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%.
High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: II. Experiment
We describe experiments carried out to evaluate a newly developed high-performance nonequilibrium-plasma magnetohydrodynamic (MHD) electrical power generator equipped with a slightly divergent supersonic channel. The slightly divergent generator and a similar-scale highly divergent generator are evaluated in shock-tube experiments. The effects of electrical conductivity control and magnetic flux density control on the generator operation are investigated, and Hall voltage–Hall current characteristics, plasma-fluid behaviour and plasma structures are described. The slightly divergent channel configuration and the application of high- and uniform-density magnetic flux overcome the disadvantages of the generator due to its compactness, and markedly improves its performance. The ratio of isentropic efficiency to enthalpy extraction ratio and the power output density are outstanding compared with previous MHD power generators. The experimental results are supported by the numerically simulated results. This paper is the second part of a duology.
Fluid Dynamics of Hypersonic Forward-Facing Cavity Flow
Hypersonic  ow over the nose of a blunt body with a forward-facing cylindrical cavity is studied. Extensive numerical results involvinga wide range of cavity depths are veri ed by experimental runs including a new set of runs performed in a quiet  ow supersonic tunnel at Mach 4. It is shown that freestream noise is the mechanism that drives resonant pressure oscillations within relatively shallow cavities. Numerical results and conventional tunnel experiments show that deeper cavities oscillate strongly without freestream noise. For shallow cavities the sensitivity of cavity ampli cation, i.e., the relative strength of resonant pressure oscillations, to the characteristics of freestreamnoise (frequency, amplitude,perturbationvariable), cavitygeometry (depth, geometric scale, lip radius), Mach number, viscous effects, and thermal wall boundary condition is studied. There is a strong dependence of oscillation strength on freestream noise frequency. Oscillation strength increases nearly proportionally to input noise amplitude, increases rapidly with cavity depth, and increases with Mach number but levels off at highMach numbers. The pressure oscillations exhibit behavior analogous to that of a damped harmonic oscillator.