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DOE OSTI2023

Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Measurements of ash deposition rates were made between the secondary superheater and reheater sections of a 450 MW cyclone-fired lignite boiler as the operational load varied from 33 to 100%. Significant reductions in deposition rates with a decrease in operational load were observed. To uncover the causative mechanisms behind these observations, operational data from the power plant were used to carry out computational fluid dynamic (CFD) simulations of the boiler. After ascertaining that the gas temperatures and velocities at various sections within the boiler were being represented adequately, decoupled simulations of the ash deposition process on the deposit probe were carried out using a finely resolved boundary layer mesh. Fly ash particle size distribution (PSD) and its concentration for the decoupled calculations were determined from stand-alone cyclone barrel simulations. The ash partitioning (mass %) between the fly ash and slag was found to be ~50:50, which was in line with previous field observations, and it did not vary significantly across different cyclone loads. The predicted PSD of the deposit ash was concentrated in the size range 10–30 microns, which was in agreement with cross-sectional images of the deposit obtained from the measurements. At lower loads, sharp variations in the deposition rates were predicted in the gas temperature range 950–1150 K. The particle kinetic energy—particle viscosity-based capture methodology utilized in this study in conjunction with appropriate ash compositions, ash viscosity models and gas temperature estimates can help estimate slagging propensities at different loads reasonably well in these systems.

Krishnamoorthy, Gautham (ORCID:0000000255205092)↗

NASA NTRS1975

Isogrid structures

Test results and related structural instability analyses are presented for a 10-foot-diameter, 37-inch-long cylinder, and a 10-foot-diameter, 40-inch-long, 45-degree conical frustum. Both structures are based upon flanged isogrids and are fabricated in 2024-T851 aluminum. Peak edge load intensities at failure were 1,654 lb/in for the cylinder and 1,457 lb/in at the small diameter of the frustum. General instability cylindrical-monocoque-structure equivalent knockdown factors for both were in good agreement (gamma = 0.48). Design analysis is also derived for estimating critical cylinder instability edge loads from the performance of two tandem isogrid members. Evaluation is made of effective skin contributing to isogrid load-carrying cross-section.

Slysh, P.↗

DOE OSTI2015

Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling

Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy’s National Renewable Energy Laboratory’s CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, their effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. For this study, load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, and conductive pathways. The technologies selected for a complete-cab package of technologies were “ultra-white” paint, advanced insulation, and advanced curtains. To measure the impact of these technologies, a nationally-averaged solar-weighted reflectivity long-haul truck paint color was determined and applied to the baseline test vehicle. Using the complete-cab package of technologies, electrical energy consumption for long-haul truck daytime rest period air conditioning was reduced by at least 35% for summer weather conditions in Colorado. The National Renewable Energy Laboratory's CoolCalc model was then used to extrapolate the performance of the thermal load reduction technologies nationally for 161 major U.S. cities using typical weather conditions for each location over an entire year.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2019

Perturbation theory to model shielding effectiveness of cavities loaded with electromagnetic dampeners

It is notable that a slotted resonant cavity with high-quality factor exhibits interior electromagnetic (EM) fields that may be even larger than the external field. The authors aspire to reduce the cavity's EM fields and quality factor over a frequency band analytically, numerically, and experimentally by introducing microwave absorbing materials in the cavity. A perturbation model approach was developed to estimate the quality factor of loaded cavities, which is validated against full-wave simulations and experiments. Conclusions with 78.7 mils (2 mm) thick ECCOSORB-MCS absorber placed on the inside cavity wall above and below the aperture slot (with only 0.026% cavity volume) result in a reduction of shielding effectiveness >19 dB and reductions in quality factor >91%, providing confirmation of the efficacy of this approach.

