This element represents a change in the prfile, such that $A_2\lt A_1$, where as $A_1$ is the inlet area and $A_2$ the one of the outlet area. Based on VDI the pressure loss coefficient is calculated as $$\zeta=0.77\cdot \text{Re}^{-0.037}-0.4\cdot\frac{A_2}{A_1}.$$ $A_1$ and $A_2$ are inlet and outlet area of the element. The inlet area is calculated based on the profile of the element, where as the outlet area is calculated using the provided diamter.
Parameter | Symbol | Unit | Description |
diameter | \(D_2\) | m | (New) diameter after the extension |