Numerical Prediction of Transitional Features of Turbulent Forced Gas Flows in Circular Tubes With Strong Heating

Ezato, Koichiro; Shehata, A. Mohsen; Kunugi, Tomoaki; McEligot, Donald M.

doi:10.1115/1.2826015

Cited by 34 publications

(26 citation statements)

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“…While Mikielewicz [1994] demonstrated that a number of popular turbulence models produce poor predictions in this regime, he also showed that the k-model of Launder and Sharma [1974] is satisfactory. For the complex turbulent and laminarizing flows induced by strong heating of a gas flow in this range, several turbulence models have been shown to give good predictions [Kawamura, 1979;Ezato et al, 1999;Nishimura et al, 2000]. Satake [1996] has extended his Direct Numerical Simulation technique to flow in a circular tube [Satake and Kunugi, 1998].…”

Section: Related Workmentioning

confidence: 99%

Measurements of Fundamental Fluid Physics of SNF Storage Canisters

Condie¹,

Creery²,

McEligot³

2001

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SummaryWith the University of Idaho, Ohio State University and Clarksean Associates, this research program has the long-term goal to develop reliable predictive techniques for the energy, mass and momentum transfer plus chemical reactions in drying / passivation (surface oxidation) operations in the transfer and storage of spent nuclear fuel (SNF) from wet to dry storage. Such techniques are needed to assist in design of future transfer and storage systems, prediction of the performance of existing and proposed systems and safety (re)evaluation of systems as necessary at later dates.Many fuel element geometries and configurations are accommodated in the storage of spent nuclear fuel. Consequently, there is no one generic fuel element / assembly, storage basket or canister and, therefore, no single generic fuel storage configuration. One can, however, identify generic flow phenomena or processes which may be present during drying or passivation in SNF canisters. The objective of the INEEL tasks was to obtain fundamental measurements of these flow processes in appropriate parameter ranges.With the University of Idaho, an idealization of a combined drying and passivation approach has been defined in order to investigate the generic flow processes. This simulation includes flow phenomena that occur in canisters for high-enrichment and medium-enrichment fuels, where fuel element spacing in the canister is increased as compared with low enrichment fuel. Canister diameter was taken as 46 cm (18 in.) and a single basket of about 1.3 meters (4 ft.) length was considered. A long central tube ("dip tube") served as the inlet as in one earlier concept for a passivation process; while this concept apparently has not yet been selected for application, it provides an excellent example of the coupled, complex phenomena which may be present in canister flows. Suggested design flow rates for this hypothesized application indicate that the Reynolds number in the inlet tube would be expected to be between 2500 and 5000, i.e., relatively low.The local distributions of convective mass transfer characteristics (drying/passivation) are expected to depend on the freestream turbulence in the flow around stored fuel elements. The magnitudes of this turbulence depend on the turbulence distributions on the upstream side of the perforated basket support plate ("inlet plenum") and, in turn, in the impinging jet and in the inlet tube. This information can assist engineers in understanding variations of surface drying and passivation through an array and approaches to modify designs to counter non-uniformities and to improve iii distribution, as well as providing bases for assessment of computational fluid dynamics codes proposed for the purpose.A water-flow experiment with a 3/4-scale model (relative to the idealized canister) has been used for overall flow visualization and velocity measurements, with and without an array of simulated fuel elements. Observations have been made with perforated plates (representing basket support plates) having...

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Section: Related Workmentioning

confidence: 99%

Measurements of Fundamental Fluid Physics of SNF Storage Canisters

Condie¹,

Creery²,

McEligot³

2001

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“…The k-ε turbulence model of Abe, Kondoh and Nagano [1994], developed for forced turbulent flow between parallel plates with the constant property idealization, has been successfully extended by Ezato et al [1999]. For thermal energy transport, the turbulent Prandtl number model of Kays and Crawford [1993] was adopted.…”

Section: Before They Can Be Applied With Confidence To Gas-cooled Sysmentioning

confidence: 99%

Fundamental Thermal Fluid Physics of High Temperature Flows in Advanced Reactor Systems - Nuclear Energy Research Initiative Program Interoffice Work Order (IWO) MSF99-0254 Final Report for Period 1 August 1999 to 31 December 2002

McEligot¹,

Condie²,

Foust³

et al. 2002

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IntroductionBackground The ultimate goal of the study is the improvement of predictive methods for safety analyses and design of advanced reactors for higher efficiency and enhanced safety and for deployable reactors for electrical power generation, process heat utilization and hydrogen generation. While key applications would be advanced gas-cooled reactors (AGCRs) using the closed Brayton cycle (CBC) for higher efficiency (such as the proposed Gas Turbine -Modular Helium Reactor (GT-MHR) of General Atomics [Neylan and Simon, 1996]), results of the proposed research should also be valuable in reactor systems with supercritical flow or superheated vapors, e.g., steam. Higher efficiency leads to lower cost/kwh and reduces life-cycle impacts of radioactive waste (by reducing waste/kwh). The outcome will also be useful for some space power and propulsion concepts and for some fusion reactor concepts as side benefits, but they are not the thrusts of the investigation. The objective of the project is to provide fundamental thermal fluid physics knowledge and measurements necessary for the development of the improved methods for the applications.