42 ENGINEERING↗

NASA NTRSDate not supplied

Coherence Analysis of the Space Launch System using Unsteady Pressure Sensitive Paint

Transonic buffet forces are a major source of unsteady loading on launch vehicles, thus requiring accurate estimation for efficient vehicle design. The state of the art in modeling these unsteady loads utilizes wind-tunnel tests where the fluctuating pressures are measured by pressure transducers (PTs) at discrete locations on a rigid buffet model. These pressures are then integrated over the surface of the vehicle to yield a series of orthogonal centerline loads called buffet forcing functions (BFFs). Typically, the PT layout aims at resolving the pressure correlation along the longitudinal axis of the vehicle. As a result, the distribution of azimuthal correlation and its impact on the estimated BFFs are not well known. To fill these gaps, extremely high-spatial-resolution uPSP data were collected for three different configurations of the Space Launch System in the NASA Ames Research Center 11-Foot Transonic Unitary Plan Wind Tunnel. The spatio-temporal behavior of the pressure correlation on these vehicles is analyzed and flow features of interest are investigated. It is shown that terminal shocks interacting with turbulence are a source of increased azimuthal coherence, especially when the shock develops at a junction. Vortex shedding off the forward attachment hardware that connects the core stage to the solid rocket boosters (SRBs) is the most severe buffet environment on the vehicle. The associated fluctuating pressures are shown to be highly coherent as far as the vehicle tail and up to 40 degrees away from the boosters. For selected areas of the vehicle, factoring the azimuthal coherence into the attenuation of discrete-measurements-based BFFs results in under prediction relative to the BFFs obtained from full integration of the uPSP data.

buffet↗

NASA NTRS2017

Wind Tunnel Strain-Gage Balance Calibration Data Analysis Using a Weighted Least Squares Approach

A new approach is presented that uses a weighted least squares fit to analyze wind tunnel strain-gage balance calibration data. The weighted least squares fit is specifically designed to increase the influence of single-component loadings during the regression analysis. The weighted least squares fit also reduces the impact of calibration load schedule asymmetries on the predicted primary sensitivities of the balance gages. A weighting factor between zero and one is assigned to each calibration data point that depends on a simple count of its intentionally loaded load components or gages. The greater the number of a data point's intentionally loaded load components or gages is, the smaller its weighting factor becomes. The proposed approach is applicable to both the Iterative and Non-Iterative Methods that are used for the analysis of strain-gage balance calibration data in the aerospace testing community. The Iterative Method uses a reasonable estimate of the tare corrected load set as input for the determination of the weighting factors. The Non-Iterative Method, on the other hand, uses gage output differences relative to the natural zeros as input for the determination of the weighting factors. Machine calibration data of a six-component force balance is used to illustrate benefits of the proposed weighted least squares fit. In addition, a detailed derivation of the PRESS residuals associated with a weighted least squares fit is given in the appendices of the paper as this information could not be found in the literature. These PRESS residuals may be needed to evaluate the predictive capabilities of the final regression models that result from a weighted least squares fit of the balance calibration data.

calibration analysis↗

NASA NTRS1970

Optimum structural design based on reliability analysis

Proof-load test improves statistical confidence in the estimate of reliability, numerical examples indicate a definite advantage of the proof-load approach in terms of savings in structural weight. The cost of establishing the statistical distribution of strength of the structural material is also introduced into the cost formulation

Heer, E.↗

NASA NTRS2007

Continental Scale Aerosol Optical Properties Over East Asia as Measured by Aeronet and Comparison to Satellite and Modeled Results

The AERONET program has operated in E. Asia since 1995 providing time continuous and time averaged ground-based column-integrated aerosol optical properties in a variety of aerosol regimes In the last four years the distribution has greatly increased in Siberia, China, SE Asia and India in particular. Commensurate with that, significant improvement in data processing algorithms (Version 2.0) and access to ancillary data products through the WWW have become available to the scientific community. At this writing the following distribution represents E and S. Asia: 5 sites operate in Siberia (2 years), 1 in Mongolia (9 years), 3 in Korea (3 to 6 years), 3 in Japan (2 to 7 years), China 11 (6 to 0 years), Taiwan 4 (7 to 2 yrs), Viet Nam 2 (4 years), Thailand 2 to 5 (4 years), and Singapore 1 (4 months), India 1 to 3 (7 to 1 years), Pakistan 2 (1 year), and UAE 3 (3 years). An analysis of the aerosol optical depth at 500 nm using annual average quality assured AERONET data (pre 2006) was used to estimate the mean annual aerosol loading by continent, sub continent and ocean. The individual site data were assumed representative of regional aerosol loading and aggregated to the sub-continental, continental and oceanic areas and presented. This analysis will be updated with more recent data with particular emphasis on seasonal results for Asia and the addition of single scattering albedo retrievals. The ground based results will be compared to MODIS collection 5 results and model estimates for E. Asia using the AERONET Synergy Tool.

