Computing flow, combustion, heat transfer and thrust in a micro-rocket via hierarchical problem decomposition

Campolo, Marina; Andreoli, Michele; Soldati, Alfredo

doi:10.1007/s10404-008-0362-9

Cited by 10 publications

(3 citation statements)

References 30 publications

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“…Heat exchangers, combustion chambers, nuclear reactors and cooling systems in electronic devices are just some of the well-known examples in which significant temperature variations typically occur within the flow. Applications relevant for the present study can be found in aerospace systems, which operate in micro-gravity conditions and require liquidbased cooling technologies to meet high thermal transfer demand (Zonta, Marchioli & Soldati 2008;Campolo, Andreoli & Soldati 2009;Lee et al 2010). In these systems, thermal and viscous properties of the liquid are critical design parameters that vary with temperature.…”

Section: Introductionmentioning

confidence: 99%

Modulation of turbulence in forced convection by temperature-dependent viscosity

2012

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In this work, we run a numerical experiment to study the behaviour of incompressible Newtonian fluids with anisotropic temperature-dependent viscosity in forced convection turbulence. We present a systematic analysis of variable-viscosity effects, isolated from gravity, with relevance for aerospace cooling/heating applications. We performed an extensive campaign based on pseudo-spectral direct numerical simulations of turbulent water channel flow in the Reynolds number parameter space. We considered constant temperature boundary conditions and different temperature gradients between the channel walls. Results indicate that average and turbulent fields undergo significant variations. Compared with isothermal flow with constant viscosity, we observe that turbulence is promoted in the cold side of the channel, characterized by viscosity locally higher than the mean: in the range of the examined Reynolds numbers and in absence of gravity, higher values of viscosity determine an increase of turbulent kinetic energy, whereas a decrease of turbulent kinetic energy is determined at the hot wall. Examining in detail the turbulent kinetic energy budget, we find that turbulence modifications are associated with changes in the rate at which energy is produced and dissipated near the walls: specifically, at the hot wall (respectively cold wall) production decreases (respectively increases) while dissipation increases (respectively decreases)

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Section: Introductionmentioning

confidence: 99%

Modulation of turbulence in forced convection by temperature-dependent viscosity

2012

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“…In this paper, we focus on the turbulence kinetic energy exchanges in strongly anisothermal wall-bounded flows at low Mach number. These flows are found in many industrial applications, including concentrated solar power plants [14,15,55,56,57,62], heat exchangers and cooling systems [73,10,35,74] or fluids at supercritical pressure within a small temperature range [68,52,47]. They are characterised by a strong influence on the energy exchanges of the walls and of temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Reynolds number on turbulence kinetic energy exchanges in flows with highly variable fluid properties

2019

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Spatial and spectral energy exchanges associated with the turbulence kinetic energy per unit mass, or half-trace of the velocity covariance tensor, are studied in an anisothermal low Mach number turbulent channel flow. The temperatures of the two channel walls are 293 K and 586 K. This generates a strong temperature gradient in the wall-normal direction. The effect of the temperature gradient on the energy exchanges is investigated using two direct numerical simulations of the channel, at the mean friction Reynolds numbers 180 and 395. The temperature gradient creates an asymmetry between the energy exchanges at the hot and cold sides, due to the variations of the local fluid properties and low Reynolds number effects. The low Reynolds number effects are smaller at higher Reynolds number, reducing the asymmetry between the hot and cold sides. We also decomposed the energy exchanges in order to study separately the mean-property terms, as found in the constant-property isothermal case, and the thermal terms, specific to flows with variable fluid properties. The significant thermal terms have a similar effect on the flow. Besides, low Reynolds number effects have a negligible impact on thermal terms and only affect mean-property terms.

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“…Over the last decade because of rapid advancement of various technologies, new approaches have been developed for applying classical combustion to novel fields such as microtechnology and nanotechnology. Many studies have been conducted to develop various microelectromechanical system‐based devices using combustion, including microthrusters, microreactors, microactuators, microrockets, and microengines . Most of these studies used a precisely designed microstructure to amplify the mechanical or thermal energies obtained from chemical combustion.…”

Section: Introductionmentioning

confidence: 99%

Phase Transformations of Cobalt Oxides in Co_xO_y-ZnO Multipod Nanostructures via Combustion from Thermopower Waves

Lee

Hwang

Choi

2015

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The study of combustion at the interfaces of materials and chemical fuels has led to developments in diverse fields such as materials chemistry and energy conversion. Recently, it has been suggested that thermopower waves can utilize chemical-thermal-electrical-energy conversion in hybrid structures comprising nanomaterials and combustible fuels to produce enhanced combustion waves with concomitant voltage generation. In this study, this is the first time that the direct phase transformation of Co-doped ZnO via instant combustion waves and its applications to thermopower waves is presented. It is demonstrated that the chemical combustion waves at the surfaces of Co3O4-ZnO multipod nanostructures (deep brown in color) enable direct phase transformations to newly formed CoO-ZnO(1-x) nanoparticles (olive green in color). The oxygen molecules are released from Co3O4-ZnO to CoO-ZnO(1-x) under high-temperature conditions in the reaction front regime in combustion, whereas the CoO-ZnO multipod nanoparticles do not undergo any transformations and thus do not experience any color change. This oxygen-release mechanism is applicable to thermopower waves, enhances the self-propagating combustion velocity, and forms lattice defects that interrupt the charge-carrier movements inside the nanostructures. The chemical transformation and corresponding energy transport observed in this study can contribute to diverse potential applications, including direct-combustion synthesis and energy conversion.

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Computing flow, combustion, heat transfer and thrust in a micro-rocket via hierarchical problem decomposition

Cited by 10 publications

References 30 publications

Modulation of turbulence in forced convection by temperature-dependent viscosity

Modulation of turbulence in forced convection by temperature-dependent viscosity

Effect of the Reynolds number on turbulence kinetic energy exchanges in flows with highly variable fluid properties

Phase Transformations of Cobalt Oxides in Co_xO_y-ZnO Multipod Nanostructures via Combustion from Thermopower Waves

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Computing flow, combustion, heat transfer and thrust in a micro-rocket via hierarchical problem decomposition

Cited by 10 publications

References 30 publications

Modulation of turbulence in forced convection by temperature-dependent viscosity

Modulation of turbulence in forced convection by temperature-dependent viscosity

Effect of the Reynolds number on turbulence kinetic energy exchanges in flows with highly variable fluid properties

Phase Transformations of Cobalt Oxides in CoxOy-ZnO Multipod Nanostructures via Combustion from Thermopower Waves

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Phase Transformations of Cobalt Oxides in Co_xO_y-ZnO Multipod Nanostructures via Combustion from Thermopower Waves