Polarity Effect and Flow Characteristics of Wire-Rod Type Electrohydrodynamic Gas Pump
The electrohydrodynamic (EHD) flow characteristics for a wire to rod type EHD gas pump have been experimentally investigated. Experiments were conducted for DC negative and positive applied high voltage to a corona wire of diameter 0.24 mm from 0-24 kV, grounding rod electrode diameter from 1.5 mm to 3.1 mm and wire/rod electrode distance to pipe diameter ratio from 0.63 to 1.16. It was observed that the polarity plays an important role, where a negative high voltage generates a higher gas flow than that of a positive polarity. The results show that a maximum of 40 L/min of gas flow rate is generated at 0.37 W energy input when the pipe diameter is 20 mm with the corona wire electrode and grounding rod electrode gap distant set to 12.6 mm under negative applied voltage compared to 25 L/min at 0.23 W energy input for the positive case at the same specific energy density.
Effects of orientation with respect to gravity for a wire-plate convergent angle electrohydrodynamic gas pump
Electrohydrodynamic (EHD) phenomena have been shown to enhance heat transfer in a variety of heat transport designs including capillary pumped loops for extraterrestrial nuclear applications. Previously, EHD enhancement has been shown to improve the heat transport of experimental CPLs. Further enhancement with the addition of EHD gas pumps to the vapour phase requires EHD gas pump phenomena and performance to be characterized with respect to gravity to determine the expected enhancement from this arrangement in zero and microgravity environments. In this paper an EHD gas pump is oriented with gravity (inverted), 90° to gravity (horizontal) and against gravity (vertical) to determine the effect gravitational and buoyancy forces have on the flow and heat transport of EHD gas pumps. The flow and temperature profiles of the pump at the outlet are presented to demonstrate the orientation effect gravity and buoyancy imposes on EHD gas pumps. The EHD number is calculated and presented. The paper determines that there is a noticeable orientation effect at lower applied voltages due to the heating effects causing recirculation in the flow being reduced with the aid of buoyancy forces. However, the effect is less noticeable at higher applied voltages due to the stronger EHD forces.
Energy skin effect of propellant particles in Electrothermal-Chemical Launcher
A numerical model of the radiation has been employed by a Monte Carlo method and statistical physics to simulate the process of a capillary plasma source for Electrothermal-Chemical (ETC) Launcher. The effect on propellants with different physical parameters is discussed. The plasma-propellant interaction is also discussed when combined with a thermal model. Results show that radiant energy only causes a small field around the plasma injector in the propellant bed. The responses of energy flux and propellant particles on radiation are both in the order of picosecond. The strong instantaneous radiation is responsible for the transmission of energy to the propellant particles leading to ignition. Compared with conventional ignition, the energy absorbed by propellant particles is used to increase quickly the temperature in the surface layer of propellant particles. This energy skin effect in the propellant particle surface appears to be the main cause of plasma ignition.