Ultrasonic regression rate measurement in solid fuel ramjets

Dijkstra, F.; Korting, P.A.O.G.; Berg, Robert

doi:10.2514/6.1990-1963

Cited by 26 publications

(9 citation statements)

References 1 publication

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“…10). This regression-rate sharp increase occurring during pressure oscillation periods has been also documented by Dijkstra et al 31 Note that the oscillatory behavior of the local regression rate is captured by the ultrasound measurement technique. The latter was modified, in the radial injection test campaign, as outlined in the "Ultrasound Signal Analysis" section, in order to get higher sampling rate and better accuracy.…”

Section: Theoretical Comparisonmentioning

confidence: 66%

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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Section: Theoretical Comparisonmentioning

confidence: 66%

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Carmicino

Sorge

2006

Journal of Propulsion and Power

103

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“…Finding the saddle point in this diagram is equivalent to finding the frequency and phase of the observed signals, and the burning rate is obtained from f , f 0 , and c(p, T ) using Eq. (2).…”

Section: Frequency Analysis (Wavelet Method)mentioning

confidence: 95%

“…Linear burning rates under steady conditions are usually obtained with the break wire method in a strand burner or with a small motor method. ONERA (French National Aerospace Research Establishment) developed an ultrasonic technique called the "round-trip technique," which can yield the burning rate characteristics of solid propellants in a sophisticated manner, and their device, electronic device for ultrasonic measurements (EDUM), is widely spread in the world and used in combustion studies of solid propellants [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Novel burning rate measurement technique for solid propellant by means of ultrasonics

Hasegawa

Hori

2010

Combust Explos Shock Waves

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A novel burning rate measurement technique for solid propellants using ultrasonics has been developed. Ultrasound is applied to the burning surface of the end-burning propellant grain from the bulk side, and the reflected wave, which is frequency-shifted by the Doppler effect, is analyzed with a wavelet technique. This method enables us to get the instantaneous linear burning rate and, thus, can be a strong tool for the instability study of solid propellants. The wavelet method is also favorable for the identification of the reflected signal from the burning surface even if the signal intensity becomes very low and indistinguishable from white noise with normal measuring techniques. Efforts have also been paid to eliminate the coupling material between the ultrasonic probe and the propellant grain to simulate the real situation of rocket motors. An oscillation deadener circuit has been successfully employed to reduce strong multi-deflection signals within a metallic plate between the probe and the propellant grain. With these two improvements, it becomes possible to detect and process the signals in longer propellant grains in the actual solid rocket motor situations.

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“…A series of ramjet tests with air and PMMA by Dijkstra [6] also reported a sudden increase of pressure. Test con¦guration was very similar to the one used in the test for DC-shift of hybrid rocket combustion in that it installed a diaphragm at the front end of fuel grain.…”

Section: Introductionmentioning

confidence: 95%

Large eddy simulations and experiments of nonlinear flow interactions in hybrid rocket combustion

Lee

2013

Progress in Propulsion Physics

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Nonlinear combustion phenomenon was investigated through an experiment in a hybrid rocket motor. A poly(methyl methacrylate) (PMMA) / gaseous oxygen (GOx) combination was used with several types of disks equipped in a prechamber with the aim of modifying the local turbulent §ow. By allowing this disturbance generated in a prechamber to interact with the shedding vortex inherently produced in the main chamber, a possibility of commonly observed nonlinear combustion feature such as DC-shift was analyzed. In a baseline test, a vortex shedding occurs due to the interaction of a main oxidizer §ow with the evaporated fuel stream coming out of the surface during the regression process. Among the several types of disks, it turned out that only the disk4 produced the excitation which subsequently suppressed the vortex shedding phenomenon in the main chamber. This descent interaction was re §ected in a sudden pressure drop (which may be described as direct current (DC) shift) of about 10 psi in the time history of the pressure during the nominal combustion. The present result with the disk4 suggests the possibility of phase cancellation between the excitation induced by the disk4 and the shedding vortex but much more work should be conducted to extract more accurate correlation of the phase information. In order to understand the baseline §ow physics, a compressible large eddy simulation (LES) was conducted with the prescribed wall blowing boundary condition. The result clearly exhibited the existence of vortex shedding phenomenon with a speci¦ed frequency. The fact that important §ow features of the present computation are quite similar to those obtained with an incompressible assumption in a §at channel suggests that both compressibility and curvature e¨ects do not dominate in the present §ow con¦guration.

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Ultrasonic regression rate measurement in solid fuel ramjets

Cited by 26 publications

References 1 publication

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Influence of a Conical Axial Injector on Hybrid Rocket Performance

Novel burning rate measurement technique for solid propellant by means of ultrasonics

Large eddy simulations and experiments of nonlinear flow interactions in hybrid rocket combustion

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