The potential of nuclear power for high-speed ocean-going air-cushion vehicles.
Performance potential of high speed ocean-going air cushion vehicles with aircraft nuclear power plants
Kascak, A. F.↗
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Development of Solid Synchronous Reluctance Rotors With Multi-Material Additive Manufacturing
Synchronous reluctance (SynR) machines are promising rare-earth material-free alternatives to permanent magnet machines. However, structural challenges limit their operating speed and power density. This paper proposes and investigates multi-material additive manufacturing (MMAM) as a key-enabler to realize power-dense and high-speed SynR machines. It does so by proposing designs that guide magnetic flux through solid rotors realized by selective placement of magnetic and non-magnetic materials. To explore this concept, first, material samples are additively manufactured and experimentally characterized to assess the structural and magnetic properties that can be expected for the proposed rotors. Second, the design space of each rotor type is explored using these measured properties within finite element analysis. The results reveal that MMAM can enable fabrication of SynR motors with power density levels that are at the leading edge of all conventional electric machine topologies. It is shown that tip speeds in excess of 300 m/s can be achieved, resulting in 3-4x improvement in power density over conventional SynR motors. A solid SynR rotor is printed in an experimental MMAM laser powder bed fusion system. The rotor is paired with an existing stator to create a functional SynR motor with a saliency ratio of 2.59 and torque rating of 4.15 Nm. This is the first publication of a SynR rotor prototype constructed via MMAM.
36 MATERIALS SCIENCE↗
Validation of Numerical Models of the Offshore Wind Turbine From the Alpha Ventus Wind Farm Against Full-Scale Measurements Within OC5 Phase III
The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project validates OWT models against the measurements recorded on a Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. The following operating conditions of the wind turbine were chosen for the validation: (1) idling below the cut-in wind speed, (2) rotor-nacelle assembly (RNA) rotation maneuver below the cut-in wind speed, (3) power production below and above the rated wind speed, and (4) shutdown. A number of validation load cases were defined based on these operating conditions. The following measurements were used for validation: (1) strains and accelerations recorded on the support structure and (2) pitch, yaw, and azimuth angles, generator speed, and electrical power recorded from the RNA. Strains were not directly available from the majority of the OWT simulation tools; therefore, strains were calculated based on out-of-plane bending moments, axial forces, and cross-sectional properties of the structural members. The simulation results and measurements were compared in terms of time series, discrete Fourier transforms, power spectral densities, and probability density functions of strains and accelerometers. A good match was achieved between the measurements and models setup by OC5 Phase III participants.
17 WIND ENERGY↗
Aerodynamic characteristics of a six-jet V/STOL configuration with four swing-out lift jets in the transition speed range
A wind-tunnel investigation has been made of the longitudinal aerodynamic characteristics and jet-interference effects of a model of a jet V/STOL variable-sweep fighter airplane that employs four direct-lift engines which swing out from the fuselage and two lift-cruise engines located in the rear part of the fuselage. Data were obtained with two wing areas for various forward speeds and power conditions in the transition speed range. The data are presented without analysis or discussion.
Carter, A. W.↗
State of the NASA Aeropropulsion Discipline Input from the Glenn Research Center
PROBLEM: Current power turbines are designed for single operating speed, and performance degrades rapidly as power turbine speed decreases. OBJECTIVES: Demonstrate 50 improvement in efficient operational capability using a Variable Speed Power Turbine concept. (Refer to figure lower left, where the goal is to raise efficiency from the current technology line to the green line which represents the AVSPOT VSPT goal.APPROACH: Conduct RD required to advance the technology readiness level of VSPT technology to TRL 4Partner with DoD and leverage DOD AVSPOT contract to share government cost (5050) of contracted efforts to GE and PW for VSPT TRL 45 demonstration.
