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 | Potential Variation of Discharge Pulses in Air at Low Pressures
Author : Pimpale, S.G.
Source : Defence Science Journal ; Vol:22(4) ; 1972 ; pp 213-214
Subject : 53 Applied Physics
Keywords : Boundary layer ;Electrode layer;Current ratio
Abstract : A decrease and/or increase of the discharge current ratio (5i/50i), the ratio of the discharge current for 5 volts discriminator bias to that for 50 volts discriminator bias, under irradiation is studied in air filled ozonizers excited by a.c. potentials kV of 50 cycles. sec./sup 1/ frequency. Results are in accord with Joshi's theory which consider that external light emits photo-electrons from an adsorption like electrode layer formed with ions and molecules of the gas on the glass wall of the discharge tube. These photo-electrons are captured by excited atoms to form also moving negative ions and bearing about the decrease in 5i/sub L/sup 50i/sup L/ as a space charge effect. The positive effect,+ delta (5i/50i), is also explained by the electronic work function at the boundary layer. |
| | Performance Comparison of Straight and Curved Diffusers
Author : Muralidhar, V. ;Chandra, Brajesh;Sullerey, R.K.
Source : Defence Science Journal ; Vol:33(2) ; 1983 ; pp 195-203
Subject : 532.542 Fluid Dynamics
Keywords : Boundary layer ;Dimensional straight;Experimental studies
Abstract : Experimental studies have been carried out to compare the performance of two dimensional straight and curved diffusers of some area ratio and effective divergence angle in the Reynolds number range of 7.8x10/sup 5/ to 1.29x10/sup 6/. Free stream turbulence effects have been studied at the increased turbulence level to 3.4per cent. The results indicate that straight diffuser pressure recovery is slightly higher as compared to the curved diffusers. However, stream turbulence, which improves the pressure recovery in both cases, has been observed to have greater effect in case of curved diffuser. Boundary layer velocity profiles on the diffuser surfaces have also been presented at various streamwise stations. It is observed that the growth of inner surface boundary layer has a major effects on losses in case of a curved diffuser. |
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