Axial field limitations in MHD generators. Topical report. [Experimental and theoretical study]
The results of an experimental and analytical investigation of axial field breakdown in non-slagging wall, combustion-driven MHD generators are presented. Some experiments and analysis were performed for a segmented Faraday generator, however more detailed studies were performed for a simplified configuration in which a voltage was applied to a pair of adjacent electrodes in the absence of a magnetic field. Cine-photographic records obtained for the simplified configuration demonstrated that breakdown could be initiated in the plasma or in the interelectrode insulator; however, for breakdown initiated in the plasma, the insulator became the dominant breakdown current carrier within a few seconds. Plasma initiated and insulator initiated breakdown resulted only when a threshold voltage was exceeded. Simple consideration indicated that an electro-thermal instability was responsible for the behavior observed in the experiments. A computer model was developed to predict the non-breakdown and incipient breakdown behavior for the inter-electrode insulator region for the simplified configuration. The two-dimensional model for the plasma included a solution of the unsteady turbulent boundary layer equations including the electron-continuity equation and a solution for the distribution of current. A separate analytical solution was obtained for the electrical behavior in the region near the cathode could be treated only in an empirical fashion. Detailed comparisons of theory and experiment indicate that even with the relatively sophisticated model utilized, only moderately good agreement is obtained.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 6440511
- Report Number(s):
- FE-2341-8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300104* -- MHD Generators-- Duct Engineering & Fluid Dynamics
BOUNDARY LAYERS
BREAKDOWN
COMBUSTION PRODUCTS
CURRENT DENSITY
CURRENTS
DATA
DATA FORMS
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
ELECTRICAL PROPERTIES
ELECTRODES
EQUIPMENT
EXPERIMENTAL DATA
GRAPHS
HALL EFFECT
HEATING
INFORMATION
INSTABILITY
JOULE HEATING
LAYERS
LIMITING VALUES
MATHEMATICAL MODELS
MHD CHANNELS
MHD GENERATORS
NUMERICAL DATA
PHYSICAL PROPERTIES
PLASMA
PLASMA DIAGNOSTICS
PLASMA HEATING
PLASMA INSTABILITY
TEMPERATURE DEPENDENCE
TEST FACILITIES
TESTING
VOLTAGE DROP