Development and Deployment of Hybrid ML Models for Critical Heat Flux Prediction in Annulus Geometries
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Furlong, Aidan [ORNL] (ORCID:0000000262912959)↗
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Method and apparatus for a substantially coaxial injector element
A system to provide a two piece robust fluid injector. According to various embodiments, the fluid injector is a fuel injector for a combustion engine. The injector includes two coaxially formed annuluses. One annulus is formed in a face plate and the second annulus or hole is defined by a tube extending through the face plate. The tube extends through the face plate in a portion of a through bore which also is used to define the second annulus. The second annulus is formed using a throughbore through which the tube extends. This allows the second annulus to always be formed inherently and precisely substantially coaxial with the first annulus. Moreover, the second annulus can be formed with a much greater tolerance than if other independent components needed to be added.
Horn, Mark D.↗
An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model
BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. Purpose and methods: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS: Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.
Evaluation Studies↗
Duct flow nonuniformities: Effect of struts in SSME HGM II(+)
A numerical study, using the INS3D flow solver, of laminar and turbulent flow around a two dimensional strut, and three dimensional flow around a strut in an annulus is presented. A multi-block procedure was used to calculate two dimensional laminar flow around two struts in parallel, with each strut represented by one computational block. Single block calculations were performed for turbulent flow around a two dimensional strut, using a Baldwin-Lomax turbulence model to parameterize the turbulent shear stresses. A modified Baldwin-Lomax model was applied to the case of a three dimensional strut in an annulus. The results displayed the essential features of wing-body flows, including the presence of a horseshoe vortex system at the junction of the strut and the lower annulus surface. A similar system was observed at the upper annulus surface. The test geometries discussed were useful in developing the capability to perform multiblock calculations, and to simulate turbulent flow around obstructions located between curved walls. Both of these skills will be necessary to model the three dimensional flow in the strut assembly of the SSME. Work is now in progress on performing a three dimensional two block turbulent calculation of the flow in the turnaround duct (TAD) and strut/fuel bowl juncture region.
Burke, Roger↗
GEOSIM: A numerical model for geophysical fluid flow simulation
A numerical model which simulates geophysical fluid flow in a wide range of problems is described in detail, and comparisons of some of the model's results are made with previous experimental and numerical studies. The model is based upon the Boussinesq Navier-Stokes equations in spherical coordinates, which can be reduced to a cylindrical system when latitudinal walls are used near the pole and the ratio of latitudinal length to the radius of the sphere is small. The equations are approximated by finite differences in the meridional plane and spectral decomposition in the azimuthal direction. The user can specify a variety of boundary and initial conditions, and there are five different spectral truncation options. The results of five validation cases are presented: (1) the transition between axisymmetric flow and baroclinic wave flow in the side heated annulus; (2) the steady baroclinic wave of the side heated annulus; (3) the wave amplitude vacillation of the side heated annulus; (4) transition to baroclinic wave flow in a bottom heated annulus; and (5) the Spacelab Geophysical Fluid Flow Cell (spherical) experiment.
Butler, Karen A.↗
Simulated altitude performance of two annular combustors with continuous axial openings for admission of primary air
Methods of introducing and distributing air and fuel in turbojet-engine combustors were evaluated with two fuels, AN-F-32 and AN-F-58. Investigations were made with two single-annulus liners in a one-quarter sector of a 25 1/2-inch-diameter turbojet combustor. Altitude performance data for these combustors are compared with existing data for a production-model double-annulus combustor. Altitude operating limits and combustion efficiencies of both single-annulus combustors were considerably higher than those of the double-annulus combustor; combustion efficiencies were insensitive to changes in fuel-air ratio.
