Temperature and concentration measurements in a solid fuel ramjet combustion chamber

Schulte, Georg; Pein, R.; Högl, Anke

doi:10.2514/3.22962

Cited by 54 publications

(12 citation statements)

References 16 publications

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“…(7) gives a theoretical value of c' as determined from the properties of the hot combustion gas. This theoretical value generally is in good agreement with the actual experimental value and has been used in design calculations (Sutton, 1986). Therefore, the characteristic exhaust velocity c' is used as a flammability criterion in the present study.…”

Section: Effects On Flammabilitysupporting

confidence: 67%

“…A joint research program has been conducted both numerically (Elands, 1987;Vos, 1987) and experimentally (Coning et al, 1990) at the Delft University of Technology and the Prins Maurits Laboratory TNO in the Netherlands. Other research on SFCC has been carried out by researchers at Technion in Israel Zvuloni et al, 1989b;Netzer and Gany, 1991;Ben-Aiosh and Gany, 1992) and at the German Aerospace Research Establishment (DLR) in Germany (Schulte, 1986;Schulte et al, 1987). These two research groups have been focusing on experimental work.…”

mentioning

confidence: 99%

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Excited Turbulent Reacting Flows in a Chamber With Gaseous Fuels Injecting Through Porous Walls

Liou

Hwang

Lien

1996

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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A numerical analysis was performed to study excited turbulent reacting flows in a combustion chamber consisting of gaseous fuels injecting through porous walls. The time-dependent axisymmetric compressible conservation equations were solved directly without using subgrid-scale turbulence models. The combustion process considered was a one-step, irreversible, and infinitely fast chemical reaction. The numerical code used the finite-volume technique, which involved alternating in time the second-order, explicit MacCormack’s and modified Godunov’s schemes. Excitations with various forcing frequencies were applied to the air inflow boundary to investigate their effects on the large-scale unsteady flow structures, vorticity dynamics, mean flame position, mean temperature distribution, and characteristic exhaust velocity. From the numerical flow visualization of the instantaneous vorticity field and the associated vorticity dynamics analysis, a rationale for the augmentation or diminution of organized vortical structures under external excitations was provided. It is found that an excitation with the fundamental frequency attains a larger high temperature recirculation zone with a higher peak temperature and hence a better flame-holding condition. An application of the active control by forcing the air inlet velocity with the fundamental frequency at various amplitudes to an original non-sustained combustion case indicates that the combustion can be sustained if an appropriate exciting amplitude is selected.

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Section: Effects On Flammabilitysupporting

confidence: 67%

mentioning

confidence: 99%

Excited Turbulent Reacting Flows in a Chamber With Gaseous Fuels Injecting Through Porous Walls

Liou

Hwang

Lien

1996

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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“…In fact, in both axial injector hybrid motor and solid fuel ramjet, three distinct flow regions exist 7 (see Fig. 1): 1) recirculation zone into which oxygen is transported from the jet core across the turbulent shear layer (Here, fuel provided from the wall is recirculated and reacts with oxygen near the head end of the grain; as pointed out by Shulte et al, 8 the flame initiates along the shear layer); 2) impingement or reattachment region where the oxygen attacks the grain surface; and 3) the zone downstream of oxidizer impingement, where the turbulent boundary layer starts developing. Within this boundary layer a diffusion flame is, instead, formed.…”

mentioning

confidence: 90%

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Carmicino

Sorge

2006

Journal of Propulsion and Power

103

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This paper analyzes the results obtained from a series of static firings of a lab-scaled hybrid rocket in which gaseous oxygen was supplied into axial-symmetric polyethylene cylindrical grains through two different injector configurations: an axial conical subsonic nozzle and a radial injector. The axial injector is interesting because of its relatively easy design, the higher regression rates, and the noticeably stable motor operation. To exploit its qualities, not only the assessment of the regression rate but rather the entire behavior of the motor is required. For the investigated set of operating conditions, the instantaneous regression rates exhibit a time dependence caused by the impinging jet zone dynamics, while the average regression rates are higher and less mass flux dependent than those achieved with the radial injection motor and expected from the classical turbulent-boundary-layer diffusionlimited theory. A comparison to the data from the radial injector was further drawn in terms of combustion efficiency and fuel regression uniformity. Concerning combustion stability, some observations are made. The radial injector, at the same mass flux and pressure, produces lower regression rates, high pressure oscillations, and worse combustion efficiency, but more uniform fuel consumption. Nomenclatureof ultrasounds in reference conditions c * = characteristic exhaust velocity c * 0 = theoretical characteristic exhaust velocity calculated at O/F c * = theoretical characteristic exhaust velocity calculated at OF D = space average port diameter D 0 = port initial diameter D 2 = average port final diameter D 2x = local port final diameter d = diameter E a = activation energy F = motor thrust G = mass flux H v = effective heat of vaporization I m = mixing index L = grain length L c = prechamber length L * = chamber characteristic length l = exponent of the Reynolds number in the mixing index definition m = exponent of the geometrical ratio in the mixing index definitioṅ m f = fuel mass flow ratė m ox = oxidizer mass flow rate = isentropic one-dimensional mass flow rate through the nozzle N = number of data points in the port diameter profiles n = exponent of mass flux OF = spatially averaged oxidizer-to-fuel ratio OF = mean value of spatially averaged oxidizer-to-fuel ratios O/F = average oxidizer to average fuel mass ratio p a = ambient pressure p e = nozzle-exit pressure R = gas constant Re = Reynolds numbeṙ r = space average regression ratė r x = local regression rate s = fuel grain thickness T w = fuel surface temperature t = time V e = isentropic one-dimensional velocity at nozzle exit x = axial abscissa z = nondimensional axial abscissa (x/L) α = nozzle divergence cone half-angle M f = measured solid fuel mass loss M f = computed solid fuel mass loss t = time step t o = ultrasounds time of flight η = c * efficiency, ratio between the actual and theoretical c * th η 0 = c * efficiency calculated at O/F λ = momentum-thrust reduction coefficient μ = gas viscosity ρ f = solid fuel density σ = standard deviation...

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“…Thus, it is obvious that the chemical reaction mainly took place in the region with more CO 2 and CO. The interface between these two regions is named as the flame surface, which was also experimentally identified in Reference [34]. There are two combustion mechanisms (diffusion process and chemical process) in the combustion chamber.…”

Section: Flow Field Characteristicsmentioning

confidence: 99%

“…While in the chamber of SFRJ, the combustion is very complex, and it is difficult to come up with an accurate model for high-density Polyethylene (HDPE) combustion. Thus, to simplify the simulation of the chemical reaction, the assumption is made that C 2 H 4 is the only pyrolysis product of polyethylene, and N 2 , CO, H 2 O, CO 2 , and O 2 are regarded as the main products in the chamber of SFRJ [34]. As Reference [35] presents, Table 1 shoes the reaction model of the gas phase.…”

Section: Chemical Reaction Modelmentioning

confidence: 99%

Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow

Chen

Cai

et al. 2019

Energies

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In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the reattachment point at first, and then the heat released in reattachment point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.

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Temperature and concentration measurements in a solid fuel ramjet combustion chamber

Cited by 54 publications

References 16 publications

Excited Turbulent Reacting Flows in a Chamber With Gaseous Fuels Injecting Through Porous Walls

Excited Turbulent Reacting Flows in a Chamber With Gaseous Fuels Injecting Through Porous Walls

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow

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