F.C. Lai

Enhancement in Gas Pumping in a Square Channel With Two-Stage Corona Wind Generator

In this paper, the flow field inside a square channel with a two-stage electrohydrodynamic (EHD) gas pump has been critically examined by experimental measurement and numerical simulation. The EHD gas pump with 28 emitting electrodes in each stage is tested for a wide range of operating voltages starting from the corona onset voltage up to 28 kV for further improvement in its performance over a single-stage one. It has been shown that the two-stage EHD gas pump can produce and sustain gas flows with a maximum velocity of 1.8 m/s. Its maximum performance of 36 L/s/W is better than that of conventional cooling fans used in personal computers. The implication for its application in thermal management and heat transfer enhancement has also been discussed.

Flow characteristics of a two stage EHD gas pump in circular pipe

Flow characteristics of a two-stage electrohydro-dynamic (EHD) gas pump in a circular tube has been experimentally investigated for two different sizes (61.8 mm and 127.8 mm in diameter). Each stage uses eight emitting electrodes flush mounted on the tube wall. Two electrode configurations, aligned and offset, with fixed spacing between electrodes have been considered in this study. The main objective of the study is to verify if a two-stage EHD pump can sustain or even increase the volume flow rate produced by a single-stage pump over a greater tube length. To this end, electrodes at both stages are charged at the same voltages in positive polarity from 18 kV to 22 kV. Velocities are measured at three cross-sections along the tube length and then integrated to obtain the volume flow rate. The velocity profile and volume flow rate delivered by the single top stage of the pump are compared with those produced by the two stages combined to give additional insight to the problem. The results obtained have important implications for practical applications of EHD gas pump.

Effect of Electrode Length on the Performance of EHD Gas Pump

The effects of electrode length on the characteristics of flow induced by an electrohydrodynamic (EHD) gas pump in circular pipe have been experimentally examined in this study. The gas pump has a diameter of 61.8 mm and uses eight evenly spaced emitting electrodes which are flush mounted on the tube inner wall. The gap distance between emitting and ground electrodes is fixed at 25 mm and two emitting electrode lengths (15 mm and 40 mm) are considered. Experiments are conducted using positive corona discharge with voltage varying from 17.5 kV to 23 kV. Several important implications from the present results for practical engineering applications are presented.

Performance of a two-stage EHD gas pump in a circular pipe operating at uneven applied voltages

The performance of a two-stage electrohydro-dynamic (EHD) gas pump in a circular tube has been investigated for operating conditions in which each stage is charged at a different voltage. The main objective of the study is to examine the characteristics of resulting flow as well as the efficient use of energy in sustaining and improving the volume flow rate produced by a single-stage pump over a greater distance. To this end, two different sizes of tube are employed (61.8 mm and 127.8 mm in diameter). Each stage uses eight emitting electrodes flush mounted on the tube wall. In addition, two electrode configurations, aligned and offset, with fixed electrode spacing have been considered. The electrodes at both stages are charged at voltages in positive polarity from 18 kV to 22 kV. The velocity profile and volume flow rate delivered are compared with those produced by the same pump operating at even voltages to provide additional insight to the problem. The results thus obtained have important implications for practical use of EHD gas pump.

Enhanced Forced Convection in a Square Channel With Two-Stage Corona Wind Generator

In this study, enhancement in forced convection inside a square channel by a two-stage electrohydrodynamic (EHD) gas pump has been examined by numerical simulations. The EHD gas pump with 28 emitting electrodes in each stage has been evaluated for a wide range of operating voltages starting from the corona threshold voltage up to 28 kV for further improvement in its performance over that of a single-stage. To achieve the maximum enhancement in heat transfer, the emitting electrodes of the corona wind generator are flush mounted on the channel walls so that the corona wind produced directly perturbs the boundary layer. The results show that EHD technique has a great potential for applications in thermal management.© 2012 ASME

Performance of a Multiple Stage EHD Gas Pump in a Square Channel

Earlier studies have shown that an electric field in the form of corona discharge can effectively produce air flow. Using this technique, it has been demonstrated that an electrohydrodynamic (EHD) gas pump can produce gas flows with a maximum velocity of 5 m/s. Its maximum performance of 34 L/s/W is better than that of conventional cooling fans used in personal computers. In this study, an EHD pump with two stages, each stage with 28 emitting electrodes, is tested for a wide range of operating voltages starting from the corona threshold voltage up to 28 kV for further improvement in its performance. To seek the relation between the pump performance and number of stages, the EHD gas pump is critically evaluated by experimental measurements and numerical simulations. The maximum performance of 34 L/s/W is achieved by using a total of 56 electrodes with 0.5 inch wide grounded plate in each stage.Copyright