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CFD Calculation of Internal Natural Convection in the Annulus between Horizontal Concentric Cylinders

Description: The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 10{sup 5} to 10{sup 8} (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 10{sup 8}, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.
Date: October 1, 2002
Creator: N.D. Francis, Jr; Itamura, M.T.; Webb, S.W. & James, D.L.
Partner: UNT Libraries Government Documents Department

Calculation of SY tank annulus continuous air monitor readings after postulated leak scenarios

Description: The objective of this work was to determine whether or not a continuous air monitor (CAM) monitoring the annulus of one of the SY Tanks would be expected to alarm after three postulated leak scenarios. Using data and references provided by Lockheed Martin`s Tank Farm personnel, estimated CAM readings were calculated at specific times after the postulated scenarios might have occurred. Potential CAM readings above background at different times were calculated for the following leak scenarios: Leak rate of 0.01 gal/min; Leak rate of 0.03 gal/min (best estimate of the maximum probable leak rate from a single-shell tank); and Leak of 73 gal (equivalent to a {1/4}-in. leak on the floor of the annulus). The equation used to make the calculations along with descriptions and/or explanations of the terms are included, as is a list of the assumptions and/or values used for the calculations.
Date: August 1, 1998
Creator: Kenoyer, J.L.
Partner: UNT Libraries Government Documents Department

The limit of the film extraction technique for annular two-phase flow in a small tube

Description: The limit of the liquid film extraction technique was identified in air-water and Freon-113 annular two-phase flow loops. The purpose of this research is to find the limit of the entrainment rate correlation obtained by Lopez de Bertodano et. al. (1998). The film extraction technique involves the suction of the liquid film through a porous tube and has been widely used to obtain annular flow entrainment and entrainment rate data. In these experiments there are two extraction probes. After the first extraction the entrained droplets in the gas core deposit on the tube wall. A new liquid film develops entirely from liquid deposition and a second liquid film extraction is performed. While it is assumed that the entire liquid film is removed after the first extraction unit, this is not true for high liquid flow. At high liquid film flows the interfacial structure of the film becomes frothy. Then the entire liquid film cannot be removed at the first extraction unit, but continues on and is extracted at the second extraction unit. A simple model to characterize the limit of the extraction technique was obtained based on the hypothesis that the transition occurs due to a change in the wave structure. The resulting dimensionless correlation agrees with the data.
Date: July 1, 1999
Creator: Helm, D.E.; Lopez de Bertodano, M. & Beus, S.G.
Partner: UNT Libraries Government Documents Department

Numerical Solution of Natural Convection in Eccentric Annuli

Description: The governing equations for transient natural convection in eccentric annular space are solved with two high-order accurate numerical algorithms. The equation set is transformed into bipolar coordinates and split into two one-dimensional equations: finite elements are used in the direction normal to the cylinder surfaces; the pseudospectral technique is used in the azimuthal direction. This report discusses those equations.
Date: September 18, 2001
Creator: Pepper, D.W.
Partner: UNT Libraries Government Documents Department

Visual Measurements of Droplet Size in Gas Liquid Annular Flow

Description: Drop size distributions have been measured for nitrogen-water annular flow in a 9.67 mm hydraulic diameter duct, at system pressures of 3.4 and 17 atm and a temperature of 38 C. These new data extend the range of conditions represented by existing data in the open literature, primarily through an increase in system pressure. Since most existing correlations were developed from data obtained at lower pressures, it should be expected that the higher-pressure data presented in this paper would not necessarily follow those correlations. The correlation of Tatterson, et al. (1977) does not predict the new data very well, while the correlation of Kataoka, et al. (1983) only predicts those data taken at the lower pressure of 3.4 atm. However, the maximum drop size correlation of Kocamustafaogullari, et al. (1994) does predict the current data to a reasonable approximation. Similarly, their correlation for the Sauter mean diameter can predict the new data, provided the coefficient in the equation is adjusted.
Date: July 1, 2000
Creator: Fore, L.B.; Ibrahim, B.B. & Beus, S.G.
Partner: UNT Libraries Government Documents Department