power turbine↗
Low Frequency ULF Waves in the Earth’s Inner Magnetosphere: Power Spectra During High Speed Streams and Quiet Solar Wind and Seeding of EMIC Waves
Here we extend the scope of the Gamayunov and Engebretson (2021, hereinafter Paper 1) work by analyzing the low frequency ultra-low-frequency (ULF) wave power spectra in the Earth’s inner magnetosphere during high speed stream (HSS) and quiet solar wind (QSW) driving conditions in the upstream solar wind (SW) and comparing our results to the results of Paper 1, where the statistics of ULF wave power spectra during coronal mass ejections (CMEs) are presented. The most important results of our statistical and comparative analyses are as follows. (a) During CMEs, HSSs, and QSW, the magnetic field power spectra of the transverse and compressional fluctuations are well approximated by power-laws in the ∼ mHz - Hz frequency range, where on average the parameters of power-law fits during CMEs and HSSs are close, and those during QSW differ considerably from the respective parameters during CMEs and HSSs. (b) The dominance of the average compressional power over the average transverse power for the low frequency ULF waves during the 0 < SYM/H . 25 nT geomagnetic conditions may serve as a proxy of HSSs in the upstream SW, whereas the opposite relation between the average powers is an indication of CMEs. (c) Independently of the SW driving conditions, a turbulent energy cascade from low frequencies in the ULF wave frequency range into the higher frequency range exists in the Earth’s inner magnetosphere, supplying the nonthermal electromagnetic seed fluctuations needed for the growth of electromagnetic ion cyclotron (EMIC) waves (∼ Hz) due to relaxation of unstable distributions of energetic magnetospheric ions.
Konstantin V. Gamayunov↗
Integrated photonic encoder for low power and high-speed image processing
Abstract Modern lens designs are capable of resolving greater than 10 gigapixels, while advances in camera frame-rate and hyperspectral imaging have made data acquisition rates of Terapixel/second a real possibility. The main bottlenecks preventing such high data-rate systems are power consumption and data storage. In this work, we show that analog photonic encoders could address this challenge, enabling high-speed image compression using orders-of-magnitude lower power than digital electronics. Our approach relies on a silicon-photonics front-end to compress raw image data, foregoing energy-intensive image conditioning and reducing data storage requirements. The compression scheme uses a passive disordered photonic structure to perform kernel-type random projections of the raw image data with minimal power consumption and low latency. A back-end neural network can then reconstruct the original images with structural similarity exceeding 90%. This scheme has the potential to process data streams exceeding Terapixel/second using less than 100 fJ/pixel, providing a path to ultra-high-resolution data and image acquisition systems.
47 OTHER INSTRUMENTATION↗
Plasma fluctuations in the solar wind
Using Ogo 5 plasma and magnetic field data, the power spectra of solar wind fluctuations are calculated over the 10 to the -3 to 10 to the -1 Hz range. It is found that the spectra calculated from flux measurements equal the density power spectra times the square of the average solar wind speed. The power spectrum relative density is of the same order of magnitude as the power spectrum of speed fluctuations relative to the Alfven speed. In cases where density and field fluctuations are inconsistent with magnetosonic waves, static inhomogeneities with a balance between electron thermal and magnetic pressures is assumed. It is also felt that a resonant proton cyclotron instability driven by the solar wind's proton thermal anisotropy may cause the observed power enhancements near 1 Hz.
Neugebauer, M.↗
Low-Speed Flight Characteristics of a Powered-Lift Jet Transport During the Landing Approach
A flight-test program to determine the flight characteristics of large jet transports equipped with powered-lift systems indicated the following results: Speed margins appear to be primarily related to power-on stall speeds. At these speed margins, the maneuver margins were adequate and did not appear to be a problem or limiting factor during powered-lift operation. No large detrimental effects on handling qualities were apparent but in some areas stability augmentation would be required to obtain satisfactory flight characteristics. Use of the powered-lift airplane would result in a sizable increase in the noise levels; these increases are primarily the result of higher engine power settings in the approach.
Schade, Robert O.↗
Experimental evaluation of a volts-per-hertz reference circuit for the isotope Brayton system
In Brayton-cycle power systems, the speed decreases rapidly with overload. If the voltage decreases linearly with speed (frequency), the power decreases as the square of the voltage. This makes the system more tolerant of overloads. A volts-per-hertz reference circuit, consisting of a volts-per-hertz sensor and a voltage limiter, was designed and fabricated. This reference circuit was incorporated in an existing voltage regulator to control a turbine-driven alternator. Test results show that the control does function to reduce voltage at speeds below the rated speed and that it performed successfully during transients.
Wimmer, H. L.↗
Rotor windage losses for Lundell alternators
The Lundell alternator is being investigated for power system applications. At the high speeds required, power loss due to windage can become high and result in significant heating of the alternator. This loss must be incorporated in the cooling design. The velocity profiles expected in these alternators are highly turbulent, and the Reynolds numbers are well above the levels previously reported; the available data could only be extrapolated. For this reason, a range of experimental data was generated to permit accurate calculation of the windage power loss for Lundell alternator design. Windage tests were conducted on two concentric rotor-stator configurations in ambient air, producing Reynolds numbers as high as 100,000. Using the data obtained, a method was developed to calculate the windage loss for any Lundell alternator given the geometry and cavity conditions.
