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DOE OSTI2023

Global cascade of kinetic energy in the ocean and the atmospheric imprint

Here, we present an estimate for the ocean's global scale transfer of kinetic energy (KE), across scales from 10 to 40,000 km. Oceanic KE transfer between gyre scales and mesoscales is induced by the atmosphere’s Hadley, Ferrel, and polar cells, and the intertropical convergence zone induces an intense downscale KE transfer. Upscale transfer peaks at 300 gigawatts across mesoscales of 120 km in size, roughly one-third the energy input by winds into the oceanic general circulation. Nearly three quarters of this “cascade” occurs south of 15°S and penetrates almost the entire water column. The mesoscale cascade has a self-similar seasonal cycle with characteristic lag time of ≈27 days per octave of length scales; transfer across 50 km peaks in spring, while transfer across 500 km peaks in summer. KE of those mesoscales follows the same cycle but peaks ≈40 days after the peak cascade, suggesting that energy transferred across a scale is primarily deposited at a scale four times larger.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Passive Mitigation of Cascading Propagation in Multi-Cell Lithium Ion Batteries

The heat generated during a single cell failure within a high energy battery system can force adjacent cells into thermal runaway, creating a cascading propagation effect through the entire system. This work examines the response of modules of stacked pouch cells after thermal runaway is induced in a single cell. The prevention of cascading propagation is explored on cells with reduced states of charge and stacks with metal plates between cells. Reduced states of charge and metal plates both reduce the energy stored relative to the heat capacity, and the results show how cascading propagation may be slowed and mitigated as this varies. These propagation limits are correlated with the stored energy density. Results show significant delays between thermal runaway in adjacent cells, which are analyzed to determine intercell contact resistances and to assess how much heat energy is transmitted to cells before they undergo thermal runaway. A propagating failure of even a small pack may stretch over several minutes including delays as each cell is heated to the point of thermal runaway. This delay is described with two new parameters in the form of gap-crossing and cell-crossing time to grade the propensity of propagation from cell to cell.

25 ENERGY STORAGE↗

DOE OSTI2020

A robust and efficient generalized real cascade model

This paper describes a new separation cascade model that allows for arbitrary cascade connectivity and includes the effects of mixing, material losses and generalized separation element performance. The model also accommodates mixtures with an arbitrary number of component species. The mathematical and numerical framework of this model includes both time-dependent and steady state cascade simulation. Robust numerical approximations of the continuous mathematical model are accomplished using the Sundials suite of nonlinear algebraic and differential-algebraic equation solvers. Verification of the model is accomplished using manufactured solutions while validation is demonstrated by comparison to published experimental results and benchmarks.

36 MATERIALS SCIENCE↗

DOE OSTI2022

GRB 110213A: A Study of Afterglow Electromagnetic Cascade Radiation

We obtained well-sampled optical photometry of GRB 110213A, including Swift/UVOT and XRT. Combining our data from those of other ground-based telescopes, we present 15 optical multicolor light curves showing similar shapes with two peaks. In contrast, in the X-ray band, only a single peak is observed between the two optical peaks. Temporal and spectral analysis of GRB 110213A shows that the X-rays differ from the optical for Phases I–III (before the second peak of the optical band at ~5.6 ks). Moreover, they have the same spectral behavior at late times (Phases IV–VI). These data indicate that the optical and X-ray emission are dominated by different components. The synchrotron-supported pair cascade emission is included in the standard external forward-shock model, which is dominated by synchrotron radiation and synchrotron self-Compton (SSC). We find that the optical bands of GRB 110213A are dominated by the cascade emission from synchrotron radiation + SSC at the early stage, while the primary synchrotron + SSC radiation dominates the X-ray band. At late stages, both the X-ray and optical bands are dominated by emission from primary synchrotron + SSC radiation. The cascade component can reasonably explain the first optical peak. In contrast, the primary synchrotron + SSC emission mainly contributes to the second peak.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

All-sky Neutrino Point-source Search with IceCube Combined Track and Cascade Data

Despite extensive efforts, discovery of high-energy astrophysical neutrino sources remains elusive. We present an event-level simultaneous maximum likelihood analysis of tracks and cascades using IceCube data collected from 2008 April 6 to 2022 May 23 to search the whole sky for neutrino sources, and using a source catalog, for coincidence of neutrino emission with gamma-ray emission. This is the first time a simultaneous fit of different detection channels is used to conduct a time-integrated all-sky scan with IceCube. Combining all-sky tracks, with superior pointing power and sensitivity in the northern sky, with all-sky cascades, with good energy resolution and sensitivity in the southern sky, we have developed the most sensitive point-source search to date by IceCube that targets the entire sky. The most significant point in the northern sky aligns with NGC 1068, a Seyfert II galaxy, which, from the catalog search, shows a 3.5σ excess over background after accounting for trials. The most significant point in the southern sky does not align with any source in the catalog and is not significant after accounting for trials. A search for the single most significant Gaussian flare at the locations of NGC 1068, PKS 1424+240, and the southern highest-significance point shows results consistent with expectations for steady emission. Notably, this is the first time that a flare shorter than four years has been excluded as being responsible for NGC 1068’s emergence as a neutrino source. Our results show that combining tracks and cascades when conducting neutrino source searches improves sensitivity and can lead to new discoveries.