Holben, B. N.↗

DOE OSTI2012

Integrated Cost and Schedule using Monte Carlo Simulation of a CPM Model - 12419

This discussion of the recommended practice (RP) 57R-09 of AACE International defines the integrated analysis of schedule and cost risk to estimate the appropriate level of cost and schedule contingency reserve on projects. The main contribution of this RP is to include the impact of schedule risk on cost risk and hence on the need for cost contingency reserves. Additional benefits include the prioritizing of the risks to cost, some of which are risks to schedule, so that risk mitigation may be conducted in a cost-effective way, scatter diagrams of time-cost pairs for developing joint targets of time and cost, and probabilistic cash flow which shows cash flow at different levels of certainty. Integrating cost and schedule risk into one analysis based on the project schedule loaded with costed resources from the cost estimate provides both: (1) more accurate cost estimates than if the schedule risk were ignored or incorporated only partially, and (2) illustrates the importance of schedule risk to cost risk when the durations of activities using labor-type (time-dependent) resources are risky. Many activities such as detailed engineering, construction or software development are mainly conducted by people who need to be paid even if their work takes longer than scheduled. Level-of-effort resources, such as the project management team, are extreme examples of time-dependent resources, since if the project duration exceeds its planned duration the cost of these resources will increase over their budgeted amount. The integrated cost-schedule risk analysis is based on: - A high quality CPM schedule with logic tight enough so that it will provide the correct dates and critical paths during simulation automatically without manual intervention. - A contingency-free estimate of project costs that is loaded on the activities of the schedule. - Resolves inconsistencies between cost estimate and schedule that often creep into those documents as project execution proceeds. - Good-quality risk data that are usually collected in risk interviews of the project team, management and others knowledgeable in the risk of the project. The risks from the risk register are used as the basis of the risk data in the risk driver method. The risk driver method is based in the fundamental principle that identifiable risks drive overall cost and schedule risk. - A Monte Carlo simulation software program that can simulate schedule risk, burn WM2012 rate risk and time-independent resource risk. The results include the standard histograms and cumulative distributions of possible cost and time results for the project. However, by simulating both cost and time simultaneously we can collect the cost-time pairs of results and hence show the scatter diagram ('football chart') that indicates the joint probability of finishing on time and on budget. Also, we can derive the probabilistic cash flow for comparison with the time-phased project budget. Finally the risks to schedule completion and to cost can be prioritized, say at the P-80 level of confidence, to help focus the risk mitigation efforts. If the cost and schedule estimates including contingency reserves are not acceptable to the project stakeholders the project team should conduct risk mitigation workshops and studies, deciding which risk mitigation actions to take, and re-run the Monte Carlo simulation to determine the possible improvement to the project's objectives. Finally, it is recommended that the contingency reserves of cost and of time, calculated at a level that represents an acceptable degree of certainty and uncertainty for the project stakeholders, be added as a resource-loaded activity to the project schedule for strategic planning purposes. The risk analysis described in this paper is correct only for the current plan, represented by the schedule. The project contingency reserve of time and cost that are the main results of this analysis apply if that plan is to be followed. Of course project managers have the option of re-planning and re-scheduling in the face of new facts, in part by mitigating risk. This analysis identifies the high-priority risks to cost and to schedule, which assist the project manager in planning further risk mitigation. Some project managers reject the results and argue that they cannot possibly be so late or so overrun. Those project managers may be wasting an opportunity to mitigate risk and get a more favorable outcome. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Effects of finite sampling on fatigue damage estimation of wind turbine components: A statistical study

The variability of the wind turbine loads complicates fatigue assessment in the design phase, as performing simulations covering the entire lifetime is computationally expensive. The current work provides important information for assessing the uncertainty in fatigue damage estimation due to finite data. Here we study the sample size effect on mean, variance, and skewness of damage in each wind bin, identify the important wind bins, and study the uncertainty propagation from each wind bin to the lifetime damage using 3600 aeroelastic simulations and bootstrapping. To achieve less than 1% error in the damage estimation across all load channels in the current case study, at least 100 turbulence seeds are needed. Damage in different wind bins follows a lognormal distribution when using the conventional approach of six seeds. The provided insights and information allow the designer to achieve a specific level of accuracy for a given computational cost using strategic bin sampling.

