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AN EXPERIMENTAL STUDY OF THE FLOW FIELD OF A TWO DIMENSIONAL PREMIXED TURBULENT FLAME

Description: A turbulent reacting shear layer in a premixed propane/air flow has been studied in a two dimensional combustor, with the flame stabilized behind a rearward facing streamlined step. Spark shadowgraphs show that in the range of velocities (7.5 to 22.5 m/sec corresponding to Reynolds numbers of .5 x 10{sup 4} cm{sup -1} to 1. 5 x 10{sup 4} cm{sup -1} ) and equivalence ratios (0.4 to 0.7) studied, the mixing layer is dominated by Brown~ Roshko type large coherent structures in both reacting and nonreacting flows. High speed schlieren movies show that these eddies are convected downstream and increase their size and spacing by combustion and coalescence with neighboring eddies. Tracing individual eddies shows, in the reacting shear layer, that, on the average, eddies accelerate as they move downstream with the highest acceleration close to the origin of the shear layer. Combustion is confined to these large structures which develop as a result of vortical action of the shear flow. On the average, the reacting eddies have a lower growth rate than nonreacting eddies. A turbulent boundary layer created by means of a tripping wire upstream of the edge of the step virtually eliminates the large coherent structures in the shear layer, while for the case in which the wire could not trigger the transition to turbulence, the large coherent structures dominated the reacting and nonreacting flows.
Date: April 1, 1980
Creator: Ganji, A.R. & Sawyer, R.F.
Partner: UNT Libraries Government Documents Department

THERMOPHORETIC VELOCITY OF LARGE AEROSOL PARTICLES

Description: The velocity of thermal repulsion of large aerosol particles has been calculated by others by equating the thermal force on a stationary partlcle to the Stokes-Cunningham viscous force. This procedure is theoretically unsound because the boundary conditions employed in the viscous force equation are erroneous when the particle moves in a thermal gradient. In the current study these difficulties have been circumvented by rederiving the thermal force equation, allowing for a relative velocity between the particle and the gas stream. The velocity of motion is then calculated by setting the net force on the particle equal to zero. The velocity obtained by this more realistic approach agrees with that calculated by the former method, which is surprising in view of the incorrect boundary conditions employed in the former method. Investigation of the drag force equation shows that the thermal force and the viscous force are exerted independently of each other, which explains this unexpected agreement, The range of applicability of the analysis is explored by comparison with available experimental data,
Date: November 1, 1965
Creator: Postma, A. K.
Partner: UNT Libraries Government Documents Department

PHYSICAL EFFECTS OF THE HANFORD WINDSTORMS OF JANUARY 11, 1972 AND JANUARY 21, 1972

Description: The windstorm of January 11 caused a minor amount of damage to the Hanford Reservation and Hanford vicinity. Damage sustained to Hanford Reservation structures (roofing, flashing, fences, windows) was approximately $20,000. One building did receive structural damage to roof members. Evidence that wind pressures did not reach 30 lb/ft{sup 2} during the January 11 windstorm was provided in the fact that specially designed exterior wall panels did not fail. These panels were designed and carefully proof-tested to insure that they would fail at a loading of 30 lb/ft{sup 2} as a requirement of structural safety in the original design-construction program in 1952-1954. There was one power outage on the Hanford Reservation due to the January 11 windstorm (Rattlesnake Mountain Observatory). Damage to power lines and electrical facilities amounted to about $1600. Damage to structures in the Hanford vicinity (excluding the Hanford Reservation) from the January 11 windstorm was estimated to cost $13,000. This does not include damage to private residences, etc., which has been estimated by others to be near $250,000. Power line damage in the Hanford vicinity amounted to about $80,000, of which $60,000 was accounted for in the loss of four transmission towers in the tie-line between Priest Rapids and Wanapum Dams. The January 21 windstorm, which struck Toppenish, Washington, was a straight-wind of the catabatic foehn type and not a tornado-type wind as described in newspaper accounts. No funnel cloud was associated with this windstorm. The maximum gust was about 85 mph at 30 ft above the ground. Cost estimates of damage in Toppenish were not available. There were no power outages or structural damage on the Hanford Reservation from the January 21 windstorm. Total damage to the Hanford Reservation from the two windstorms was estimated to be about $22,500.
Date: June 1, 1972
Creator: Henager, C. H. & Fuquay, J. J.
Partner: UNT Libraries Government Documents Department

Computational fluid dynamic modeling of fluidized-bed polymerization reactors

Description: Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.
Date: November 2, 2012
Creator: Rokkam, Ram
Partner: UNT Libraries Government Documents Department

LESSONS LEARNED - STARTUP AND TRANSITION TO OPERATIONS AT THE 200 WEST PUMP AND TREAT FACILITY

Description: This document lists key Lessons Learned from the Startup Team for the 200 West Pump and Treat Facility Project. The Startup Team on this Project was an integrated, multi-discipline team whose scope was Construction Acceptance Testing (CAT), functional Acceptance Testing Procedures (ATP), and procedure development and implementation. Both maintenance and operations procedures were developed. Included in the operations procedures were the process unit operations. In addition, a training and qualification program was also part of the scope.
Date: October 3, 2012
Creator: DE, FINK; GG, BERGQUIST & SP, BURKE
Partner: UNT Libraries Government Documents Department

