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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1976

Some measurements of an EBF powered-lift wake

Results from a wind tunnel investigation in which velocity vector measurements were obtained in the near wake of an externally blown flap powered lift configuration were analyzed. These measurements were used to develop spanwise distributions for the momentum strength and location of the engine exhaust stream tube with the results used as input parameters to one jet flap analytical method. It is shown that a comparison of the momentum coefficients obtained from forward speed wake surveys with the predicted values from static force data results in a good correlation, which verifies the use of the flap thrust recovery factor as a means of predicting the momentum strength at the flap trailing edge. Also, when wake survey distributions of momentum strength and direction are used as input parameters to one analytical jet flap method, the results show reasonable agreement between the experimental data and analytical results.

Johnson, W. G., Jr.↗

NASA NTRS1990

A fiber optic sensor for noncontact measurement of shaft speed, torque, and power

A fiber optic sensor which enables noncontact measurement of the speed, torque and power of a rotating shaft was fabricated and tested. The sensor provides a direct measurement of shaft rotational speed and shaft angular twist, from which torque and power can be determined. Angles of twist between 0.005 and 10 degrees were measured. Sensor resolution is limited by the sampling rate of the analog to digital converter, while accuracy is dependent on the spot size of the focused beam on the shaft. Increasing the sampling rate improves measurement resolution, and decreasing the focused spot size increases accuracy. Digital processing allows for enhancement of an electronically or optically degraded signal.

Madzsar, George C.↗

NASA NTRS1990

A fiber optic sensor for noncontact measurement of shaft speed, torque and power

Madzsar, George C.↗

DOE OSTI2023

Field Measurement and Analysis of Frequency and RoCoF for Low-Inertia Power Systems

The frequency measurement and rate of change of frequency (RoCoF) calculations are important for active power, frequency control, and frequency-related protection in power system operations. With the rapid decrease in inertia under modern power systems, however, multiple power variations introduced by variable renewable energy bring large RoCoF and introduce oscillations in frequency measurements. To shed light on this issue, this article proposes a frequency measurement and RoCoF analysis technology, as well as the sensitivity analysis for the real low-inertia power grid. First, a real-world event in an island power grid is analyzed as an example, and an event numerical model is estimated considering four uncertainties, including event RoCoF, oscillation magnitude, oscillation frequency, and underfrequency load-shedding threshold. Then, a sensitivity analysis is performed using the Sobol indices method and quasi-Monte Carlo simulations to identify the dominant uncertainties based on the event model. Here, the dominant uncertainties are compared to provide a guideline for the frequency estimation algorithm selection under different event cases. This algorithm is compared with an enhanced zero-crossing algorithm and gives a 3.41% better RoCoF error rate. Finally, an experiment is conducted using universal grid analyzers to validate the simulation results and the theoretical analysis.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NASA NTRS1990

Dynamic Power Spectral Analysis of Solar Measurements from Photospheric, Chromospheric, and Coronal Sources

An important aspect in the power spectral analysis of solar variability is the quasistationary and quasiperiodic nature of solar periodicities. In other words, the frequency, phase, and amplitude of solar periodicities vary on time scales ranging from active region lifetimes to solar cycle time scales. Here, researchers employ a dynamic, or running, power spectral density analysis to determine many periodicities and their time-varying nature in the projected area of active sunspot groups (S sub act). The Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor (SMM/ACRIM) total solar irradiance (S), the Nimbus-7 MgII center-to-wing ratio (R (MgII sub c/w)), the Ottawa 10.7 cm flux (F sub 10.7), and the GOES background x ray flux (X sub b) for the maximum, descending, and minimum portions of solar cycle 21 (i.e., 1980 to 1986) are used. The technique dramatically illustrates several previously unrecognized periodicities. For example, a relatively stable period at about 51 days has been found in those indices which are related to emerging magnetic fields. The majority of solar periodicities, particularly around 27, 150 and 300 days, are quasiperiodic because they vary in amplitude and frequency throughout the solar cycle. Finally, it is shown that there are clear differences between the power spectral densities of solar measurements from photospheric, chromospheric, and coronal sources.

Bouwer, S. D.↗

DOE OSTI2018

Addressing solar power plant heat transfer fluid degradation: Experimental measurements of hydrogen transport properties in binary eutectic biphenyl/diphenyl ether

Not Available

Beckers, Koenraad F.↗

DOE OSTI2017

Synchronized Wireless Measurement of High-Voltage Power System Frequency Using Mobile Embedded Systems

This paper focuses on synchronized wireless measurement of high-voltage (HV) power system frequency using mobile embedded systems (MESs) integrated with a wireless electric field sensor (WEFS). Unlike traditional synchronized frequency measurement devices, which rely on potential transformers and current transformers physically connected to system elements, a WEFS is used to realize wireless signal acquisition in the vicinity of any HV apparatus. The MES performs real-time frequency estimation using a recursive discrete Fourier transform based algorithm. Network time protocol (NTP) is used for time synchronization, increasing the system flexibility by eliminating global positioning system reliance. An NTP-based synchronized sampling control method is proposed and implemented in MES to compensate the sampling time error caused by local time drift and division residue. The proposed system has the advantages of portability and lower cost, making it highly accessible and useful for a wide array of synchronized frequency measurement applications. Experiment results verify the accuracy and effectiveness of the proposed system.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2019

