tapkoeffisienter

Tapkoeffisienter, often referred to as loss coefficients, are dimensionless numbers used in fluid dynamics to quantify energy losses in a piping system caused by components such as taps, valves, fittings, bends, tees, and sudden changes in geometry. They appear in the energy equation as Δp = K · ρ · v^2 / 2, where Δp is the pressure drop across the element, ρ is the fluid density, v is the reference velocity (usually the upstream velocity), and K is the loss coefficient. An alternative form uses head loss: Δh_L = K · v^2 / (2g).

Determination and variation: The value of K depends on the component’s geometry, surface roughness, Reynolds number, and flow regime (laminar versus turbulent). For a given part, K can change with the opening of a valve or throttle position and may differ for clockwise versus counterclockwise flow in certain fittings. Values are typically obtained from experimental measurements or published tables and standards, and sometimes computed with computational fluid dynamics for complex configurations.

Applications and use: Tapkoeffisienter are used in hydraulic network analysis, pump and pipe sizing, and energy efficiency calculations. They allow engineers to estimate total head losses by summing the coefficients of successive components along a flow path, often using a common reference velocity or corresponding local velocities.

Relation to other concepts: Local losses described by K coefficients are distinct from friction losses expressed by the Darcy–Weisbach friction factor f, which accounts for energy loss along the length of straight pipe. Tapkoeffisienter provide a practical framework for modeling energy losses associated with fittings and devices embedded in a flow system.