Abbasi, R. [Loyola University, Chicago, IL (United↗

NASA NTRS1971

Nuclear electromagnetic cascades from nuclei with Z larger than or equal to 3

A Monte Carlo simulation method was developed for studying nuclear-electromagnetic cascades initiated by high energy nuclei with Z or = 3 incident on heavy absorbers. The calculations are based on a cascade model which was first adjusted until it agreed with measurements made with protons at an accelerator. Modifications of the model used for protons include the incorporation of the probabilities for fragmentation of heavy nuclei into lighter nuclei, alpha particles, and nucleons. Mean values and fluctuations of the equivalent numbers of particles in the cascades at various depths in an iron absorber are presented for protons, carbon, and iron nuclei over the 30 to 300 GeV/nucleon energy range.

Jones, W. V.↗

NASA NTRS1972

Comparison of heat-transfer test data for a chordwise-finned, impingement-cooled turbine vane tested in a four-vane cascade and a research engine

The heat-transfer characteristics of a chordwise-finned, impingement-cooled vane were investigated in both a modified J-57 research engine and a four-vane cascade. The data were compared by a correlation of temperature difference ratio with coolant- to gas-flow ratio and also by two modifications of this correlation. The results indicated that the cascade vane temperature data can generally be used to represent the engine vane temperature data. A discussion of engine and cascade gas-side heat-transfer coefficients is also presented. A redesign of the vane leading edge could significantly increase the potential turbine-inlet temperature operating limit.

Gladden, H. J.↗

NASA NTRS1973

Stopping pions in high-energy nuclear cascades.

Results of Monte Carlo calculations for the number and energy spectra of charged pions from nuclear-electromagnetic cascades developing in rock are presented for primary hadron energies ranging from 3 to 3000 GeV. These spectra are given as functions of the longitudinal depth in the absorber and the lateral distance from the cascade axis. The number of charged pions which stop in the absorber increases with the primary energy of the hadron initiating the cascade.

Jones, W. V.↗

NASA NTRS1974

Cold-air annular-cascade investigation of aerodynamic performance of cooled turbine vanes. 1: Facility description and base (solid) vane performance

The aerodynamic performance of a solid vane was experimentally determined in a full-annular cascade, where three-dimensional effects could be obtained. This vane was of the same size and profile as the cooled vanes to be subsequently tested. The vanes were tested over a pressure ratio range that corresponded to mean-radius ideal aftermixed critical velocity ratios of 0.71 to 0.89. Overall vane aftermixed efficiencies were obtained over this range of critical velocity ratios and compared with results from a four-vane annular-sector cascade. The variation in vane aftermixed conditions and vane aftermixed efficiency with radius were also obtained and compared with design values. Vane surface static-pressure distributions were measured and compared with theory and with the results obtained in the four-vane cascade.

Goldman, L. J.↗

NASA NTRS1974

Performance of a model cascade thrust reverser for short-haul applications

Aerodynamic and acoustic characteristics are presented for a cowlmounted, model cascade thrust reverser suitable for short-haul aircraft. Thrust reverser efficiency and the influence on fan performance were determined from isolated fan-driven models under static and forward velocity conditions. Cascade reverser noise characteristics were determined statically in an isolated pipe-flow test, while aerodynamic installation effects were determined with a wind-tunnel, fan-powered airplane model. Application of test results to short-haul aircraft calculations demonstrated that such a cascade thrust reverser may be able to meet both the performance and noise requirements for short-haul aircraft operation. However, aircraft installation effects can be quite significant.

Dietrich, D. A.↗

NASA NTRS1974

Results from cascade thrust reverser noise and suppression experiments

Results from experimental work on model scale cascade reversers with cold airflow are presented. Sound power levels, directivity, and spectral characteristics for cascade reversers are reported. Effect of cascade exit area ratio, vane profile shape, and emission arc are discussed. Model equivalent diameters varied from 3 to 5 inches; pressure ratios ranged from 1.15 to 3.0. Depending on the reverser type, acoustic power was proportional to the 4.5- to 6-th power of ideal jet velocity. Reverser noise peaked at higher frequency and was more omnidirectional than nozzle-alone jet noise. Appreciable reduction in sideline noise was obtained from plane shields.

Gutierrez, O. A.↗

NASA NTRS1975

Aerodynamic performance of a fully film cooled core turbine vane tested with cold air in a two-dimensional cascade

The aerodynamic performance of a fully film cooled core turbine vane was investigated experimentally in a two-dimensional cascade of 10 vanes. Three of the 10 vanes were cooled; the others were solid (uncooled) vanes. Cold air was used for both the primary and coolant flows. The cascade test covered a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95 and a range of coolant flow rates to 7.5 percent of the primary flow. The coolant flow was varied by changing the coolant supply pressure. The principal measurements were cross-channel surveys of exit total pressure, static pressure, and flow angle. The results presented include exit survey data and overall performance in terms of loss, flow angle, and weight flow for the range of exit velocity ratios and coolant flows investigated. The performance of the cooled vane is compared with the performance of an uncooled vane of the same profile and also with the performance obtained with a single cooled vane in the 10-vane cascade.