Ferrules seals

Description: A device is provided for sealing an inner tube and an outer tube without excessively deforming the tubes. The device includes two ferrules which cooperate to form a vacuum-tight seal between the inner tube and outer tube and having mating surfaces such that overtightening is not possible.
Date: June 19, 1981
Creator: Smith, J.L.
Partner: UNT Libraries Government Documents Department

Supercement for Annular Seal and Long-Term Integrity in Deep, Hot Wells "DeepTrek"

Description: The purpose of this project is to formulate a 'Supercement' designed for improving the long-term sealing integrity in HPHT wells. Phase I concentrated on chemistry studies and screening tests to design and evaluate Portland-based, hybrid Portland, and non-Portland-based cement systems suitable for further scale-up testing. Phase II work concentrated on additional lab and field testing to reduce the candidate materials list to two systems, as well as scaleup activities aimed at verifying performance at the field scale. Phase II was extended thorough a proposal to develop additional testing capabilities aimed at quantifying cementing material properties and performance that were previously not possible. Phase III focused on bringing the material(s) developed in previous Phases to commercialization, through Field Trials, Cost/Benefit Analysis, and Technology Transfer. Extensive development and testing work throughout the project led to Phase III commercialization of two very different materials: (1) Highly-expansive cement (Portland-based), patent pending as 'PRESTRESSED CEMENT'; and (2) Epoxy Resin (non-Portland-based), patent pending. Trade name is Ultra Seal-R. In Phase III, work concentrated on application of the Supercement materials in various increasingly-challenging wells. Previous testing revealed that PRESTRESSED CEMENT, when applied in weak or unconsolidated formations, tends to expand away from the central pipe, restricting the applicability of this material to competent formations. Tests were devised to quantify this effect so the material could be applied in appropriate wells. Additionally, the testing was needed because of industry resistance to expansive cements, due to previous marketing attempts with other materials that were less than successful. Field trials with the Epoxy Resin currently numbers in the hundreds of jobs at up to 295 deg F, with a large percentage being completely successful. Both the PRESTRESSED CEMENT as well as the Ultra Seal-R represent materials fulfilling the objectives of the DeepTrek project.
Date: August 31, 2007
Creator: Technologies, CSI
Partner: UNT Libraries Government Documents Department

Heat Transfer Phenomena in Supercritical Water Nuclear Reactors

Description: A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in ancircular and square annular flow channel. A series of integral heat transfer measurements has been carried out over a wide range of heat flux, mas velocity and bulk water temperatures at a pressure of 25 MPa. The circular annular test section geometry is a 1.07 cm diameter heater rod within a 4.29 diameter flow channel.
Date: October 3, 2007
Creator: Anderson, Mark H.; Corradini, Michael L.; Bonazza, Riccardo & Licht, Jeremy R.
Partner: UNT Libraries Government Documents Department

CC Cryostat Vacuum Pumping Efficiency

Description: This report calculates the effect of the conductances of the pumping lines on the pumping speeds of the vacuum pumps being used to pump the inner vessel, and annular space, vacuum tight during the CC Cryostat testing. Effective pumping speeds were calculated for various values of pressure via the above stated formulas (see calculations). Conductances of valves, elbows, and tees were calculated with the help of ref. 1, and the volumes of the inner vessel and annular space were calculated wtth the aid of ref. 2. The major results of these calculations follow. The attached graphs show the effective pumping speed vs. pressure, as well as the pressure vs. pumpdown time for both the inner vessel pumpdown and the annular space pumpdown. Many intervals of pressure were chosen in order to give a complete picture of the effects on the pumping speed, and pumpdown time. An important rule of thumb is that the effective pumping speed be close to the intrinsic pump speed in the region of interest for the best efficiency. With an infinite conductance, these quantities become equal. In the case of the annular space pumpdown. the effective pumping speed is within approximately 15% of the intrinsic pump speed for pressures down to 6000{mu}, and at that point, the conductance effects slow the system down and provide a 49% difference at 1000{mu}. To Improve these numbers, the line length must be shortened, or even better, the line diameter increased. As far as pumpdown time is concerned, the actual pumpdown was completed in a reasonable amount of time, and would have been even better if the pumping system did not lag due to a leaK and its repair time. The inner vessel pumpdown shows a pumpdown time near 1 hour to reach 100{mu} pressure. The effective pumping speed matches ...
Date: October 13, 1987
Creator: Fitzpatrick, J.B.
Partner: UNT Libraries Government Documents Department

