An Experimental Investigation into the Pressure Drop for Turbulent Flow 90º Elbow Bends

The prediction of the pressure drop for turbulent single-phase fluid flow around sharp 90º bends is difficult owing to the complexity of the flow arising from frictional and separation effects. Several empirical equations exist, which accurately predict the pressure loss due to frictional effects. More recently, Crawford et al. [1] proposed an equation for the prediction of pressure loss due to separation of the flow. This work proposes a new composite equation for the prediction of pressure drop due to separation of the flow, which incorporates bends with ratio R/r <2. A new composite equation is proposed to predict pressure losses over the Reynolds number range 4 x 10³ - 3 x 10⁵. The predictions from the new equation are within a range of -4 to +6 per cent of existing experimental data.