Laser Fusion: The First Ten Years 1962-1972

Description: This account of the beginning of the program on laser fusion at Livermore in 1962, and its subsequent development during the decade ending in 1972, was originally prepared as a contribution to the January 1991 symposium 'Achievements in Physics' honoring Professor Keith Brueckner upon his retirement from the University of San Diego at La Jolla. It is a personal recollection of work at Livermore from my vantage point as its scientific leader, and of events elsewhere that I thought significant. This period was one of rapid growth in which the technology of high-power short-pulse lasers needed to drive the implosion of thermonuclear fuel to the temperature and density needed for ignition was developed, and in which the physics of the interaction of intense light with plasmas was explored both theoretically and experimentally.
Date: June 25, 2004
Creator: Kidder, R. E.
Partner: UNT Libraries Government Documents Department

Effective Specific Impulse of a Pulsed Rocket Engine

Description: The specific impulse achieved in a pulsed rocket engine augmented with a fissioning nuclear bomb could be greater than that of any continuous flow engine. To a certain extent, this increase in specific impulse would be obtained at the expense of motor weight and average thrust. This paper considers the first of these limitations, motor weight, and estimates the highest effective specific impulse to be expected from a nuclear-pulsed rocket motor with respect to the weight of the motor.
Date: May 5, 1965
Creator: Platt, E. A. & Hanner, D. W.
Partner: UNT Libraries Government Documents Department

TIME-WALK CHARACTERISTICS OF AN IMPROVED CONSTANT FRACTION DISCRIMINATOR

Description: A modification to a constant fraction discriminator design published earlier makes the observed time walk less than 30 ps over an input voltage range of 0.15 to 2.5 V. This performance makes time-walk corrections unnecessary in many situations.
Date: September 1, 1980
Creator: Wozniak, G. J.; Richardson, L. W. & Maier, M. R.
Partner: UNT Libraries Government Documents Department

Comment on Temperature-Pressure Equilibrium Between Dispersed and Continuous Phases of a Material

Description: This memo calls attention to the fact that the relationship between equilibrium temperature and the pressures in two phases of a material is {Delta}sdT = {Delta}(vdP) , and not, as now routinely assumed by bubble investigators, the Clausius-Clapeyron equation {Delta}sdT = {Delta}vdP . If one phase is discontinuous (subscript "d") and consists of spheres of radius r in a continuous phase (subscript "c") whose pressure is held constant, then the equilibrium temperature will be above the saturation temperature of the continuous phase by an amount ({Delta}T{sub sup}){sub c} = 2 {integral}{sub 0}{sup ({sigma}/r){sub e}}(v{sub d}/{delta}s)d({sigma}/r) and above the saturation temperature of the discontinuous phase by an amount ({Delta}T{sub sup}){sub d} = 2 {integral}{sub 0}{sup ({sigma}/r){sub e}}(v{sub c}/{delta}s)d({sigma}/r)
Date: September 2, 1969
Creator: Lyon, R. N.
Partner: UNT Libraries Government Documents Department

COST AND SCHEDULE FOR DRILLING AND MINING UNDERGROUND TEST FACILITIES

Description: Cost estimates and lead times are calculated for a mining and drilling program to establish underground test facilities at depths of 300, 700 and 1500 metres. Estimates are provided for establishing the facility in an existing mine and in a mine opened for the facility. The Stripa test facility in Sweden is used as a model in this study for the facility design and the drilling program. Cost estimates and lead time range from just less than $1.5 million and 10 months for an existing mine at 300 metres to $15 million and 58 months for a new mine at 1500 metres. Lithologies of granite, high-grade metamorphic rock. sedimentary rock with argillaceous strata at the depth of the facility. and tuffaceous rock were considered; the effect of lithology on the cost and schedule of opening a test facility was found to be relatively insignificant.
Date: September 1, 1980
Creator: Lamb, D. W.
Partner: UNT Libraries Government Documents Department

NUMERICAL MODELING OF TURBULENT FLOW IN A COMBUSTION TUNNEL

Description: A numerical technique for the analysis of turbulent flow associated with combustion is presented, The technique utilizes Chorin's RVM (Random Vortex Method), an algorithm capable of tracing the action of elementary turbulent eddies and their cumulative effects without imposing any restriction upon their motion. In the past RVM has been used with success to treat non-reacting turbulent flows, revealing, in particular, the mechanics of large scale flow patterns, the so-called coherent structures. Introduced here is a flame propagation algorithm, also developed by Chorin, in conjunction with volume sources modeling the mechanical effects of the exothermic process of combustion. As an illustration of its use, the technique is applied to flow in a combustion tunnel where the flame is stabilized by a back-facing step. Solutions for both non-reacting and reacting flow fields are obtained, under the restriction of a set of most stringent idealizations, mimicking nonetheless quite satisfactorily the essential features of turbulent combustion in a lean propane-air mixture that were observed in the laboratory by means of high speed schlieren cinematography.
Date: September 1, 1980
Creator: Ghoniem, A. F.; Chorin, A. J. & Oppenheim, A. K.
Partner: UNT Libraries Government Documents Department