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Results for “hybrid simulation”

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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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Hybrid simulations of whistler waves generation and current closure by a pulsed tether in the ionosphere

The dynamic response of a magnetized collisionless plasma to an externally driven, finite size, sudden switch-on current source across the magnetic field has been studied using a two dimensional hybrid code. It was found that the predominant plasma response was the excitation of whistler waves and the formation of current closure by induced currents in the plasma. The results show that the current closure path consists of: (a) two antiparallel field-aligned current channels at the end of the imposed current sheet; and (b) a cross-field current region connecting these channels. The formation of the current closure path occured in the whistler timescale much shorter than that of MHD and the closure region expanded continuously in time. The current closure process was accompanied by significant energy loss due to whistler radiation.

Chang, C. L.↗
NASA NTRS1979

Wind Energy System Time-domain (WEST) analyzers using hybrid simulation techniques

Two stand-alone analyzers constructed for real time simulation of the complex dynamic characteristics of horizontal-axis wind energy systems are described. Mathematical models for an aeroelastic rotor, including nonlinear aerodynamic and elastic loads, are implemented with high speed digital and analog circuitry. Models for elastic supports, a power train, a control system, and a rotor gimbal system are also included. Limited correlation efforts show good comparisons between results produced by the analyzers and results produced by a large digital simulation. The digital simulation results correlate well with test data.

Hoffman, J. A.↗
NASA NTRS1991

Hybrid simulation of the formation of a hot flow anomaly

The interaction of current sheets embedded in the upstream flow with a shock, relevant to the study of the earth's bow shock, is examined. It is shown that a hot flow anomaly (HFA) can be generated by a direct method that does not involve an instability. The HFA is shown to be due to the interaction of reflected ions with the current sheets. An important part of the interaction, pointed out by Burgess (1989), is that for a class of current sheets reflected ions are always focused toward the current sheet by the motional electric field, while for another class of current sheets the electric field defocuses reflected ions away from the current sheet. In addition, not just the behavior of reflected ions upstream of the shock but also the behavior of those behind the shock front is related to HFA formation.

Thomas, V. A.↗