Theoretical Modeling and Numerical Simulation Challenges of Combustion Processes of Hybrid Rockets

Kuo, Kenneth K.; Houim, Ryan W.

doi:10.2514/6.2011-5608

Cited by 23 publications

(16 citation statements)

References 31 publications

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“…The unstable waves then break up into droplets by the Plateau-Rayleigh instability mechanism (primary break-up). According to Kuo and Houim [25], droplet entrainment occurs from the unstable waves when the force of surface tension in the waves is smaller than the interfacial shear force between the streaming gas flow and the waves. Droplets are then accelerated by the main gas flow and break up into smaller droplets or rebound.…”

Section: Kelvin Helmholtz Instabilitymentioning

confidence: 99%

Theoretical and experimental analysis of liquid layer instability in hybrid rocket engines

Kobald¹,

Verri

Schlechtriem³

2015

CEAS Space J

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Section: Kelvin Helmholtz Instabilitymentioning

confidence: 99%

Theoretical and experimental analysis of liquid layer instability in hybrid rocket engines

Kobald¹,

Verri

Schlechtriem³

2015

CEAS Space J

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“…1,2 On the other hand, there are some technical challenges 1, 3-6 to be overcome before achieving the same level of maturity as solid and liquid traditional systems, such as low regression rate, reduced combustion efficiency and combustion instability. Especially, low regression rate is one of the most significant shortcomings of conventional hybrid rockets.…”

Section: Introductionmentioning

confidence: 98%

Numerical Analysis of Port Diameter Effect on Hybrid Rocket Fuel Regression Rate with Axial Injection

Bianchi¹,

Nasuti

Carmicino

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Numerical simulations of the flowfield in a hybrid rocket motor are carried out with a Reynolds averaged Navier-Stokes solver including detailed gas surface interaction modeling based on surface mass and energy balances. Results are compared with several test data obtained from two dedicated test campaigns conducted with static firings of a laboratoryscaled hybrid rocket in which gaseous oxygen is fed into axisymmetric hydroxyl-terminated polybutadiene cylindrical grains through an axial conical subsonic nozzle. A first numerical rebuilding of all of the firing tests has been performed to validate the model, highlighting its prediction capabilities and modeling limits. Despite the several geometrical simplifications, which allowed relatively modest grid sizes to be used and efficient parametrical analysis to be performed, the presented CFD approach is fairly able to capture the main features of the motor internal ballistics both in terms of average chamber pressure and regression rate trends with oxidizer mass flux and port diameter. Computed flowfields showed the establishment of a significant recirculation region at the motor head end, which promotes propellant mixing, and raises the fuel regression rate. Numerical simulations, supported by the experimental results, demonstrated the main role played by the characteristics of this particular injection configuration in determining the fuel regression rate spatial distribution and trend, and clarified the mechanism for which the port diameter has a direct influence on the fuel regression. Nomenclaturē m = time-averaged mass flow rate, kg/ṡ ω i = species source term in control surface, kg/m 2 · ṡ m = mass blowing rate per unit area, kg/m 2 · ṡ q = heat flux, W/m 2 r = regression rate, m/ṡ w i = species source term in control volume, kg/m 3 · s η = inward (from solid to gas) coordinate normal to surface ρ = density, kg/m 3 D im = effective diffusion coefficient, m 2 /s h = enthalpy, J/kg k = thermal conductivity, W/m · K M = molecular weight of the species, kg/kmole N = number of species p = pressure, N/m 2 T = temperature, K v = velocity component normal to surface, m/s y = mass fraction y + = dimensionless wall distance Subscripts f = fuel i = species s = solid material w = wall Superscripts = average in time and spacê = average in space

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“…1 Nevertheless, the hybrid rocket engine development has not achieved the same level of maturity as solid and liquid traditional systems and requires a better understanding of the physico-chemical phenomena that control the combustion process and of the fluid dynamics inside the motor. [1][2][3][4][5][6][7] The knowledge of the complex interactions among fluid dynamics, solid fuel pyrolysis, oxidizer atomization and vaporization, mixing and combustion in the gas phase, nozzle thermochemical erosion, particulate formation, and radiative characteristics of the gas and the flame can only be improved by combined experimental and numerical research activities. The numerical study of the flow in the combustion chamber and in the nozzle of a hybrid propellant rocket requires the ability to adequately describe the interaction between the reacting flow and the solid surface through suitable gas-surface interaction (GSI) modeling.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of GOX/HTPB Hybrid Rocket Flowfields and Comparison with Experiments

Bianchi¹,

Betti

Nasuti

et al. 2014

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

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Numerical simulations of the flowfield in a GOX/HTPB hybrid rocket engine are carried out with a Reynolds averaged Navier-Stokes solver including detailed gas surface interaction modeling based on surface mass and energy balances. Fuel pyrolysis is modeled via finite-rate Arrhenius kinetics. A simplified two-step global reaction mechanism is considered for the gas-phase chemistry to model the combustion of 1,3-butadiene in oxygen. Results are compared with firing test data from a lab-scale hybrid rocket in which gaseous oxygen is fed into axisymmetric HTPB cylindrical grains through an axial conical subsonic nozzle. With the oxidizer fed by this kind of injector, which generates nonuniform conditions at the entrance of the fuel port, the fuel regression rate is shown to increase several times with respect to the case of homogeneous injection of the oxidizer through all the grain port area, in agreement with the experimental findings. The spatial distribution of the regression rate is substantially different from the one expected in a turbulent developing flow, because of the presence of a strong recirculation zone. Numerical simulations, yet not capturing the absolute regression rate values, are fairly able to predict the main ballistic features, i.e. the regression rate weaker dependence on the mass flux, the influence of port diameter and the pressure evolution over time

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Theoretical Modeling and Numerical Simulation Challenges of Combustion Processes of Hybrid Rockets

Cited by 23 publications

References 31 publications

Theoretical and experimental analysis of liquid layer instability in hybrid rocket engines

Theoretical and experimental analysis of liquid layer instability in hybrid rocket engines

Numerical Analysis of Port Diameter Effect on Hybrid Rocket Fuel Regression Rate with Axial Injection

Numerical Modeling of GOX/HTPB Hybrid Rocket Flowfields and Comparison with Experiments

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