Supersonic Magnetohydrodynamic (MHD) Power Generation System and Its Preliminary Experiment
Magneto hydrodynamic (MHD) power generation system has an important potential application in high-speed aero craft. According to the principles of MHD power generation, shock tunnel and ionization, a supersonic MHD power generation system is developed and introduced in this paper. Helium is used for driver gas and argon for driven gas. Equilibrium contact surface operating mode is selected to obtain high temperature, and the K2CO3 powder seed is added into the driven section so that the supersonic flow is electric. When M=2.0 and B=0.5 T, the power generation system is set up to know the experimental conditions. The nozzle entry total pressure is about 0.35 MPa while total temperature about 3965.1 K, and the nozzle exit velocity is calculated 1530.8 m/s. A preliminary experimental investigation is at length carried out by measuring the voltage and current of the segmented MHD power generation channel. Average electrical conductivity is estimated to be 15 S/m approximately. When load factor is 0.5, the maximum power density of this MHD power generation channel is about 2.195 MW/m3, while the maximum value of enthalpy extraction rate tends to be about 0.255%.
Magnetohydrodynamic Power Generation Using Externally Ionized, Cold, Supersonic Air as Working Fluid
Magnetohydrodynamic (MHD) power extraction from cold air has been demonstrated using short-duration, high-repetition rate, high-voltage pulses (2 ns, 100 kHz, 5 kV/cm) to ionize a Mach 3 (600 m/s), 0.04 kg/m 3 flow. Because the power used to ionize the flow using such a method was less than 1% of the total flow enthalpy, the flow was not heated significantly. A few tens of milliwatts were extracted from the 3-cm cube region of ionization, which scales to hundreds of kilowatts of power in higher velocity, larger-scale devices that would be appropriate for flight applications. Peak electron number densities between 5 × 10 11 and 10 12 cm -3 are reported from complementary measurements using microwave absorption in a variable magnetic field. The Hall parameter was estimated from the electrical properties of the MHD channel. Modeling predictions were found to be in agreement with experimentally extracted Faraday current measured between the high-voltage pulses. Modeling also confirmed that the electrons have low energy between the pulses and that the resultant cathode and anode voltage falls are quite low, on the order of 1 V.
Double-discharge arrangement for CW electrical excitation of supersonic flows. [for lasing action
A simple double−discharge electrode arrangement for the cw excitation of supersonic molecular gas flows is described. Stable discharges in N2 and N2/CO mixtures, with E/N of 2.0−2.5×10−16 V cm2 and a power loading of 2.6×10−2 eV/molecule, were achieved.