17 WIND ENERGY↗

NASA NTRS1979

Forecasting of loading on the Deep Space Network for proposed future NASA mission sets

The paper describes a computer program, DSNLOAD, which provides the Deep Space Network (DSN) loading information given a proposed future NASA mission set. The DSNLOAD model includes required pre- and post-calibration periods, and station 'overhead' such as maintenance or 'down' time. The analysis is presented which transforms station view period data for the mission set into loading matrices used to assess loading requirement. Assessment of future loading on the DSN for a set of NASA missions by estimating the tracking situation and presenting the DSN loading data, and a flowchart for selecting a possible future mission, determining a heliocentric orbit for the mission, generating view period schedules, and converting these schedules into basic loading data for each mission for each station are given. The tracking schedule model which considers the tracking schedule to be represented by passes of maximum required length and centered within the view period of available tracking time for each mission is described, and, finally, an example of typical loading study is provided.

Webb, W. A.↗

NASA NTRS1986

Combined bearing and bypass loading on a graphite/epoxy laminate

A combined experimental and analytical study was conducted to determine the behavior of a graphite/epoxy laminate subjected to combined bearing and bypass loading. Single-fastener quasi-isotropic specimens were loaded at various bearing-bypass ratios until damage was produced at the fastener hole. Damage-onset strengths and damage modes were then analyzed using local hole-boundary stresses calculated by a finite-element analysis. The tension data showed the expected linear interaction for combined bearing and bypass loading with damage developing in the net-section tension mode. However, the compression bearing-bypass strengths showed an unexpected interaction involving the bearing mode. Compressive bypass loads reduced the bearing strength by decreasing the bolt-hole contact arc and thus increasing the severity of the bearing loads. The bearing stresses at the hole boundary were not accurately estimated by superposition of the stress components for separate bearing and bypass loading. However, superposition produced reasonably accurate estimates for tangential stresses especially near the specimen net-section.

Crews, J. H., Jr.↗

NASA NTRS2011

Observational Evidence of Aerosol Enhancement of Lightning Activity and Convective Invigoration

Lightning activity over the West Pacific Ocean east of the Philippines is usually much less frequent than over the nearby maritime continents. However, in 2005 the Lightning Imaging Sensor (LIS) aboard the TRMM satellite observed anomalously high lightning activity in that area. In the same year the Moderate resolution Imaging Spectroradiometer (MODIS) measured anomalously high aerosol loading. The high aerosol loading was traced to volcanic activity, and not to any factor linked to meteorology, disentangling the usual convolution between aerosols and meteorology. We show that in general lightning activity is tightly correlated with aerosol loadings at both inter-annual and biweekly time scales. We estimate that a approximately 60% increase in aerosol loading leads to more than 150% increase in lightning flashes. Aerosols increase lightning activity through modification of cloud microphysics. Cloud ice particle sizes are reduced and cloud glaciation is delayed to colder temperature when aerosol loading is increased. TRMM precipitation radar measurements indicate that anomalously high aerosol loading is associated with enhanced cloud mixed phase activity and invigorated convection over the maritime ocean. These observed associations between aerosols, cloud microphysics, morphology and lightning activity are not related to meteorological variables or ENSO events. The results have important implications for understanding the variability of lightning and resulting aerosol-chemistry interactions.

Yuan, Tianle↗

NASA NTRS1996

Internal loading of an inhomogeneous compressible Earth with phase boundaries

The geoid and the boundary topography caused by mass loads inside the earth were estimated. It is shown that the estimates are affected by compressibility, by a radially varying density distribution, and by the presence of phase boundaries with density discontinuities. The geoid predicted in the chemical boundary case is 30 to 40 percent smaller than that predicted in the phase case. The effects of compressibility and radially varying density are likely to be small. The inner core-outer core topography for loading inside the mantle and for loading inside the inner core were computed.

