- 맥동충돌제트의 열전달 특성
- ㆍ 저자명
- 이은현,이대희,이준식,Lee. Eun-Hyun,Lee. Dae-Hee,Lee. Joon-Sik
- ㆍ 간행물명
- 大韓機械學會論文集. Transactions of the Korean society of mechanical engineers. B. B
- ㆍ 권/호정보
- 2002년|26권 7호|pp.903-910 (8 pages)
- ㆍ 발행정보
- 대한기계학회
- ㆍ 파일정보
- 정기간행물| PDF텍스트
- ㆍ 주제분야
- 기타
The present study aims to investigate the heat transfer characteristics of a pulsating axisymmetric air jet impinging on a heated wall. An axisymmetric contraction nozzle is used to obtain uniform profiles for the mean velocity and turbulence intensity at the nozzle exit. Measurements of the time averaged temperature on the impingement surface are conducted using a Thermochrornatic Liquid Crystal(TLC) technique for steady and pulsating jets at the jet Reynolds numbers of 20000, 30000 and 40000. Considered are pulsation frequencies of 10 and 20 Hz, corresponding to Strouhal numbers below 0.06 based on nozzle width and jet discharge velocity. In addition, the effect of nozzle-to-plate distances in the range of 2 to 10 on heat transfer characteristics is assessed. The pulsating impinging jet provides more uniform heat transfer coefficient near the impingement region, irrespective of H/D. Based on the measured data, a good correlation as a function of the jet Reynolds and Nusselt numbers is reported. It is also found that an exponent m in the relation of Nu ${propto};Re^m$ depends on both r/D and H/D, by which the impinging jet flows are highly affected.