High pressure annular two-phase flow in a narrow duct. Part 1: Local measurements in the droplet field, and Part 2: Three-field modeling

Description: In Part 1, detailed measurements were made in a high pressure, adiabatic (boiled at the inlet) annular flow in a narrow, high aspect ratio duct using a gamma densitometer, hot-film anemometer and high-speed video photography. Measurements of void fraction, droplet frequency, velocity, drop size, and interfacial area concentration have been made to support the three field computational capability. An important aspect of this testing is the use of a modeling fluid (R-134a) in a vertical duct which permits visual access in annular flow. This modeling fluid accurately simulates the low liquid-to-vapor density ratio of steam-water flows at high pressures. These measurements have been taken in a narrow duct of hydraulic diameter 4.85 mm, and a cross-section aspect ratio of 22.5. However, the flow displays profiles of various shapes not only in the narrow dimension, but also in the width dimension. In particular, the shape of the droplet profiles depends on the entrained droplet flux from the edges in the vapor core. The average diameter from these profiles compare well with the models developed in the literature. Interfacial area concentration for these low density ratio flows is higher than the highest concentration reported for air-water flows. Video records show that along with the bow-shaped waves, three-dimensional {lambda}-shaped waves appear in annular flows for high flow rates. Part 2 outlines the development of a three-field modeling approach in annular flow and the predictive capability of an analysis code. Models have been developed here or adapted from the literature for the thin film near the wall as well as the droplets in the vapor core, and have been locally applied in a fully developed, two-phase adiabatic boiling annular flow in a duct heated at the inlet at high pressure. Numerical results have been obtained using these models that are required for the closure ...
Date: July 1999
Creator: Trabold, T. A. & Kumar, R.
Partner: UNT Libraries Government Documents Department

Annular flow of R-134a through a high aspect ratio duct: Local void fraction, droplet velocity and droplet size measurements

Description: Local measurements were made in annular flow of R-134a through a vertical duct. Using a gamma densitometer, hot-film anemometer and laser Doppler velocimeter, profiles of void fraction, liquid droplet frequency and droplet velocity were acquired across the narrow test section dimension. Based upon these results, data for liquid droplet size were obtained and compared to previous experimental results from the literature. These data are useful for developing an improved understanding of practical two-phase refrigerant flows, and for assessment of advanced two-fluid computer codes.
Date: November 1, 1998
Creator: Trabold, T.A.; Kumar, R. & Vassallo, P.F.
Partner: UNT Libraries Government Documents Department

Predicting multidimensional annular flow with a locally based two-fluid model

Description: The purpose of this work was to: develop a methodology to predict annular flows using a multidimensional four-field, two-fluid Computational Fluid Dynamics (CFD) computer code; develop closure models which use the CFD predicted local velocities, phasic volume fractions, etc...; implement a numerical method which allows the discretized equations to have the same characteristics as the differential form; and compare predicted results to local flow field data taken in a R-134a working fluid test section.
Date: June 1, 1998
Creator: Antal, S.P.; Edwards, D.P. & Strayer, T.D.
Partner: UNT Libraries Government Documents Department

