국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Development of a Temperature Measurement System With Application to a Jet in a Cross Flow Experiment
저자	Candace Wark and John F. Foss
Keyword	Dilution jet mixing; Temperature measurement
URL	http://gltrs.grc.nasa.gov/reports/1985/CR-174896.pdf
보고서번호	NASA CR-174896
발행년도	1985
출처	NASA Glenn Research Center
ABSTRACT	A temperature measurement system, which allows the simultaneous sampling (each 0.64 m/s) of up to 80 separatethermocouples, has been developed. The minimum resolution for the system corresponds to ?.16 좧 per least significant bit of the A/D converter. Electronic and thermal noise give an effective resolution of nominally ?.44 좧. The time constant values l, for each of the 64 thermocouples, were determined experimentally at 7 mps. A "universal" form of the velocity dependence: l = l(u) for 2 ?u ?12 mps, was analytically inferred and experimentally verified for four thermocouples. Software routines were used to correct the measured temperatures for the effect of l for each thermocouple. The temperature measurement system has been utilized to study the thermal field of a heated jet discharging perpendicularly into a low (/U?= 0.6 percent) and a high (/U?= 34 percent) disturbance level cross stream for a given momentum flux ratio (J = ) and for three overheated values (Tj - T? = 22.2, 41.7, 66.2 좧). The peak instantaneous temperatures (X/d = 3 - 4) reveal that strong molecular diffusion has been operative: (T - T?/(Tj - T? ?0.25. Various measures of the thermal field, for the disturbed case, suggest that the jet column remains relatively compact while being buffeted by the ambient turbulence field and that its penetration, into the cross wind, is inhibited by the presence of the strong disturbance field.