COMBUSTION - TURBINE ENGINES↗
Degradation of Victoria Crater, Mars
The $\sim$750 m diameter and $\sim$75 m deep Victoria crater in Meridiani Planum, Mars, presents evidence for significant degradation including a low, serrated, raised rim characterized by alternating alcoves and promontories, a surrounding low relief annulus, and a floor partially covered by dunes. The amount and processes of degradation responsible for the modified appearance of Victoria crater were evaluated using images obtained in situ by the Mars Exploration Rover Opportunity in concert with a digital elevation model created using orbital HiRISE images. Opportunity traversed along the north and northwest rim and annulus, but sufficiently characterized features visible in the DEM to enable detailed measurements of rim relief, ejecta thickness, and wall slopes around the entire degraded, primary impact structure. Victoria retains a 5 m raised rim consisting of 1-2 m of uplifted rocks overlain by 3 m of ejecta at the rim crest. The rim is $\sim$120 to 220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine craters 500 to 750 m across indicate the original, pristine crater was close to 600 m in diameter. Hence, the crater has been erosionally widened by approximately 150 m and infilled by about 50 m of sediments. Eolian processes are responsible for modification at Victoria, but lesser contributions from mass wasting or other processes cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for $\sim$50 m widening across a WNW-ESE diameter. The volume of material eroded from the crater walls and rim is $\sim$20% less than the volume of sediments partially filling the crater, indicating eolian infilling from sources outside the crater over time. The annulus formed when $\sim$1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped darker, regional basaltic sands.
Wilson, Sharon A.↗
Electric propulsion device for high power applications
An electric propulsion device is disclosed having an anode and a cathode. The propulsion device includes a discharge annulus having the anode adjacent an end region thereof. At least one inlet aperture is adjacent the anode, the aperture(s) having propellant gas flow therethrough into the discharge annulus. The propellant gas has an ionization potential. Opposed, dielectric walls define the annulus, with at least one of the opposed dielectric walls having pores therein, the pores having cooling gas flow therethrough into the discharge annulus and substantially adjacent the opposed dielectric wall(s). The cooling gas has an ionization potential higher than the ionization energy of the propellant gas. The cooling gas is adapted to substantially prevent at least one of secondary electron emission and sputtering of the dielectric walls.
Roy, Subrata↗
Observations of Mare Serenitatis from lunar orbit and their interpretation
Visual observations are investigated of color differences of Serenitatis mare materials from orbit complement photography and other remotely sensed data. The light tan gray inner fill of the Serenitatis basin is younger than the dark blue gray annulus; the latter continues into and appears to be contemporaneous with the fill of Mare Tranquillitatis. Mare ridges occur in both the inner basin fill and the dark annulus of Serenitatis. Ridges are interpreted as the result of structural deformation and up-doming after the solidification of the basaltic lavas. On the southeastern rim of the Serenitatis basin is the darkes blue gray unit within which Apollo 17 landed. Highland massifs surrounding this unit have unstable slopes which are believed to be the result of localized tectonic activity. On the southwest rim of the basin are the dark tan to brown gray mantling materials of the Sulpicius Gallus Formation. Farther west on the rim are dark blue grap patches which resemble the mare material of the Serenitatis dark annulus.
El-Baz, F.↗
Laser geodynamic satellite thermal/optical/vibrational analysis and testing, volume 2, book 2
The main tasks described involved an interferometric evaluation of several cubes, a prediction of their dihedral angles, a comparison of these predictions with independent measurements, a prediction and comparison of far field performance, recommendations as to revised dihedral angles and a subsequent analysis of cubes which were reworked to confirm the recommendations. A tolerance study and theoretical evaluation of several cubes was also performed to aid in understanding the results. The far field characteristics evaluated included polarization effects and treated both intensity distribution and encircled energy data. The energy in the 13.2 - 16.9 arc-sec annular region was tabulated as an indicator of performance sensitivity. The results are provided in viewgraph form, and show the average dihedral angle of an original set of test cubes to have been 1.8 arc-sec with an average far field annulus diameter of 18 arc-sec. Since the peak energy in the 13.2 - 16.9 arc-sec annulus was found to occur for a 1.35 arc-sec cube, and since cube tolerances were shown to increase the annulus diameter slightly, a nominal dihedral angle of 1.25 arc-sec was recommended.