Gorland, S. H.↗
Effect of Helicopter Performance of Modifications in Profile-Drag Characteristics of Rotor-Blade Airfoil Sections
Rough conventional, smooth conventional, and laminar-flow or low-drag sections were tested. The items covered are rotor thrust for fixed power in hovering, range and endurance at cruising speed, and power required at high-forward speed. Calculations indicated that a smooth conventional section gives marked performance gains. Smaller gains are obtainable by using a low-drag section. At high speeds or loads the low-drag section is inferior to the smooth conventional section.
Gustafson, F.B.↗
Wheel speed management control system for spacecraft
A spacecraft attitude control system uses at least four reaction wheels. In order to minimize reaction wheel speed and therefore power, a wheel speed management system is provided. The management system monitors the wheel speeds and generates a wheel speed error vector. The error vector is integrated, and the error vector and its integral are combined to form a correction vector. The correction vector is summed with the attitude control torque command signals for driving the reaction wheels.
Goodzeit, Neil E.↗
Summary of low-speed longitudinal aerodynamics of two powered close-coupled wing-canard fighter configurations
Investigations of the low speed longitudinal characteristics of two powered close coupled wing-canard fighter configurations are discussed. Data obtained at angles of attack from -2 deg to 42 deg, Mach numbers from 0.12 to 0.20, nozzle and flap deflections from 0 deg to 40 deg, and thrust coefficients from 0 to 2.0, to represent both high angle of attack subsonic maneuvering characteristics and conventional takeoff and landing characteristics are examined. Data obtained with the nozzles deflected either 60 deg or 90 deg and the flaps deflected 60 deg to represent vertical or short takeoff and landing characteristics are discussed.
Paulson, J. W., Jr.↗
Civil applications of high-speed rotorcraft and powered-lift aircraft configurations
Advanced subsonic vertical and short takeoff and landing (V/STOL) aircraft configurations offer new transportation options for civil applications. Described is a range of vehicles from low-disk to high-disk loading aircraft, including high-speed rotorcraft, V/STOL aircraft, and short takeoff and landing (STOL) aircraft. The status and advantages of the various configurations are described. Some of these show promise for relieving congestion in high population-density regions and providing transportation opportunities for low population-density regions.
Albers, James A.↗
Multiroller traction drive speed reducer: Evaluation for automotive gas turbine engine
Tests were conducted on a nominal 14:1 fixed-ratio Nasvytis multiroller traction drive retrofitted as the speed reducer in an automotive gas turbine engine. Power turbine speeds of 45,000 rpm and a drive output power of 102 kW (137 hp) were reached. The drive operated under both variable roller loading (proportional to torque) and fixed roller loading (automatic loading mechanism locked). The drive operated smoothly and efficiently as the engine speed reducer. Engine specific fuel consumption with the traction speed reducer was comparable to that with the original helical gearset.
Rohn, D. A.↗
High-Speed Multiprocessing For Engine Simulation
Parallel microprocessors have computational power and speed for realistic simulations. Interactive information bus links front-end processor and computational processors. Real-time information bus links real-time extension processor and pre-processors. Computational processor and preprocessor communicate through shared memory. System used to simulate small turboshaft engine to demonstrate potential of multiprocessing in such applications. Real-time simulations aid development of new digital engine controls enabling testing of hardware and software under realistic conditions.
Milner, Edward J.↗
Oscillating surge wave energy converter using a novel above-water power takeoff with belt-arc speed amplification
We investigate the performance of a novel power takeoff (PTO) featuring belt-arc speed amplification for oscillating surge wave energy converters (OSWECs), aiming to address the challenges of extremely low rotary speed and large torque under the low-frequency ocean wave excitations. The belt-arc design significantly increases the rotary speed of the generator, enabling generator downsizing and decreasing the powertrain friction losses. The design also allows for placing the generator above water, eliminating the need for high Ingress Protection ratings for the generator and powertrain, and potentially leading to substantial reductions in capital and maintenance costs. Using the linear potential wave theory, the dynamics of the integrated system are analyzed, and key parameters are identified. To validate the numerical analysis, a 1:10 scale model is designed, fabricated, and tested in a wave tank. Performance evaluations are conducted under regular and irregular wave conditions, with quantified effects of parameter tuning. The results reveal an optimal wave-to-electric efficiency of 48% under regular wave excitation and 20% under irregular excitation. Furthermore, these findings underscore the effectiveness of the proposed novel PTO design in addressing the challenges of low rotation speed and large torque inherent in OSWECs, demonstrating its ability to efficiently convert wave power into electricity.
16 TIDAL AND WAVE POWER↗