Modeling of heat and mass transfer in accelerator targets during postulated accidents

Unal, Cetin; Bohl, W.R.; Pasamehmetoglu, Kemal

doi:10.1016/s0029-5493(99)00297-6

Cited by 8 publications

(4 citation statements)

References 15 publications

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“…The incoming flow temperature and pressure are T t 3000 K and p t 6:9 MPa, respectively, and the outer boundary of the nozzle material is assumed to be adiabatic. The maximum erosion rates obtained from the three sets of kinetics data [22,24,25] are 0.078, 0.069, and 0:047 mm=s, respectively. The most severe erosion occurs near the throat, due to the enhanced heat transfer in that region.…”

Section: Resultsmentioning

confidence: 94%

“…As shown in Table 2, three different sets of kinetics data [22,24,25] are available for the reaction between W and H 2 O at high temperatures. It is important to make a judicious selection of the data that yield the most accurate erosion rate.…”

Section: Resultsmentioning

confidence: 99%

“…Several experimental studies have been devoted to the oxidation of tungsten with steam [5,[22][23][24][25][26] and CO 2 [5,21] at high temperatures. There seems to be a fair bit of disagreement about the form of the final oxidation product.…”

Section: A Heterogeneous Kinetics Of Tungstenmentioning

confidence: 99%

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Chemical Erosion of Refractory-Metal Nozzle Inserts in Solid-Propellant Rocket Motors

Thakre

Yang

2009

Journal of Propulsion and Power

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An integrated theoretical/numerical framework is established and validated to study the chemical erosion of refractory-metal (tungsten, rhenium, and molybdenum) nozzle inserts in solid-rocket-motor environments, with a primary focus on tungsten. The formulation takes into account multicomponent thermofluid dynamics in the gas phase, heterogeneous reactions at the surface, energy transport in the solid phase, and nozzle material properties. Typical combustion species of nonmetallized ammonium-perchlorate/hydroxyl-terminated-polybutadiene propellants at practical motor operating conditions are considered. The erosion rates calculated by employing three different sets of chemical kinetics data available in the literature for the tungsten-steam reaction have been compared. The effect of considering either of two different tungsten oxides, WO 2 or WO 3 , as the final product of surface reactions is also investigated. The predicted erosion rates compare well with experimental data. The oxidizing species of H 2 O proved more detrimental than CO 2 in dictating the tungsten nozzle erosion. The material recession rate is controlled by heterogeneous chemical kinetics because the diffusion limit is not reached. The erosion rate increases with increasing chamber pressure, mainly due to higher convective heat transfer and enhanced heterogeneous surface reactions. The tungsten nozzle erodes much more slowly than graphite, but at a rate comparable with that of rhenium. The molybdenum nozzle exhibits the least erosion for flame temperatures lower than 2860 K. Its low melting temperature (2896 K), however, restricts applications for propellants with high flame temperatures.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Chemical Erosion of Refractory-Metal Nozzle Inserts in Solid-Propellant Rocket Motors

Thakre

Yang

2009

Journal of Propulsion and Power

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“…Double-diffusive (thermo-solutal) convection flows are also of interest in many branches of engineering sciences including energy storage [20] , nuclear reactor leakage hazards [21] , nanotechnological materials processing [22], heat exchangers [23]. In natural convection heat and mass transfer, thermal and species buoyancy effects play a significant role.…”

Section: Introductionmentioning

confidence: 99%