Simulations of Solid-Propellant Rockets:  Effects of Aluminum Droplet Size Distribution

Najjar, Fady; Ferry, Jim; Haselbacher, Andreas; Balachandar, S.

doi:10.2514/1.17326

Cited by 60 publications

(27 citation statements)

References 32 publications

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“…A nominal value of 2700 kg/m 3 is assigned for the aluminum particles' density (ρm); one can note that, in practice, liquid (molten) aluminum has a somewhat lower density (around 2400 kg/m 3 ) should the particle's core be liquid, versus solid. In this regard, for some particles transferring from one state to another [24], one can also note that aluminum oxide is significantly heavier, at 3800 kg/m 3 .…”

Section: Resultsmentioning

confidence: 99%

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Greatrix

2015

Energies

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Abstract:The ability to predict the expected internal behaviour of a given solid-propellant rocket motor under transient conditions is important. Research towards predicting and quantifying undesirable transient axial combustion instability symptoms typically necessitates a comprehensive numerical model for internal ballistic simulation under dynamic flow and combustion conditions. On the mitigation side, one in practice sees the use of inert or reactive particles for the suppression of pressure wave development in the motor chamber flow. With the focus of the present study placed on reactive particles, a numerical internal ballistic model incorporating relevant elements, such as a transient, frequency-dependent combustion response to axial pressure wave activity above the burning propellant surface, is applied to the investigation of using aluminum particles within the central internal flow (particles whose surfaces nominally regress with time, as a function of current particle size, as they move downstream) as a means of suppressing instability-related symptoms in a cylindrical-grain motor. The results of this investigation reveal that the loading percentage and starting size of the aluminum particles have a significant influence on reducing the resulting transient pressure wave magnitude.

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Section: Resultsmentioning

confidence: 99%

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Greatrix

2015

Energies

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“…This collision process is driven by the relative velocity between the particle and the surrounding alumina. The model of alumina deposition is given by [24]:…”

Section: Aluminum Particle Combustion Modelmentioning

confidence: 99%

Numerical Simulation of a Vortex Combustor Based on Aluminum and Steam

et al. 2016

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Abstract:In this paper we report a new development in the numerical model for aluminum-steam combustion. This model is based on the diffusion flame of the continuum regime and the thermal equilibrium between the particle and the flow field, which can be used to calculate the aluminum particle combustion model for two phase calculation conditions. The model prediction is in agreement with the experimental data. A new type of vortex combustor is proposed to increase the efficiency of the combustion of aluminum and steam, and the mathematical model of the two phase reacting flow in this combustor is established. The turbulence effects are modeled using the Reynolds Stress Model (RSM) with Linear Pressure-Strain approach, and the Eddy-Dissipation model is used to simulate the gas phase combustion. Aluminum particles are injected into the vortex combustor, forming a swirling flow around the chamber, whose trajectories are traced using the Discrete Phase Model (DPM). The simulation results show that the vortex combustor can achieve highly efficient combustion of aluminum and steam. The influencing factors, such as the eccentric distance of the inlet of aluminum particles, particle size and steam inlet diameter, etc., are studied.

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“…In large-scale numerical simulations that involve particle burning and agglomeration, average speeds and accelerations within the chamber have routinely been estimated directly from the Taylor-Culick solution. One may refer in this regard to the work of Najjar et al (2006), Balachandar et al (2001), as well as others. In reactive flow simulations, the Taylor-Culick solution is so valuable in estimating the bulk gas motion that it has been either built into some codes or used as a benchmark to verify computations.…”

Section: Introductionmentioning

confidence: 99%

On the Lagrangian optimization of wall-injected flows: from the Hart–McClure potential to the Taylor–Culick rotational motion

Saad

Majdalani

2009

Proc. R. Soc. A.

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The Taylor-Culick solution for a porous cylinder is often used to describe the bulk gas motion in idealized representations of solid rocket motors. However, other approximate solutions may be found that satisfy the same fundamental constraints. In this vein, steeper or smoother profiles may be observed in either experimental or numerical tests, particularly in the presence of intense levels of acoustic energy. In this study, we use the Lagrangian optimization principle to arrive at multiple solutions that can help to explain the practically observed motions. We then search for the extreme states that display either the least or the most kinetic energy. These are derived and found to be dependent on the chamber's aspect ratio. By assuming a slender case, simple expressions are retrieved from which both the rotational Taylor-Culick and the irrotational HartMcClure solutions are recovered as special cases. At the outset, a new family of flow approximations is derived extending from purely potential to highly rotational fields. These are constructed, verified and catalogued based on their kinetic energies. To help understand the tendency of a motion to shift energy states, a second law analysis is performed and used to rank these solutions based on their entropy content. Interestingly, the Taylor-Culick profile is found to represent an equilibrium state entailing the most energy and entropy among those starting from the rest. A formal extension of Kelvin's minimum energy theorem to an open region is then pursued, followed by a direct implementation to the problem at hand. Three other flow motions with open boundaries are examined to further exemplify the application of Kelvin's extended criteria. Our efforts illustrate the overarching harmony that exists between Lagrange's minimization principle and Kelvin's minimum energy theorem; both converge on the potential solution as the least kinetic energy bearer even when the velocity at the open barrier is finite.

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Simulations of Solid-Propellant Rockets: Effects of Aluminum Droplet Size Distribution

Cited by 60 publications

References 32 publications

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Numerical Evaluation of the Use of Aluminum Particles for Enhancing Solid Rocket Motor Combustion Stability

Numerical Simulation of a Vortex Combustor Based on Aluminum and Steam

On the Lagrangian optimization of wall-injected flows: from the Hart–McClure potential to the Taylor–Culick rotational motion

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