Defraigne, P.↗

DOE OSTI2016

Modeling used fuel response to normal conditions of transportation package drops to access geometric sensitivities

The US Department of Energy Used Fuel Disposition program is performing research to determine the loading conditions that used nuclear fuel (UNF) experiences during normal conditions of transportation (NCT). This loading environment includes mechanical shock and vibration as the UNF is transported by rail or truck, and it also includes potential package free drop conditions, which are the topic of this study. NCT drop test requirements for UNF package designs are defined in 10 CFR 71.71. The free drop test height is 30 cm for the UNF packages considered in this study. Explicit dynamic finite element models of generic rail and truck UNF packages containing a highly resolved 17x17 PWR fuel assembly are used to estimate the potential range of loading experienced by UNF during NCT horizontal package drops onto an unyielding surface. There are many variables and uncertainties that can affect the loading of UNF during this type of free drop scenario. This study focuses on geometric variables, such as gap conditions and small adjustments to the angle of impact, in a number of analysis cases. The LS-DYNA finite element analyses calculate detailed results for all the components of the fuel assembly. The results show that the peak localized axial strain in the fuel cladding is estimated to be 0.006421 (nominal) with an upper bound of 0.014511, based on the peak instantaneous bending moment of 63.65 N-m and other uncertainty factors. For the assumed low burnup condition of the UNF, the cladding yield strain is 0.011027 and the failure strain is 0.015574, which means that the calculated upper bound strain approaches the cladding failure limit without exceeding it. The peak shear force on the cladding was calculated to be 7879 N. This could be significant to cladding integrity if applied to the UNF in a situation where the fuel pellets do not support the shear transfer. Further evaluation is needed to determine if this is a credible threat to cladding integrity for these 30 cm free drop scenarios.

42 ENGINEERING↗

DOE OSTI2021

Managing Army Plug Load Equipment Energy Use: Vending Machines

Vending machines consume the most energy of individual plug load devices common to Army buildings. As a group, they rank fourth in total electricity consumption, behind only clothes dryers, laptop computers, and telecom loads. Upgrading 80% of the estimated 22,000 refrigerated vending machines on Army installations to the latest ENERGY STAR ® performance and optimizing their efficiency settings could save 31 million kWh and $2 million per year.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS1974

Earth Observatory Satellite system definition study. Report no. 3: Design/cost tradeoff studies. Appendix D: EOS configuration design data. Part 1: Spacecraft configuration

The results of structural studies of the Earth Observatory Satellite (EOS) which define the member sizes to meet the vehicle design requirements are presented. The most significant requirements in sizing the members are the stiffness required to meet the launch vehicle design frequencies both in the late al and in the longitudinal directions. The selected configurations, both baseline and preferred, for the Delta and Titan launch vehicles were evaluated for stiffness requirements. The structural idealization used to estimate the stiffness of each structural arrangement, was based on an evaluation of primary loads paths, effectivity of structural members, and estimated sizes for the preferred configurations. The study included an evaluation of the following structural materials: (1) aluminum alloys, (2) titanium alloys, (3) beryllium, (4) beryllium/aluminum alloy, and (5) composite materials.

Source record↗

NASA NTRS2017

Satellites May Underestimate Rice Residue and Associated Burning Emissions in Vietnam

In this study, we estimate rice residue, associated burning emissions, and compare results with existing emissions inventories employing a bottom-up approach. We first estimated field-level post-harvest rice residues, including separate fuel-loading factors for rice straw and rice stubble. Results suggested fuel-loading factors of 0.27 kg/sq m (+/-0.033), 0.61 kg/sq m (+/-0.076), and 0.88 kg/sq m (+/-0.083) for rice straw, stubble, and total post-harvest biomass, respectively. Using these factors, we quantified potential emissions from rice residue burning and compared our estimates with other studies. Our results suggest total rice residue burning emissions as 2.24 Gg PM2.5, 36.54 Gg CO and 567.79 Gg CO2 for Hanoi Province, which are significantly higher than earlier studies. We attribute our higher emission estimates to improved fuel-loading factors; moreover, we infer that some earlier studies relying on residue-to-product ratios could be underestimating rice residue emissions by more than a factor of 2.3 for Hanoi, Vietnam. Using the rice planted area data from the Vietnamese government, and combining our fuel-loading factors, we also estimated rice residue PM2.5 emissions for the entirety of Vietnam and compared these estimates with an existing all-sources emissions inventory, and the Global Fire Emissions Database (GFED). Results suggest 75.98 Gg of PM2.5 released from rice residue burning accounting for 12.8% of total emissions for Vietnam. The GFED database suggests 42.56 Gg PM2.5 from biomass burning with 5.62 Gg attributed to agricultural waste burning indicating satellite-based methods may be significantly underestimating emissions. Our results not only provide improved residue and emission estimates, but also highlight the need for emissions mitigation from rice residue burning.

Air pollution↗