Predicting multidimensional annular flows with a locally based two-fluid model

Description: Annular flows are a well utilized flow regime in many industrial applications, such as, heat exchangers, chemical reactors and industrial process equipment. These flows are characterized by a droplet laden vapor core with a thin, wavy liquid film wetting the walls. The prediction of annular flows has been largely confined to one-dimensional modeling which typically correlates the film thickness, droplet loading, and phase velocities by considering the average flow conditions and global mass and momentum balances to infer the flow topology. In this paper, a methodology to predict annular flows using a locally based two-fluid model of multiphase flow is presented. The purpose of this paper is to demonstrate a modeling approach for annular flows using a multifield, multidimensional two-fluid model and discuss the need for further work in this area.
Date: June 1, 1998
Creator: Antal, S.P. Edwards, D.P. & Strayer, T.D.
Partner: UNT Libraries Government Documents Department

Project W-320 high vacuum 241-AY-102 annulus ventilation system operability test report

Description: This report documents the test results of OTP-320-001, Tank 241-AY-102 Annulus Ventilation System Testing. Included in the appendices are: (1) Supporting documentation prepared to demonstrate the structural integrity of the tank at high annulus vacuum (<20 INWG), and (2) a report that identifies potential cross connections between the primary and annulus ventilation systems. These cross connections were verified to be eliminated prior to the start of testing.
Date: March 12, 1998
Creator: Bailey, J. W.
Partner: UNT Libraries Government Documents Department

Parametric Investigations of Miniaturized Cylindrical and Annular Hall Thrusters

Description: A cylindrical geometry Hall thruster may overcome certain physical and technological limitations in scaling down of Hall thrusters to miniature sizes. The absence of the inner wall and use of the cusp magnetic field can potentially reduce heating of the thruster parts and erosion of the channel. A 2.6 cm miniaturized Hall thruster of a flexible design was built and successfully operated in the power range of 50-300 W. Comparison of preliminary results obtained for cylindrical and annular thruster configurations is presented.
Date: October 16, 2001
Creator: Smirnov, A.; Raitses, Y. & Fisch, N.J.
Partner: UNT Libraries Government Documents Department

Mechanical Analysis of an SM 2 Blk IV restrained firing within a concentric canister launcher test unit

Description: The Office of Naval Research (ONR) and PMS512 have undertaken a program to develop a new Vertical Launching System (VLS) for future generation ships, such as the DD-21 Destroyer. The Naval Sea Systems Command Combat Weapons Program (NAVSEA 05K) and Naval Surface Warfare Center Dahlgren Division (NSWCDD) are working jointly with industry and universities to develop one such launcher design, the Concentric Canister Launcher (CCL). The basic CCL design consists of a tube made of two concentric cylinders; one end is open, the other is sealed with a hemispherical end cap. During firing, the missile exhaust gas is turned 180 degrees by the hemispherical end cap and flows through the annular space between inner and outer cylinders. Depending on the missile utilized and the particular service environment of the CCL, maximum temperatures within the cylinder material have been calculated to exceed 2000 F. In an earlier study [1], the authors determined the high temperature mechanical properties of several candidate alloys being considered for fabrication of the CCL. This study [1] found that, of these candidate materials, titanium alloys exhibit higher yield stresses than that of 316L stainless steel at temperatures up to about 1000 F; above 1500 F, the yield stress of 316L stainless steel is comparable to those of the titanium alloys. The 316L stainless steel was found to strain harden (increase its flow stress with increasing strain) at temperatures up to about 1800 F. The ability of the 316L stainless steel to strain harden at high temperatures may provide an added margin of safety for engineering design of the CCL. The objective of the current study was to perform a computer simulation of the structural response of a CCL during a restrained firing, one in which a SM-2 Blk IV missile would fail to exit the canister. A ...
Date: March 1, 1999
Creator: Kassner, M C; Kennedy, T C; Puttapitukporn, T & Rosen, R S
Partner: UNT Libraries Government Documents Department

Interfacial area and interfacial transfer in two-phase flow systems. Annual technical progress report, 1991--1992

Description: Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow. (DLC)
Date: August 1, 1992
Creator: Kojasoy, G.
Partner: UNT Libraries Government Documents Department