Fluctuations in combustion-driven MHD generators
Results of an experimental and theoretical investigation of inherent fluctuations that occur within combustion-driven MHD generators are presented. The primary concern was to determine the presence and effects of axially-propagating, linear hydrodynamic traveling-waves of the magnetoacoustic and magnetoentropic types. The possible development of large fluctuations in high magnetic interaction MHD generators caused by hydrodynamic traveling-waves propagating with increasing amplitude was considered. Experimentally, time-resolved measurements of pressures, electrode currents, and internal differential voltages within a laboratory-scale, combustion-driven MHD generator facility were analyzed. A special probe-tube microphone provided a sensitive measurement of the pressure fluctuations within a combustion-driven MHD generator duct. The time-resolved measurements were analyzed in terms of statistical properties such as relative fluctuation levels, spectraldensity functions, cross-correlation coefficients, and coherence and relative phase functions. The presence and subsequent electrical effects of axially-propagating acoustic and entropy waves were observed. At low mean fluid velocities during MHD generator operation with high current densities, 1.0 Amp/cm/sup 2/, and with applied magnetic field, 2.4 Tesla, fluctuations in the current-magnetic field interaction force caused by the electrical conductivity variations associated with the entropy waves resulted in a threefold increase in pressure fluctuation levels within the upstream part of the MHD duct. Hydrodynamic traveling-waves within an MHD duct were theoretically investigated by considering a first-order linearization analysis of the controlling, quasi-one dimensional fluid and electrical equations of an MHD generator. Comparisons between experimental results and a theoretical model were in qualitative agreement.
- Research Organization:
- Stanford Univ., CA (USA). High Temperature Gasdynamics Lab.
- DOE Contract Number:
- AC01-80ET15611
- OSTI ID:
- 6849304
- Report Number(s):
- DOE/ET/15611-1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HYDROMAGNETIC WAVES
MATHEMATICAL MODELS
MAGNETOHYDRODYNAMICS
MHD GENERATORS
FLUCTUATIONS
CORRELATIONS
EDDY CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTRODES
ENTROPY
EXPERIMENTAL DATA
FLOW RATE
GRAPHS
INSTABILITY
MAGNETOACOUSTIC WAVES
MEASURING INSTRUMENTS
MEASURING METHODS
PHASE STUDIES
PRESSURE MEASUREMENT
SPECTRAL DENSITY
TEST FACILITIES
THEORETICAL DATA
TIME DEPENDENCE
TRAVELLING WAVES
VOLTAGE DROP
WAVE PROPAGATION
CURRENTS
DATA
DIRECT ENERGY CONVERTERS
ELECTRICAL PROPERTIES
FLUID MECHANICS
FUNCTIONS
HYDRODYNAMICS
INFORMATION
MECHANICS
NUMERICAL DATA
PHYSICAL PROPERTIES
SPECTRAL FUNCTIONS
THERMODYNAMIC PROPERTIES
VARIATIONS
300104* - MHD Generators- Duct Engineering & Fluid Dynamics
640430 - Fluid Physics- Magnetohydrodynamics