Research And Development Of Small Explosive Driven MHD Generator

The explosive driven magnetohydrodynamic generator (ED-MHDG) is a device in which the high temperature, high pressure and high speed explosion plasma is produced in a special plasma producer, and then rushes into the MHD channel with electrodes and magnetic field. According to the Faraday's Law, the motion of the conductive detonation products through the magnetic field generates electrical potential differences at electrodes. These electrodes conduct current to an external load which receives the electrical energy from the system. The ED-MHD generator has the advantages of high power density, fast start-up, repetitive operating, and easy maintenance etc;it is suitable to be high pulse power source.Research and development of small ED-MHD generator have been investigated systematically. Based on the analyses of the theory of ED-MHD generator, the reusable explosion plasma producer has been developed;the MHD channel built with stainless steel and glass fibre reinforced plastic has been studied in detail;pulsed magnet and its test and control system have been developed, the completed system is integrated and some MHD power generation experiments are conducted.The main results from the research and development of the small ED-MHD generator are :1. At present, experiment is most important method to study ED-MHD generator. To build a reusable test device is the foundation for research on ED-MHD generator. The first experimental system for investigating the ED-MHD generator has been developed in China. The system includes a measuring unit which can monitor and record the output voltage and current of ED-MHD generator, pulsed pressures in explosion plasma producer and MHD channel, current in magnet coils, velocity of plasma in MHD channel, and can also measure the magnetic field in channel, and some power generation experiments were conducted.2. The reusable explosion plasma producer is the main device of repetitive explosive driven MHD generator. The vessel can be used as plasma producer must bewith the ratio of inner diameter to shaped charges less than 1.5. Analyses and experimental results show that the shaped charge blasting in explosion plasma producer is near wall detonation, which is certain to give breakage to plasma producer wall. Methods which can make the plasma producer reusable consists of nesting structure filling with energy absorbing material and applying heat treatment to inner chamber to improve the rigidity.3. A strong pulsed magnet has been developed, which can endure repetitious operation of 24kV pulsed voltage, 74.3kA current and high field of to 8 Tesla. Experimental results show that the pulsed magnet has the enough mechanical and thermal stability, and the magnet is sufficient to be used in ED-MHD generator research.4. The MHD channels built with glass fibre reinforced plastic and stainless steel materials have been developed successfully. The pulsed magnetic field in MHD channel with different materials has been studied. Analyses and experimental results show that the phase of current in magnet coils is the same as the magnetic field in glass fibre reinforced plastic channel;but in stainless steel channel, the current in coil and magnetic field in channel are different phase, and the amplitude of magnetic field is less than that in glass fibre reinforced plastic channel. The higher the conductance and permeability are, the smaller the amplitude of magnetic field and the more different the phase between the current in magnet coil and magnetic field in channel. With reinforcement, the intensity of glass fibre reinforced plastic channel meets the needs of experimental researches on ED-MHD generator.5. A set of test system for the studies on ED-MHD generator has been developed, which consists of pulsed pressure of explosion products testing system, pulsed magnetic field measurement system, high voltage isolation system.6. The primary experimental research on the integrated ED-MHD generators has been carried out, and results show that all key parts of the experimental device are all in a good condition after several detonations. The basic rules of experimental procedures have been investigated, and it is helpful for further safe and successful studies on ED-MHD generator.