- 오목한 표면위에 분사되는 경사충돌제트에 대한 국소열전달계수의 측정
- ㆍ 저자명
- 임경빈,김학주
- ㆍ 간행물명
- 空氣 調和·冷凍 工學 論文集
- ㆍ 권/호정보
- 1998년|10권 3호|pp.324-333 (10 pages)
- ㆍ 발행정보
- 대한설비공학회
- ㆍ 파일정보
- 정기간행물| PDF텍스트
- ㆍ 주제분야
- 기타
Measurements of the local heat transfer coefficients on a hemispherically concave surface with a round oblique impinging jet were made. The liquid crystal transient method was used for these measurements. This method, which is a variation of the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystal for the surface temperature measurements. The Reynolds number used was 23,000 and the nozzle -to -jet distance was L/d=2, 4, 6, 8 and 10 and the jet angle was $alpha$=0$^{circ}$, 15$^{circ}$, 30$^{circ}$and 40$^{circ}$. In the experiment, the maximum Nusselt number at all region occurred at L/d(equation omitted)6 and Nusselt number decreases as the inclined jet angle increases. For the normal jet the contours of constant Nusselt number are circular and as the jet is inclined closer and closer to the surface the contours become elliptical shape. The decreasing rate of the Nusselt number at X/d> 0(upstream) on a surface curvature are higher than those on a flate plate and the decreasing rate of the Nusselt number at X/d <0(downstream) on a surface curvature are lower than those on a flate plate. And also, the decreasing rate of local Nusselt number distribution at X/d <0(upstream) exhibit lower than with X/d <0(downstream) as jet angle increases. The second maximum Nusselt number occurred at long distance from stagnation point as jet angle increases.