Ehsan Motamedian - Chem.Eng.Dept., Iran university of sci.& Tech.Tehran
Norolah Kasiri - Chem.Eng.Dept., Iran university of sci.& Tech.Tehran
Ahad Hghaemi - Jaber ibn Laboratory , Atomic energy organization of Iran , Tehran

In this research the influences of horizontal 90◦ and 180◦ bends on the two phase pressure loss and flow pattern for air–water mixtures inside a 2.4 cm smooth pipe are investigated. Based on experimental pressure loss data in bends a prediction model is proposed. Comparison of new model with previous models in the literature shows that this model provides a better estimate of pressure loss in bends. Several experiments are also accomplished to observe flow pattern in presence of bends. In region of flow, the flow pattern in the recovery region is temporarily turned into annular flow. Based on the present visualization, two flow pattern maps are proposed to describe the effect of bends on transition of flow pattern.

Bend; Two phase flow; Pressure loss; Flow pattern; Model