層流形プラズマジエット

概要

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It has been observed that a laminar jet has virtually no acoustic power output and has a sharp, long luminescent form. A laminar jet generator were designed, with which the measurement were performed to investigate laminar conditions as to arc mode, noise level, Reynolds number (Re) and a form of plasma jet. The concluding remarks of this experimental investigation are as follows. For laminar and transitional flow, arc mode was in the steady mode, while was in the restrike or takeover mode for turbulent flow. Sound pressure level for laminar jet was higher than noise level based on auditory sense, but for turbulent jet, the former was less than the latter. It was assumed that turbulent jet noise was caused by turbulent eddy in jet as well as the variation in pressure based on motion of anode spot on the nozzle. The acoustic power of a jet was dependent upon fourth power of jet velocity. The operating conditions under which the three regimes occurred were a follows : for Re>200,the flow was laminar ; for <200 Re<400,the flow was transitional and for Re>400,the flow was turbulent. A laminar jet has a long plum, whose length reached twice larger than the core section and for the same power input, a laminar jet length was four times longer than a turbulent of it. The thermal efficiency for a laminar jet in the optimum operating condition reached about 55%.
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