A Study on Pressure Distribution, Wall Shear Stress and Friction Factor of Developing Turbulent Pulsating Flows in a Square Duct(Ⅰ), -Experimental Analysis-

정4각단면덕트의 입구영역에서 난류맥동유동의 압력분포, 전단응력분포와 관마찰계수에 관한 연구(Ⅰ), - 실험해석-

In the present study, the pressure distribution, wall shear stress distribution and friction factor of developing turbulent pulsating flows are investigated theoretically and experimentally in the entrance region of a square duct. The pressure distribution for turbulent pulsating flows are in good agreement with the theoretical values. The time-averaged pressure gradients of the turbulent pulsating flows show the same tendency as those of turbulent steady flows as the time-averged Reynolds number $(Re_{ta})$ increase. Mean shear stresses in the turbulent pulsating flow increase more in the inlet flow region than in the fully developed flow region and approach to almost constant value in the fully developed flow region. In the turbulent pulsating flow, the friction factor of the quasi-steady state flow $({\lambda}_{q, tu})$ follow friction factor's law in turbulent steady flow. The entrance length of the turbulent pulsating flow is not influenced by the time-averaged Reynolds number $(Re_{ta})$ and it is about 40 times as large as the hydraulic diameter.