Source record↗
Laser anemometer measurements at the exit of a T63 combustor
In the first practical application of laser anemometry to an actual gas turbine engine combustor, the mean velocity and turbulent intensity profiles were measured in a steady-flow combustion rig across an annulus simulating a turbine inlet; to establish a basis for comparison with similar measurements to be made in an operating engine and to confirm current turbine aerodynamics and heat transfer design assumptions. It was necessary to develop a new experimental technique for traversing the annulus due to differential thermal expansion of the cantilevered combustion rig and a new computer-graphics analysis technique for analyzing the velocity histograms due to the high background light intensity. The axial mean velocity and turbulent intensity were uniform across the annulus under all operating conditions and the flow had little or no swirl component. The isothermal mean velocity was doubled by the burning of fuel, however, the isothermal turbulent intensity was relatively unaffected.
Zimmerman, D. R.↗
Interaction of compressor rotor blade wake with wall boundary layer/vortex in the end-wall region
This paper reports the experimental study of the three-dimensional characteristics of the mean velocity of the rotor wake inside the annulus- and hub-wall boundary layers. The measurements were taken with a rotating three-sensor hot wire behind the rotor. This set of measurements probably represents the first set of comprehensive measurements taken inside the annulus- and hub-wall boundary layers. The wake was surveyed at several radial locations inside the boundary layer region and at several axial locations. Interaction of the wake with the annulus-wall boundary layer, secondary flow, tip-leakage flow, and the trailing vortex system results in slower decay and larger width of the wake. The presence of a strong vortex and its merger with the wake is also observed. The end-wall boundary layers and the secondary flow were found to have a substantial effect on both the decay characteristics and the profile of the wake. These and other measurements are reported and interpreted in this paper.
Lakshminarayana, B.↗
Effects of blade loading and rotation on compressor rotor wake in end wall regions
This study was carried out to understand the effects of blade loading and rotation on the rotor end wall flow structure, including the wake. The measurements were taken with a stationary three sensor hot wire located at the exit of a compressor rotor. The signal was ensemble averaged to derive all the three components of velocity and six components of stresses at the exit. Measurements were made at two different rotational speeds (1753 and 1010 rpm) and at two differing blade loadings at several radii near the hub and the annulus wall. The wake decay in the annulus wall region is found to be much more rapid than the mid span regions. Furthermore, both the loading and rotation of the blade have appreciable influence on the end wall flow and wake structure. Interaction of the annulus and hub wall boundary layers (and secondary flow resulting from these) have appreciable influence on the wake structure in the endwall regions.
Lakshminarayana, B.↗
Laser Doppler velocimeter measurement in the tip region of a compressor rotor
The axial and tangential velocity components near the tip region of a compressor rotor were measured by a laser Doppler velocimeter. The measurements were taken at 25 radial locations in the outer twenty percent of the blade span and at 10 axial locations upstream, inside and at the exit of the rotor. The results are interpreted to derive the behavior of the leakage flow, annulus wall boundary layer growth, inviscid effects and the rotor wake decay characteristics in the tip region. The inviscid and annulus wall boundary layer effects dominate up to quarter chord, beyond which the leakage phenomena has a major influence in altering the flow characteristics in the outer ten percent of the blade span. The annulus wall boundary layer undergoes drastic change through the passage. The velocity field measured near the leading edge reveals the effects of rapid acceleration near the suction surface and the stagnation point on the pressure surface.
Murthy, K. N. S.↗
Semiempirical method of determining flow coefficients for pitot rake mass flow rate measurements
Flow coefficients applicable to area-weighted pitot rake mass flow rate measurements are presented for fully developed, turbulent flow in an annulus. A turbulent velocity profile is generated semiempirically for a given annulus hub-to-tip radius ratio and integrated numerically to determine the ideal mass flow rate. The calculated velocities at each probe location are then summed, and the flow rate as indicated by the rake is obtained. The flow coefficient to be used with the particular rake geometry is subsequently obtained by dividing the ideal flow rate by the rake-indicated flow rate. Flow coefficients ranged from 0.903 for one probe placed at a radius dividing two equal areas to 0.984 for a 10-probe area-weighted rake. Flow coefficients were not a strong function of annulus hub-to-tip radius ratio for rakes with three or more probes. The semiempirical method used to generate the turbulent velocity profiles is described in detail.
