The Numerical Simulation for Continuous Plasma Arc Generator Nozzle
|School||Harbin Engineering University|
|Course||Power Machinery and Engineering|
|Keywords||gas turbine plasma constituent plasma arc magnetism induce arc numericalsimulation|
As a new ignition device for gas turbine, plasma ignition technology has many advantages such as high and intensive ignition energy, high speed of chemical reaction, etc. It can also greatly improve the ignition reliability and fule density limitation of gas turbine. This research provides certain theoretical basis for the design of the continuous-arc plasma ignition generator.Firstly, the nonlinear equations, which were used to obtain the plasma composition of different temperature, have been set up based on electron energy balance, chemical reaction balance, state equations, law of mass action, etc. Heat transfer and fluid flow process of plasma arc were simulated according to the mathematical model which was consisted of conservation equations for mass, momentum, energy and the Maxwell equations and discharge properties of the plasma arc.Secondly, in this research, the numerical simulation was achieved by using the finite element software ANSYS. Multi field coupling including electric field, magnetic field and flow field, was adopted and the analysis results will be called from one field to next one. The simulation process chose appropriate element type according to the physical property of arc, input each physical properties of plasma in different temperature, set up the simplified geometrical model, exerted the appropriate boundary condition and carried out calculation at last. After calculation, the distribution of the characteristic parameters, such as current density, voltage, magnetic force, magnetic flux density, temperature and velocity of plasma arc were analysed. To investigate the influence of magnetic force generated by inductance magnetic field on the plasma temperature and velocity, the results of flow field with and without magnetic force were comparatively analyzed. In order to design a plasma ignition generator with higher temperature, larger speed, longer plasma arc and maximize extend the life of the electrode, parameters of the plasma ignition generator, the different working currents, inlet air velocity, inward contractive size of cathode, diameter of outlet channel for arc and lengh of outlet channel for arc were simulated and comparatively analyzed respectively.Finally, the methods of magnetism-induced arc and magnetism-compressed arc were adopted to obtain a plasma arc with fine rigidity and high temperature. The implementation method applyed extra magnatic field to plasma arc,because the extra magnatic field would influence the moving direction and velocity of charged particles. In this research, different magnetic vector potential was applied in different positions, which were simulated and comparatively analyzed respectively.At last, an optimal position and vector value were obtained.