Characteristics of Combustion-Driven CO2 Gasdynamic Laser (II) Effect of Expansion Length of Supersonic Nozzle

The experimental and numerical studies for the effect of expansion length of supersonic nozzle for a combustion-driven CO2 gasdynamic laser facility on the small-signal gain characteristics are presented. Two types of nozzle of Circular-Circular (C-C) and Shock Free (SF) with area ratio of 20 which...

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Published inJOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES Vol. 48; no. 559; pp. 257 - 264
Main Authors WATANUKI, Tadaharu, OGURA, Eiji, MIZOBUCHI, Yasuhiro, MOMO, Satoru, KUBOT, Hirotoshi
Format Journal Article
LanguageJapanese
Published THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 05.08.2000
Subjects
Aerodynamics
CO2 Gasdynamic Laser
Expansion Length
Small-Signal Gain
Supersonic Nozzle
Vibrationally Nonequilibrium Flows
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Summary:The experimental and numerical studies for the effect of expansion length of supersonic nozzle for a combustion-driven CO2 gasdynamic laser facility on the small-signal gain characteristics are presented. Two types of nozzle of Circular-Circular (C-C) and Shock Free (SF) with area ratio of 20 which are able to realize Mach number of 4.7 with vibrationally nonequilibrium flow are used. For C-C nozzle at expansion length of 30mm, maximum value of the smallsignal gain coefficient is measured as 0.5m-1, and also for SF nozzle at expansion length of 45, 30 and 20mm they are 0.2 to 0.3m-1. It is shown that the higher small-signal gain coefficient is obtained at shorter nozzle expansion length, which suggests generation of a laser output extraction over the threshold value.
ISSN:1344-6460
2432-3691
DOI:10.2322/jjsass.48.257