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“…Special attention was given to properly reproduce the near-wall asymptotic behavior. The second full LR model (further denoted as Ezato [8]) is a recent improvement of existing LR thermal entry-flow models that has been validated in strongly laminarizing turbulent channel flows. In all models, the turbulent species Schmidt numbers were 0.9, C l ‫ס‬ 0.09, and C e2 ‫ס‬ 1.0.…”

Section: Turbulence Modelingmentioning

confidence: 99%

“…[21]). At the wall ( y ‫ס‬ 0), the measured temperature profile (average between both plate distributions) was used as energy boundary condition; in both full LR models ‫ס‬ at y ‫ס‬ 0 [8,20].…”

Section: Numerical Approachmentioning

confidence: 99%

“…Such models should describe the transitional channel entry flow in the presence of both surface and gaseous combustion. Turbulence enhances the transport toward-or-away the catalyst and the induced thermochemical fluctuations augment the average gaseous reaction rates; the heat transfer from the hot catalytic surfaces and the exothermicity of the gaseous pathway can, in turn, result in strong laminarization of the turbulent flow [8,9]. For the high CST Reynolds numbers, direct numerical simulations are currently not possible, whereas large eddy simulations have subgrid model limitations in wall-bounded flows [10].…”

Section: Introductionmentioning

confidence: 99%

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An experimental and numerical investigation of turbulent catalytically stabilized channel flow combustion of hydrogen/air mixtures over platinum

Appel

Mantzaras

Schaeren

et al. 2002

Proceedings of the Combustion Institute

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The turbulent catalytically stabilized combustion (CST) of fuel-lean hydrogen/air mixtures over platinum was investigated experimentally and numerically in channel-flow configurations. Experiments were performed in an optically accessible catalytic channel reactor, established by two Pt-coated ceramic plates 300 mm long and placed 7 mm apart, with incoming Reynolds numbers of 15,000 and 30,000. Planar laserinduced fluorescence of the OH radical was used to monitor the onset of homogeneous (gas-phase) ignition, one-dimensional (across the 7 mm transverse direction) Raman measurements of major species and temperature assessed the turbulent scalar transport, laser doppler velocimetry yielded the inlet velocity and turbulence, and thermocouples embedded beneath the catalyst provided the surface temperature distribution. Computations were carried out with a two-dimensional elliptic fluid mechanical code that included elementary heterogeneous and homogeneous chemical reaction schemes. Three different low-Reynolds number near-wall turbulence models were examined, in conjunction with a thermochemistry model that included a presumed-shape (Gaussian) probability density function approach for the gaseous reactions and a laminar-like closure for catalytic reactions. Comparisons between predictions and measurements have shown that key CST issues, such as catalytic fuel conversion and onset of homogeneous ignition, are strongly dependent on the particular turbulence model. Moreover, the discrepancies between predictions and measurements were ascribed to the capacity of the various turbulence models to capture the strong flow laminarization induced by the heat transfer from the hot catalytic surfaces. A turbulence model that yields good agreement with the measurements is presented as particularly suited for CST. Experiments and predictions have shown that a continuous increase of the turbulent transport led to incomplete combustion through the gaseous reaction zone with subsequent catalytic conversion of the leaked fuel and, finally, to extinction of the gaseous flame.

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Numerical Prediction of Transitional Features of Turbulent Forced Gas Flows in Circular Tubes With Strong Heating

Cited by 34 publications

References 38 publications

Measurements of Fundamental Fluid Physics of SNF Storage Canisters

Measurements of Fundamental Fluid Physics of SNF Storage Canisters

Fundamental Thermal Fluid Physics of High Temperature Flows in Advanced Reactor Systems - Nuclear Energy Research Initiative Program Interoffice Work Order (IWO) MSF99-0254 Final Report for Period 1 August 1999 to 31 December 2002

An experimental and numerical investigation of turbulent catalytically stabilized channel flow combustion of hydrogen/air mixtures over platinum

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