Effects of scale on supersonic combustor performance

Diskin, G. S.; Northam, G. B.

doi:10.2514/6.1987-2164

Cited by 24 publications

(23 citation statements)

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“…Diskin et. al., introduced empirical model of mixing efficiency distribution based on experimental data on socalled dual-mode combustion [16], the flow structure being essentially the same to that observed in the present study with 'ramjet mode' combustion. Note that the fast chemistry condition was expected in the present condition, so that mixing efficiency was close to combustion efficiency.…”

Section: Engine Performancementioning

confidence: 84%

Performance of a Rocket-Ramjet Combined-Cycle Engine Model under Ramjet-Mode Operations

Tomioka¹,

Kato²,

Tani³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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A rocket-ramjet combined cycle engine model, embedding twin rocket chamber on top wall side of a scramjet flow-pass, was tested under ramjet-(dual-) mode operation at M6 flight conditions. The rocket chamber was driven with gaseous hydrogen and oxygen at nominal operation condition of 0.6 MPa in chamber pressure and 6.0 in mixture ratio. Gaseous hydrogen was also injected through injector orifices within the 'ramjet' combustor to pressurize the combustor. A simple, one-dimensional calculation was conducted based on wall pressure measurement to evaluate combustion mode and engine performance. Engine exhaust samplings as well as Pitot pressure measurements were conducted to evaluate the calculation results. Different combustion modes were observed, which were found to have sizable effects on the engine performance. Nomenclature A= cross-sectional area F, ΔF = thrust, thrust increment from reference state O/F = rocket chamber mixture mass ratio Isp, ΔIsp = specific impulse, specific impulse based on thrust increment M = Mach number p, P, q = static pressure, total pressure, dynamic pressure X, Y, Z = stream-wise location from imaginative leading edge of top wall, span-wise location from engine center line, height from top wall φ, φ eff = equivalence ratio, effective equivalence ratio (η c ×φ) η c = combustion efficiency Subscripts: 1 = at engine entrance a = freestream c = rocket chamber eff = effective w = wall

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Section: Engine Performancementioning

confidence: 84%

Performance of a Rocket-Ramjet Combined-Cycle Engine Model under Ramjet-Mode Operations

Tomioka¹,

Kato²,

Tani³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

View full text Add to dashboard Cite

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“…1 ' 4 The condition was also observed in experiments and numerical simulations of scramjet combustors. 5 ' 8 With recent progress of the researches on the hypersonic air-breathing engines, the dual-mode operation is focused again. 4 ' 9 In a design of the hypersonic vehicle, a 1-D simulation model of the dual-mode operation is already included.…”

Section: Amentioning

confidence: 99%

Dual-mode operation in a scramjet combustor

Kanda¹,

Chinzei²,

Kudo³

et al. 2001

10th AIAA/NAL-NASDA-ISAS International Space Planes and Hypersonic Systems and Technologies Conference

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The dual-mode operation was studied experimentally in a Mach 2.5 wind tunnel, to which a scramjet combustor model was connected directly. The total temperature and the total pressure of the air were 2000 K and 1.0 MPa, respectively. The air was heated in a vitiation heater. The mole fraction of oxygen was 21 %. Two kinds of the ramjet-mode operation and a scramjet-mode operation were attained. In a ramjetmode operation, the air was decelerated in the straight duct section. Subsonic combustion and the acceleration around the entrance of the divergent section followed. In another ramjet-mode, the air was decelerated in the divergent section, subsonic combustion followed, and the gas was choked at the exit of the combustor. These operating modes were attained in the same combustor and at the same fuel flow rate by changing the fuel injection position. There was no significant difference in the thrust increment among the three operating modes.

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“…The step height was based on the criteria of Ref. 11. The x coordinate was along the direction of flow, whereas the y coordinate was perpendicular to the x axis.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Autoignited Combustion Testing in a Water-Cooled Scramjet Combustor

Kanda

Chinzei

Kudo

et al. 2004

Journal of Propulsion and Power

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A water-cooled scramjet combustor was tested to study the effects of pressure, combustor length, fuel-injection style, and wall temperature on autoignited combustion performance. The tests were conducted with an inflow Mach number of 2.5; total pressure of air of 1, 1.5, and 2 MPa; and total temperature of air from 1200 to 2600 K. High-enthalpy air was produced using a vitiation heater. The combustion condition was detected by an increase of temperature in the combustor, which was related to a local combustion condition. When hydrogen fuel was supplied transversely to the combustor wall downstream of the backward-facing step, the autoignited combustion performance degraded with an increase of the airflow pressure under a condition of low total temperature of the vitiated air. The ignition region was around the second explosion limit. The presence of H 2 O in the air further retarded ignition under the high-pressure condition. In high-temperature conditions, the combustion performance was improved by the increase of pressure. With the long combustor with a downstream extension, the autoignited combustion limit on the air temperature became lower. A long separation region was presumed to exist downstream of the transverse fuel jet. Under such conditions, the residence time of the mixture increased, and the ability of autoignited combustion could be improved. This effect of the extension of the combustor length decreased with the increase of pressure. Parallel fuel injection from the step base showed low autoignited combustion ability. In the parallel injection, autoignition would initiate at the base of the step, where the pressure was low and the size of the base was small. In the water-cooled combustor, the autoignited combustion limit on the air temperature was higher than that in the uncooled combustor. This fact suggested that the ignition source existed near the wall, for example, in the separation region. NomenclatureA = cross section of airflow duct a = cross section of fuel injector D = diameter of the fuel injection port H = height of combustor flow path H MID = height of Mach disk in the fuel injected transversely to the wall M = Mach numbeṙ m= mass flow rate P ta = total pressure of the vitiated air P w = wall pressure q = dynamic pressure T ta = total temperature of the vitiated air V = velocity W = width at the exit of the facility nozzle x = distance from the step along flow direction (see Fig. 1) y = vertical distance from the midpoint of the combustor z = spanwise distance from the center plane of the combustor . Member AIAA. γ = ratio of specific heats T = difference of measured gas temperature after fuel injection from that before injection ρ = density τ = time φ = equivalence ratio Subscripts ex = combustor with extension f = fuel ig = ignition no ex = combustor with no extension r = residence ∞ = primary airflow

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Effects of scale on supersonic combustor performance

Cited by 24 publications

References 0 publications

Performance of a Rocket-Ramjet Combined-Cycle Engine Model under Ramjet-Mode Operations

Performance of a Rocket-Ramjet Combined-Cycle Engine Model under Ramjet-Mode Operations

Dual-mode operation in a scramjet combustor

Autoignited Combustion Testing in a Water-Cooled Scramjet Combustor

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