Stabe, R. G.↗

NASA NTRS1975

Effect of electron divergence in air gaps on the measurement of the energy of cascades in emulsion chambers

The effect of an increase in electron density in the vicinity of the cascade axis caused by an avalanche passing through the gap between lead filters of the emulsion chamber was investigated experimentally. Optical densities were measured in three X-ray films spaced at 400, 800 and 1200 micrometer from the filter surface having a thickness of 6 cascade units. The optical densities of blackening spots caused by electron photon cascades of 1 to 2, 2 to 7 and greater than 7 BeV energies were measured. The results prove the presence of a gap between the filter and the nuclear emulsion which results in the underestimation of energy by several tenths of a percent.

Apanasenko, A. V.↗

NASA NTRS1975

On the investigation of cascade and turbomachinery rotor wake characteristics

The objective of the investigation reported in this thesis is to study the characteristics of a turbomachinery rotor wake, both analytically and experimentally. The constitutive equations for the rotor wake are developed using generalized tensors and a non-inertial frame of reference. Analytical and experimental investigation is carried out in two phases; the first phase involved the study of a cascade wake in the absence of rotation and three dimensionality. In the second phase the wake of a rotor is studied. Simplified two- and three-dimensional models are developed for the prediction of the mean velocity profile of the cascade and the rotor wake, respectively, using the principle of self-similarity. The effect of various major parameters of the rotor and the flow geometry is studied on the development of a rotor wake. Laws governing the decay of the wake velocity defect in a cascade and rotor wake as a function of downstream distance from the trailing edge, pressure gradient and other parameters are derived.

Raj, R.↗

NASA NTRS1974

Performance of a model cascade thrust reverser for short-haul applications

Aerodynamic and acoustic characteristics are presented for a cowl-mounted, model cascade thrust reverser suitable for short-haul aircraft. Thrust reverser efficiency and the influence on fan performance were determined from isolated fan-driven models under static and forward velocity conditions. Cascade reverser noise characteristics were determined statically in an isolated pipe-flow test, while aerodynamic installation effects were determined with a wind-tunnel, fan-powered airplane model. Application of test results to short-haul aircraft calculations demonstrate that such a cascade thrust reverser may be able to meet both the performance and noise requirements for short-haul aircraft operation. However, aircraft installation effects can be quite significant.

Dietrich, D. A.↗

NASA NTRS1976

The passage of a distorted velocity field through a cascade of airfoils

An analysis has been developed to predict the unsteady force and moment generated by the passage of a timewise periodic total pressure distortion through an arbitrary cascade of airfoils. The mathematical formulation of this analysis is based on the assumption that the magnitudes of the timewise fluctuations of the variables which describe the flow field are small compared to their time average values. This assumption permits the development of a linear unsteady perturbation analysis about a steady flow field. In addition to this linearization assumption the fluid medium is assumed to be incompressible and inviscid. The mathematical development begins by decomposing the velocity field surrounding an infinite cascade of airfoils into its irrotational and rotational components. The rotational component is associated with an upstream unsteady total pressure distortion and is defined in terms of the vorticity field associated with the distortion pattern. The irrotational component is further decomposed into a steady and unsteady part. A combined analytical and numerical procedure has been developed to solve the field equations which govern the rotational and irrotational velocity fields. Results of this analysis show a strong influence of mean loading on the unsteady force generated by the passage of a one dimensional gust through a cascade of compressor blades.

Adamczyk, J. J.↗

NASA NTRS1980

An implicit finite-difference code for inviscid and viscous cascade flow

An implicit finite-difference code is developed to solve either inviscid or viscous flow about two-dimensional cascade blade elements. General coordinate transformations are used so that boundaries can coincide with coordinate lines, and an automatic grid generation routine based on elliptic partial differential equations is employed to mesh arbitrary cascade elements. Characteristic combinations of the differential equations are used at inflow and outflow boundaries. Computed results for both inviscid and viscous flow are compared with other existing cascade solutions and experimental data.

Steger, J. L.↗

NASA NTRS1980

On nonlinear cascades of enstrophy over the tropics at 200 mb during two Northern Hemisphere summers

Diagnostic computations of nonlinear cascades of enstrophy have been performed in the wavenumber domain for two northern summers. Attention is focused on the interactions among the waves, the interaction between the zonal flow and a given wave and the exchanges due to the beta effect. It is found that two wave ranges (low and intermediate wavenumbers) cascade enstrophy to two ranges of wavenumbers. Calculations are also performed to evaluate the contribution from the standing (92-day mean) and transient modes to the nonlinear enstrophy cascade.

Chen, T.-C.↗