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Thermophysics and Aeromechanics

2011 year, number 1

Flow fluctuation measurement in the flow-through path of continuous electric-discharge СО2в€’laser contour

V.N. Zinoviev, V.A. Lebiga, A.YU. Pak, YU.V. Afonin, A.M. Orishich
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS
Keywords: gas laser, air gap, velocity fluctuations, hot-wire anemometer
Pages: 65-71


We have experimentally proved the applicability of hot-wire anemometer method to measure fluctuations at low pressures and gas flow rates when medium is no longer considered as continuous. Use of individual calibration at working conditions serves to apply standard technique for determination of sensitivity coefficients of hot-wire probes. Additional investigations are necessary to take into account influence of Knudsen number and, possibly, other parameters in heat transfer law presented as criterial dependence of Nusselt number on Reynolds number. Hot-wire measurement of mean velocity distribution and their fluctuations in the flow-through path of electric-discharge CO2 laser have been performed. The level of velocity fluctuations in the vicinity of anode is high that is caused by the zone of interacting flows from the ventilators rotating in opposite directions forming in the symmetry plane. Placing of the damping screen between the ventilator and air gap allows decreasing fluctuations intensity to the acceptable level. It has been ascertained that the vortex shedding with high intensity of fluctuations which influence is noticeable in significant part of air gap is formed in the wake behind the streamlined cathode. However, pulsation level in the proper gap does not exceed permissible values.