On-Sky Performance of the SPT-3G Frequency-Domain Multiplexed Readout

Frequency-domain multiplexing (fMux) is an established technique for the readout of large arrays of transition-edge sensor (TES) bolometers. Each TES in a multiplexing module has a unique AC voltage bias that is selected by a resonant filter. This scheme provides for the operation and readout of multiple bolometers on a single pair of wires, reducing thermal loading onto sub-Kelvin stages. The current receiver on the South Pole Telescope, SPT-3G, uses a 68x fMux system to operate its large-format camera of ~16,000 TES bolometers. We present here the successful implementation and performance of the SPT-3G readout as measured on-sky. Characterization of the noise reveals a median pair-differenced 1/f knee frequency of 33 mHz, indicating that low-frequency noise in the readout will not limit SPT-3G’s measurements of sky power on large angular scales. Measurements further show that the median readout white noise level in each of the SPT-3G observing bands is below the expectation for photon noise, demonstrating that SPT-3G is operating in the photon-noise-dominated regime.

47 OTHER INSTRUMENTATION↗

DOE OSTI2016

Planck intermediate results: XLI. A map of lensing-induced B -modes

The secondary cosmic microwave background (CMB) B-modes stem from the post-decoupling distortion of the polarization E-modes due to the gravitational lensing effect of large-scale structures. These lensing-induced B-modes constitute both a valuable probe of the dark matter distribution and an important contaminant for the extraction of the primary CMB B-modes from inflation. Planck provides accurate nearly all-sky measurements of both the polarization E-modes and the integrated mass distribution via the reconstruction of the CMB lensing potential. By combining these two data products, we have produced in this paper an all-sky template map of the lensing-induced B-modes using a real-space algorithm that minimizes the impact of sky masks. The cross-correlation of this template with an observed (primordial and secondary) B-mode map can be used to measure the lensing B-mode power spectrum at multipoles up to 2000. In particular, when cross-correlating with the B-mode contribution directly derived from the Planck polarization maps, we obtain lensing-induced B-mode power spectrum measurement at a significance level of 12σ, which agrees with the theoretical expectation derived from the Planck best-fit Λ cold dark matter model. This unique nearly all-sky secondary B-mode template, which includes the lensing-induced information from intermediate to small (10 ≲ ℓ ≲ 1000) angular scales, is delivered as part of the Planck 2015 public data release. Finally, it will be particularly useful for experiments searching for primordial B-modes, such as BICEP2/Keck Array or LiteBIRD, since it will enable an estimate to be made of the lensing-induced contribution to the measured total CMB B-modes.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2012

Testing gyrokinetic simulations of electron turbulence

An extensive set of tests comparing gyrokinetic predictions of temperature-gradient driven electron turbulence to power balance transport analyses and fluctuation measurements are presented. These tests use data from an L-mode validation study on the DIII-D tokamak (Luxon 2002 Nucl. Fusion 42 614) in which the local value of $a/L_{T_{\rm e} } =-(a/T_{\rm e} )({\rm d}T_{\rm e} /{\rm d}r)$ is varied by modulated electron cyclotron heating; the GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) is used to make the gyrokinetic predictions. Using a variety of novel measures, both local and global nonlinear simulations are shown to predict key characteristics of the electron energy flux Qe and long-wavelength (low-k) Te fluctuations, but systematically underpredict (by roughly a factor of two) the ion energy flux Qi. A new synthetic diagnostic for comparison to intermediate wavelength Doppler backscattering measurements is presented, and used to compare simulation predictions against experiment. In contrast to the agreement observed in the low-k Te fluctuation comparisons, little agreement is found between the predicted and measured intermediate-k density fluctuation responses. The results presented in this paper significantly expand upon those previously reported in DeBoo et al (2010 Phys. Plasmas 17 056105), comparing transport and multiple turbulence predictions from numerically converged local and global simulations for all four experimental heating configurations (instead of only fluxes and low-k Te fluctuations for one condition) to measurements and power balance analyses.

Physics↗

DOE OSTI2013

Amplifier Test

For this test, we used the existing back end configuration. For the burst type signal we used the excitation system, and for the continuous type signal we used an arbitrary function generator. The frequencies of the signal are 100, 200, 300, 400 MHz. The signals were adjusted to be approximately the same level when input into the back end chain. At the MUX out load we measure the signal with a Tektronix oscilloscope, triggering on the load signal itself, recording 1K turns (fiducial triggers). The negative (${V{_{load}^{-p}}}$) and positive (${V{_{load}^{p}}}$) peak voltages generated were recorded, from which peak to peak voltages (${V{_{load}^{pp}}}$) were computed. The input signal was attenuated by 10 dB compared to the normal operating signal used for beam excitation as a cautionary measure. One measurement was made at normal operating power. We measure the loads of two amplifiers, amp 2 and amp 4.

