216 [2,3]. There were also studies on hydrocarbon-fuelled scramjets with the upper speed limit on §ight Mach number established in the Mach range of 810 [4]. In either case, the §ow velocity at the entrance of combustor can achieve a Mach number of 45.…”

Section: Introductionmentioning

confidence: 98%

Specific features of ignition and flameholding of hydrocarbon fuels in high-speed flow

Goldfeld

2016

Progress in Propulsion Physics

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The paper describes the results of experimental investigations of a supersonic combustion chamber with solid and discrete cavities at the entrance Mach numbers of 3 and 3.5. Kerosene and propane were used as fuel. The conditions required for self-ignition and intense combustion of the fuels were determined. The possibility of e©cient combustion in a supersonic §ow was demonstrated. Analysis of applicability of existing criteria predicting the conditions of self-ignition and extinction of combustion has been performed based on the experimental results obtained.

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Upper Bounds on the Flight Speed of Hydrocarbon-Fueled Scramjet-Powered Vehicles

Cited by 41 publications

References 1 publication

Plasma Torch Atomizer-Igniter for Supersonic Combustion of Liquid Hydrocarbon Fuels

Plasma Torch Atomizer-Igniter for Supersonic Combustion of Liquid Hydrocarbon Fuels

Investigation of Ethylene Fuel Combustion in a Dual-Mode Combustor

Specific features of ignition and flameholding of hydrocarbon fuels in high-speed flow

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