Transition of Turbulent Kinetic Energy Through a Serial Unit of Straight-Duct, Contraction and Free-Jet

상류유동전개부, 수축부 및 자유분사류로 이어지는 유동장에서의 난류에너지 천이에 대한 연구

The transition of turbulent kinetic energy(TKE) balance along the centerline of the flow unit, which is composed of straight-duct, contraction and free-jet, has been investigated by the hot-wire anemometry. It is found that the mean turbulent kinetic energy is balanced by the dissipation in the internal flow region ; by the production and the dissipation, through contraction ; and by the dissipation, in initial region(X〈8D) of free-jet. But in the developing region (8D〈X〈20D) it is balanced by all of the three(ie, diffusion, production and dissipation). Finally, in the downstream of free-jet, the mean TKE is balanced again by dissipation like as the beginning. The decay-laws along the centerline are checked in the region of free jet as well as in the straightduct. After the developing region of free-jet also exist the decay-laws, the exponent of the axial turbulence being bigger than of the radial.

본 연구에서는 축대칭 유동장치를 구성하여 열선 풍속계를 이용, 중심축에 따 른 난류쇠퇴양식을 살펴보고 동시에 난류에너지천이에 대한 세밀한 분석을 통하여 각 각 상류유동전개부, 수축부 및 자유분사류로 연속되는 3개의 유동 구조속에서 어떻게 천이해 갈 것인가를 측정하여 축대칭 유동의 난류구조 변천에 대한 기초 실험자료로 제시하고저 한다.