ACCPHY↗

DOE OSTI2023

Loose Belt Fault Detection and Virtual Flow Meter Development Using Identified Data-driven Energy Model for Fan Systems

An energy model that correlates fan airflow, head, speed, and system power input is essential to detect device faults and optimize control strategies in fan systems. Since the application of variable-frequency drives (VFDs) makes the motor-efficiency data published by manufacturers inapplicable for VFD–motor–fan systems, the fan efficiency and drive (belt–motor–VFD) efficiency must be identified for each individual system to obtain accurate energy models. The objectives of this paper are to identify an energy model of existing VFD–motor–fan systems using available experimental data and demonstrate its applications in loose belt fault detection and virtual airflow meter development for optimal control. First, an approach is developed to identify the fan head, fan efficiency, and drive-efficiency curves using available fan head, speed, and system power input as well as temporarily measured airflow rate without measuring shaft power. Then, the energy model is identified for an existing VFD–motor–fan system. Finally, the identified model is applied to detect the slipped belt faults and develop the virtual airflow meter. The experiment results reveal that the developed approach can effectively obtain the energy model of VFD–motor–fan systems and the model can be applied to effectively detect slipped belt faults and accurately calculate the fan airflow rate.

42 ENGINEERING↗

NASA NTRS1971

Parametric testing of an externally configured thermionic converter

A 25.4-cm long externally configured converter was performance tested by electrically heating the emitter to simulate reactor thermal power input. The measured maximum output power was limited by the maximum input power available from the electric RF induction heater. With maximum heater input power, the converter electric output was 178 W (1.95 W/sq cm) at an emitter temperature of 1946 K. This electric output power was smaller than expected. A reactor-core-length (25.4-cm long) cylindrical thermionic converter power and maintaining the emitter-to-collector gap without shorting are of major importance to the feasibility of a 25.4-cm-long reactor fuel element. The emitter of the converter is located externally to the collector to increase the fuel-volume fraction and to allow redundant collector cooling in a reactor configuration.

Shimada, K.↗

NASA NTRS1980

Conceptual design study of concentrator enhanced solar arrays for space applications. Performance evaluation of 5 KW and 20 KW systems in Si and GaAs at 1 AU employing a flat plate trough concentrator

A simple, efficient and very lightweight preliminary design for a 5 KW and 20 KW BOL output concentrated array evolved and is described by drawings. The relative effectiveness of this design, as compared to an unconcentrated planar array of equal power output, was measured by comparing power to mass performance of and the solar cell area required by each. Improvements in power to mass performance as high as 42% together with array area size reduction of 57% are possible in GaAs systems. By contrast, when the same concentrator design is applied to silicon systems, no improvement in power to mass can be obtained although array area reductions as high as 35% are obtainable.

Source record↗

NASA NTRS1987

A closed-loop causal model of workload based on a comparison of fuzzy and crisp measurements techniques

Fuzzy and crisp measurements of workload are compared for a tracking task that varied in bandwidth and order of control. Fuzzy measures are as powerful as crisp measures, and can under certain conditions give extra insights into workload causality. Both methods suggest that workload arises in a system in which effort, performance, difficulty, and task variables are linked in a closed loop. Marked individual differences were found. Future work on the fuzzy measurement of workload is justified.

Moray, Neville↗

NASA NTRS1987

Quasi-Lagrangian measurements of density surface fluctuations and power spectra in the stratosphere

Pressure and temperature data from eight superpressure balloon flights at 26 km in the southern hemisphere stratosphere are analyzed. The balloons, which float on a constant density surface, travel steadily westward during summer and eastward during winter, as expected from local climatology. Two types of fluctuations are observed: neutral buoyancy oscillations (NBO) of around 4 min, and 0.1- to 1-hour oscillations that are characterized as small-amplitude density surface fluctuations. Lapse rates and densities are calculated and found to agree well with the expected values. Examples of wave damping and simultaneous fluctuation at two nearby balloons are presented. Spectral analysis is performed clearly showing the NBO and that the majority of the power is in the mesoscale range. Spectral slopes of power versus frequency are measured to be on the average -2.18 + or - 0.24 for pressure and -1.72 + or - 0.24 for temperature. These slopes are compared to the predictions of turbulence theories and the theory of a universal gravity wave spectrum.

Quinn, Elizabeth P.↗

NASA NTRS2003

Characterization of future deep space computing loads

This paper reports on the characteristics of a future deep space computing application. This includes the testbed used to make the measurements, the application suite itself, the scenarios measured, the detailed power and performance measurements taken, and the timing characteristics of the system.

deep space mission↗

NASA NTRS2003

Characterization of future deep space computing loads

This paper reports on the characteristics of a future deep space computing application. This includes the testbed used to make the measurements. the application suite itself, the scenarios measured. the detailed power and performance measurements taken, and the timing characteristics ofthe system.

Toomarian, N. Benny↗