Trefny, C. J.↗
Coronae on Venus observations and models of origin
The Venera 15/16 spacecraft revealed a number of features of unknown origin including coronae, elongate to circular structures with a complex interior surrounded by an annulus of concentric ridges. Eighteen coronae were identified in Venera 15/16 data of Venus; an additional thirteen possible coronae are found in Pioneer Venus and Arecibo data. Coronae, with maximum widths of 160 to over 650 km, are found primarily in two clusters in the Northern Hemisphere located to the east and west of Ishtar Terra. Another possible cluster is located in Themis Regio in the Southern Hemisphere. The majority of coronae are at least partially raised less than 1.5 km above the surrounding region, and over half are partially surrounded by a peripheral trough. A sequence of events for coronae has been determined through mapping. Prior to corona formation, regional compression or extension creates bands of lineaments along which coronae tend to later form. During the early stages of corona formation, relatively raised topography is produced by uplift and volcanic construction. The evolution of coronae and their general characteristics have been compared to two models of corona origin: hotspots and sinking mantle diapirs. In the hotspot or rising mantle diapir model, heating and melting at depth create uplift at the surface. Uplift is accompanied by central extension, facilitating volcanism. Gravitational relaxation of the uplifted region follows producing the compressional features within the annulus and the peripheral trough. Both models can predict the major characteristics and evolutionary sequence of coronae. The sinking diapir model does predict an early-time low and central compression as well as broadening and shallowing of the peripheral trough with time, all of which are not observed at current data resolution. In addition, the sinking mantle diapir mode predicts more simultaneous formation of the high topography, annulus and trough unlike the hotspot or rising mantle diapir mode. High resolution Magellan data will be used to distinguish between the two models of corona origin.
Stofan, E. R.↗
Coronae of Mnemosyne Regio - Morphology and origin
The Mnemosine Regio area of Venus contains seven of the circular-to-elliptical structures, characterized by an annulus of concentric ridges, that are known as 'coronae'. Several corona-origin models are presently considered, and it is found that the processes associated with diapirism or hot-spots, and the gravitational relaxation of high topography, are most consistent with the topography and morphology of these coronae. The sequence of the formation and evolution of the coronae proceeds from regional volcanic and tectonic activity, through localized uplift and volcanism, to annulus and trough formation related to gravitational relaxation, and finally local volcanic flooding of the corona, annulus, and trough.
Stofan, Ellen R.↗
One-dimensional cloud fluid model for propagating star formation
The aim of this project was to study the propagation of star formation (SF) with a self-consistent deterministic model for the interstellar gas. The questions of under what conditions does star formation propagate in this model and what are the mechanisms of the propagation are explored. Here, researchers used the deterministic Oort-type cloud fluid model of Scalo and Struck-Marcell (1984, also see the review of Struck-Marcell, Scalo and Appleton 1987). This cloud fluid approach includes simple models for the effects of cloud collisional coalescence or disruption, collisional energy dissipation, and cloud disruption and acceleration as the result of young star winds, HII regions and supernovae. An extensive one-zone parameter study is presented in Struck-Marcell and Scalo (1987). To answer the questions above, researchers carried out one-dimensional calculations for an annulus within a galactic disk, like the so-called solar neighborhood of the galactic chemical evolution. In the calculations the left-hand boundary is set equal to the right hand boundary. The calculation is obviously idealized; however, it is computationally convenient to study the first order effects of propagating star formation. The annulus was treated as if it were at rest, i.e., in the local rotating frame. This assumption may remove some interesting effects of a supersonic gas flow, but was necessary to maintain a numerical stability in the annulus. The results on the one-dimensional propagation of SF in the Oort cloud fluid model follow: (1) SF is propagated by means of hydrodynamic waves, which can be generated by external forces or by the pressure generated by local bursts. SF is not effectively propagated via diffusion or variation in cloud interaction rates without corresponding density and velocity changes. (2) The propagation and long-range effects of SF depend on how close the gas density is to the critical threshold value, i.e., on the susceptibility of the medium.
Titus, Timothy N.↗