- 고분자용액에 의한 유체수송관벽의 저항감소 -III. 저항감소유체의 입구흐름 영역에 대한 고찰-
- ㆍ 저자명
- 김영보,유경옥
- ㆍ 간행물명
- 韓國火災學會誌
- ㆍ 권/호정보
- 1991년|5권 2호|pp.21-35 (15 pages)
- ㆍ 발행정보
- 한국화재소방학회
- ㆍ 파일정보
- 정기간행물| PDF텍스트
- ㆍ 주제분야
- 기타
As a part of studies of drag reduction phenomenon, at the entrance flow region of abrupt contraction tube flowing water, dilute and concentrated drag reducing polymer solutions contraction losses are estimated experimentally. Futher more, entrance lengths are considered theoretically and are measured experimentally. In the present experiment, fluid temperature is fixed l$0^{circ}C$ and flow rates are 3,000<Re<20,000. The data for concentrated drag reducing polymer solutions in turbulent flow show that drag reduction is increased as increasing flow rates at the fully developed flow region, but it is decreased as increasing flow rates at the entrance flow region, and that entrance lengths and contraction losses are significantly larger than those of Newtonian fluids. Dilute polymer solutions show that contraction losses and entry lengths for these materials are indistinguishable from the values for Newtonian Fluids. From the theoretical consideration the entrance lengths are somewhat insensitive to Deborah Number. Some experimental measurements on entrance lengths using drag reducing polymer solutions made in this work show a good agreement with the theoretical predictions.